From: Yuchung Cheng Date: Sat, 17 Oct 2015 04:57:41 +0000 (-0700) Subject: tcp: apply Kern's check on RTTs used for congestion control X-Git-Tag: v3.16.35~971 X-Git-Url: http://git.ipfire.org/gitweb.cgi?a=commitdiff_plain;h=dec3ceaf2159f46364a9d0f67c43e5fb37ae1d60;p=thirdparty%2Fkernel%2Fstable.git tcp: apply Kern's check on RTTs used for congestion control commit 9e45a3e36b363cc4c79c70f2b4f994e66543a219 upstream. 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 [ luis: backported to 3.16: adjusted context ] Signed-off-by: Luis Henriques --- diff --git a/net/ipv4/tcp_input.c b/net/ipv4/tcp_input.c index 0cdaa633059b6..e3d40a303b8f0 100644 --- a/net/ipv4/tcp_input.c +++ b/net/ipv4/tcp_input.c @@ -2891,9 +2891,6 @@ 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; @@ -3115,7 +3112,7 @@ static int tcp_clean_rtx_queue(struct sock *sk, int prior_fackets, flag |= FLAG_SACK_RENEGING; skb_mstamp_get(&now); - if (first_ackt.v64) { + if (first_ackt.v64 && !(flag & FLAG_RETRANS_DATA_ACKED)) { seq_rtt_us = skb_mstamp_us_delta(&now, &first_ackt); ca_seq_rtt_us = skb_mstamp_us_delta(&now, &last_ackt); }