Fix PCM drain synchronization - use mutex for sync

src/ba-transport.c

@@ -94,8 +94,7 @@ static int transport_pcm_init(
 	ba_transport_pcm_volume_set(&pcm->volume[1], NULL, NULL, NULL);
 
 	pthread_mutex_init(&pcm->mutex, NULL);
-	pthread_mutex_init(&pcm->synced_mtx, NULL);
-	pthread_cond_init(&pcm->synced, NULL);
+	pthread_cond_init(&pcm->cond, NULL);
 
 	pcm->ba_dbus_path = g_strdup_printf("%s/%s/%s",
 			t->d->ba_dbus_path, transport_get_dbus_path_type(t->profile),
@@ -112,8 +111,7 @@ static void transport_pcm_free(
 	pthread_mutex_unlock(&pcm->mutex);
 
 	pthread_mutex_destroy(&pcm->mutex);
-	pthread_mutex_destroy(&pcm->synced_mtx);
-	pthread_cond_destroy(&pcm->synced);
+	pthread_cond_destroy(&pcm->cond);
 
 	if (pcm->ba_dbus_path != NULL)
 		g_free(pcm->ba_dbus_path);
@@ -164,7 +162,7 @@ static int transport_thread_init(
 	th->pipe[1] = -1;
 
 	pthread_mutex_init(&th->mutex, NULL);
-	pthread_cond_init(&th->changed, NULL);
+	pthread_cond_init(&th->cond, NULL);
 
 	if (pipe(th->pipe) == -1)
 		return -1;
@@ -198,7 +196,7 @@ static void transport_thread_cancel(struct ba_transport_thread *th) {
 	 * supposed to be synchronous. */
 	if (th->state == BA_TRANSPORT_THREAD_STATE_JOINING) {
 		while (!pthread_equal(th->id, config.main_thread))
-			pthread_cond_wait(&th->changed, &th->mutex);
+			pthread_cond_wait(&th->cond, &th->mutex);
 		pthread_mutex_unlock(&th->mutex);
 		return;
 	}
@@ -230,7 +228,7 @@ static void transport_thread_cancel(struct ba_transport_thread *th) {
 	pthread_mutex_unlock(&th->mutex);
 
 	/* Notify others that the thread has been terminated. */
-	pthread_cond_broadcast(&th->changed);
+	pthread_cond_broadcast(&th->cond);
 
 }
 
@@ -239,7 +237,7 @@ static void transport_thread_cancel(struct ba_transport_thread *th) {
 static void transport_thread_cancel_wait(struct ba_transport_thread *th) {
 	pthread_mutex_lock(&th->mutex);
 	while (!pthread_equal(th->id, config.main_thread))
-		pthread_cond_wait(&th->changed, &th->mutex);
+		pthread_cond_wait(&th->cond, &th->mutex);
 	pthread_mutex_unlock(&th->mutex);
 }
 
@@ -254,7 +252,7 @@ static void transport_thread_free(
 	if (th->pipe[1] != -1)
 		close(th->pipe[1]);
 	pthread_mutex_destroy(&th->mutex);
-	pthread_cond_destroy(&th->changed);
+	pthread_cond_destroy(&th->cond);
 }
 
 int ba_transport_thread_set_state(
@@ -278,7 +276,7 @@ int ba_transport_thread_set_state(
 	pthread_mutex_unlock(&th->mutex);
 
 	if (!skip)
-		pthread_cond_signal(&th->changed);
+		pthread_cond_signal(&th->cond);
 
 	return 0;
 }
@@ -1498,18 +1496,17 @@ int ba_transport_pcm_drain(struct ba_transport_pcm *pcm) {
 	if (pthread_equal(pcm->th->id, config.main_thread))
 		return errno = ESRCH, -1;
 
-#if DEBUG
 	pthread_mutex_lock(&pcm->mutex);
-	debug("PCM drain: %d", pcm->fd);
-	pthread_mutex_unlock(&pcm->mutex);
-#endif
 
-	pthread_mutex_lock(&pcm->synced_mtx);
+	debug("PCM drain: %d", pcm->fd);
 
