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Commit c7004482 authored by David S. Miller's avatar David S. Miller
Browse files

tcp: Respect SO_RCVLOWAT in tcp_poll(). 



Based upon a report by Vito Caputo.

Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent 6252352d

net/ipv4/tcp.c

+8 −4
Original line number Diff line number Diff line
@@ -384,13 +384,17 @@ unsigned int tcp_poll(struct file *file, struct socket *sock, poll_table *wait) 


	/* Connected? */

	if ((1 << sk->sk_state) & ~(TCPF_SYN_SENT | TCPF_SYN_RECV)) {

		int target = sock_rcvlowat(sk, 0, INT_MAX);



		if (tp->urg_seq == tp->copied_seq &&

		    !sock_flag(sk, SOCK_URGINLINE) &&

		    tp->urg_data)

			target--;



		/* Potential race condition. If read of tp below will

		 * escape above sk->sk_state, we can be illegally awaken

		 * in SYN_* states. */

		if ((tp->rcv_nxt != tp->copied_seq) &&

		    (tp->urg_seq != tp->copied_seq ||

		     tp->rcv_nxt != tp->copied_seq + 1 ||

		     sock_flag(sk, SOCK_URGINLINE) || !tp->urg_data))

		if (tp->rcv_nxt - tp->copied_seq >= target)

			mask |= POLLIN | POLLRDNORM;



		if (!(sk->sk_shutdown & SEND_SHUTDOWN)) {