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Date: Tue, 13 Nov 2012 10:39:14 +0100
From: Jiri Slaby <jslaby@...e.cz>
To: Takashi Iwai <tiwai@...e.de>
CC: Jaroslav Kysela <perex@...ex.cz>, alsa-devel@...a-project.org,
LKML <linux-kernel@...r.kernel.org>,
USB list <linux-usb@...r.kernel.org>,
Jiri Slaby <jirislaby@...il.com>
Subject: Re: Sound+USB: deadlock problem
On 11/13/2012 09:45 AM, Takashi Iwai wrote:
> At Tue, 13 Nov 2012 09:30:10 +0100,
> Jiri Slaby wrote:
>>
>> On 11/13/2012 09:28 AM, Takashi Iwai wrote:
>>> At Tue, 13 Nov 2012 09:26:17 +0100,
>>> Jiri Slaby wrote:
>>>>
>>>> Hello,
>>>>
>>>> I've just plugged+unplugged+plugged my USB audio card and the audio
>>>> subsystem got stuck:
>>>
>>> Which kernel? If it's older than 3.7-rc5, could you try 3.7-rc5?
>>
>> Oh, forgot to mention:
>> 3.7.0-rc5-next-20121112_64+
>
> Through a quick glance, one of mutex locks seems stuck.
> Just a blind short -- does the patch below cure the problem?
Yes, this helps.
Adding a LOCKDEP splash _before_ applying the patch:
======================================================
[ INFO: possible circular locking dependency detected ]
3.7.0-rc5-next-20121112_64-ldep+ #15 Not tainted
-------------------------------------------------------
khubd/446 is trying to acquire lock:
(&pcm->open_mutex){+.+.+.}, at: [<ffffffff8154c555>]
snd_pcm_dev_disconnect+0x45/0x1f0
but task is already holding lock:
(register_mutex#2){+.+.+.}, at: [<ffffffff8154c533>]
snd_pcm_dev_disconnect+0x23/0x1f0
which lock already depends on the new lock.
the existing dependency chain (in reverse order) is:
-> #2 (register_mutex#2){+.+.+.}:
[<ffffffff810c5e8a>] lock_acquire+0x5a/0x70
[<ffffffff81697fa9>] mutex_lock_nested+0x69/0x3a0
[<ffffffff8154c533>] snd_pcm_dev_disconnect+0x23/0x1f0
[<ffffffff815462e2>] snd_device_disconnect+0x62/0xa0
[<ffffffff815463bc>] snd_device_disconnect_all+0x3c/0x60
[<ffffffff81540ec7>] snd_card_disconnect+0x147/0x1d0
[<ffffffff8158c328>] usb_audio_disconnect+0x98/0x1d0
[<ffffffff814aa4fe>] usb_unbind_interface+0x5e/0x1a0
[<ffffffff81404ad7>] __device_release_driver+0x77/0xe0
[<ffffffff81404d49>] device_release_driver+0x29/0x40
[<ffffffff814044aa>] bus_remove_device+0xfa/0x170
[<ffffffff81401917>] device_del+0x127/0x1c0
[<ffffffff814a7f20>] usb_disable_device+0xb0/0x270
[<ffffffff8149ea0d>] usb_disconnect+0xad/0x160
[<ffffffff814a12bc>] hub_thread+0x71c/0x1730
[<ffffffff810967e6>] kthread+0xd6/0xe0
[<ffffffff8169c2ec>] ret_from_fork+0x7c/0xb0
-> #1 (&chip->shutdown_rwsem){++++++}:
[<ffffffff810c5e8a>] lock_acquire+0x5a/0x70
[<ffffffff816993b7>] down_read+0x47/0x5c
[<ffffffff8158cf9c>] snd_usb_autoresume+0x2c/0x60
[<ffffffff81594e2f>] snd_usb_pcm_open+0x20f/0x4a0
[<ffffffff815950db>] snd_usb_playback_open+0xb/0x10
[<ffffffff81553c0e>] snd_pcm_open_substream+0x4e/0x90
[<ffffffff81553d02>] snd_pcm_open+0xb2/0x250
[<ffffffff81553f53>] snd_pcm_playback_open+0x43/0x70
[<ffffffff8153fb9a>] snd_open+0xba/0x200
[<ffffffff81152766>] chrdev_open+0x96/0x1c0
[<ffffffff8114c766>] do_dentry_open.isra.16+0x1e6/0x280
[<ffffffff8114c836>] finish_open+0x36/0x70
[<ffffffff8115c53e>] do_last.isra.64+0x2ce/0xcc0
[<ffffffff8115cfe3>] path_openat.isra.65+0xb3/0x4d0
[<ffffffff8115d66c>] do_filp_open+0x3c/0x90
[<ffffffff8114d8af>] do_sys_open+0xef/0x1d0
[<ffffffff8114d9ac>] sys_open+0x1c/0x20
[<ffffffff8169c392>] system_call_fastpath+0x16/0x1b
-> #0 (&pcm->open_mutex){+.+.+.}:
