Merge branch 'mptcp-fixes-for-connect-selftest-flakes'

Matthieu Baerts says:

====================
mptcp: fixes for connect selftest flakes

Last week, Jakub reported [1] that the MPTCP Connect selftest was
unstable. It looked like it started after the introduction of some fixes
[2]. After analysis from Paolo, these patches revealed existing bugs,
that should be fixed by the following patches.

- Patch 1: Make sure ACK are sent when MPTCP-level window re-opens. In
  some corner cases, the other peer was not notified when more data
  could be sent. A fix for v5.11, but depending on a feature introduced
  in v5.19.

- Patch 2: Fix spurious wake-up under memory pressure. In this
  situation, the userspace could be invited to read data not being there
  yet. A fix for v6.7.

- Patch 3: Fix a false positive error when running the MPTCP Connect
  selftest with the "disconnect" cases. The userspace could disconnect
  the socket too soon, which would reset (MP_FASTCLOSE) the connection,
  interpreted as an error by the test. A fix for v5.17.

Link: https://lore.kernel.org/20250107131845.5e5de3c5@kernel.org [1]
Link: https://lore.kernel.org/20241230-net-mptcp-rbuf-fixes-v1-0-8608af434ceb@kernel.org [2]
====================

Link: https://patch.msgid.link/20250113-net-mptcp-connect-st-flakes-v1-0-0d986ee7b1b6@kernel.org


Signed-off-by: Jakub Kicinski <kuba@kernel.org>