diff options
author | Takashi Iwai <tiwai@suse.de> | 2011-02-22 10:21:18 +0100 |
---|---|---|
committer | Takashi Iwai <tiwai@suse.de> | 2011-02-23 08:15:43 +0100 |
commit | 382225e62bdb8059b7f915b133426425516dd300 (patch) | |
tree | 25f85ecb38145f3ca1547685066b2bf9057e3c72 /sound/usb/card.c | |
parent | ALSA: HDA: Fix mic initialization in VIA auto parser (diff) | |
download | linux-382225e62bdb8059b7f915b133426425516dd300.tar.xz linux-382225e62bdb8059b7f915b133426425516dd300.zip |
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>
Diffstat (limited to 'sound/usb/card.c')
-rw-r--r-- | sound/usb/card.c | 4 |
1 files changed, 4 insertions, 0 deletions
diff --git a/sound/usb/card.c b/sound/usb/card.c index 800f7cb4f251..c0f8270bc199 100644 --- a/sound/usb/card.c +++ b/sound/usb/card.c @@ -323,6 +323,7 @@ static int snd_usb_audio_create(struct usb_device *dev, int idx, return -ENOMEM; } + mutex_init(&chip->shutdown_mutex); chip->index = idx; chip->dev = dev; chip->card = card; @@ -531,6 +532,7 @@ static void snd_usb_audio_disconnect(struct usb_device *dev, void *ptr) chip = ptr; card = chip->card; mutex_lock(®ister_mutex); + mutex_lock(&chip->shutdown_mutex); chip->shutdown = 1; chip->num_interfaces--; if (chip->num_interfaces <= 0) { @@ -548,9 +550,11 @@ static void snd_usb_audio_disconnect(struct usb_device *dev, void *ptr) snd_usb_mixer_disconnect(p); } usb_chip[chip->index] = NULL; + mutex_unlock(&chip->shutdown_mutex); mutex_unlock(®ister_mutex); snd_card_free_when_closed(card); } else { + mutex_unlock(&chip->shutdown_mutex); mutex_unlock(®ister_mutex); } } |