Bluetooth: Force -EIO from tty read/write if .activate() fails

If rfcomm_dlc_open() fails, set tty into error state which returns
-EIO from reads and writes.
Signed-off-by: Peter Hurley <peter@hurleysoftware.com>
Tested-By: Alexander Holler <holler@ahsoftware.de>
Signed-off-by: Marcel Holtmann <marcel@holtmann.org>

net/bluetooth/rfcomm/tty.c

@@ -111,8 +111,12 @@ static void rfcomm_dev_destruct(struct tty_port *port)
 static int rfcomm_dev_activate(struct tty_port *port, struct tty_struct *tty)
 {
 	struct rfcomm_dev *dev = container_of(port, struct rfcomm_dev, port);
+	int err;
 
-	return rfcomm_dlc_open(dev->dlc, &dev->src, &dev->dst, dev->channel);
+	err = rfcomm_dlc_open(dev->dlc, &dev->src, &dev->dst, dev->channel);
+	if (err)
+		set_bit(TTY_IO_ERROR, &tty->flags);
+	return err;
 }
 
 /* we block the open until the dlc->state becomes BT_CONNECTED */