syzbot

Bluetooth: hci1: command 0x0406 tx timeout
Bluetooth: hci1: hardware error 0x00
============================================
WARNING: possible recursive locking detected
syzkaller #0 Not tainted
--------------------------------------------
kworker/u5:3/5796 is trying to acquire lock:
ffff88802f35fd38 ((wq_completion)hci1){+.+.}-{0:0}, at: touch_wq_lockdep_map kernel/workqueue.c:3138 [inline]
ffff88802f35fd38 ((wq_completion)hci1){+.+.}-{0:0}, at: __flush_workqueue+0x128/0x1380 kernel/workqueue.c:3168

but task is already holding lock:
ffff88802f35fd38 ((wq_completion)hci1){+.+.}-{0:0}, at: process_one_work kernel/workqueue.c:2609 [inline]
ffff88802f35fd38 ((wq_completion)hci1){+.+.}-{0:0}, at: process_scheduled_works+0x957/0x15b0 kernel/workqueue.c:2711

other info that might help us debug this:
 Possible unsafe locking scenario:

       CPU0
       ----
  lock((wq_completion)hci1);
  lock((wq_completion)hci1);

 *** DEADLOCK ***

 May be due to missing lock nesting notation

2 locks held by kworker/u5:3/5796:
 #0: ffff88802f35fd38 ((wq_completion)hci1){+.+.}-{0:0}, at: process_one_work kernel/workqueue.c:2609 [inline]
 #0: ffff88802f35fd38 ((wq_completion)hci1){+.+.}-{0:0}, at: process_scheduled_works+0x957/0x15b0 kernel/workqueue.c:2711
 #1: ffffc9000469fd00 ((work_completion)(&hdev->error_reset)){+.+.}-{0:0}, at: process_one_work kernel/workqueue.c:2609 [inline]
 #1: ffffc9000469fd00 ((work_completion)(&hdev->error_reset)){+.+.}-{0:0}, at: process_scheduled_works+0x957/0x15b0 kernel/workqueue.c:2711

stack backtrace:
CPU: 0 PID: 5796 Comm: kworker/u5:3 Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/02/2025
Workqueue: hci1 hci_error_reset
Call Trace:
 <TASK>
 dump_stack_lvl+0x16c/0x230 lib/dump_stack.c:106
 check_deadlock kernel/locking/lockdep.c:3062 [inline]
 validate_chain kernel/locking/lockdep.c:3856 [inline]
 __lock_acquire+0x5d40/0x7c80 kernel/locking/lockdep.c:5137
 lock_acquire+0x197/0x410 kernel/locking/lockdep.c:5754
 touch_wq_lockdep_map kernel/workqueue.c:3138 [inline]
 __flush_workqueue+0x141/0x1380 kernel/workqueue.c:3168
 drain_workqueue+0xd3/0x380 kernel/workqueue.c:3332
 destroy_workqueue+0xc4/0xf20 kernel/workqueue.c:4826
 hci_release_dev+0xe2/0x1400 net/bluetooth/hci_core.c:2744
 bt_host_release+0x82/0x90 net/bluetooth/hci_sysfs.c:87
 device_release+0x96/0x1c0 drivers/base/core.c:-1
 kobject_cleanup lib/kobject.c:689 [inline]
 kobject_release lib/kobject.c:720 [inline]
 kref_put include/linux/kref.h:65 [inline]
 kobject_put+0x221/0x470 lib/kobject.c:737
 process_one_work kernel/workqueue.c:2634 [inline]
 process_scheduled_works+0xa45/0x15b0 kernel/workqueue.c:2711
 worker_thread+0xa55/0xfc0 kernel/workqueue.c:2792
 kthread+0x2fa/0x390 kernel/kthread.c:388
 ret_from_fork+0x48/0x80 arch/x86/kernel/process.c:152
 ret_from_fork_asm+0x11/0x20 arch/x86/entry/entry_64.S:293
 </TASK>