i8042 lockdep false positive.

From: Dave Jones
Date: Fri Apr 13 2007 - 15:14:39 EST


I just had a user file the report below, which iirc, was deemed a false
positive. Didn't we add something to the code so that lockdep would
ignore what this was doing ? Did we regress?

(This was .21-rc5, during resume)

Dave

> =============================================
> [ INFO: possible recursive locking detected ]
> 2.6.20-1.3062.fc7 #1
> ---------------------------------------------
> kseriod/216 is trying to acquire lock:
> (&ps2dev->cmd_mutex){--..}, at: [<c0614fa2>] mutex_lock+0x21/0x24
>
> but task is already holding lock:
> (&ps2dev->cmd_mutex){--..}, at: [<c0614fa2>] mutex_lock+0x21/0x24
>
> other info that might help us debug this:
> 5 locks held by kseriod/216:
> #0: (serio_mutex){--..}, at: [<c0614fa2>] mutex_lock+0x21/0x24
> #1: (&s->rwsem){----}, at: [<c05882de>] serio_find_driver+0x13/0x50
> #2: (&serio->drv_mutex){--..}, at: [<c0614fa2>] mutex_lock+0x21/0x24
> #3: (psmouse_mutex){--..}, at: [<c0614fa2>] mutex_lock+0x21/0x24
> #4: (&ps2dev->cmd_mutex){--..}, at: [<c0614fa2>] mutex_lock+0x21/0x24
>
> stack backtrace:
> [<c04061e9>] show_trace_log_lvl+0x1a/0x2f
> [<c04067ad>] show_trace+0x12/0x14
> [<c0406831>] dump_stack+0x16/0x18
> [<c0442089>] __lock_acquire+0x11f/0xba4
> [<c0442f00>] lock_acquire+0x56/0x6f
> [<c0614e0a>] __mutex_lock_slowpath+0xf7/0x26e
> [<c0614fa2>] mutex_lock+0x21/0x24
> [<c058ad30>] ps2_command+0x92/0x319
> [<c05912d8>] psmouse_sliced_command+0x1c/0x5a
> [<c0594861>] synaptics_pt_write+0x1e/0x41
> [<c058ac0c>] ps2_sendbyte+0x39/0xcb
> [<c058adaa>] ps2_command+0x10c/0x319
> [<c0590f13>] psmouse_probe+0x1d/0x6c
> [<c0591f90>] psmouse_connect+0xed/0x205
> [<c05882a3>] serio_connect_driver+0x1e/0x2e
> [<c05882c9>] serio_driver_probe+0x16/0x18
> [<c0562b45>] really_probe+0xc7/0x150
> [<c0562c63>] driver_probe_device+0x95/0xa1
> [<c0562c77>] __device_attach+0x8/0xa
> [<c0562035>] bus_for_each_drv+0x3a/0x65
> [<c0562d00>] device_attach+0x68/0x7d
> [<c05882e9>] serio_find_driver+0x1e/0x50
> [<c0588f39>] serio_thread+0x153/0x2a6
> [<c043830f>] kthread+0xb3/0xdc
> [<c0405cd3>] kernel_thread_helper+0x7/0x10
> =======================


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