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From: Esko Mobius <echoowall@gmail.com>
To: netdev-bot+sinfo@kernel.org
Cc: davem@davemloft.net, pabeni@redhat.com, ncardwell@google.com,
	horms@kernel.org, kuba@kernel.org, kuniyu@google.com,
	shuah@kernel.org, edumazet@kernel.org,
	linux-kselftest@vger.kernel.org, linux-kernel@vger.kernel.org,
	panweiping3@gmail.com, netdev@vger.kernel.org
Subject: Re: [PATCH net-next v2 0/4] tcp: fix tcp_base_mss on passive connections and test MTU probing
Date: Sun, 8 Nov 2026 22:58:50 +0800	[thread overview]
Message-ID: <6A5F2D50-D257-4F6B-A1B6-BE08489591F6@gmail.com> (raw)
In-Reply-To: <179414895487.488859.839196891969031483@kernel.org>

> How the issue was discovered
Hi,

This came up while adding packetdrill coverage for tcp_mtu_probing=2.
The test work involved comparing the initial send MSS and what happened
after the first probe was acknowledged on active and passive IPv4
connections.

With tcp_base_mss=1024, the active connection started at 1024 as
expected. The passive connection started at 1460, and its send MSS
dropped to 1242 after the first probe was acknowledged. That led to
checking the passive setup path, where tcp_v4_syn_recv_sock() called
tcp_sync_mss() before tcp_init_transfer() enabled MTU probing.

Thanks,
Yongjian

      reply	other threads:[~2026-11-08 14:59 UTC|newest]

Thread overview: 7+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2026-11-08 14:39 Yongjian Wang via B4 Relay
2026-11-08 14:39 ` [PATCH net-next v2 1/4] tcp: initialize MTU probing before syncing MSS at connection setup Yongjian Wang via B4 Relay
2026-11-08 14:39 ` [PATCH net-next v2 2/4] selftests/net: packetdrill: test tcp_base_mss on passive connections Yongjian Wang via B4 Relay
2026-11-08 14:39 ` [PATCH net-next v2 3/4] selftests/net: packetdrill: add TCP black hole detection test Yongjian Wang via B4 Relay
2026-11-08 14:39 ` [PATCH net-next v2 4/4] selftests/net: packetdrill: add TCP MTU probing test Yongjian Wang via B4 Relay
2026-11-08 14:42 ` [PATCH net-next v2 0/4] tcp: fix tcp_base_mss on passive connections and test MTU probing netdev-bot+sinfo
2026-11-08 14:58   ` Esko Mobius [this message]

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