From: Kuniyuki Iwashima <kuniyu@google.com>
To: Yongjian Wang <echoowall@gmail.com>
Cc: pabeni@redhat.com, kuba@kernel.org, shuah@kernel.org,
edumazet@kernel.org, horms@kernel.org, ncardwell@google.com,
davem@davemloft.net, linux-kernel@vger.kernel.org,
linux-kselftest@vger.kernel.org, netdev@vger.kernel.org,
panweiping3@gmail.com
Subject: Re: [PATCH net-next v4 3/4] selftests/net: packetdrill: add TCP black hole detection tests
Date: Sat, 14 Nov 2026 06:18:15 +0000 [thread overview]
Message-ID: <avf9HomOtgXYiRLX@google.com> (raw)
In-Reply-To: <20261111-mtu-probing-series-v4-3-6f2e484ca8ea@gmail.com>
On Wed, 11 Nov 2026 00:45:57 +0800, Yongjian Wang wrote:
> Black hole detection (net.ipv4.tcp_mtu_probing=1) has no selftest
> coverage.
>
> Add a test that only sets tcp_mtu_probing=1 on top of the default
> settings. A full-sized segment keeps timing out without any ICMP
> feedback. Check that the MSS drops to tcp_base_mss once tcp_retries1
> is exceeded, and that the smaller MSS is also used for new data after
> the retransmission is acknowledged.
>
> Add a shorter variant with tcp_retries1=1 and TLP disabled, so that
> every retransmission comes from the RTO timer, which is what
> tcp_write_timeout() counts.
>
> Signed-off-by: Yongjian Wang <echoowall@gmail.com>
Reviewed-by: Kuniyuki Iwashima <kuniyu@google.com>
next prev parent reply other threads:[~2026-11-14 6:18 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-11-10 16:45 [PATCH net-next v4 0/4] tcp: fix tcp_base_mss on passive connections and test MTU probing Yongjian Wang via B4 Relay
2026-11-10 16:45 ` [PATCH net-next v4 1/4] tcp: initialize MTU probing before syncing MSS at connection setup Yongjian Wang via B4 Relay
2026-11-10 16:45 ` [PATCH net-next v4 2/4] selftests/net: packetdrill: test tcp_base_mss on passive connections Yongjian Wang via B4 Relay
2026-11-14 6:14 ` Kuniyuki Iwashima
2026-11-10 16:45 ` [PATCH net-next v4 3/4] selftests/net: packetdrill: add TCP black hole detection tests Yongjian Wang via B4 Relay
2026-11-14 6:18 ` Kuniyuki Iwashima [this message]
2026-11-10 16:45 ` [PATCH net-next v4 4/4] selftests/net: packetdrill: add TCP MTU probing test Yongjian Wang via B4 Relay
2026-11-14 6:22 ` Kuniyuki Iwashima
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