logger: proper error handling if writer thread creation fails

src/modules/logger/log_writer.cpp

@@ -48,7 +48,7 @@ void LogWriter::stop_log()
 	notify();
 }
 
-pthread_t LogWriter::thread_start()
+int LogWriter::thread_start(pthread_t &thread)
 {
 	pthread_attr_t thr_attr;
 	pthread_attr_init(&thr_attr);
@@ -60,15 +60,10 @@ pthread_t LogWriter::thread_start()
 
 	pthread_attr_setstacksize(&thr_attr, 1024);
 
-	pthread_t thr;
-
-	if (0 != pthread_create(&thr, &thr_attr, &LogWriter::run_helper, this)) {
-		PX4_WARN("error creating logwriter thread");
-	}
-
+	int ret = pthread_create(&thread, &thr_attr, &LogWriter::run_helper, this);
 	pthread_attr_destroy(&thr_attr);
 
-	return thr;
+	return ret;
 }
 
 void LogWriter::thread_stop()

src/modules/logger/log_writer.h

@@ -17,7 +17,12 @@ class LogWriter
 public:
 	LogWriter(uint8_t *buffer, size_t buffer_size);
 
-	pthread_t thread_start();
+	/**
+	 * start the thread
+	 * @param thread will be set to the created thread on success
+	 * @return 0 on success, error number otherwise (@see pthread_create)
+	 */
+	int thread_start(pthread_t &thread);
 
 	void thread_stop();
 

src/modules/logger/logger.cpp

@@ -402,7 +402,12 @@ void Logger::run()
 //	add_topic("estimator_status");
 	add_topic("vehicle_status", 100);
 
-	_writer_thread = _writer.thread_start();
+	int ret = _writer.thread_start(_writer_thread);
+
+	if (ret) {
+		PX4_ERR("logger: failed to create writer thread (%i)", ret);
+		return;
+	}
 
 	_task_should_exit = false;
 
@@ -584,7 +589,7 @@ void Logger::run()
 	_writer.notify();
 
 	// wait for thread to complete
-	int ret = pthread_join(_writer_thread, NULL);
+	ret = pthread_join(_writer_thread, NULL);
 
 	if (ret) {
 		PX4_WARN("join failed: %d", ret);