The following commit has been merged in the linux branch: commit 3702b082281929cf1bdf14f67eb0619aab58b496 Author: Mark Hills mark@pogo.org.uk Date: Sat Oct 24 12:59:35 2009 +0100
ALSA: snd-usb-caiaq: Missing lock around use of buffer positions
Fix a race which causes snd_pcm_update_hw_ptr_pos() to report a bug.
Signed-off-by: Mark Hills mark@pogo.org.uk Acked-by: Daniel Mack daniel@caiaq.de Signed-off-by: Takashi Iwai tiwai@suse.de
diff --git a/sound/usb/caiaq/audio.c b/sound/usb/caiaq/audio.c index 121af06..e76017c 100644 --- a/sound/usb/caiaq/audio.c +++ b/sound/usb/caiaq/audio.c @@ -269,16 +269,22 @@ snd_usb_caiaq_pcm_pointer(struct snd_pcm_substream *sub) { int index = sub->number; struct snd_usb_caiaqdev *dev = snd_pcm_substream_chip(sub); + snd_pcm_uframes_t ptr; + + spin_lock(&dev->spinlock);
if (dev->input_panic || dev->output_panic) - return SNDRV_PCM_POS_XRUN; + ptr = SNDRV_PCM_POS_XRUN;
if (sub->stream == SNDRV_PCM_STREAM_PLAYBACK) - return bytes_to_frames(sub->runtime, + ptr = bytes_to_frames(sub->runtime, dev->audio_out_buf_pos[index]); else - return bytes_to_frames(sub->runtime, + ptr = bytes_to_frames(sub->runtime, dev->audio_in_buf_pos[index]); + + spin_unlock(&dev->spinlock); + return ptr; }
/* operators for both playback and capture */