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: Takashi Iwai <tiwai@suse.de>

1 files changed, 20 insertions, 53 deletions

diff --git a/sound/core/pcm_native.c b/sound/core/pcm_native.c
index 59e5fbe6af51..561d6d95a2d3 100644
--- a/sound/core/pcm_native.c
+++ b/sound/core/pcm_native.c
@@ -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;