From 56cc1c9c99c423e52a31a1251f1e40e521a65bc8 Mon Sep 17 00:00:00 2001 From: Eric Dumazet Date: Thu, 11 Feb 2016 08:58:18 -0800 Subject: [PATCH] tcp: do not set rtt_min to 1 commit 372022830b06d9980c7e8b41fa0a4081cff883b0 upstream. There are some cases where rtt_us derives from deltas of jiffies, instead of using usec timestamps. Since we want to track minimal rtt, better to assume a delta of 0 jiffie might be in fact be very close to 1 jiffie. It is kind of sad jiffies_to_usecs(1) calls a function instead of simply using a constant. Fixes: f672258391b42 ("tcp: track min RTT using windowed min-filter") Signed-off-by: Eric Dumazet Signed-off-by: Neal Cardwell Cc: Yuchung Cheng Signed-off-by: David S. Miller Signed-off-by: Greg Kroah-Hartman --- net/ipv4/tcp_input.c | 5 ++++- 1 file changed, 4 insertions(+), 1 deletion(-) diff --git a/net/ipv4/tcp_input.c b/net/ipv4/tcp_input.c index 88bfd663d9a2..64c7265793a5 100644 --- a/net/ipv4/tcp_input.c +++ b/net/ipv4/tcp_input.c @@ -2926,7 +2926,10 @@ static void tcp_update_rtt_min(struct sock *sk, u32 rtt_us) { const u32 now = tcp_time_stamp, wlen = sysctl_tcp_min_rtt_wlen * HZ; struct rtt_meas *m = tcp_sk(sk)->rtt_min; - struct rtt_meas rttm = { .rtt = (rtt_us ? : 1), .ts = now }; + struct rtt_meas rttm = { + .rtt = likely(rtt_us) ? rtt_us : jiffies_to_usecs(1), + .ts = now, + }; u32 elapsed; /* Check if the new measurement updates the 1st, 2nd, or 3rd choices */