tty_register_ldisc(N_X25, NULL); 
tty_unregister_ldisc(N_X25); 
static void __exit exit_x25_asy(void){	struct net_device *dev;	int i;	for (i = 0; i < x25_asy_maxdev; i++) {		dev = x25_asy_devs[i];		if (dev) {			struct x25_asy *sl = dev->priv;			spin_lock_bh(&sl->lock);			if (sl->tty) 				tty_hangup(sl->tty);			spin_unlock_bh(&sl->lock);			/*			 * VSV = if dev->start==0, then device			 * unregistered while close proc.			 */			unregister_netdev(dev);			free_netdev(dev);		}	}	kfree(x25_asy_devs);	tty_register_ldisc(N_X25, NULL);}
4520	/local/tlutelli/issta_data/temp/c/2005_temp/2005/4520/64ccd715d3cf498318b14b646ce5f97e7ab15bb5/x25_asy.c/buggy/drivers/net/wan/x25_asy.c