diff options
| author | Wei Wang <weiwan@google.com> | 2017-12-12 16:28:58 -0800 |
|---|---|---|
| committer | David S. Miller <davem@davemloft.net> | 2017-12-13 16:01:17 -0500 |
| commit | 9ee11bd03cb1a5c3ca33c2bb70e7ed325f68890f (patch) | |
| tree | 1e05b6639cbd8684e6bd85f9cc7bf02da14e2484 /net/ipv4 | |
| parent | c009cb842fcc0f84536a9d2692e6f063af5ac5c6 (diff) | |
tcp: fix potential underestimation on rcv_rtt
When ms timestamp is used, current logic uses 1us in
tcp_rcv_rtt_update() when the real rcv_rtt is within 1 - 999us.
This could cause rcv_rtt underestimation.
Fix it by always using a min value of 1ms if ms timestamp is used.
Fixes: 645f4c6f2ebd ("tcp: switch rcv_rtt_est and rcvq_space to high resolution timestamps")
Signed-off-by: Wei Wang <weiwan@google.com>
Signed-off-by: Eric Dumazet <edumazet@google.com>
Acked-by: Neal Cardwell <ncardwell@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'net/ipv4')
| -rw-r--r-- | net/ipv4/tcp_input.c | 10 |
1 files changed, 6 insertions, 4 deletions
diff --git a/net/ipv4/tcp_input.c b/net/ipv4/tcp_input.c index 9550cc42de2d..45f750e85714 100644 --- a/net/ipv4/tcp_input.c +++ b/net/ipv4/tcp_input.c @@ -508,9 +508,6 @@ static void tcp_rcv_rtt_update(struct tcp_sock *tp, u32 sample, int win_dep) u32 new_sample = tp->rcv_rtt_est.rtt_us; long m = sample; - if (m == 0) - m = 1; - if (new_sample != 0) { /* If we sample in larger samples in the non-timestamp * case, we could grossly overestimate the RTT especially @@ -547,6 +544,8 @@ static inline void tcp_rcv_rtt_measure(struct tcp_sock *tp) if (before(tp->rcv_nxt, tp->rcv_rtt_est.seq)) return; delta_us = tcp_stamp_us_delta(tp->tcp_mstamp, tp->rcv_rtt_est.time); + if (!delta_us) + delta_us = 1; tcp_rcv_rtt_update(tp, delta_us, 1); new_measure: @@ -563,8 +562,11 @@ static inline void tcp_rcv_rtt_measure_ts(struct sock *sk, (TCP_SKB_CB(skb)->end_seq - TCP_SKB_CB(skb)->seq >= inet_csk(sk)->icsk_ack.rcv_mss)) { u32 delta = tcp_time_stamp(tp) - tp->rx_opt.rcv_tsecr; - u32 delta_us = delta * (USEC_PER_SEC / TCP_TS_HZ); + u32 delta_us; + if (!delta) + delta = 1; + delta_us = delta * (USEC_PER_SEC / TCP_TS_HZ); tcp_rcv_rtt_update(tp, delta_us, 0); } } |