Fix tty_kref leak when tty_buffer_request room fails in dma-rx path.
Note that the tty ref isn't really needed anymore, but as the leak has
always been there, fixing it before removing should makes it easier to
backport the fix.
Cc: stable@vger.kernel.org
Signed-off-by: Johan Hovold <jhovold@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
                dev_warn(port->dev, "Rx overrun: dropping %u bytes\n",
                         size - room);
        if (!room)
-               return room;
+               goto out;
 
        tty_insert_flip_string(tport, sg_virt(&priv->sg_rx), size);
 
        port->icount.rx += room;
+out:
        tty_kref_put(tty);
 
        return room;