serio_serdev: possible locking bug

[asheplyakov]

[    3.421187] =============================
[    3.423482] [ BUG: Invalid wait context ]
[    3.425797] 5.15.60-00033-g26215205c6c7 #1 Not tainted
[    3.428140] -----------------------------
[    3.430481] kworker/5:1/58 is trying to lock:
[    3.432793] ffff0008027f5e10 (&serdev->write_lock){....}-{3:3}, at: serdev_device_write+0x74/0x140
[    3.435177] other info that might help us debug this:
[    3.437521] context-{4:4}
[    3.439818] 6 locks held by kworker/5:1/58:
[    3.442106]  #0: ffff00080000dd38 ((wq_completion)events_long){+.+.}-{0:0}, at: process_one_work+0x1cc/0x6c0
[    3.444489]  #1: ffff80000a2bbdc0 (serio_event_work){+.+.}-{0:0}, at: process_one_work+0x1cc/0x6c0
[    3.446883]  #2: ffff8000092d4f78 (serio_mutex){+.+.}-{3:3}, at: serio_handle_event+0x4c/0x310
[    3.449272]  #3: ffff000800b49378 (&dev->mutex){....}-{3:3}, at: __device_attach+0x40/0x1f0
[    3.451639]  #4: ffff000800b491d8 (&serio->drv_mutex){+.+.}-{3:3}, at: serio_driver_probe+0x3c/0x70
[    3.454008]  #5: ffff00080104d640 (&psm->lock){....}-{2:2}, at: ps2mult_reset+0x2c/0x84
[    3.456371] stack backtrace:
[    3.458691] CPU: 5 PID: 58 Comm: kworker/5:1 Not tainted 5.15.60-00033-g26215205c6c7 #1
[    3.461059] Hardware name: Elpitech ET101-A/ET111-MB, BIOS 5.5 07/14/2022
[    3.463414] Workqueue: events_long serio_handle_event
[    3.465789] Call trace:
[    3.468139]  dump_backtrace+0x0/0x1e0
[    3.470501]  show_stack+0x24/0x30
[    3.472849]  dump_stack_lvl+0x8c/0xb8
[    3.475199]  dump_stack+0x1c/0x38
[    3.477528]  __lock_acquire+0x96c/0x20d0
[    3.479865]  lock_acquire.part.0+0xf0/0x250
[    3.482203]  lock_acquire+0x6c/0x8c
[    3.484526]  __mutex_lock+0x8c/0x460
[    3.486844]  mutex_lock_nested+0x4c/0x60
[    3.489162]  serdev_device_write+0x74/0x140
[    3.491476]  ss_serio_write+0x40/0x74
[    3.493753]  ps2mult_reset+0x44/0x84
[    3.496043]  ps2mult_connect+0x1f8/0x260
[    3.498306]  serio_driver_probe+0x4c/0x70
[    3.500560]  really_probe+0xc4/0x470
[    3.502787]  __driver_probe_device+0x11c/0x190
[    3.505002]  driver_probe_device+0x48/0x110
[    3.507219]  __device_attach_driver+0xa4/0x140
[    3.508184] ata1: SATA link down (SStatus 0 SControl 300)
[    3.509436]  bus_for_each_drv+0x84/0xe0
[    3.509444]  __device_attach+0xb0/0x1f0
[    3.509450]  device_initial_probe+0x20/0x30
[    3.509457]  bus_probe_device+0xac/0xb4
[    3.509463]  device_add+0x39c/0x8b0
[    3.522521]  serio_handle_event+0x298/0x310
[    3.524632]  process_one_work+0x264/0x6c0
[    3.526736]  worker_thread+0x80/0x444
[    3.528459] rtc-pcf2127-i2c 0-0051: registered as rtc0
[    3.528809]  kthread+0x148/0x160
[    3.528819]  ret_from_fork+0x10/0x20
[    3.528856] ps2mult serio0: TQC PS/2 Multiplexer port at serio
[    3.531426] rtc-pcf2127-i2c 0-0051: setting system clock to 2022-08-18T08:59:23 UTC (1660813163)
[    3.533025] ps2mult serio0: TQC PS/2 Multiplexer port at serio