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Commit dd04bb12 authored by Jaroslav Kysela's avatar Jaroslav Kysela
Browse files

ALSA: snd-aloop - fix locking issues (running flag updates) 



On SMP machines, the cable->running update must be atomic, otherwise
stream is not started correctly sometimes.

Signed-off-by: default avatarJaroslav Kysela <perex@perex.cz>
parent e74670b6

sound/drivers/aloop.c

+19 −13
Original line number Diff line number Diff line
@@ -263,13 +263,17 @@ static int loopback_trigger(struct snd_pcm_substream *substream, int cmd) 
			return err;

		dpcm->last_jiffies = jiffies;

		dpcm->pcm_rate_shift = 0;

		loopback_timer_start(dpcm);

		spin_lock(&cable->lock);	

		cable->running |= (1 << substream->stream);

		spin_unlock(&cable->lock);

		loopback_timer_start(dpcm);

		if (substream->stream == SNDRV_PCM_STREAM_PLAYBACK)

			loopback_active_notify(dpcm);

		break;

	case SNDRV_PCM_TRIGGER_STOP:

		spin_lock(&cable->lock);	

		cable->running &= ~(1 << substream->stream);

		spin_unlock(&cable->lock);

		loopback_timer_stop(dpcm);

		if (substream->stream == SNDRV_PCM_STREAM_PLAYBACK)

			loopback_active_notify(dpcm);
@@ -454,28 +458,30 @@ static void loopback_bytepos_update(struct loopback_pcm *dpcm, 
	}

}



static void loopback_pos_update(struct loopback_cable *cable)

static unsigned int loopback_pos_update(struct loopback_cable *cable)

{

	struct loopback_pcm *dpcm_play =

			cable->streams[SNDRV_PCM_STREAM_PLAYBACK];

	struct loopback_pcm *dpcm_capt =

			cable->streams[SNDRV_PCM_STREAM_CAPTURE];

	unsigned long delta_play = 0, delta_capt = 0;

	unsigned int running;



	spin_lock(&cable->lock);	

	if (cable->running & (1 << SNDRV_PCM_STREAM_PLAYBACK)) {

	running = cable->running;

	if (running & (1 << SNDRV_PCM_STREAM_PLAYBACK)) {

		delta_play = jiffies - dpcm_play->last_jiffies;

		dpcm_play->last_jiffies += delta_play;

	}



	if (cable->running & (1 << SNDRV_PCM_STREAM_CAPTURE)) {

	if (running & (1 << SNDRV_PCM_STREAM_CAPTURE)) {

		delta_capt = jiffies - dpcm_capt->last_jiffies;

		dpcm_capt->last_jiffies += delta_capt;

	}



	if (delta_play == 0 && delta_capt == 0) {

		spin_unlock(&cable->lock);

		return;

		return running;

	}

		

	if (delta_play > delta_capt) {
@@ -490,29 +496,29 @@ static void loopback_pos_update(struct loopback_cable *cable) 


	if (delta_play == 0 && delta_capt == 0) {

		spin_unlock(&cable->lock);

		return;

		return running;

	}

	/* note delta_capt == delta_play at this moment */

	loopback_bytepos_update(dpcm_capt, delta_capt, BYTEPOS_UPDATE_COPY);

	loopback_bytepos_update(dpcm_play, delta_play, BYTEPOS_UPDATE_POSONLY);

	spin_unlock(&cable->lock);

	return running;

}



static void loopback_timer_function(unsigned long data)

{

	struct loopback_pcm *dpcm = (struct loopback_pcm *)data;

	int stream;

	unsigned int running;



	loopback_pos_update(dpcm->cable);

	stream = dpcm->substream->stream;

	if (dpcm->cable->running & (1 << stream))

	running = loopback_pos_update(dpcm->cable);

	if (running & (1 << dpcm->substream->stream)) {

		loopback_timer_start(dpcm);

		if (dpcm->period_update_pending) {

			dpcm->period_update_pending = 0;

		if (dpcm->cable->running & (1 << stream))

			snd_pcm_period_elapsed(dpcm->substream);

		}

	}

}



static snd_pcm_uframes_t loopback_pointer(struct snd_pcm_substream *substream)

{