[3.19.y-ckt stable] Patch "tcp: apply Kern's check on RTTs used for congestion control" has been added to staging queue
Kamal Mostafa
kamal at canonical.com
Mon Nov 30 22:11:03 UTC 2015
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-3.19.y-queue branch of the 3.19.y-ckt extended stable tree
which can be found at:
http://kernel.ubuntu.com/git/ubuntu/linux.git/log/?h=linux-3.19.y-queue
This patch is scheduled to be released in version 3.19.8-ckt11.
If you, or anyone else, feels it should not be added to this tree, please
reply to this email.
For more information about the 3.19.y-ckt tree, see
https://wiki.ubuntu.com/Kernel/Dev/ExtendedStable
Thanks.
-Kamal
------
>From 188f5b612b8e8b8528af568659964a99f3e8f1da Mon Sep 17 00:00:00 2001
From: Yuchung Cheng <ycheng at 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 at google.com>
Signed-off-by: Neal Cardwell <ncardwell at google.com>
Signed-off-by: Eric Dumazet <edumazet at google.com>
Signed-off-by: David S. Miller <davem at davemloft.net>
Signed-off-by: Kamal Mostafa <kamal at canonical.com>
---
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 08ccca6..8e967ef 100644
--- a/net/ipv4/tcp_input.c
+++ b/net/ipv4/tcp_input.c
@@ -2907,9 +2907,6 @@ 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;
@@ -3151,7 +3148,7 @@ 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_seq_rtt_us = skb_mstamp_us_delta(&now, &last_ackt);
}
--
1.9.1
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