usb 6-1: USB disconnect, device number 71
======================================================
WARNING: possible circular locking dependency detected
5.4.0-rc1+ #0 Not tainted
------------------------------------------------------
kworker/1:7/6014 is trying to acquire lock:
ffffffff8721edc8 (minor_rwsem#2){++++}, at: usb_deregister_dev+0x95/0x230 drivers/usb/core/file.c:239
but task is already holding lock:
ffffffff872bd4e0 (open_disc_mutex){+.+.}, at: tower_disconnect+0x45/0x300 drivers/usb/misc/legousbtower.c:945
which lock already depends on the new lock.
the existing dependency chain (in reverse order) is:
-> #1 (open_disc_mutex){+.+.}:
__mutex_lock_common kernel/locking/mutex.c:956 [inline]
__mutex_lock+0x158/0x1360 kernel/locking/mutex.c:1103
tower_open+0xce/0x9b0 drivers/usb/misc/legousbtower.c:335
usb_open+0x1df/0x270 drivers/usb/core/file.c:48
chrdev_open+0x219/0x5c0 fs/char_dev.c:414
do_dentry_open+0x494/0x1120 fs/open.c:797
do_last fs/namei.c:3408 [inline]
path_openat+0x1430/0x3ff0 fs/namei.c:3525
do_filp_open+0x1a1/0x280 fs/namei.c:3555
do_sys_open+0x3c0/0x580 fs/open.c:1097
do_syscall_64+0xb7/0x580 arch/x86/entry/common.c:290
entry_SYSCALL_64_after_hwframe+0x49/0xbe
-> #0 (minor_rwsem#2){++++}:
check_prev_add kernel/locking/lockdep.c:2476 [inline]
check_prevs_add kernel/locking/lockdep.c:2581 [inline]
validate_chain kernel/locking/lockdep.c:2971 [inline]
__lock_acquire+0x1f74/0x3b60 kernel/locking/lockdep.c:3955
lock_acquire+0x127/0x320 kernel/locking/lockdep.c:4487
down_write+0x92/0x150 kernel/locking/rwsem.c:1534
usb_deregister_dev+0x95/0x230 drivers/usb/core/file.c:239
tower_disconnect+0xa8/0x300 drivers/usb/misc/legousbtower.c:951
usb_unbind_interface+0x1bd/0x8a0 drivers/usb/core/driver.c:423
__device_release_driver drivers/base/dd.c:1134 [inline]
device_release_driver_internal+0x42f/0x500 drivers/base/dd.c:1165
bus_remove_device+0x2dc/0x4a0 drivers/base/bus.c:532
device_del+0x420/0xb20 drivers/base/core.c:2375
usb_disable_device+0x211/0x690 drivers/usb/core/message.c:1237
usb_disconnect+0x284/0x8d0 drivers/usb/core/hub.c:2199
hub_port_connect drivers/usb/core/hub.c:4949 [inline]
hub_port_connect_change drivers/usb/core/hub.c:5213 [inline]
port_event drivers/usb/core/hub.c:5359 [inline]
hub_event+0x1454/0x3640 drivers/usb/core/hub.c:5441
process_one_work+0x92b/0x1530 kernel/workqueue.c:2269
worker_thread+0x96/0xe20 kernel/workqueue.c:2415
kthread+0x318/0x420 kernel/kthread.c:255
ret_from_fork+0x24/0x30 arch/x86/entry/entry_64.S:352
other info that might help us debug this:
Possible unsafe locking scenario:
CPU0 CPU1
---- ----
lock(open_disc_mutex);
lock(minor_rwsem#2);
lock(open_disc_mutex);
lock(minor_rwsem#2);
*** DEADLOCK ***
6 locks held by kworker/1:7/6014:
#0: ffff8881d9165528 ((wq_completion)usb_hub_wq){+.+.}, at: __write_once_size include/linux/compiler.h:226 [inline]
#0: ffff8881d9165528 ((wq_completion)usb_hub_wq){+.+.}, at: arch_atomic64_set arch/x86/include/asm/atomic64_64.h:34 [inline]
#0: ffff8881d9165528 ((wq_completion)usb_hub_wq){+.+.}, at: atomic64_set include/asm-generic/atomic-instrumented.h:855 [inline]
#0: ffff8881d9165528 ((wq_completion)usb_hub_wq){+.+.}, at: atomic_long_set include/asm-generic/atomic-long.h:40 [inline]
#0: ffff8881d9165528 ((wq_completion)usb_hub_wq){+.+.}, at: set_work_data kernel/workqueue.c:620 [inline]
#0: ffff8881d9165528 ((wq_completion)usb_hub_wq){+.+.}, at: set_work_pool_and_clear_pending kernel/workqueue.c:647 [inline]
#0: ffff8881d9165528 ((wq_completion)usb_hub_wq){+.+.}, at: process_one_work+0x827/0x1530 kernel/workqueue.c:2240
#1: ffff8881b7c67dd0 ((work_completion)(&hub->events)){+.+.}, at: process_one_work+0x85b/0x1530 kernel/workqueue.c:2244
#2: ffff8881d5fa8a80 (&dev->mutex){....}, at: device_lock include/linux/device.h:1462 [inline]
