diff options
| author | Omair Mohammed Abdullah <omair.m.abdullah@linux.intel.com> | 2012-09-29 12:24:05 +0530 |
|---|---|---|
| committer | Takashi Iwai <tiwai@suse.de> | 2012-10-06 16:50:28 +0200 |
| commit | d4f1e48bd11e3df6a26811f7a1f06c4225d92f7d (patch) | |
| tree | 9095cf6f07b86a43df416c7ebdd261967935053d | |
| parent | d17344b3547669f5b6ee4fda993d03737a141bd6 (diff) | |
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>
| -rw-r--r-- | sound/drivers/aloop.c | 6 |
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) { |