+	pcm->synced = false;
 	ba_transport_thread_signal_send(pcm->th, BA_TRANSPORT_THREAD_SIGNAL_PCM_SYNC);
-	pthread_cond_wait(&pcm->synced, &pcm->synced_mtx);
 
-	pthread_mutex_unlock(&pcm->synced_mtx);
+	while (!pcm->synced)
+		pthread_cond_wait(&pcm->cond, &pcm->mutex);
+
+	pthread_mutex_unlock(&pcm->mutex);
 
 	/* TODO: Asynchronous transport release.
 	 *

src/ba-transport.h

@@ -60,8 +60,10 @@ struct ba_transport_pcm {
 	/* PCM stream operation mode */
 	enum ba_transport_pcm_mode mode;
 
-	/* PCM access guard */
+	/* guard PCM data updates */
 	pthread_mutex_t mutex;
+	/* updates notification */
+	pthread_cond_t cond;
 
 	/* FIFO file descriptor */
 	int fd;
@@ -80,6 +82,9 @@ struct ba_transport_pcm {
 	 * audio encoding or decoding and data transfer. */
 	unsigned int delay;
 
+	/* indicates whether FIFO buffer was synchronized */
+	bool synced;
+
 	/* internal software volume control */
 	bool soft_volume;
 
@@ -99,10 +104,6 @@ struct ba_transport_pcm {
 		double scale;
 	} volume[2];
 
-	/* data synchronization */
-	pthread_mutex_t synced_mtx;
-	pthread_cond_t synced;
-
 	/* exported PCM D-Bus API */
 	char *ba_dbus_path;
 	bool ba_dbus_exported;
@@ -138,8 +139,10 @@ struct ba_transport_thread {
 	/* backward reference to transport */
 	struct ba_transport *t;
 
-	/* guard thread structure */
+	/* guard transport thread data updates */
 	pthread_mutex_t mutex;
+	/* state/id updates notification */
+	pthread_cond_t cond;
 
 	/* current state of the thread */
 	enum ba_transport_thread_state state;
@@ -153,9 +156,6 @@ struct ba_transport_thread {
 	/* notification PIPE */
 	int pipe[2];
 
-	/* state/id changed notification */
-	pthread_cond_t changed;
-
 };
 
 int ba_transport_thread_set_state(

src/bluealsa-dbus.c

@@ -496,7 +496,7 @@ static void bluealsa_pcm_open(GDBusMethodInvocation *inv, void *userdata) {
 		/* wait until ready to process audio */
 		pthread_mutex_lock(&th->mutex);
 		while ((state = th->state) < BA_TRANSPORT_THREAD_STATE_RUNNING)
-			pthread_cond_wait(&th->changed, &th->mutex);
+			pthread_cond_wait(&th->cond, &th->mutex);
 		pthread_mutex_unlock(&th->mutex);
 
 		/* bail if something has gone wrong */

src/io.c

@@ -181,7 +181,7 @@ ssize_t io_pcm_read(
 				errno == EINTR)
 			continue;
 		if (ret == 0) {
-			debug("PCM has been closed: %d", fd);
+			debug("PCM client closed connection: %d", fd);
 			ba_transport_pcm_release(pcm);
 		}
 	}
@@ -237,7 +237,7 @@ ssize_t io_pcm_write(
 			case EPIPE:
 				/* This errno value will be received only, when the SIGPIPE
 				 * signal is caught, blocked or ignored. */
-				debug("PCM has been closed: %d", fd);
+				debug("PCM client closed connection: %d", fd);
 				ba_transport_pcm_release(pcm);
 				ret = 0;
 				/* fall-through */
@@ -337,7 +337,10 @@ ssize_t io_poll_and_read_pcm(
 	/* Poll for reading with optional sync timeout. */
 	switch (poll_rv) {
 	case 0:
-		pthread_cond_signal(&pcm->synced);
+		pthread_mutex_lock(&pcm->mutex);
+		pcm->synced = true;
+		pthread_mutex_unlock(&pcm->mutex);
+		pthread_cond_signal(&pcm->cond);
 		io->timeout = -1;
 		return 0;
 	case -1: