serdev: ttyport: add missing open() error handling

Add missing error handling for tty-driver open() which may fail (e.g. if
resource allocation fails or if a port is being disconnected).

Note that close() must be called also in case of failed open() and that
the operation sanity check is amended to catch buggy drivers.

Signed-off-by: Johan Hovold <johan@kernel.org>
Acked-by: Rob Herring <robh@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/tty/serdev/serdev-ttyport.c

@@ -96,16 +96,21 @@ static int ttyport_open(struct serdev_controller *ctrl)
 	struct serport *serport = serdev_controller_get_drvdata(ctrl);
 	struct tty_struct *tty;
 	struct ktermios ktermios;
+	int ret;
 
 	tty = tty_init_dev(serport->tty_drv, serport->tty_idx);
 	if (IS_ERR(tty))
 		return PTR_ERR(tty);
 	serport->tty = tty;
 
-	if (!tty->ops->open)
+	if (!tty->ops->open || !tty->ops->close) {
+		ret = -ENODEV;
 		goto err_unlock;
+	}
 
-	tty->ops->open(serport->tty, NULL);
+	ret = tty->ops->open(serport->tty, NULL);
+	if (ret)
+		goto err_close;
 
 	/* Bring the UART into a known 8 bits no parity hw fc state */
 	ktermios = tty->termios;
@@ -123,11 +128,13 @@ static int ttyport_open(struct serdev_controller *ctrl)
 	tty_unlock(serport->tty);
 	return 0;
 
+err_close:
+	tty->ops->close(tty, NULL);
 err_unlock:
 	tty_unlock(tty);
 	tty_release_struct(tty, serport->tty_idx);
 
-	return -ENODEV;
+	return ret;
 }
 
 static void ttyport_close(struct serdev_controller *ctrl)