From 9e45a3e36b363cc4c79c70f2b4f994e66543a219 Mon Sep 17 00:00:00 2001 From: Yuchung Cheng Date: Fri, 16 Oct 2015 21:57:41 -0700 Subject: [PATCH] tcp: apply Kern's check on RTTs used for congestion control Currently ca_seq_rtt_us does not use Kern's check. Fix that by checking if any packet acked is a retransmit, for both RTT used for RTT estimation and congestion control. Fixes: 5b08e47ca ("tcp: prefer packet timing to TS-ECR for RTT") Signed-off-by: Yuchung Cheng Signed-off-by: Neal Cardwell Signed-off-by: Eric Dumazet Signed-off-by: David S. Miller --- net/ipv4/tcp_input.c | 5 +---- 1 file changed, 1 insertion(+), 4 deletions(-) diff --git a/net/ipv4/tcp_input.c b/net/ipv4/tcp_input.c index 944eaca..62ee71ef 100644 --- a/net/ipv4/tcp_input.c +++ b/net/ipv4/tcp_input.c @@ -2925,9 +2925,6 @@ static inline bool tcp_ack_update_rtt(struct sock *sk, const int flag, * Karn's algorithm forbids taking RTT if some retransmitted data * is acked (RFC6298). */ - if (flag & FLAG_RETRANS_DATA_ACKED) - seq_rtt_us = -1L; - if (seq_rtt_us < 0) seq_rtt_us = sack_rtt_us; @@ -3169,7 +3166,7 @@ static int tcp_clean_rtx_queue(struct sock *sk, int prior_fackets, flag |= FLAG_SACK_RENEGING; skb_mstamp_get(&now); - if (likely(first_ackt.v64)) { + if (likely(first_ackt.v64) && !(flag & FLAG_RETRANS_DATA_ACKED)) { seq_rtt_us = skb_mstamp_us_delta(&now, &first_ackt); ca_rtt_us = skb_mstamp_us_delta(&now, &last_ackt); } -- 2.7.4