diff mbox

[3.16.y-ckt,stable] Patch "tcp: apply Kern's check on RTTs used for congestion control" has been added to staging queue

Message ID 1448886905-17432-1-git-send-email-luis.henriques@canonical.com
State New
Headers show

Commit Message

Luis Henriques Nov. 30, 2015, 12:35 p.m. UTC 
This is a note to let you know that I have just added a patch titled

    tcp: apply Kern's check on RTTs used for congestion control

to the linux-3.16.y-queue branch of the 3.16.y-ckt extended stable tree 
which can be found at:

    http://kernel.ubuntu.com/git/ubuntu/linux.git/log/?h=linux-3.16.y-queue

This patch is scheduled to be released in version 3.16.7-ckt21.

If you, or anyone else, feels it should not be added to this tree, please 
reply to this email.

For more information about the 3.16.y-ckt tree, see
https://wiki.ubuntu.com/Kernel/Dev/ExtendedStable

Thanks.
-Luis

------

From 4368da561b82c87871734e3f4858c0e15d0091ed Mon Sep 17 00:00:00 2001
From: Yuchung Cheng <ycheng@google.com>
Date: Fri, 16 Oct 2015 21:57:41 -0700
Subject: 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 <ycheng@google.com>
Signed-off-by: Neal Cardwell <ncardwell@google.com>
Signed-off-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
[ luis: backported to 3.16: adjusted context ]
Signed-off-by: Luis Henriques <luis.henriques@canonical.com>
---
 net/ipv4/tcp_input.c | 5 +----
 1 file changed, 1 insertion(+), 4 deletions(-)
diff mbox

Patch

diff --git a/net/ipv4/tcp_input.c b/net/ipv4/tcp_input.c
index 0cdaa633059b..e3d40a303b8f 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);
 	}