[PATCH 2/3] ALSA: dummy: Implement sync_stop for systimer, too

[Takashi Iwai]

The systimer backend invokes timer_delete() at stopping the PCM, but
it misses its synchronization, which might lead to concurrent changes
or releases at PCM prepare or free.  Use the sync_stop callback to
assure the synchronization of timer deletion.

Signed-off-by: Takashi Iwai <tiwai@xxxxxxx>
---
 sound/drivers/dummy.c | 9 +++++++++
 1 file changed, 9 insertions(+)

diff --git a/sound/drivers/dummy.c b/sound/drivers/dummy.c
index ddd4da058693..3bc0289e3518 100644
--- a/sound/drivers/dummy.c
+++ b/sound/drivers/dummy.c
@@ -286,6 +286,14 @@ static int dummy_systimer_stop(struct snd_pcm_substream *substream)
 	return 0;
 }
 
+static int dummy_systimer_sync_stop(struct snd_pcm_substream *substream)
+{
+	struct dummy_systimer_pcm *dpcm = substream->runtime->private_data;
+
+	timer_delete_sync(&dpcm->timer);
+	return 0;
+}
+
 static int dummy_systimer_prepare(struct snd_pcm_substream *substream)
 {
 	struct snd_pcm_runtime *runtime = substream->runtime;
@@ -351,6 +359,7 @@ static const struct dummy_timer_ops dummy_systimer_ops = {
 	.prepare =	dummy_systimer_prepare,
 	.start =	dummy_systimer_start,
 	.stop =		dummy_systimer_stop,
+	.sync_stop =	dummy_systimer_sync_stop,
 	.pointer =	dummy_systimer_pointer,
 };
 
-- 
2.55.0