#2: ffff8881d5fa8a80 (&dev->mutex){....}, at: hub_event+0x17c/0x3640 drivers/usb/core/hub.c:5387
#3: ffff8881cbf17900 (&dev->mutex){....}, at: device_lock include/linux/device.h:1462 [inline]
#3: ffff8881cbf17900 (&dev->mutex){....}, at: usb_disconnect+0x91/0x8d0 drivers/usb/core/hub.c:2190
#4: ffff8881af18f890 (&dev->mutex){....}, at: device_release_driver_internal+0x23/0x500 drivers/base/dd.c:1162
#5: ffffffff872bd4e0 (open_disc_mutex){+.+.}, at: tower_disconnect+0x45/0x300 drivers/usb/misc/legousbtower.c:945
stack backtrace:
CPU: 1 PID: 6014 Comm: kworker/1:7 Not tainted 5.4.0-rc1+ #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
Workqueue: usb_hub_wq hub_event
Call Trace:
__dump_stack lib/dump_stack.c:77 [inline]
dump_stack+0xca/0x13e lib/dump_stack.c:113
check_noncircular+0x32e/0x3e0 kernel/locking/lockdep.c:1809
check_prev_add kernel/locking/lockdep.c:2476 [inline]
check_prevs_add kernel/locking/lockdep.c:2581 [inline]
validate_chain kernel/locking/lockdep.c:2971 [inline]
__lock_acquire+0x1f74/0x3b60 kernel/locking/lockdep.c:3955
lock_acquire+0x127/0x320 kernel/locking/lockdep.c:4487
down_write+0x92/0x150 kernel/locking/rwsem.c:1534
usb_deregister_dev+0x95/0x230 drivers/usb/core/file.c:239
tower_disconnect+0xa8/0x300 drivers/usb/misc/legousbtower.c:951
usb_unbind_interface+0x1bd/0x8a0 drivers/usb/core/driver.c:423
__device_release_driver drivers/base/dd.c:1134 [inline]
device_release_driver_internal+0x42f/0x500 drivers/base/dd.c:1165
bus_remove_device+0x2dc/0x4a0 drivers/base/bus.c:532
device_del+0x420/0xb20 drivers/base/core.c:2375
usb_disable_device+0x211/0x690 drivers/usb/core/message.c:1237
usb_disconnect+0x284/0x8d0 drivers/usb/core/hub.c:2199
hub_port_connect drivers/usb/core/hub.c:4949 [inline]
hub_port_connect_change drivers/usb/core/hub.c:5213 [inline]
port_event drivers/usb/core/hub.c:5359 [inline]
hub_event+0x1454/0x3640 drivers/usb/core/hub.c:5441
process_one_work+0x92b/0x1530 kernel/workqueue.c:2269
worker_thread+0x96/0xe20 kernel/workqueue.c:2415
kthread+0x318/0x420 kernel/kthread.c:255
ret_from_fork+0x24/0x30 arch/x86/entry/entry_64.S:352
legousbtower 6-1:0.219: LEGO USB Tower #-160 now disconnected
usb 6-1: new high-speed USB device number 72 using dummy_hcd
usb 6-1: Using ep0 maxpacket: 8
usb 6-1: config 0 has an invalid interface number: 219 but max is 0
usb 6-1: config 0 has no interface number 0
usb 6-1: config 0 interface 219 altsetting 0 endpoint 0xF has an invalid bInterval 0, changing to 7
usb 6-1: config 0 interface 219 altsetting 0 endpoint 0x83 has an invalid bInterval 0, changing to 7
usb 6-1: New USB device found, idVendor=0694, idProduct=0001, bcdDevice=fb.88
usb 6-1: New USB device strings: Mfr=0, Product=0, SerialNumber=0
usb 6-1: config 0 descriptor??
legousbtower 6-1:0.219: LEGO USB Tower firmware version is 129.136 build 65535
legousbtower 6-1:0.219: LEGO USB Tower #-160 now attached to major 180 minor 0
usb 6-1: USB disconnect, device number 72
legousbtower 6-1:0.219: LEGO USB Tower #-160 now disconnected
usb 6-1: new high-speed USB device number 73 using dummy_hcd
usb 6-1: Using ep0 maxpacket: 8
usb 6-1: config 0 has an invalid interface number: 219 but max is 0
usb 6-1: config 0 has no interface number 0
usb 6-1: config 0 interface 219 altsetting 0 endpoint 0xF has an invalid bInterval 0, changing to 7
usb 6-1: config 0 interface 219 altsetting 0 endpoint 0x83 has an invalid bInterval 0, changing to 7
usb 6-1: New USB device found, idVendor=0694, idProduct=0001, bcdDevice=fb.88
usb 6-1: New USB device strings: Mfr=0, Product=0, SerialNumber=0
usb 6-1: config 0 descriptor??
legousbtower 6-1:0.219: LEGO USB Tower firmware version is 129.136 build 65535
legousbtower 6-1:0.219: LEGO USB Tower #-160 now attached to major 180 minor 0