Fix MAVLink app teardown with mavlink stop-all command

src/modules/mavlink/mavlink_main.cpp

@@ -1629,7 +1629,7 @@ Mavlink::task_main(int argc, char *argv[])
 	mavlink_update_system();
 
 	/* start the MAVLink receiver */
-	_receive_thread = MavlinkReceiver::receive_start(this);
+	MavlinkReceiver::receive_start(&_receive_thread, this);
 
 	MavlinkOrbSubscription *param_sub = add_orb_subscription(ORB_ID(parameter_update));
 	uint64_t param_time = 0;
@@ -1988,6 +1988,9 @@ Mavlink::task_main(int argc, char *argv[])
 		_task_running = true;
 	}
 
+	/* first wait for threads to complete before tearing down anything */
+	pthread_join(_receive_thread, NULL);
+
 	delete _subscribe_to_stream;
 	_subscribe_to_stream = nullptr;
 
@@ -2015,10 +2018,7 @@ Mavlink::task_main(int argc, char *argv[])
 
 	_subscriptions = nullptr;
 
-	/* wait for threads to complete */
-	pthread_join(_receive_thread, NULL);
-
-	if (_uart_fd >= 0) {
+	if (_uart_fd >= 0 && !_is_usb_uart) {
 		/* reset the UART flags to original state */
 		tcsetattr(_uart_fd, TCSANOW, &uart_config_original);
 

src/modules/mavlink/mavlink_receiver.cpp

@@ -1918,7 +1918,7 @@ MavlinkReceiver::receive_thread(void *arg)
 		}
 	}
 
-	return NULL;
+	return nullptr;
 }
 
 void MavlinkReceiver::print_status()
@@ -1951,15 +1951,15 @@ void *MavlinkReceiver::start_helper(void *context)
 
 	MavlinkReceiver *rcv = new MavlinkReceiver((Mavlink *)context);
 
-	rcv->receive_thread(NULL);
+	void* ret = rcv->receive_thread(NULL);
 
 	delete rcv;
 
-	return nullptr;
+	return ret;
 }
 
-pthread_t
-MavlinkReceiver::receive_start(Mavlink *parent)
+void
+MavlinkReceiver::receive_start(pthread_t *thread, Mavlink *parent)
 {
 	pthread_attr_t receiveloop_attr;
 	pthread_attr_init(&receiveloop_attr);
@@ -1976,9 +1976,7 @@ MavlinkReceiver::receive_start(Mavlink *parent)
 	(void)pthread_attr_setschedparam(&receiveloop_attr, &param);
 
 	pthread_attr_setstacksize(&receiveloop_attr, 2100);
-	pthread_t thread;
-	pthread_create(&thread, &receiveloop_attr, MavlinkReceiver::start_helper, (void *)parent);
+	pthread_create(thread, &receiveloop_attr, MavlinkReceiver::start_helper, (void *)parent);
 
 	pthread_attr_destroy(&receiveloop_attr);
-	return thread;
 }

src/modules/mavlink/mavlink_receiver.h

@@ -106,12 +106,11 @@ public:
 	 */
 	void		print_status();
 
-	static pthread_t receive_start(Mavlink *parent);
+	static void receive_start(pthread_t *thread, Mavlink *parent);
 
 	static void *start_helper(void *context);
 
 private:
-	Mavlink	*_mavlink;
 
 	void handle_message(mavlink_message_t *msg);
 	void handle_message_command_long(mavlink_message_t *msg);
@@ -163,6 +162,7 @@ private:
 
 	bool	evaluate_target_ok(int command, int target_system, int target_component);
 
+	Mavlink	*_mavlink;
 	mavlink_status_t status;
 	struct vehicle_local_position_s hil_local_pos;
 	struct vehicle_land_detected_s hil_land_detector;