From 9e450c1ecb027417c99eba651413d2a6ba6ffc1f Mon Sep 17 00:00:00 2001 From: Yuchung Cheng Date: Mon, 29 Apr 2019 15:46:15 -0700 Subject: [PATCH] tcp: better SYNACK sent timestamp Detecting spurious SYNACK timeout using timestamp option requires recording the exact SYNACK skb timestamp. Previously the SYNACK sent timestamp was stamped slightly earlier before the skb was transmitted. This patch uses the SYNACK skb transmission timestamp directly. Signed-off-by: Yuchung Cheng Signed-off-by: Neal Cardwell Signed-off-by: Eric Dumazet Signed-off-by: David S. Miller --- net/ipv4/tcp_input.c | 2 +- net/ipv4/tcp_output.c | 4 ++++ 2 files changed, 5 insertions(+), 1 deletion(-) diff --git a/net/ipv4/tcp_input.c b/net/ipv4/tcp_input.c index 695f840..30c6a42 100644 --- a/net/ipv4/tcp_input.c +++ b/net/ipv4/tcp_input.c @@ -6319,7 +6319,7 @@ static void tcp_openreq_init(struct request_sock *req, req->cookie_ts = 0; tcp_rsk(req)->rcv_isn = TCP_SKB_CB(skb)->seq; tcp_rsk(req)->rcv_nxt = TCP_SKB_CB(skb)->seq + 1; - tcp_rsk(req)->snt_synack = tcp_clock_us(); + tcp_rsk(req)->snt_synack = 0; tcp_rsk(req)->last_oow_ack_time = 0; req->mss = rx_opt->mss_clamp; req->ts_recent = rx_opt->saw_tstamp ? rx_opt->rcv_tsval : 0; diff --git a/net/ipv4/tcp_output.c b/net/ipv4/tcp_output.c index 3206192..0c4ed66 100644 --- a/net/ipv4/tcp_output.c +++ b/net/ipv4/tcp_output.c @@ -3247,7 +3247,11 @@ struct sk_buff *tcp_make_synack(const struct sock *sk, struct dst_entry *dst, skb->skb_mstamp_ns = cookie_init_timestamp(req); else #endif + { skb->skb_mstamp_ns = tcp_clock_ns(); + if (!tcp_rsk(req)->snt_synack) /* Timestamp first SYNACK */ + tcp_rsk(req)->snt_synack = tcp_skb_timestamp_us(skb); + } #ifdef CONFIG_TCP_MD5SIG rcu_read_lock(); -- 2.7.4