Commit d2ccd7bc authored Aug 09, 2018 by Yuchung Cheng Committed by David S. Miller Aug 11, 2018

tcp: avoid resetting ACK timer in DCTCP



The recent fix of acking immediately in DCTCP on CE status change
has an undesirable side-effect: it also resets TCP ack timer and
disables pingpong mode (interactive session). But the CE status
change has nothing to do with them. This patch addresses that by
using the new one-time immediate ACK flag instead of calling
tcp_enter_quickack_mode().

Signed-off-by: Yuchung Cheng <ycheng@google.com>
Signed-off-by: Neal Cardwell <ncardwell@google.com>
Signed-off-by: Wei Wang <weiwan@google.com>
Signed-off-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

parent 466466dc

net/ipv4/tcp_dctcp.c

+2 −2

Original line number	Diff line number	Diff line
		@@ -136,7 +136,7 @@ static void dctcp_ce_state_0_to_1(struct sock *sk)
		*/
		if (inet_csk(sk)->icsk_ack.pending & ICSK_ACK_TIMER)
		__tcp_send_ack(sk, ca->prior_rcv_nxt);
		tcp_enter_quickack_mode(sk, 1);
		inet_csk(sk)->icsk_ack.pending \|= ICSK_ACK_NOW;
		}

		ca->prior_rcv_nxt = tp->rcv_nxt;
		@@ -157,7 +157,7 @@ static void dctcp_ce_state_1_to_0(struct sock *sk)
		*/
		if (inet_csk(sk)->icsk_ack.pending & ICSK_ACK_TIMER)
		__tcp_send_ack(sk, ca->prior_rcv_nxt);
		tcp_enter_quickack_mode(sk, 1);
		inet_csk(sk)->icsk_ack.pending \|= ICSK_ACK_NOW;
		}

		ca->prior_rcv_nxt = tp->rcv_nxt;

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