spin_unlock(&current->files->file_lock);
rcu_read_unlock();
static struct tty_struct *get_tty(int fd){	struct file *filp;	struct tty_struct *ttyp = NULL;	spin_lock(&current->files->file_lock);	filp = fcheck(fd);	if(filp && filp->private_data) {		ttyp = (struct tty_struct *) filp->private_data;		if(ttyp->magic != TTY_MAGIC)			ttyp =NULL;	}	spin_unlock(&current->files->file_lock);	return ttyp;}