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

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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>
This commit is contained in:
Yuchung Cheng 2015-10-16 21:57:41 -07:00 committed by David S. Miller
parent c8fdc32491
commit 9e45a3e36b
1 changed files with 1 additions and 4 deletions
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5
net/ipv4/tcp_input.c
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@ -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);
}