px4_module: use px4_atomic_t

src/drivers/batt_smbus/batt_smbus.cpp

@@ -132,13 +132,13 @@ int BATT_SMBUS::task_spawn(int argc, char *argv[])
 
 	for (unsigned i = 0; i < NUM_BUS_OPTIONS; i++) {
 
-		if (_object == nullptr && (busid == BATT_SMBUS_BUS_ALL || bus_options[i].busid == busid)) {
+		if (!is_running() && (busid == BATT_SMBUS_BUS_ALL || bus_options[i].busid == busid)) {
 
 			SMBus *interface = new SMBus(bus_options[i].busnum, BATT_SMBUS_ADDR);
 			BATT_SMBUS *dev = new BATT_SMBUS(interface, bus_options[i].devpath);
 
 			// Successful read of device type, we've found our battery
-			_object = dev;
+			_object.store(dev);
 			_task_id = task_id_is_work_queue;
 
 			int result = dev->get_startup_info();

src/drivers/heater/heater.cpp

@@ -92,7 +92,7 @@ int Heater::controller_period(char *argv[])
 int Heater::custom_command(int argc, char *argv[])
 {
 	// Check if the driver is running.
-	if (!is_running() && !_object) {
+	if (!is_running()) {
 		PX4_INFO("not running");
 		return PX4_ERROR;
 	}
@@ -240,7 +240,7 @@ void Heater::initialize_trampoline(void *argv)
 		return;
 	}
 
-	_object = heater;
+	_object.store(heater);
 	heater->start();
 }
 

src/drivers/px4fmu/fmu.cpp

@@ -1008,7 +1008,7 @@ PX4FMU::cycle_trampoline(void *arg)
 			return;
 		}
 
-		_object = dev;
+		_object.store(dev);
 	}
 
 	dev->cycle();

src/drivers/rc_input/RCInput.cpp

@@ -189,7 +189,7 @@ RCInput::cycle_trampoline(void *arg)
 			return;
 		}
 
-		_object = dev;
+		_object.store(dev);
 	}
 
 	dev->cycle();

src/modules/events/send_event.cpp

@@ -113,7 +113,7 @@ void SendEvent::initialize_trampoline(void *arg)
 	}
 
 	send_event->start();
-	_object = send_event;
+	_object.store(send_event);
 }
 
 void SendEvent::cycle_trampoline(void *arg)

src/modules/land_detector/LandDetector.cpp

@@ -92,7 +92,7 @@ void LandDetector::_cycle()
 {
 	perf_begin(_cycle_perf);
 
-	if (_object == nullptr) { // not initialized yet
+	if (_object.load() == nullptr) { // not initialized yet
 		// Advertise the first land detected uORB.
 		_landDetected.timestamp = hrt_absolute_time();
 		_landDetected.freefall = false;
@@ -110,7 +110,7 @@ void LandDetector::_cycle()
 
 		_check_params(true);
 
-		_object = this;
+		_object.store(this);
 	}
 
 	_check_params(false);

src/modules/load_mon/load_mon.cpp

@@ -151,7 +151,7 @@ int LoadMon::task_spawn(int argc, char *argv[])
 		return ret;
 	}
 
-	_object = obj;
+	_object.store(obj);
 	_task_id = task_id_is_work_queue;
 	return 0;
 }

src/modules/wind_estimator/wind_estimator_main.cpp

@@ -173,7 +173,7 @@ WindEstimatorModule::cycle_trampoline(void *arg)
 			return;
 		}
 
-		_object = dev;
+		_object.store(dev);
 	}
 
 	if (dev) {

src/platforms/px4_module.h

@@ -41,6 +41,7 @@
 #include <unistd.h>
 #include <stdbool.h>
 
+#include <px4_atomic.h>
 #include <px4_time.h>
 #include <px4_log.h>
 #include <px4_tasks.h>
@@ -174,10 +175,10 @@ public:
 		argv += 1;
 #endif
 
-		_object = T::instantiate(argc, argv);
+		T *object = T::instantiate(argc, argv);
+		_object.store(object);
 
-		if (_object) {
+		if (object) {
-			T *object = (T *)_object;
 			object->run();
 
 		} else {
@@ -229,8 +230,9 @@ public:
 		lock_module();
 
 		if (is_running()) {
-			if (_object) {
+			T *object = _object.load();
-				T *object = (T *)_object;
+
+			if (object) {
 				object->request_stop();
 
 				unsigned int i = 0;
@@ -247,10 +249,8 @@ public:
 
 						_task_id = -1;
 
-						if (_object) {
+						delete _object.load();
-							delete _object;
+						_object.store(nullptr);
-							_object = nullptr;
-						}
 
 						ret = -1;
 						break;
@@ -279,8 +279,8 @@ public:
 		int ret = -1;
 		lock_module();
 
-		if (is_running() && _object) {
+		if (is_running() && _object.load()) {
-			T *object = (T *)_object;
+			T *object = _object.load();
 			ret = object->print_status();
 
 		} else {
@@ -326,7 +326,7 @@ protected:
 	 */
 	virtual void request_stop()
 	{
-		_task_should_exit = true;
+		_task_should_exit.store(true);
 	}
 
 	/**
@@ -335,7 +335,7 @@ protected:
 	 */
 	bool should_exit() const
 	{
-		return _task_should_exit;
+		return _task_should_exit.load();
 	}
 
 	/**
@@ -351,10 +351,8 @@ protected:
 		// - deleting the object must take place inside the lock.
 		lock_module();
 
-		if (_object) {
+		delete _object.load();
-			delete _object;
+		_object.store(nullptr);
-			_object = nullptr;
-		}
 
 		_task_id = -1; // Signal a potentially waiting thread for the module to exit that it can continue.
 		unlock_module();
@@ -372,7 +370,7 @@ protected:
 			/* Wait up to 1s. */
 			px4_usleep(2500);
 
-		} while (!_object && ++i < 400);
+		} while (!_object.load() && ++i < 400);
 
 		if (i == 400) {
 			PX4_ERR("Timed out while waiting for thread to start");
@@ -387,14 +385,14 @@ protected:
 	 */
 	static T *get_instance()
 	{
-		return (T *)_object;
+		return (T *)_object.load();
 	}
 
 	/**
 	 * @var _object Instance if the module is running.
 	 * @note There will be one instance for each template type.
 	 */
-	static volatile T *_object;
+	static px4::atomic<T *> _object;
 
 	/** @var _task_id The task handle: -1 = invalid, otherwise task is assumed to be running. */
 	static int _task_id;
@@ -420,11 +418,11 @@ private:
 	}
 
 	/** @var _task_should_exit Boolean flag to indicate if the task should exit. */
-	volatile bool _task_should_exit = false;
+	px4::atomic_bool _task_should_exit{false};
 };
 
 template<class T>
-volatile T *ModuleBase<T>::_object = nullptr;
+px4::atomic<T *> ModuleBase<T>::_object{nullptr};
 
 template<class T>
 int ModuleBase<T>::_task_id = -1;