Make sure to hold the tty lock as required when calling tty-driver
close() (e.g. to avoid racing with hangup()).
Note that the serport active flag is currently set under the lock at
controller open, but really isn't protected by it.
Fixes: cd6484e183 ("serdev: Introduce new bus for serial attached devices")
Signed-off-by: Johan Hovold <johan@kernel.org>
Cc: stable <stable@vger.kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
90dbad8cd6