[<ffffffff810c5968>] __lock_acquire+0x1c38/0x1c40
[<ffffffff810c5e8a>] lock_acquire+0x5a/0x70
[<ffffffff81697fa9>] mutex_lock_nested+0x69/0x3a0
[<ffffffff8154c555>] snd_pcm_dev_disconnect+0x45/0x1f0
[<ffffffff815462e2>] snd_device_disconnect+0x62/0xa0
[<ffffffff815463bc>] snd_device_disconnect_all+0x3c/0x60
[<ffffffff81540ec7>] snd_card_disconnect+0x147/0x1d0
[<ffffffff8158c328>] usb_audio_disconnect+0x98/0x1d0
[<ffffffff814aa4fe>] usb_unbind_interface+0x5e/0x1a0
[<ffffffff81404ad7>] __device_release_driver+0x77/0xe0
[<ffffffff81404d49>] device_release_driver+0x29/0x40
[<ffffffff814044aa>] bus_remove_device+0xfa/0x170
[<ffffffff81401917>] device_del+0x127/0x1c0
[<ffffffff814a7f20>] usb_disable_device+0xb0/0x270
[<ffffffff8149ea0d>] usb_disconnect+0xad/0x160
[<ffffffff814a12bc>] hub_thread+0x71c/0x1730
[<ffffffff810967e6>] kthread+0xd6/0xe0
[<ffffffff8169c2ec>] ret_from_fork+0x7c/0xb0
other info that might help us debug this:
Chain exists of:
&pcm->open_mutex --> &chip->shutdown_rwsem --> register_mutex#2
Possible unsafe locking scenario:
CPU0 CPU1
---- ----
lock(register_mutex#2);
lock(&chip->shutdown_rwsem);
lock(register_mutex#2);
lock(&pcm->open_mutex);
*** DEADLOCK ***
6 locks held by khubd/446:
#0: (&__lockdep_no_validate__){......}, at: [<ffffffff814a0c7e>]
hub_thread+0xde/0x1730
#1: (&__lockdep_no_validate__){......}, at: [<ffffffff8149e9c1>]
usb_disconnect+0x61/0x160
#2: (&__lockdep_no_validate__){......}, at: [<ffffffff81404d41>]
device_release_driver+0x21/0x40
#3: (register_mutex#5){+.+.+.}, at: [<ffffffff8158c2c5>]
usb_audio_disconnect+0x35/0x1d0
#4: (&chip->shutdown_rwsem){++++++}, at: [<ffffffff8158c2d5>]
usb_audio_disconnect+0x45/0x1d0
#5: (register_mutex#2){+.+.+.}, at: [<ffffffff8154c533>]
snd_pcm_dev_disconnect+0x23/0x1f0
stack backtrace:
Pid: 446, comm: khubd Not tainted 3.7.0-rc5-next-20121112_64-ldep+ #15
Call Trace:
[<ffffffff81691220>] print_circular_bug+0x1fb/0x20c
[<ffffffff810c5968>] __lock_acquire+0x1c38/0x1c40
[<ffffffff81546a6e>] ? snd_unregister_oss_device+0x9e/0x120
[<ffffffff810c5e8a>] lock_acquire+0x5a/0x70
[<ffffffff8154c555>] ? snd_pcm_dev_disconnect+0x45/0x1f0
[<ffffffff81697fa9>] mutex_lock_nested+0x69/0x3a0
[<ffffffff8154c555>] ? snd_pcm_dev_disconnect+0x45/0x1f0
[<ffffffff8154c555>] snd_pcm_dev_disconnect+0x45/0x1f0
[<ffffffff815462e2>] snd_device_disconnect+0x62/0xa0
[<ffffffff815463bc>] snd_device_disconnect_all+0x3c/0x60
[<ffffffff81540ec7>] snd_card_disconnect+0x147/0x1d0
[<ffffffff8158c328>] usb_audio_disconnect+0x98/0x1d0
[<ffffffff814aa4fe>] usb_unbind_interface+0x5e/0x1a0
[<ffffffff81404ad7>] __device_release_driver+0x77/0xe0
[<ffffffff81404d49>] device_release_driver+0x29/0x40
[<ffffffff814044aa>] bus_remove_device+0xfa/0x170
[<ffffffff81401917>] device_del+0x127/0x1c0
[<ffffffff8149e9c1>] ? usb_disconnect+0x61/0x160
[<ffffffff814a7f20>] usb_disable_device+0xb0/0x270
[<ffffffff8149ea0d>] usb_disconnect+0xad/0x160
[<ffffffff814a12bc>] hub_thread+0x71c/0x1730
[<ffffffff810c689d>] ? trace_hardirqs_on_caller+0x10d/0x1e0
[<ffffffff81096d70>] ? __init_waitqueue_head+0x60/0x60
[<ffffffff814a0ba0>] ? usb_remote_wakeup+0x70/0x70
[<ffffffff810967e6>] kthread+0xd6/0xe0
[<ffffffff8169b65b>] ? _raw_spin_unlock_irq+0x2b/0x50
[<ffffffff81096710>] ? kthread_create_on_node+0x140/0x140
[<ffffffff8169c2ec>] ret_from_fork+0x7c/0xb0
[<ffffffff81096710>] ? kthread_create_on_node+0x140/0x140
--
js
suse labs
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