Commit 2f5a4117 authored by Jakub Kicinski's avatar Jakub Kicinski
Browse files

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: default avatarJakub Kicinski <kuba@kernel.org>
parents 680367bc 8cc8d749

net/ipv4/tcp_input.c

+2 −1
Original line number Diff line number Diff line
@@ -4845,8 +4845,9 @@ static void tcp_ofo_queue(struct sock *sk) 


		if (before(TCP_SKB_CB(skb)->seq, dsack_high)) {

			__u32 dsack = dsack_high;



			if (before(TCP_SKB_CB(skb)->end_seq, dsack_high))

				dsack_high = TCP_SKB_CB(skb)->end_seq;

				dsack = TCP_SKB_CB(skb)->end_seq;

			tcp_dsack_extend(sk, TCP_SKB_CB(skb)->seq, dsack);

		}

		p = rb_next(p);

tools/testing/selftests/net/packetdrill/tcp_dsack_mult.pkt

0 → 100644
+45 −0
Original line number Diff line number Diff line 
// SPDX-License-Identifier: GPL-2.0

// Test various DSACK (RFC 2883) behaviors.



--mss=1000



`./defaults.sh`





    0 socket(..., SOCK_STREAM, IPPROTO_TCP) = 3

   +0 setsockopt(3, SOL_SOCKET, SO_REUSEADDR, [1], 4) = 0

   +0 bind(3, ..., ...) = 0

   +0 listen(3, 1) = 0



   +0 < S 0:0(0) win 32792 <mss 1000,sackOK,nop,nop,nop,wscale 7>

   +0 > S. 0:0(0) ack 1 <mss 1460,nop,nop,sackOK,nop,wscale 8>

  +.1 < . 1:1(0) ack 1 win 1024

   +0 accept(3, ..., ...) = 4



// First SACK range.

   +0 < P. 1001:2001(1000) ack 1 win 1024

   +0 > . 1:1(0) ack 1 <nop, nop, sack 1001:2001>



// Check SACK coalescing (contiguous sequence).

   +0 < P. 2001:3001(1000) ack 1 win 1024

   +0 > . 1:1(0) ack 1 <nop,nop,sack 1001:3001>



// Check we have two SACK ranges for non contiguous sequences.

   +0 < P. 4001:5001(1000) ack 1 win 1024

   +0 > . 1:1(0) ack 1 <nop,nop,sack 4001:5001 1001:3001>



// Three ranges.

   +0 < P. 7001:8001(1000) ack 1 win 1024

   +0 > . 1:1(0) ack 1 <nop,nop,sack 7001:8001 4001:5001 1001:3001>



// DSACK (1001:3001) + SACK (6001:7001)

   +0 < P. 1:6001(6000) ack 1 win 1024

   +0 > . 1:1(0) ack 6001 <nop,nop,sack 1001:3001 7001:8001>



// DSACK (7001:8001)

   +0 < P. 6001:8001(2000) ack 1 win 1024

   +0 > . 1:1(0) ack 8001 <nop,nop,sack 7001:8001>



// DSACK for an older segment.

   +0 < P. 1:1001(1000) ack 1 win 1024

   +0 > . 1:1(0) ack 8001 <nop,nop,sack 1:1001>