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authorOmair Mohammed Abdullah <omair.m.abdullah@linux.intel.com>2012-09-29 12:24:05 +0530
committerTakashi Iwai <tiwai@suse.de>2012-10-06 16:50:28 +0200
commitd4f1e48bd11e3df6a26811f7a1f06c4225d92f7d (patch)
tree9095cf6f07b86a43df416c7ebdd261967935053d /sound/drivers
parentd17344b3547669f5b6ee4fda993d03737a141bd6 (diff)
downloadvexpress-lsk-d4f1e48bd11e3df6a26811f7a1f06c4225d92f7d.tar.gz
ALSA: aloop - add locking to timer access
When the loopback timer handler is running, calling del_timer() (for STOP trigger) will not wait for the handler to complete before deactivating the timer. The timer gets rescheduled in the handler as usual. Then a subsequent START trigger will try to start the timer using add_timer() with a timer pending leading to a kernel panic. Serialize the calls to add_timer() and del_timer() using a spin lock to avoid this. Signed-off-by: Omair Mohammed Abdullah <omair.m.abdullah@linux.intel.com> Signed-off-by: Vinod Koul <vinod.koul@linux.intel.com> Cc: <stable@vger.kernel.org> Signed-off-by: Takashi Iwai <tiwai@suse.de>
Diffstat (limited to 'sound/drivers')
-rw-r--r--sound/drivers/aloop.c6
1 files changed, 6 insertions, 0 deletions
diff --git a/sound/drivers/aloop.c b/sound/drivers/aloop.c
index 5a34355e78e..0fe6d64ff84 100644
--- a/sound/drivers/aloop.c
+++ b/sound/drivers/aloop.c
@@ -120,6 +120,7 @@ struct loopback_pcm {
unsigned int last_drift;
unsigned long last_jiffies;
struct timer_list timer;
+ spinlock_t timer_lock;
};
static struct platform_device *devices[SNDRV_CARDS];
@@ -170,6 +171,7 @@ static void loopback_timer_start(struct loopback_pcm *dpcm)
unsigned long tick;
unsigned int rate_shift = get_rate_shift(dpcm);
+ spin_lock(&dpcm->timer_lock);
if (rate_shift != dpcm->pcm_rate_shift) {
dpcm->pcm_rate_shift = rate_shift;
dpcm->period_size_frac = frac_pos(dpcm, dpcm->pcm_period_size);
@@ -182,12 +184,15 @@ static void loopback_timer_start(struct loopback_pcm *dpcm)
tick = (tick + dpcm->pcm_bps - 1) / dpcm->pcm_bps;
dpcm->timer.expires = jiffies + tick;
add_timer(&dpcm->timer);
+ spin_unlock(&dpcm->timer_lock);
}
static inline void loopback_timer_stop(struct loopback_pcm *dpcm)
{
+ spin_lock(&dpcm->timer_lock);
del_timer(&dpcm->timer);
dpcm->timer.expires = 0;
+ spin_unlock(&dpcm->timer_lock);
}
#define CABLE_VALID_PLAYBACK (1 << SNDRV_PCM_STREAM_PLAYBACK)
@@ -667,6 +672,7 @@ static int loopback_open(struct snd_pcm_substream *substream)
dpcm->substream = substream;
setup_timer(&dpcm->timer, loopback_timer_function,
(unsigned long)dpcm);
+ spin_lock_init(&dpcm->timer_lock);
cable = loopback->cables[substream->number][dev];
if (!cable) {