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Commit d3a7dcfe authored by Takashi Iwai's avatar Takashi Iwai
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ALSA: pcm - Simplify snd_pcm_drain() implementation 



Simplify snd_pcm_drain() implementation and avoid unneeded array-
allocation for waitqueues.  Instead, one waitqueue is used for the
first draining stream, and wait until all streams finished.

Signed-off-by: default avatarTakashi Iwai <tiwai@suse.de>
parent 87bfa1db

sound/core/pcm_native.c

+20 −53
Original line number Diff line number Diff line
@@ -1387,11 +1387,6 @@ static struct action_ops snd_pcm_action_drain_init = { 
	.post_action = snd_pcm_post_drain_init

};



struct drain_rec {

	struct snd_pcm_substream *substream;

	wait_queue_t wait;

};



static int snd_pcm_drop(struct snd_pcm_substream *substream);



/*
@@ -1407,10 +1402,9 @@ static int snd_pcm_drain(struct snd_pcm_substream *substream, 
	struct snd_card *card;

	struct snd_pcm_runtime *runtime;

	struct snd_pcm_substream *s;

	wait_queue_t wait;

	int result = 0;

	int i, num_drecs;

	int nonblock = 0;

	struct drain_rec *drec, drec_tmp, *d;



	card = substream->pcm->card;

	runtime = substream->runtime;
@@ -1433,38 +1427,10 @@ static int snd_pcm_drain(struct snd_pcm_substream *substream, 
	} else if (substream->f_flags & O_NONBLOCK)

		nonblock = 1;



	if (nonblock)

		goto lock; /* no need to allocate waitqueues */



	/* allocate temporary record for drain sync */

	down_read(&snd_pcm_link_rwsem);

	if (snd_pcm_stream_linked(substream)) {

		drec = kmalloc(substream->group->count * sizeof(*drec), GFP_KERNEL);

		if (! drec) {

			up_read(&snd_pcm_link_rwsem);

			snd_power_unlock(card);

			return -ENOMEM;

		}

	} else

		drec = &drec_tmp;



	/* count only playback streams */

	num_drecs = 0;

	snd_pcm_group_for_each_entry(s, substream) {

		runtime = s->runtime;

		if (s->stream == SNDRV_PCM_STREAM_PLAYBACK) {

			d = &drec[num_drecs++];

			d->substream = s;

			init_waitqueue_entry(&d->wait, current);

			add_wait_queue(&runtime->sleep, &d->wait);

		}

	}

	up_read(&snd_pcm_link_rwsem);



 lock:

	snd_pcm_stream_lock_irq(substream);

	/* resume pause */

	if (substream->runtime->status->state == SNDRV_PCM_STATE_PAUSED)

	if (runtime->status->state == SNDRV_PCM_STATE_PAUSED)

		snd_pcm_pause(substream, 0);



	/* pre-start/stop - all running streams are changed to DRAINING state */
@@ -1479,25 +1445,35 @@ static int snd_pcm_drain(struct snd_pcm_substream *substream, 


	for (;;) {

		long tout;

		struct snd_pcm_runtime *to_check;

		if (signal_pending(current)) {

			result = -ERESTARTSYS;

			break;

		}

		/* all finished? */

		for (i = 0; i < num_drecs; i++) {

			runtime = drec[i].substream->runtime;

			if (runtime->status->state == SNDRV_PCM_STATE_DRAINING)

		/* find a substream to drain */

		to_check = NULL;

		snd_pcm_group_for_each_entry(s, substream) {

			if (s->stream != SNDRV_PCM_STREAM_PLAYBACK)

				continue;

			runtime = s->runtime;

			if (runtime->status->state == SNDRV_PCM_STATE_DRAINING) {

				to_check = runtime;

				break;

			}

		if (i == num_drecs)

			break; /* yes, all drained */



		}

		if (!to_check)

			break; /* all drained */

		init_waitqueue_entry(&wait, current);

		add_wait_queue(&to_check->sleep, &wait);

		set_current_state(TASK_INTERRUPTIBLE);

		snd_pcm_stream_unlock_irq(substream);

		up_read(&snd_pcm_link_rwsem);

		snd_power_unlock(card);

		tout = schedule_timeout(10 * HZ);

		snd_power_lock(card);

		down_read(&snd_pcm_link_rwsem);

		snd_pcm_stream_lock_irq(substream);

		remove_wait_queue(&to_check->sleep, &wait);

		if (tout == 0) {

			if (substream->runtime->status->state == SNDRV_PCM_STATE_SUSPENDED)

				result = -ESTRPIPE;
@@ -1512,16 +1488,7 @@ static int snd_pcm_drain(struct snd_pcm_substream *substream, 


 unlock:

	snd_pcm_stream_unlock_irq(substream);



	if (!nonblock) {

		for (i = 0; i < num_drecs; i++) {

			d = &drec[i];

			runtime = d->substream->runtime;

			remove_wait_queue(&runtime->sleep, &d->wait);

		}

		if (drec != &drec_tmp)

			kfree(drec);

	}

	up_read(&snd_pcm_link_rwsem);

	snd_power_unlock(card);



	return result;