modules: make sure we deactivate the graph safely

Use the loop lock to ensure the loop is not using the graph anymore when
the deactivate or reset it.

src/modules/module-filter-chain.c

@@ -1041,6 +1041,7 @@ struct impl {
 	struct spa_hook graph_listener;
 	uint32_t n_inputs;
 	uint32_t n_outputs;
+	bool graph_active;
 
 	struct spa_latency_info latency[2];
 	struct spa_process_latency_info process_latency;
@@ -1131,6 +1132,7 @@ static void playback_process(void *d)
 	pw_log_trace_fp("%p: stride:%d size:%d requested:%"PRIu64" (%"PRIu64")", impl,
 			stride, data_size, out->requested, out->requested * stride);
 
+	if (impl->graph_active)
 		spa_filter_graph_process(impl->graph, cin, cout, data_size / sizeof(float));
 
 done:
@@ -1140,6 +1142,62 @@ done:
 		pw_stream_queue_buffer(impl->playback, out);
 }
 
+static int activate_graph(struct impl *impl)
+{
+	char rate[64];
+	int res;
+
+	if (impl->graph_active)
+		return 0;
+
+	snprintf(rate, sizeof(rate), "%lu", impl->rate);
+	res = spa_filter_graph_activate(impl->graph, &SPA_DICT_ITEMS(
+				SPA_DICT_ITEM(SPA_KEY_AUDIO_RATE, rate)));
+
+	if (res >= 0) {
+		struct pw_loop *data_loop = pw_stream_get_data_loop(impl->playback);
+		pw_loop_lock(data_loop);
+		impl->graph_active = true;
+		pw_loop_unlock(data_loop);
+	}
+	return res;
+}
+
+static int deactivate_graph(struct impl *impl)
+{
+	struct pw_loop *data_loop;
+
+	if (!impl->graph_active)
+		return 0;
+
+	data_loop = pw_stream_get_data_loop(impl->playback);
+
+	pw_loop_lock(data_loop);
+	impl->graph_active = false;
+	pw_loop_unlock(data_loop);
+
+	return spa_filter_graph_deactivate(impl->graph);
+}
+
+static int reset_graph(struct impl *impl)
+{
+	struct pw_loop *data_loop = pw_stream_get_data_loop(impl->playback);
+	int res;
+	bool old_active = impl->graph_active;
+
+	pw_loop_lock(data_loop);
+	impl->graph_active = false;
+	pw_loop_unlock(data_loop);
+
+	res = spa_filter_graph_reset(impl->graph);
+
+	pw_loop_lock(data_loop);
+	impl->graph_active = old_active;
+	pw_loop_unlock(data_loop);
+
+	return res;
+}
+
 static void update_latencies(struct impl *impl)
 {
 	struct spa_latency_info latency;
@@ -1249,7 +1307,6 @@ static void io_changed(void *data, uint32_t id, void *area, uint32_t size)
 static void param_changed(struct impl *impl, uint32_t id, const struct spa_pod *param,
 		enum spa_direction direction, struct pw_stream *stream, struct pw_stream *other)
 {
-	struct spa_filter_graph *graph = impl->graph;
 	int res;
 
 	switch (id) {
@@ -1260,7 +1317,7 @@ static void param_changed(struct impl *impl, uint32_t id, const struct spa_pod *
 		if (param == NULL) {
 			pw_log_info("module %p: filter deactivate", impl);
 			if (direction == SPA_DIRECTION_INPUT)
-				spa_filter_graph_deactivate(graph);
+				deactivate_graph(impl);
 			impl->rate = 0;
 		} else {
 			if ((res = spa_format_audio_raw_parse(param, &info)) < 0)
@@ -1309,13 +1366,12 @@ static void playback_state_changed(void *data, enum pw_stream_state old,
 		enum pw_stream_state state, const char *error)
 {
 	struct impl *impl = data;
-	struct spa_filter_graph *graph = impl->graph;
 	int res;
 
 	switch (state) {
 	case PW_STREAM_STATE_PAUSED:
 		pw_stream_flush(impl->playback, false);
-		spa_filter_graph_reset(graph);
+		reset_graph(impl);
 		break;
 	case PW_STREAM_STATE_UNCONNECTED:
 		pw_log_info("module %p: unconnected", impl);
@@ -1335,15 +1391,11 @@ static void playback_state_changed(void *data, enum pw_stream_state old,
 			goto error;
 		}
 		if (impl->rate != target) {
-			char rate[64];
 			impl->rate = target;
-			snprintf(rate, sizeof(rate), "%lu", impl->rate);
+			deactivate_graph(impl);
-			spa_filter_graph_deactivate(graph);
-			if ((res = spa_filter_graph_activate(graph,
-					&SPA_DICT_ITEMS(
-						SPA_DICT_ITEM(SPA_KEY_AUDIO_RATE, rate)))) < 0)
-				goto error;
 		}
+		if ((res = activate_graph(impl)) < 0)
+			goto error;
 		break;
 	}
 	default: