Donate to e Foundation | Murena handsets with /e/OS | Own a part of Murena! Learn more

Commit 4bd43f2c authored by Alan Cox's avatar Alan Cox Committed by Linus Torvalds
Browse files

tty: Fix close races in USB serial 



USB serial has always had races where the tty port usage count can hit zero
during a receive event. The internal locking is a mutex so we can't use
that in the IRQ handlers.

With krefs we can tackle this differently but we still need to be careful.

Signed-off-by: default avatarAlan Cox <alan@redhat.com>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent 7e94b1d9

drivers/usb/serial/usb-serial.c

+10 −5
Original line number Original line Diff line number Diff line
@@ -269,15 +269,19 @@ static void serial_close(struct tty_struct *tty, struct file *filp) 
		return;

		return;

	}

	}





	--port->port.count;

	if (port->port.count == 1)

	if (port->port.count == 0)

		/* only call the device specific close if this

		/* only call the device specific close if this

		 * port is being closed by the last owner */

		 * port is being closed by the last owner. Ensure we do

		 * this before we drop the port count. The call is protected

		 * by the port mutex

		 */

		port->serial->type->close(tty, port, filp);

		port->serial->type->close(tty, port, filp);





	if (port->port.count == (port->console? 1 : 0)) {

	if (port->port.count == (port->console ? 2 : 1)) {

		struct tty_struct *tty = tty_port_tty_get(&port->port);

		struct tty_struct *tty = tty_port_tty_get(&port->port);

		if (tty) {

		if (tty) {

			/* We must do this before we drop the port count to

			   zero. */

			if (tty->driver_data)

			if (tty->driver_data)

				tty->driver_data = NULL;

				tty->driver_data = NULL;

			tty_port_tty_set(&port->port, NULL);

			tty_port_tty_set(&port->port, NULL);
@@ -285,13 +289,14 @@ static void serial_close(struct tty_struct *tty, struct file *filp) 
		}

		}

	}

	}





	if (port->port.count == 0) {

	if (port->port.count == 1) {

		mutex_lock(&port->serial->disc_mutex);

		mutex_lock(&port->serial->disc_mutex);

		if (!port->serial->disconnected)

		if (!port->serial->disconnected)

			usb_autopm_put_interface(port->serial->interface);

			usb_autopm_put_interface(port->serial->interface);

		mutex_unlock(&port->serial->disc_mutex);

		mutex_unlock(&port->serial->disc_mutex);

		module_put(port->serial->type->driver.owner);

		module_put(port->serial->type->driver.owner);

	}

	}

	--port->port.count;





	mutex_unlock(&port->mutex);

	mutex_unlock(&port->mutex);

	usb_serial_put(port->serial);

	usb_serial_put(port->serial);