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charset="us-ascii" 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 Reviewed-by: Kuniyuki Iwashima