[PATCH net-next 0/4] tcp: fix tcp_base_mss on passive connections and test MTU probing

[Yongjian Wang via B4 Relay <devnull+echoowall.gmail.com@kernel.org>]

While adding selftests for MTU probing, I noticed that passive
connections do not start at tcp_base_mss with tcp_mtu_probing=2.
Patch 1 fixes that and patch 2 adds a regression test.

This has been wrong since 2014 and only matters with a non-default
sysctl, so I am sending it to net-next. Patch 1 changes behaviour for
users of tcp_mtu_probing=2. Please let me know if you would prefer it
to go through net or to be backported to stable.

Patches 3 and 4 add the missing coverage for black hole detection
(tcp_mtu_probing=1) and for the MTU search on active connections
(tcp_mtu_probing=2).

---
Yongjian Wang (4):
      tcp: sync MSS after enabling MTU probing on passive connections
      selftests/net: packetdrill: test tcp_base_mss on passive connections
      selftests/net: packetdrill: add TCP black hole detection test
      selftests/net: packetdrill: add TCP MTU probing test

 net/ipv4/tcp_input.c                               |  1 +
 .../net/packetdrill/tcp_mtu_probing_blackhole.pkt  | 37 +++++++++++++++++++
 .../net/packetdrill/tcp_mtu_probing_passive.pkt    | 27 ++++++++++++++
 .../net/packetdrill/tcp_mtu_probing_search.pkt     | 43 ++++++++++++++++++++++
 4 files changed, 108 insertions(+)
---
base-commit: 4dd16e31135ea8437a720222df34e8745f385d6d
change-id: 20261103-mtu-probing-series-a87b39fdbedf

Best regards,
--  
Yongjian Wang <echoowall@gmail.com>