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Commit 21cb2a2e authored by Takashi Iwai's avatar Takashi Iwai Committed by Jaroslav Kysela
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[ALSA] Fix races between PCM drain and other ops 



PCM Midlevel
Fix semaphore races between PCM drain and other ops.

Signed-off-by: default avatarTakashi Iwai <tiwai@suse.de>
parent ce43fbae

sound/core/pcm_native.c

+36 −34
Original line number Diff line number Diff line
@@ -1368,43 +1368,32 @@ static int snd_pcm_drain(snd_pcm_substream_t *substream) 
	if (runtime->status->state == SNDRV_PCM_STATE_OPEN)

		return -EBADFD;



	down_read(&snd_pcm_link_rwsem);

	snd_power_lock(card);

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

		result = snd_power_wait(card, SNDRV_CTL_POWER_D0, substream->ffile);

		if (result < 0)

			goto _unlock;

		if (result < 0) {

			snd_power_unlock(card);

			return result;

		}

	}



	/* 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) {

			result = -ENOMEM;

			goto _unlock;

			up_read(&snd_pcm_link_rwsem);

			snd_power_unlock(card);

			return -ENOMEM;

		}

	} else

		drec = &drec_tmp;



	snd_pcm_stream_lock_irq(substream);

	/* resume pause */

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

		snd_pcm_pause(substream, 0);



	/* pre-start/stop - all running streams are changed to DRAINING state */

	result = snd_pcm_action(&snd_pcm_action_drain_init, substream, 0);

	if (result < 0)

		goto _end;



	/* check streams with PLAYBACK & DRAINING */

	/* count only playback streams */

	num_drecs = 0;

	snd_pcm_group_for_each(pos, substream) {

		snd_pcm_substream_t *s = snd_pcm_group_substream_entry(pos);

		runtime = s->runtime;

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

			runtime->status->state = SNDRV_PCM_STATE_SETUP;

			continue;

		}

		if (s->stream == SNDRV_PCM_STREAM_PLAYBACK) {

			d = &drec[num_drecs++];

			d->substream = s;
@@ -1418,9 +1407,21 @@ static int snd_pcm_drain(snd_pcm_substream_t *substream) 
				runtime->stop_threshold = runtime->buffer_size;

		}

	}



	up_read(&snd_pcm_link_rwsem);

	if (! num_drecs)

		goto _end;

		goto _error;



	snd_pcm_stream_lock_irq(substream);

	/* resume pause */

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

		snd_pcm_pause(substream, 0);



	/* pre-start/stop - all running streams are changed to DRAINING state */

	result = snd_pcm_action(&snd_pcm_action_drain_init, substream, 0);

	if (result < 0) {

		snd_pcm_stream_unlock_irq(substream);

		goto _error;

	}



	for (;;) {

		long tout;
@@ -1428,6 +1429,15 @@ static int snd_pcm_drain(snd_pcm_substream_t *substream) 
			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)

				break;

		}

		if (i == num_drecs)

			break; /* yes, all drained */



		set_current_state(TASK_INTERRUPTIBLE);

		snd_pcm_stream_unlock_irq(substream);

		snd_power_unlock(card);
@@ -1444,15 +1454,11 @@ static int snd_pcm_drain(snd_pcm_substream_t *substream) 
			}

			break;

		}

		/* all finished? */

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

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

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

				break;

		}

		if (i == num_drecs)

			break;

	}



	snd_pcm_stream_unlock_irq(substream);



 _error:

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

		d = &drec[i];

		runtime = d->substream->runtime;
@@ -1460,13 +1466,9 @@ static int snd_pcm_drain(snd_pcm_substream_t *substream) 
		runtime->stop_threshold = d->stop_threshold;

	}



 _end:

	snd_pcm_stream_unlock_irq(substream);

	if (drec != &drec_tmp)

		kfree(drec);

 _unlock:

	snd_power_unlock(card);

	up_read(&snd_pcm_link_rwsem);



	return result;

}