ALSA: pcm_core: Fix wake_up() optimization

This change fixes the "ALSA: pcm_lib - optimize wake_up() calls for PCM I/O"
commit. New sleeping queue is introduced to separate user space and kernel
space wake_ups. runtime->nowake is renamed to twake (transfer wake).
Signed-off-by: Jaroslav Kysela <perex@perex.cz>

include/sound/pcm.h

@@ -311,8 +311,9 @@ struct snd_pcm_runtime {
 	struct snd_pcm_mmap_control *control;
 
 	/* -- locking / scheduling -- */
-	unsigned int nowake: 1;		/* no wakeup (data-copy in progress) */
-	wait_queue_head_t sleep;
+	unsigned int twake: 1;		/* do transfer (!poll) wakeup */
+	wait_queue_head_t sleep;	/* poll sleep */
+	wait_queue_head_t tsleep;	/* transfer sleep */
 	struct fasync_struct *fasync;
 
 	/* -- private section -- */

sound/core/pcm.c

@@ -894,6 +894,7 @@ int snd_pcm_attach_substream(struct snd_pcm *pcm, int stream,
 	memset((void*)runtime->control, 0, size);
 
 	init_waitqueue_head(&runtime->sleep);
+	init_waitqueue_head(&runtime->tsleep);
 
 	runtime->status->state = SNDRV_PCM_STATE_OPEN;
 

sound/core/pcm_lib.c

@@ -285,8 +285,8 @@ int snd_pcm_update_state(struct snd_pcm_substream *substream,
 			return -EPIPE;
 		}
 	}
-	if (!runtime->nowake && avail >= runtime->control->avail_min)
-		wake_up(&runtime->sleep);
+	if (avail >= runtime->control->avail_min)
+		wake_up(runtime->twake ? &runtime->tsleep : &runtime->sleep);
 	return 0;
 }
 
@@ -1692,7 +1692,7 @@ static int wait_for_avail_min(struct snd_pcm_substream *substream,
 	long tout;
 
 	init_waitqueue_entry(&wait, current);
-	add_wait_queue(&runtime->sleep, &wait);
+	add_wait_queue(&runtime->tsleep, &wait);
 	for (;;) {
 		if (signal_pending(current)) {
 			err = -ERESTARTSYS;
@@ -1735,7 +1735,7 @@ static int wait_for_avail_min(struct snd_pcm_substream *substream,
 			break;
 	}
  _endloop:
-	remove_wait_queue(&runtime->sleep, &wait);
+	remove_wait_queue(&runtime->tsleep, &wait);
 	*availp = avail;
 	return err;
 }
@@ -1794,7 +1794,7 @@ static snd_pcm_sframes_t snd_pcm_lib_write1(struct snd_pcm_substream *substream,
 		goto _end_unlock;
 	}
 
-	runtime->nowake = 1;
+	runtime->twake = 1;
 	while (size > 0) {
 		snd_pcm_uframes_t frames, appl_ptr, appl_ofs;
 		snd_pcm_uframes_t avail;
@@ -1816,7 +1816,7 @@ static snd_pcm_sframes_t snd_pcm_lib_write1(struct snd_pcm_substream *substream,
 		if (frames > cont)
 			frames = cont;
 		if (snd_BUG_ON(!frames)) {
-			runtime->nowake = 0;
+			runtime->twake = 0;
 			snd_pcm_stream_unlock_irq(substream);
 			return -EINVAL;
 		}
@@ -1855,7 +1855,7 @@ static snd_pcm_sframes_t snd_pcm_lib_write1(struct snd_pcm_substream *substream,
 		}
 	}
  _end_unlock:
-	runtime->nowake = 0;
+	runtime->twake = 0;
 	if (xfer > 0 && err >= 0)
 		snd_pcm_update_state(substream, runtime);
 	snd_pcm_stream_unlock_irq(substream);
@@ -2016,7 +2016,7 @@ static snd_pcm_sframes_t snd_pcm_lib_read1(struct snd_pcm_substream *substream,
 		goto _end_unlock;
 	}
 
-	runtime->nowake = 1;
+	runtime->twake = 1;
 	while (size > 0) {
 		snd_pcm_uframes_t frames, appl_ptr, appl_ofs;
 		snd_pcm_uframes_t avail;
@@ -2045,7 +2045,7 @@ static snd_pcm_sframes_t snd_pcm_lib_read1(struct snd_pcm_substream *substream,
 		if (frames > cont)
 			frames = cont;
 		if (snd_BUG_ON(!frames)) {
-			runtime->nowake = 0;
+			runtime->twake = 0;
 			snd_pcm_stream_unlock_irq(substream);
 			return -EINVAL;
 		}
@@ -2078,7 +2078,7 @@ static snd_pcm_sframes_t snd_pcm_lib_read1(struct snd_pcm_substream *substream,
 		xfer += frames;
 	}
  _end_unlock:
-	runtime->nowake = 0;
+	runtime->twake = 0;
 	if (xfer > 0 && err >= 0)
 		snd_pcm_update_state(substream, runtime);
 	snd_pcm_stream_unlock_irq(substream);

sound/core/pcm_native.c

@@ -919,6 +919,7 @@ static void snd_pcm_post_stop(struct snd_pcm_substream *substream, int state)
 		runtime->status->state = state;
 	}
 	wake_up(&runtime->sleep);
+	wake_up(&runtime->tsleep);
 }
 
 static struct action_ops snd_pcm_action_stop = {
@@ -1004,6 +1005,7 @@ static void snd_pcm_post_pause(struct snd_pcm_substream *substream, int push)
 					 SNDRV_TIMER_EVENT_MPAUSE,
 					 &runtime->trigger_tstamp);
 		wake_up(&runtime->sleep);
+		wake_up(&runtime->tsleep);
 	} else {
 		runtime->status->state = SNDRV_PCM_STATE_RUNNING;
 		if (substream->timer)
@@ -1061,6 +1063,7 @@ static void snd_pcm_post_suspend(struct snd_pcm_substream *substream, int state)
 	runtime->status->suspended_state = runtime->status->state;
 	runtime->status->state = SNDRV_PCM_STATE_SUSPENDED;
 	wake_up(&runtime->sleep);
+	wake_up(&runtime->tsleep);
 }
 
 static struct action_ops snd_pcm_action_suspend = {