static int inet_csk_wait_for_connect(struct sock *sk, long timeo)
{
	struct inet_connection_sock *icsk = inet_csk(sk);
	DEFINE_WAIT(wait);
	int err;

	/*
	 * True wake-one mechanism for incoming connections: only
	 * one process gets woken up, not the 'whole herd'.
	 * Since we do not 'race & poll' for established sockets
	 * anymore, the common case will execute the loop only once.
	 *
	 * Subtle issue: "add_wait_queue_exclusive()" will be added
	 * after any current non-exclusive waiters, and we know that
	 * it will always _stay_ after any new non-exclusive waiters
	 * because all non-exclusive waiters are added at the
	 * beginning of the wait-queue. As such, it's ok to "drop"
	 * our exclusiveness temporarily when we get woken up without
	 * having to remove and re-insert us on the wait queue.
	 */
	for (;;) {
		prepare_to_wait_exclusive(sk_sleep(sk), &wait,
					  TASK_INTERRUPTIBLE);
		release_sock(sk);
		if (reqsk_queue_empty(&icsk->icsk_accept_queue))
			timeo = schedule_timeout(timeo);
		sched_annotate_sleep();
		lock_sock(sk);
		err = 0;
		if (!reqsk_queue_empty(&icsk->icsk_accept_queue))
			break;
		err = -EINVAL;
		if (sk->sk_state != TCP_LISTEN)
			break;
		err = sock_intr_errno(timeo);
		if (signal_pending(current))
			break;
		err = -EAGAIN;
		if (!timeo)
			break;
	}
	finish_wait(sk_sleep(sk), &wait);
	return err;
}
static int inet_csk_wait_for_connect(struct sock *sk, long timeo)
{
	struct inet_connection_sock *icsk = inet_csk(sk);
	DEFINE_WAIT(wait);
	int err;

	 
	for (;;) {
		prepare_to_wait_exclusive(sk_sleep(sk), &wait,
					  TASK_INTERRUPTIBLE);
		release_sock(sk);
		if (reqsk_queue_empty(&icsk->icsk_accept_queue))
			timeo = schedule_timeout(timeo);
		sched_annotate_sleep();
		lock_sock(sk);
		err = 0;
		if (!reqsk_queue_empty(&icsk->icsk_accept_queue))
			break;
		err = -EINVAL;
		if (sk->sk_state != TCP_LISTEN)
			break;
		err = sock_intr_errno(timeo);
		if (signal_pending(current))
			break;
		err = -EAGAIN;
		if (!timeo)
			break;
	}
	finish_wait(sk_sleep(sk), &wait);
	return err;
}