From: Takashi Iwai <tiwai@suse.de>
Date: Tue, 8 Jan 2008 17:00:04 +0000 (+0100)
Subject: [ALSA] Fix PCM write blocking
X-Git-Tag: v2.6.25-rc1~1127^2~152
X-Git-Url: https://err.no/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=fa5717f2099aadb2083d5df4d19af8f9685fa03e;p=linux-2.6

[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 48ffa40967..f9f9b3fe95 100644
--- 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;