commit daf82bd24e308c5a83758047aff1bd81edda4f11 upstream.

gserial_alloc_line() misses locking (for a release barrier) while
resetting port entry on TTY allocation failure. Fix this.

Cc: stable@vger.kernel.org
Signed-off-by: NMichał Mirosław <mirq-linux@rere.qmqm.pl>
Reviewed-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>
Tested-by: NLadislav Michl <ladis@linux-mips.org>
Signed-off-by: NFelipe Balbi <felipe.balbi@linux.intel.com>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>