commit d3a7b83f upstream.

tty_unlock is used on all other exits from the function.
Signed-off-by: Julia Lawall <Julia.Lawall@lip6.fr>
Acked-by: Jiri Slaby <jslaby@suse.cz>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>