diff options
author | Takashi Iwai <tiwai@suse.de> | 2012-11-13 11:22:48 +0100 |
---|---|---|
committer | Xavier Boudet <x-boudet@ti.com> | 2012-11-19 10:21:31 +0100 |
commit | 2a682e70adc69b6b6633f345170a7f0604d67c8f (patch) | |
tree | 6b6a84e984519b51471f26949258bcd0651bf65a /debian.ti-omap4/abi/3.4.0-1489.10/armhf/omap4.modules | |
parent | d7972057f488c5e600124d12287de8b8944a8cd4 (diff) |
ALSA: usb-audio: Fix mutex deadlock at disconnection
commit 10e44239f67d0b6fb74006e61a7e883b8075247a upstream.
The recent change for USB-audio disconnection race fixes introduced a
mutex deadlock again. There is a circular dependency between
chip->shutdown_rwsem and pcm->open_mutex, depicted like below, when a
device is opened during the disconnection operation:
A. snd_usb_audio_disconnect() ->
card.c::register_mutex ->
chip->shutdown_rwsem (write) ->
snd_card_disconnect() ->
pcm.c::register_mutex ->
pcm->open_mutex
B. snd_pcm_open() ->
pcm->open_mutex ->
snd_usb_pcm_open() ->
chip->shutdown_rwsem (read)
Since the chip->shutdown_rwsem protection in the case A is required
only for turning on the chip->shutdown flag and it doesn't have to be
taken for the whole operation, we can reduce its window in
snd_usb_audio_disconnect().
Reported-by: Jiri Slaby <jslaby@suse.cz>
Signed-off-by: Takashi Iwai <tiwai@suse.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'debian.ti-omap4/abi/3.4.0-1489.10/armhf/omap4.modules')
0 files changed, 0 insertions, 0 deletions