[PATCH] ALSA: pcm: Add stream lock during PCM reset ioctl operations

[Takashi Iwai]

snd_pcm_reset() is a non-atomic operation, and it's allowed to run
during the PCM stream running.  It implies that the manipulation of
hw_ptr and other parameters might be racy.

This patch adds the PCM stream lock at appropriate places in
snd_pcm_*_reset() actions for covering that.

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

diff --git a/sound/core/pcm_native.c b/sound/core/pcm_native.c
index 0e4fbf5fd87b..704fdc9ebf91 100644
--- a/sound/core/pcm_native.c
+++ b/sound/core/pcm_native.c
@@ -1864,11 +1864,13 @@ static int snd_pcm_do_reset(struct snd_pcm_substream *substream,
 	int err = snd_pcm_ops_ioctl(substream, SNDRV_PCM_IOCTL1_RESET, NULL);
 	if (err < 0)
 		return err;
+	snd_pcm_stream_lock_irq(substream);
 	runtime->hw_ptr_base = 0;
 	runtime->hw_ptr_interrupt = runtime->status->hw_ptr -
 		runtime->status->hw_ptr % runtime->period_size;
 	runtime->silence_start = runtime->status->hw_ptr;
 	runtime->silence_filled = 0;
+	snd_pcm_stream_unlock_irq(substream);
 	return 0;
 }
 
@@ -1876,10 +1878,12 @@ static void snd_pcm_post_reset(struct snd_pcm_substream *substream,
 			       snd_pcm_state_t state)
 {
 	struct snd_pcm_runtime *runtime = substream->runtime;
+	snd_pcm_stream_lock_irq(substream);
 	runtime->control->appl_ptr = runtime->status->hw_ptr;
 	if (substream->stream == SNDRV_PCM_STREAM_PLAYBACK &&
 	    runtime->silence_size > 0)
 		snd_pcm_playback_silence(substream, ULONG_MAX);
+	snd_pcm_stream_unlock_irq(substream);
 }
 
 static const struct action_ops snd_pcm_action_reset = {
-- 
2.31.1