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authorNeal Cardwell2013-03-04 00:23:05 -0600
committerDavid S. Miller2013-03-04 13:12:07 -0600
commitaab2b4bf224ef8358d262f95b568b8ad0cecf0a0 (patch)
treee16e5214f01f53975cb214dc98d153c9c96fe7db
parentd2123be0e55101742dacd6dae60cdd0f1e2ef302 (diff)
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tcp: fix double-counted receiver RTT when leaving receiver fast path
We should not update ts_recent and call tcp_rcv_rtt_measure_ts() both before and after going to step5. That wastes CPU and double-counts the receiver-side RTT sample. Signed-off-by: Neal Cardwell <ncardwell@google.com> Acked-by: Eric Dumazet <edumazet@google.com> Signed-off-by: David S. Miller <davem@davemloft.net>
-rw-r--r--net/ipv4/tcp_input.c6
1 files changed, 3 insertions, 3 deletions
diff --git a/net/ipv4/tcp_input.c b/net/ipv4/tcp_input.c
index a759e19496d..0d9bdacce99 100644
--- a/net/ipv4/tcp_input.c
+++ b/net/ipv4/tcp_input.c
@@ -5485,6 +5485,9 @@ int tcp_rcv_established(struct sock *sk, struct sk_buff *skb,
5485 if (tcp_checksum_complete_user(sk, skb)) 5485 if (tcp_checksum_complete_user(sk, skb))
5486 goto csum_error; 5486 goto csum_error;
5487 5487
5488 if ((int)skb->truesize > sk->sk_forward_alloc)
5489 goto step5;
5490
5488 /* Predicted packet is in window by definition. 5491 /* Predicted packet is in window by definition.
5489 * seq == rcv_nxt and rcv_wup <= rcv_nxt. 5492 * seq == rcv_nxt and rcv_wup <= rcv_nxt.
5490 * Hence, check seq<=rcv_wup reduces to: 5493 * Hence, check seq<=rcv_wup reduces to:
@@ -5496,9 +5499,6 @@ int tcp_rcv_established(struct sock *sk, struct sk_buff *skb,
5496 5499
5497 tcp_rcv_rtt_measure_ts(sk, skb); 5500 tcp_rcv_rtt_measure_ts(sk, skb);
5498 5501
5499 if ((int)skb->truesize > sk->sk_forward_alloc)
5500 goto step5;
5501
5502 NET_INC_STATS_BH(sock_net(sk), LINUX_MIB_TCPHPHITS); 5502 NET_INC_STATS_BH(sock_net(sk), LINUX_MIB_TCPHPHITS);
5503 5503
5504 /* Bulk data transfer: receiver */ 5504 /* Bulk data transfer: receiver */