[alsa-devel] [PATCH - JACK IO plug 1/2 v2] jack: Avoid call to snd_pcm_avail_update() from JACK thread

[twischer at de.adit-jv.com]

From: Timo Wischer <twischer at de.adit-jv.com>

snd_pcm_avail_update() can call snd_pcm_jack_stop() but
snd_pcm_jack_stop() should not be called by the JACK thread.
It should only be called by the thread how has called
snd_pcm_jack_start().

In addition the execution of snd_pcm_avail_update() can take a while.
Therefore it should not be called by the JACK thread to not block this
thread.

Signed-off-by: Timo Wischer <twischer at de.adit-jv.com>
---
v2 uses snd_pcm_uframes_t as type for avail and does not check for avail < 0
becasue snd_pcm_ioplug_avail() will never retrun a value < 0

diff --git a/jack/pcm_jack.c b/jack/pcm_jack.c
index e3df4d2..5a57e13 100644
--- a/jack/pcm_jack.c
+++ b/jack/pcm_jack.c
@@ -62,13 +62,13 @@ static int snd_pcm_jack_stop(snd_pcm_ioplug_t *io);
 static int pcm_poll_block_check(snd_pcm_ioplug_t *io)
 {
 	static char buf[32];
-	snd_pcm_sframes_t avail;
+	snd_pcm_uframes_t avail;
 	snd_pcm_jack_t *jack = io->private_data;
 
 	if (io->state == SND_PCM_STATE_RUNNING ||
 	    (io->state == SND_PCM_STATE_PREPARED && io->stream == SND_PCM_STREAM_CAPTURE)) {
-		avail = snd_pcm_avail_update(io->pcm);
-		if (avail >= 0 && avail < jack->min_avail) {
+		avail = snd_pcm_ioplug_avail(io, jack->hw_ptr, io->appl_ptr);
+		if (avail < jack->min_avail) {
 			while (read(io->poll_fd, &buf, sizeof(buf)) == sizeof(buf))
 				;
 			return 1;
@@ -81,11 +81,11 @@ static int pcm_poll_block_check(snd_pcm_ioplug_t *io)
 static int pcm_poll_unblock_check(snd_pcm_ioplug_t *io)
 {
 	static char buf[1];
-	snd_pcm_sframes_t avail;
+	snd_pcm_uframes_t avail;
 	snd_pcm_jack_t *jack = io->private_data;
 
-	avail = snd_pcm_avail_update(io->pcm);
-	if (avail < 0 || avail >= jack->min_avail) {
+	avail = snd_pcm_ioplug_avail(io, jack->hw_ptr, io->appl_ptr);
+	if (avail >= jack->min_avail) {
 		write(jack->fd, &buf, 1);
 		return 1;
 	}
-- 
2.7.4