Reduce complexity of __tty_hangup(); separate SIGHUP signalling
into tty_signal_session_leader().
Signed-off-by: NPeter Hurley <peter@hurleysoftware.com>
Acked-by: NJiri Slaby <jslaby@suse.cz>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>