output: consistently lock audio output objects

Always keep the audio_output object locked within the output thread,
unless a plugin method is called.  This fixes several race conditions.

1 files changed, 39 insertions, 12 deletions

diff --git a/src/output_control.c b/src/output_control.c
index 6512cbe74..46d8f8696 100644
--- a/src/output_control.c
+++ b/src/output_control.c
@@ -24,6 +24,7 @@
 #include "mixer_control.h"
 #include "mixer_plugin.h"
 #include "filter_plugin.h"
+#include "notify.h"
 
 #include <assert.h>
 #include <stdlib.h>
@@ -39,8 +40,10 @@ struct notify audio_output_client_notify;
 static void ao_command_wait(struct audio_output *ao)
 {
 	while (ao->command != AO_COMMAND_NONE) {
-		notify_signal(&ao->notify);
+		g_cond_signal(ao->cond);
+		g_mutex_unlock(ao->mutex);
 		notify_wait(&audio_output_client_notify);
+		g_mutex_lock(ao->mutex);
 	}
 }
 
@@ -56,7 +59,7 @@ static void ao_command_async(struct audio_output *ao,
 {
 	assert(ao->command == AO_COMMAND_NONE);
 	ao->command = cmd;
-	notify_signal(&ao->notify);
+	g_cond_signal(ao->cond);
 }
 
 void
@@ -74,7 +77,9 @@ audio_output_enable(struct audio_output *ao)
 		audio_output_thread_start(ao);
 	}
 
+	g_mutex_lock(ao->mutex);
 	ao_command(ao, AO_COMMAND_ENABLE);
+	g_mutex_unlock(ao->mutex);
 }
 
 void
@@ -91,7 +96,9 @@ audio_output_disable(struct audio_output *ao)
 		return;
 	}
 
+	g_mutex_lock(ao->mutex);
 	ao_command(ao, AO_COMMAND_DISABLE);
+	g_mutex_unlock(ao->mutex);
 }
 
 static bool
@@ -157,23 +164,31 @@ audio_output_update(struct audio_output *ao,
 {
 	assert(mp != NULL);
 
+	g_mutex_lock(ao->mutex);
+
 	if (ao->enabled && ao->really_enabled) {
 		if (ao->fail_timer == NULL ||
-		    g_timer_elapsed(ao->fail_timer, NULL) > REOPEN_AFTER)
-			return audio_output_open(ao, audio_format, mp);
+		    g_timer_elapsed(ao->fail_timer, NULL) > REOPEN_AFTER) {
+			bool success = audio_output_open(ao, audio_format, mp);
+			g_mutex_unlock(ao->mutex);
+			return success;
+		}
 	} else if (audio_output_is_open(ao))
 		audio_output_close(ao);
 
+	g_mutex_unlock(ao->mutex);
 	return false;
 }
 
 void
 audio_output_play(struct audio_output *ao)
 {
-	if (!ao->open)
-		return;
+	g_mutex_lock(ao->mutex);
 
-	notify_signal(&ao->notify);
+	if (audio_output_is_open(ao))
+		g_cond_signal(ao->cond);
+
+	g_mutex_unlock(ao->mutex);
 }
 
 void audio_output_pause(struct audio_output *ao)
@@ -184,27 +199,37 @@ void audio_output_pause(struct audio_output *ao)
 		   mixer_auto_close()) */
 		mixer_auto_close(ao->mixer);
 
-	ao_command_async(ao, AO_COMMAND_PAUSE);
+	g_mutex_lock(ao->mutex);
+	if (audio_output_is_open(ao))
+		ao_command_async(ao, AO_COMMAND_PAUSE);
+	g_mutex_unlock(ao->mutex);
 }
 
 void audio_output_cancel(struct audio_output *ao)
 {
-	ao_command_async(ao, AO_COMMAND_CANCEL);
+	g_mutex_lock(ao->mutex);
+	if (audio_output_is_open(ao))
+		ao_command_async(ao, AO_COMMAND_CANCEL);
+	g_mutex_unlock(ao->mutex);
 }
 
 void audio_output_close(struct audio_output *ao)
 {
-	assert(!ao->open || ao->fail_timer == NULL);
-
 	if (ao->mixer != NULL)
 		mixer_auto_close(ao->mixer);
 
+	g_mutex_lock(ao->mutex);
+
+	assert(!ao->open || ao->fail_timer == NULL);
+
 	if (ao->open)
 		ao_command(ao, AO_COMMAND_CLOSE);
 	else if (ao->fail_timer != NULL) {
 		g_timer_destroy(ao->fail_timer);
 		ao->fail_timer = NULL;
 	}
+
+	g_mutex_unlock(ao->mutex);
 }
 
 void audio_output_finish(struct audio_output *ao)
@@ -214,7 +239,9 @@ void audio_output_finish(struct audio_output *ao)
 	assert(ao->fail_timer == NULL);
 
 	if (ao->thread != NULL) {
+		g_mutex_lock(ao->mutex);
 		ao_command(ao, AO_COMMAND_KILL);
+		g_mutex_unlock(ao->mutex);
 		g_thread_join(ao->thread);
 	}
 
@@ -223,7 +250,7 @@ void audio_output_finish(struct audio_output *ao)
 
 	ao_plugin_finish(ao->plugin, ao->data);
 
-	notify_deinit(&ao->notify);
+	g_cond_free(ao->cond);
 	g_mutex_free(ao->mutex);
 
 	filter_free(ao->filter);