From 382225e62bdb8059b7f915b133426425516dd300 Mon Sep 17 00:00:00 2001 From: Takashi Iwai Date: Tue, 22 Feb 2011 10:21:18 +0100 Subject: 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 Cc: [CL: also serialize hw_params callback] Signed-off-by: Clemens Ladisch Signed-off-by: Takashi Iwai --- sound/usb/usbaudio.h | 1 + 1 file changed, 1 insertion(+) (limited to 'sound/usb/usbaudio.h') diff --git a/sound/usb/usbaudio.h b/sound/usb/usbaudio.h index db3eb21627ee..6e66fffe87f5 100644 --- a/sound/usb/usbaudio.h +++ b/sound/usb/usbaudio.h @@ -36,6 +36,7 @@ struct snd_usb_audio { struct snd_card *card; u32 usb_id; int shutdown; + struct mutex shutdown_mutex; unsigned int txfr_quirk:1; /* Subframe boundaries on transfers */ int num_interfaces; int num_suspended_intf; -- cgit v1.2.3