Linux kernel mirror (for testing)
git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
kernel
os
linux
Merge branch 'tcp-fix-dsack-bug-with-non-contiguous-ranges'
Eric Dumazet says:
====================
tcp: fix DSACK bug with non contiguous ranges
This series combines a fix from xin.guo and a new packetdrill test.
====================
Link: https://patch.msgid.link/20250626123420.1933835-1-edumazet@google.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
+47
-1
+2
-1
net/ipv4/tcp_input.c
+2
-1
net/ipv4/tcp_input.c
···
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if (before(TCP_SKB_CB(skb)->seq, dsack_high)) {
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__u32 dsack = dsack_high;
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+
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if (before(TCP_SKB_CB(skb)->end_seq, dsack_high))
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-
dsack_high = TCP_SKB_CB(skb)->end_seq;
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+
dsack = TCP_SKB_CB(skb)->end_seq;
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4851
tcp_dsack_extend(sk, TCP_SKB_CB(skb)->seq, dsack);
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}
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p = rb_next(p);
+45
tools/testing/selftests/net/packetdrill/tcp_dsack_mult.pkt
+45
tools/testing/selftests/net/packetdrill/tcp_dsack_mult.pkt
···
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+
// SPDX-License-Identifier: GPL-2.0
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+
// Test various DSACK (RFC 2883) behaviors.
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+
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+
--mss=1000
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+
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`./defaults.sh`
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+
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+
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+
0 socket(..., SOCK_STREAM, IPPROTO_TCP) = 3
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+0 setsockopt(3, SOL_SOCKET, SO_REUSEADDR, [1], 4) = 0
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+
+0 bind(3, ..., ...) = 0
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+0 listen(3, 1) = 0
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+
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+0 < S 0:0(0) win 32792 <mss 1000,sackOK,nop,nop,nop,wscale 7>
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+
+0 > S. 0:0(0) ack 1 <mss 1460,nop,nop,sackOK,nop,wscale 8>
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+
+.1 < . 1:1(0) ack 1 win 1024
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+
+0 accept(3, ..., ...) = 4
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+
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// First SACK range.
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+0 < P. 1001:2001(1000) ack 1 win 1024
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+0 > . 1:1(0) ack 1 <nop, nop, sack 1001:2001>
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+
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// Check SACK coalescing (contiguous sequence).
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+0 < P. 2001:3001(1000) ack 1 win 1024
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+0 > . 1:1(0) ack 1 <nop,nop,sack 1001:3001>
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+
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+
// Check we have two SACK ranges for non contiguous sequences.
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+0 < P. 4001:5001(1000) ack 1 win 1024
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+0 > . 1:1(0) ack 1 <nop,nop,sack 4001:5001 1001:3001>
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+
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// Three ranges.
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+0 < P. 7001:8001(1000) ack 1 win 1024
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+
+0 > . 1:1(0) ack 1 <nop,nop,sack 7001:8001 4001:5001 1001:3001>
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+
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// DSACK (1001:3001) + SACK (6001:7001)
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+0 < P. 1:6001(6000) ack 1 win 1024
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+0 > . 1:1(0) ack 6001 <nop,nop,sack 1001:3001 7001:8001>
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+
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// DSACK (7001:8001)
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+0 < P. 6001:8001(2000) ack 1 win 1024
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+0 > . 1:1(0) ack 8001 <nop,nop,sack 7001:8001>
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+
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// DSACK for an older segment.
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+0 < P. 1:1001(1000) ack 1 win 1024
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+
+0 > . 1:1(0) ack 8001 <nop,nop,sack 1:1001>