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authorYuchung Cheng2019-04-29 15:46:15 -0700
committerDavid S. Miller2019-05-01 11:47:54 -0400
commit9e450c1ecb027417c99eba651413d2a6ba6ffc1f (patch)
treef399effe5bad9cdffefb6485555f269016233c71 /net/ipv4
parent7c1f08154c4e34d10be41156375ce2b8ab591b0f (diff)
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 <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>
Diffstat (limited to 'net/ipv4')
-rw-r--r--net/ipv4/tcp_input.c2
-rw-r--r--net/ipv4/tcp_output.c4
2 files changed, 5 insertions, 1 deletions
diff --git a/net/ipv4/tcp_input.c b/net/ipv4/tcp_input.c
index 695f840acc14..30c6a42b1f5b 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 32061928b054..0c4ed66dc1bf 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();