fix race when ending freewheeling (from torben)

git-svn-id: svn+ssh://jackaudio.org/trunk/jack@3879 0c269be4-1314-0410-8aa9-9f06e86f4224

jack/engine.h

@@ -111,8 +111,10 @@ struct _jack_engine {
     unsigned long   fifo_size;
     unsigned long   external_client_cnt;
     int		    rtpriority;
-    char	    freewheeling;
+    volatile char   freewheeling;
+    volatile char   stop_freewheeling;
     jack_client_id_t fwclient;
+    pthread_t       freewheel_thread;
     char	    verbose;
     char	    do_munlock;
     const char	   *server_name;
@@ -122,7 +124,6 @@ struct _jack_engine {
     int		    feedbackcount;
     int             removing_clients;
     pid_t           wait_pid;
-    pthread_t       freewheel_thread;
     int             nozombies;
     volatile int    problems;
 

jackd/engine.c

@@ -1749,6 +1749,7 @@ jack_engine_new (int realtime, int rtpriority, int do_mlock, int do_unlock,
 	engine->server_name = server_name;
 	engine->temporary = temporary;
 	engine->freewheeling = 0;
+	engine->stop_freewheeling = 0;
 	engine->fwclient = 0;
 	engine->feedbackcount = 0;
 	engine->wait_pid = wait_pid;
@@ -2019,7 +2020,7 @@ jack_engine_freewheel (void *arg)
 
 	client = jack_client_internal_by_id (engine, engine->fwclient);
 
-	while (engine->freewheeling) {
+	while (!engine->stop_freewheeling) {
 
 		jack_run_one_cycle (engine, engine->control->buffer_size, 0.0f);
 
@@ -2067,6 +2068,7 @@ jack_start_freewheeling (jack_engine_t* engine, jack_client_id_t client_id)
 	}
 
 	engine->freewheeling = 1;
+	engine->stop_freewheeling = 0;
 
 	event.type = StartFreewheel;
 	jack_deliver_event_to_all (engine, &event);
@@ -2104,13 +2106,15 @@ jack_stop_freewheeling (jack_engine_t* engine, int engine_exiting)
 	   to exit.
 	*/
 
-	engine->fwclient = 0;
-	engine->freewheeling = 0;
+	engine->stop_freewheeling = 1;
 
 	VERBOSE (engine, "freewheeling stopped, waiting for thread");
 	pthread_join (engine->freewheel_thread, &ftstatus);
 	VERBOSE (engine, "freewheel thread has returned");
 
+	engine->fwclient = 0;
+	engine->freewheeling = 0;
+
 	if (!engine_exiting) {
 		/* tell everyone we've stopped */