52 lines
1.9 KiB
Diff
52 lines
1.9 KiB
Diff
From 598856407d4e20ebb4de01a91a93d89325924d43 Mon Sep 17 00:00:00 2001
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From: Damian Lukowski <damian@tvk.rwth-aachen.de>
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Date: Wed, 10 Feb 2010 18:04:08 -0800
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Subject: [PATCH] tcp: fix ICMP-RTO war
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Make sure, that TCP has a nonzero RTT estimation after three-way
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handshake. Currently, a listening TCP has a value of 0 for srtt,
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rttvar and rto right after the three-way handshake is completed
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with TCP timestamps disabled.
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This will lead to corrupt RTO recalculation and retransmission
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flood when RTO is recalculated on backoff reversion as introduced
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in "Revert RTO on ICMP destination unreachable"
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(f1ecd5d9e7366609d640ff4040304ea197fbc618).
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This behaviour can be provoked by connecting to a server which
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"responds first" (like SMTP) and rejecting every packet after
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the handshake with dest-unreachable, which will lead to softirq
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load on the server (up to 30% per socket in some tests).
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Thanks to Ilpo Jarvinen for providing debug patches and to
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Denys Fedoryshchenko for reporting and testing.
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Changes since v3: Removed bad characters in patchfile.
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Reported-by: Denys Fedoryshchenko <denys@visp.net.lb>
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Signed-off-by: Damian Lukowski <damian@tvk.rwth-aachen.de>
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Signed-off-by: David S. Miller <davem@davemloft.net>
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---
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net/ipv4/tcp_input.c | 6 ++----
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1 files changed, 2 insertions(+), 4 deletions(-)
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diff --git a/net/ipv4/tcp_input.c b/net/ipv4/tcp_input.c
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index 28e0296..3fddc69 100644
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--- a/net/ipv4/tcp_input.c
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+++ b/net/ipv4/tcp_input.c
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@@ -5783,11 +5783,9 @@ int tcp_rcv_state_process(struct sock *sk, struct sk_buff *skb,
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/* tcp_ack considers this ACK as duplicate
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* and does not calculate rtt.
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- * Fix it at least with timestamps.
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+ * Force it here.
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*/
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- if (tp->rx_opt.saw_tstamp &&
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- tp->rx_opt.rcv_tsecr && !tp->srtt)
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- tcp_ack_saw_tstamp(sk, 0);
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+ tcp_ack_update_rtt(sk, 0, 0);
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if (tp->rx_opt.tstamp_ok)
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tp->advmss -= TCPOLEN_TSTAMP_ALIGNED;
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--
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1.6.6.1
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