Commit 6e97ba55 authored by Eric Dumazet's avatar Eric Dumazet Committed by David S. Miller
Browse files

tcp: set TCP_DEFER_ACCEPT locklessly 



rskq_defer_accept field can be read/written without
the need of holding the socket lock.

Signed-off-by: default avatarEric Dumazet <edumazet@google.com>
Acked-by: default avatarSoheil Hassas Yeganeh <soheil@google.com>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent a81722dd

net/ipv4/tcp.c

+6 −7
Original line number Diff line number Diff line
@@ -3479,6 +3479,12 @@ int do_tcp_setsockopt(struct sock *sk, int level, int optname, 
		else

			WRITE_ONCE(tp->linger2, val * HZ);

		return 0;

	case TCP_DEFER_ACCEPT:

		/* Translate value in seconds to number of retransmits */

		WRITE_ONCE(icsk->icsk_accept_queue.rskq_defer_accept,

			   secs_to_retrans(val, TCP_TIMEOUT_INIT / HZ,

					   TCP_RTO_MAX / HZ));

		return 0;

	}



	sockopt_lock_sock(sk);
@@ -3584,13 +3590,6 @@ int do_tcp_setsockopt(struct sock *sk, int level, int optname, 
			tp->save_syn = val;

		break;



	case TCP_DEFER_ACCEPT:

		/* Translate value in seconds to number of retransmits */

		WRITE_ONCE(icsk->icsk_accept_queue.rskq_defer_accept,

			   secs_to_retrans(val, TCP_TIMEOUT_INIT / HZ,

					   TCP_RTO_MAX / HZ));

		break;



	case TCP_WINDOW_CLAMP:

		err = tcp_set_window_clamp(sk, val);

		break;

net/ipv4/tcp_input.c

+1 −1
Original line number Diff line number Diff line
@@ -6324,7 +6324,7 @@ static int tcp_rcv_synsent_state_process(struct sock *sk, struct sk_buff *skb, 
		if (fastopen_fail)

			return -1;

		if (sk->sk_write_pending ||

		    icsk->icsk_accept_queue.rskq_defer_accept ||

		    READ_ONCE(icsk->icsk_accept_queue.rskq_defer_accept) ||

		    inet_csk_in_pingpong_mode(sk)) {

			/* Save one ACK. Data will be ready after

			 * several ticks, if write_pending is set.

net/ipv4/tcp_minisocks.c

+1 −1
Original line number Diff line number Diff line
@@ -792,7 +792,7 @@ struct sock *tcp_check_req(struct sock *sk, struct sk_buff *skb, 
		return sk;



	/* While TCP_DEFER_ACCEPT is active, drop bare ACK. */

	if (req->num_timeout < inet_csk(sk)->icsk_accept_queue.rskq_defer_accept &&

	if (req->num_timeout < READ_ONCE(inet_csk(sk)->icsk_accept_queue.rskq_defer_accept) &&

	    TCP_SKB_CB(skb)->end_seq == tcp_rsk(req)->rcv_isn + 1) {

		inet_rsk(req)->acked = 1;

		__NET_INC_STATS(sock_net(sk), LINUX_MIB_TCPDEFERACCEPTDROP);