[ALSA] Fix PCM write blocking

The snd_pcm_lib_write1() may block in some weird condition:
  - the stream isn't started
  - avail_min is big (e.g. period size)
  - partial write up to buffer_size - avail_min
The patch fixes this invalid blocking problem.

Signed-off-by: Takashi Iwai <tiwai@suse.de>
Signed-off-by: Jaroslav Kysela <perex@perex.cz>

diff --git a/sound/core/pcm_lib.c b/sound/core/pcm_lib.c
index 48ffa40..f9f9b3f 100644 (file)
--- a/sound/core/pcm_lib.c
+++ b/sound/core/pcm_lib.c
@@ -1655,8 +1655,11 @@ static snd_pcm_sframes_t snd_pcm_lib_write1(struct snd_pcm_substream *substream,
                if (runtime->sleep_min == 0 && runtime->status->state == SNDRV_PCM_STATE_RUNNING)
                        snd_pcm_update_hw_ptr(substream);
                avail = snd_pcm_playback_avail(runtime);
-               if (((avail < runtime->control->avail_min && size > avail) ||
-                  (size >= runtime->xfer_align && avail < runtime->xfer_align))) {
+               if (!avail ||
+                   (snd_pcm_running(substream) &&
+                    ((avail < runtime->control->avail_min && size > avail) ||
+                     (size >= runtime->xfer_align &&
+                      avail < runtime->xfer_align)))) {
                        wait_queue_t wait;
                        enum { READY, SIGNALED, ERROR, SUSPENDED, EXPIRED, DROPPED } state;
                        long tout;