Is communicating with a std::jthread via a std::atomic<bool> flag set by slots safe?

[andyP]

When watching a recorded online presentation named "Multithreading with Qt" by Giuseppe D’Angelo I notice that he recommends to avoid adding slots to QThread.
In the example he uses (at 50 minutes) his QThread has a Socket member variable that he creates in the run() of his thread. Not sure which class Socket actually is meant to be, but I am guessing QTcpSocket.
His thread has a slot and this will be called from the main thread since a QThread has affinity with the main thread (when it is created there).
I understand that this is a problem since QTcpSocket is reentrant but not thread safe.
I guess the same goes for QSerialPort? I should never use these in more than one thread?

In my code I have a class like this:

class Thread : public QObject {
	Q_OBJECT
public:
	Thread(); // will start threadFunction() in m_thread
public slots:
	void start() {
		m_running = true;
	}
	void stop() {
		m_running = false;
	}
private:
	void threadFunction(); // runs a forever loop and if m_running do some work
	std::atomic<bool> m_running{ false };
	std::jthread m_thread;
};

The slots start() and stop() will be called from another non main thread. Thread is created in the main thread.

Is this safe?

[Christian Ehrlicher]

@andyP said in Is communicating with a std::jthread via a std::atomic<bool> flag set by slots safe?:

Is this safe?

Yes, but it's safe even without any Qt.

[andyP]

@Christian-Ehrlicher: thank you for your help!