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charset="utf-8" Message-Id: <20261026-advmss-revert-v1-1-272fa4b7ecb6@gmail.com> References: <20261026-advmss-revert-v1-0-272fa4b7ecb6@gmail.com> In-Reply-To: <20261026-advmss-revert-v1-0-272fa4b7ecb6@gmail.com> To: netdev@vger.kernel.org Cc: Jakub Kicinski , Paolo Abeni , "David S. Miller" , Simon Horman , David Ahern , Ido Schimmel , Jiayuan Chen , Shuah Khan , Thorsten Leemhuis , regressions@lists.linux.dev, linux-kselftest@vger.kernel.org, linux-kernel@vger.kernel.org, stable@vger.kernel.org, Esko Mobius , Eric Dumazet X-Mailer: b4 0.16.0 X-Developer-Signature: v=1; a=ed25519-sha256; t=1792999388; l=5480; i=echoowall@gmail.com; s=20261026; h=from:subject:message-id; bh=uFnONYx2E6brR0l6+uJjUZUsugs/bXfH+6zBoDLWc54=; b=ULddStXmSXwCyHaZ46Fz3sv7//3MUR2oEh/dcoU8rRoKUg6NFa32swzD10M6rBqiBLz6pxB/j 8ErFryqgmZfDuAGhVRXuNpw3laLQd4RMH3tfo21TFP6t+nVr47rQerU X-Developer-Key: i=echoowall@gmail.com; a=ed25519; pk=9XP6JhqjjPsHCF6UZZZTeqTRnXIa4+ufggnxXtTJ+no= X-Endpoint-Received: by B4 Relay for echoowall@gmail.com/20261026 with auth_id=1323 X-Original-From: Esko Mobius Reply-To: echoowall@gmail.com Content-Transfer-Encoding: 7bit From: Esko Mobius This reverts commit e5c8e301b497 ("selftests: net: packetdrill: add tests for advertised MSS with PMTU exceptions"). These tests assert the behaviour introduced by commit 2640e6419594 ("net: advertise TCP MSS from the configured MTU, not the learned PMTU"), which is reverted in the next patch because it causes a regression. Remove them first so the series stays bisectable. Signed-off-by: Esko Mobius --- .../net/packetdrill/tcp_advmss_pmtu_ipv4.pkt | 67 ---------------------- .../net/packetdrill/tcp_advmss_pmtu_ipv6.pkt | 67 ---------------------- 2 files changed, 134 deletions(-) diff --git a/tools/testing/selftests/net/packetdrill/tcp_advmss_pmtu_ipv4.pkt b/tools/testing/selftests/net/packetdrill/tcp_advmss_pmtu_ipv4.pkt deleted file mode 100644 index f2ef931b7..000000000 --- a/tools/testing/selftests/net/packetdrill/tcp_advmss_pmtu_ipv4.pkt +++ /dev/null @@ -1,67 +0,0 @@ -// SPDX-License-Identifier: GPL-2.0 -// -// Test that IPv4 advertised MSS in SYN-ACK is derived from the configured -// interface MTU (1500 -> MSS 1460), not the ICMP-learned Path MTU. - ---ip_version=ipv4 - -`./defaults.sh -ethtool -K tun0 tso off -` - -// -// Connection 1: Learn PMTU exception (MTU 1200 -> MSS 1160) -// - 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 65535 - +0 > S. 0:0(0) ack 1 - +.1 < . 1:1(0) ack 1 win 257 - +0 accept(3, ..., ...) = 4 - -// Send a full 1460-byte segment - +0 write(4, ..., 1460) = 1460 - +0 > P. 1:1461(1460) ack 1 - -// ICMP Fragmentation Needed arrives indicating next-hop MTU 1200 - +0 < icmp unreachable frag_needed mtu 1200 [1:1461(1460)] - -// Local host retransmits using the learned MTU 1200 (MSS = 1200 - 40 = 1160) - +0 > . 1:1161(1160) ack 1 - +0 > P. 1161:1461(300) ack 1 - +0 < R 1:1(0) ack 1461 win 0 - -// Close connection 1 and listener - +0 close(4) = 0 - +0 close(3) = 0 - -// -// Connection 2: New connection from the same peer -// - +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 65535 - -// Verify: SYN-ACK MUST advertise configured MSS 1460, NOT the learned PMTU MSS 1160 - +0 > S. 0:0(0) ack 1 - +0 < . 1:1(0) ack 1 win 257 - +0 accept(3, ..., ...) = 4 - -// Verify: Outgoing transmit MSS is still constrained by the learned PMTU 1200 - +0 write(4, ..., 1460) = 1460 - +0 > . 1:1161(1160) ack 1 - +0 > P. 1161:1461(300) ack 1 - +0 < . 1:1(0) ack 1461 win 257 - -// Clean up - +0 close(4) = 0 - +0 > F. 1461:1461(0) ack 1 - +0 < F. 1:1(0) ack 1462 win 257 - +0 > . 1462:1462(0) ack 2 - +0 close(3) = 0 diff --git a/tools/testing/selftests/net/packetdrill/tcp_advmss_pmtu_ipv6.pkt b/tools/testing/selftests/net/packetdrill/tcp_advmss_pmtu_ipv6.pkt deleted file mode 100644 index c7638b11a..000000000 --- a/tools/testing/selftests/net/packetdrill/tcp_advmss_pmtu_ipv6.pkt +++ /dev/null @@ -1,67 +0,0 @@ -// SPDX-License-Identifier: GPL-2.0 -// -// Test that IPv6 advertised MSS in SYN-ACK is derived from the configured -// interface MTU (1520 -> MSS 1460), not the ICMPv6-learned Path MTU. - ---ip_version=ipv6 - -`./defaults.sh -ethtool -K tun0 tso off -` - -// -// Connection 1: Learn PMTU exception (MTU 1280 -> MSS 1220) -// - 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 65535 - +0 > S. 0:0(0) ack 1 - +.1 < . 1:1(0) ack 1 win 257 - +0 accept(3, ..., ...) = 4 - -// Send a full 1460-byte segment - +0 write(4, ..., 1460) = 1460 - +0 > P. 1:1461(1460) ack 1 - -// ICMPv6 Packet Too Big arrives indicating next-hop MTU 1280 - +0 < icmp packet_too_big mtu 1280 [1:1461(1460)] - -// Local host retransmits using the learned MTU 1280 (MSS = 1280 - 40 - 20 = 1220) - +0 > . 1:1221(1220) ack 1 - +0 > P. 1221:1461(240) ack 1 - +0 < R 1:1(0) ack 1461 win 0 - -// Close connection 1 and listener - +0 close(4) = 0 - +0 close(3) = 0 - -// -// Connection 2: New connection from the same peer -// - +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 65535 - -// Verify: SYN-ACK MUST advertise configured MSS 1460, NOT the learned PMTU MSS 1220 - +0 > S. 0:0(0) ack 1 - +0 < . 1:1(0) ack 1 win 257 - +0 accept(3, ..., ...) = 4 - -// Verify: Outgoing transmit MSS is still constrained by the learned PMTU 1280 - +0 write(4, ..., 1460) = 1460 - +0 > . 1:1221(1220) ack 1 - +0 > P. 1221:1461(240) ack 1 - +0 < . 1:1(0) ack 1461 win 257 - -// Clean up - +0 close(4) = 0 - +0 > F. 1461:1461(0) ack 1 - +0 < F. 1:1(0) ack 1462 win 257 - +0 > . 1462:1462(0) ack 2 - +0 close(3) = 0 -- Git-157)