static void con_shutdown(struct tty_struct *tty)
{
	struct vc_data *vc = tty->driver_data;
	BUG_ON(vc == NULL);
	console_lock();
	vc->port.tty = NULL;
	console_unlock();
}
static void con_shutdown(struct tty_struct *tty)
{
	struct vc_data *vc = tty->driver_data;
	BUG_ON(vc == NULL);
	console_lock();
	vc->port.tty = NULL;
	console_unlock();
}