4.2.8-ckt1 -stable review patch.  If anyone has any objections, please let me 
know.

------------------

From: Yuchung Cheng <ych...@google.com>

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 <ych...@google.com>
Signed-off-by: Neal Cardwell <ncardw...@google.com>
Signed-off-by: Eric Dumazet <eduma...@google.com>
Signed-off-by: David S. Miller <da...@davemloft.net>
Signed-off-by: Kamal Mostafa <ka...@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 77730b4..297b358 100644
--- a/net/ipv4/tcp_input.c
+++ b/net/ipv4/tcp_input.c
@@ -2902,9 +2902,6 @@ 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;
 
@@ -3146,7 +3143,7 @@ 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);
        }
-- 
1.9.1

--
To unsubscribe from this list: send the line "unsubscribe stable" in
the body of a message to majord...@vger.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html

Reply via email to