ALSA: snd-usb-caiaq: Lock on stream start/unpause

Fix a bug which can result in white noise from the driver after stream
start or unpause.

Signed-off-by: Mark Hills <mark@pogo.org.uk>
Acked-by: Daniel Mack <daniel@caiaq.de>
Signed-off-by: Takashi Iwai <tiwai@suse.de>

1 files changed, 4 insertions, 0 deletions

diff --git a/sound/usb/caiaq/audio.c b/sound/usb/caiaq/audio.c
index e76017cd5acf..86b2c3b92df5 100644
--- a/sound/usb/caiaq/audio.c
+++ b/sound/usb/caiaq/audio.c
@@ -62,10 +62,14 @@ static void
 activate_substream(struct snd_usb_caiaqdev *dev,
                    struct snd_pcm_substream *sub)
 {
+        spin_lock(&dev->spinlock);
+
         if (sub->stream == SNDRV_PCM_STREAM_PLAYBACK)
                 dev->sub_playback[sub->number] = sub;
         else
                 dev->sub_capture[sub->number] = sub;
+
+        spin_unlock(&dev->spinlock);
 }
 
 static void