[alsa-devel] [PATCH] ALSA: pcm: Update the state properly before notification

[Takashi Iwai]

Some state changes (e.g. snd_pcm_stop()) sets the runtime state after
calling snd_timer_notify().  This is basically racy, since the
notification may wakes up the user even before the state change.
Although the possibility is low, we should set the state before the
notifications.

Signed-off-by: Takashi Iwai <tiwai at suse.de>
---
 sound/core/pcm_native.c | 8 ++++----
 1 file changed, 4 insertions(+), 4 deletions(-)

diff --git a/sound/core/pcm_native.c b/sound/core/pcm_native.c
index ca224fa2a33a..dfb5031969f8 100644
--- a/sound/core/pcm_native.c
+++ b/sound/core/pcm_native.c
@@ -1052,10 +1052,10 @@ static void snd_pcm_post_stop(struct snd_pcm_substream *substream, int state)
 	struct snd_pcm_runtime *runtime = substream->runtime;
 	if (runtime->status->state != state) {
 		snd_pcm_trigger_tstamp(substream);
+		runtime->status->state = state;
 		if (substream->timer)
 			snd_timer_notify(substream->timer, SNDRV_TIMER_EVENT_MSTOP,
 					 &runtime->trigger_tstamp);
-		runtime->status->state = state;
 	}
 	wake_up(&runtime->sleep);
 	wake_up(&runtime->tsleep);
@@ -1204,11 +1204,11 @@ static void snd_pcm_post_suspend(struct snd_pcm_substream *substream, int state)
 {
 	struct snd_pcm_runtime *runtime = substream->runtime;
 	snd_pcm_trigger_tstamp(substream);
+	runtime->status->suspended_state = runtime->status->state;
+	runtime->status->state = SNDRV_PCM_STATE_SUSPENDED;
 	if (substream->timer)
 		snd_timer_notify(substream->timer, SNDRV_TIMER_EVENT_MSUSPEND,
 				 &runtime->trigger_tstamp);
-	runtime->status->suspended_state = runtime->status->state;
-	runtime->status->state = SNDRV_PCM_STATE_SUSPENDED;
 	wake_up(&runtime->sleep);
 	wake_up(&runtime->tsleep);
 }
@@ -1311,10 +1311,10 @@ static void snd_pcm_post_resume(struct snd_pcm_substream *substream, int state)
 {
 	struct snd_pcm_runtime *runtime = substream->runtime;
 	snd_pcm_trigger_tstamp(substream);
+	runtime->status->state = runtime->status->suspended_state;
 	if (substream->timer)
 		snd_timer_notify(substream->timer, SNDRV_TIMER_EVENT_MRESUME,
 				 &runtime->trigger_tstamp);
-	runtime->status->state = runtime->status->suspended_state;
 }
 
 static struct action_ops snd_pcm_action_resume = {
-- 
2.1.3