int tcp_set_rcvlowat(struct sock *sk, int val)
{
	int cap;

	if (sk->sk_userlocks & SOCK_RCVBUF_LOCK)
		cap = sk->sk_rcvbuf >> 1;
	else
		cap = sock_net(sk)->ipv4.sysctl_tcp_rmem[2] >> 1;
	val = min(val, cap);
	sk->sk_rcvlowat = val ? : 1;

	/* Check if we need to signal EPOLLIN right now */
	tcp_data_ready(sk);

	if (sk->sk_userlocks & SOCK_RCVBUF_LOCK)
		return 0;

	val <<= 1;
	if (val > sk->sk_rcvbuf) {
		sk->sk_rcvbuf = val;
		tcp_sk(sk)->window_clamp = tcp_win_from_space(sk, val);
	}
	return 0;
}
int tcp_set_rcvlowat(struct sock *sk, int val)
{
	int cap;

	if (sk->sk_userlocks & SOCK_RCVBUF_LOCK)
		cap = sk->sk_rcvbuf >> 1;
	else
		cap = sock_net(sk)->ipv4.sysctl_tcp_rmem[2] >> 1;
	val = min(val, cap);
	sk->sk_rcvlowat = val ? : 1;

	 
	tcp_data_ready(sk);

	if (sk->sk_userlocks & SOCK_RCVBUF_LOCK)
		return 0;

	val <<= 1;
	if (val > sk->sk_rcvbuf) {
		sk->sk_rcvbuf = val;
		tcp_sk(sk)->window_clamp = tcp_win_from_space(sk, val);
	}
	return 0;
}