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authorKenneth Klette Jonassen <kennetkl@ifi.uio.no>2015-04-11 02:17:49 +0200
committerDavid S. Miller <davem@davemloft.net>2015-04-13 13:54:25 -0400
commit3d0d26c7976bf190c3f1d2efbc31462db8246bc0 (patch)
tree09b3b238bb8292ad5a2eacc770ea63b5ef457d74
parent4577139b2dabf58973d59d157aae4ddd3bde863a (diff)
tcp: fix bogus RTT for CC when retransmissions are acked
Since retransmitted segments are not used for RTT estimation, previously SACKed segments present in the rtx queue are used. This estimation can be several times larger than the actual RTT. When a cumulative ack covers both previously SACKed and retransmitted segments, CC may thus get a bogus RTT. Such segments previously had an RTT estimation in tcp_sacktag_one(), so it seems reasonable to not reuse them in tcp_clean_rtx_queue() at all. Afaik, this has had no effect on SRTT/RTO because of Karn's check. Signed-off-by: Kenneth Klette Jonassen <kennetkl@ifi.uio.no> Acked-by: Neal Cardwell <ncardwell@google.com> Tested-by: Neal Cardwell <ncardwell@google.com> Acked-by: Yuchung Cheng <ycheng@google.com> Signed-off-by: David S. Miller <davem@davemloft.net>
-rw-r--r--net/ipv4/tcp_input.c10
1 files changed, 4 insertions, 6 deletions
diff --git a/net/ipv4/tcp_input.c b/net/ipv4/tcp_input.c
index 031cf72cd05c..a7ef679dd3ea 100644
--- a/net/ipv4/tcp_input.c
+++ b/net/ipv4/tcp_input.c
@@ -3099,17 +3099,15 @@ static int tcp_clean_rtx_queue(struct sock *sk, int prior_fackets,
if (sacked & TCPCB_SACKED_RETRANS)
tp->retrans_out -= acked_pcount;
flag |= FLAG_RETRANS_DATA_ACKED;
- } else {
+ } else if (!(sacked & TCPCB_SACKED_ACKED)) {
last_ackt = skb->skb_mstamp;
WARN_ON_ONCE(last_ackt.v64 == 0);
if (!first_ackt.v64)
first_ackt = last_ackt;
- if (!(sacked & TCPCB_SACKED_ACKED)) {
- reord = min(pkts_acked, reord);
- if (!after(scb->end_seq, tp->high_seq))
- flag |= FLAG_ORIG_SACK_ACKED;
- }
+ reord = min(pkts_acked, reord);
+ if (!after(scb->end_seq, tp->high_seq))
+ flag |= FLAG_ORIG_SACK_ACKED;
}
if (sacked & TCPCB_SACKED_ACKED)