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23 October 2021, 00:29:24 UTC
Revision 382225e62bdb8059b7f915b133426425516dd300 authored by Takashi Iwai on 22 February 2011, 09:21:18 UTC, committed by Takashi Iwai on 23 February 2011, 07:15:43 UTC 
ALSA: usb-audio: fix oops due to cleanup race when disconnecting
 
When a USB audio device is disconnected, snd_usb_audio_disconnect()
kills all audio URBs.  At the same time, the application, after being
notified of the disconnection, might close the device, in which case
ALSA calls the .hw_free callback, which should free the URBs too.

Commit de1b8b93a0ba "[ALSA] Fix hang-up at disconnection of usb-audio"
prevented snd_usb_hw_free() from freeing the URBs to avoid a hang that
resulted from this race, but this introduced another race because the
URB callbacks could now be executed after snd_usb_hw_free() has
returned, and try to access already freed data.

Fix the first race by introducing a mutex to serialize the disconnect
callback and all PCM callbacks that manage URBs (hw_free and hw_params).

Reported-and-tested-by: Pierre-Louis Bossart <pierre-louis.bossart@intel.com>
Cc: <stable@kernel.org>
[CL: also serialize hw_params callback]
Signed-off-by: Clemens Ladisch <clemens@ladisch.de>
Signed-off-by: Takashi Iwai <tiwai@suse.de>
1 parent 3064967
History
Tip revision: 382225e62bdb8059b7f915b133426425516dd300 authored by Takashi Iwai on 22 February 2011, 09:21:18 UTC
ALSA: usb-audio: fix oops due to cleanup race when disconnecting
Tip revision: 382225e
File Mode Size
hw_breakpoint
kdb
kfifo
kobject
kprobes
trace_events
tracepoints
Kconfig -rw-r--r-- 1.7 KB
Makefile -rw-r--r-- 140 bytes
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