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charset="utf-8" Message-Id: <20261103-mtu-probing-series-v1-2-a2809e725aaa@gmail.com> References: <20261103-mtu-probing-series-v1-0-a2809e725aaa@gmail.com> In-Reply-To: <20261103-mtu-probing-series-v1-0-a2809e725aaa@gmail.com> To: ncardwell@google.com, horms@kernel.org, edumazet@kernel.org, kuba@kernel.org, kuniyu@google.com, shuah@kernel.org, davem@davemloft.net, pabeni@redhat.com Cc: netdev@vger.kernel.org, panweiping3@gmail.com, linux-kselftest@vger.kernel.org, linux-kernel@vger.kernel.org, Yongjian Wang X-Mailer: b4 0.16.0 X-Developer-Signature: v=1; a=ed25519-sha256; t=1793689782; l=1593; i=echoowall@gmail.com; s=20261026; h=from:subject:message-id; bh=dWQVgF2dw8T0SSpgY/AM6QslZB53fGfIfx1Y00i/T1Y=; b=EUAy+44N/Aadqf+6luPFXKqwJIevQdyUzQ8tGceh1AG3X5RIO09T99kBFBskFg2pC/dWI/DzC 7TsdxEjlfsaB1lNzfSvYe25BQNTlX97QXPV+usQkg4OdWtCv6n2ll1a 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: Yongjian Wang Reply-To: echoowall@gmail.com Content-Transfer-Encoding: 7bit From: Yongjian Wang Check that a passive connection starts at tcp_base_mss with net.ipv4.tcp_mtu_probing=2, as an active connection does. Signed-off-by: Yongjian Wang --- .../net/packetdrill/tcp_mtu_probing_passive.pkt | 27 ++++++++++++++++++++++ 1 file changed, 27 insertions(+) diff --git a/tools/testing/selftests/net/packetdrill/tcp_mtu_probing_passive.pkt b/tools/testing/selftests/net/packetdrill/tcp_mtu_probing_passive.pkt new file mode 100644 index 000000000..14bae144c --- /dev/null +++ b/tools/testing/selftests/net/packetdrill/tcp_mtu_probing_passive.pkt @@ -0,0 +1,27 @@ +// SPDX-License-Identifier: GPL-2.0 +// Test that a passive connection starts at tcp_base_mss with tcp_mtu_probing=2, +// the same way as an active connection. + +`./defaults.sh +sysctl -q net.ipv4.tcp_mtu_probing=2 +sysctl -q net.ipv4.tcp_base_mss=1024 +sysctl -q net.ipv4.tcp_timestamps=0` + + 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 65535 + +0 accept(3, ..., ...) = 4 + +// The initial window is sent with tcp_base_mss, not the peer's MSS. + +0 write(4, ..., 10240) = 10240 + +0 > P. 1:2049(2048) ack 1 + +0 > P. 2049:4097(2048) ack 1 + +0 > P. 4097:6145(2048) ack 1 + +0 > P. 6145:8193(2048) ack 1 + +0 > P. 8193:10241(2048) ack 1 + +.1 < . 1:1(0) ack 10241 win 65535 -- Git-157)