Merge branch 'mptcp-avoid-dup-nl-events-and-propagate-error'

Merge branch 'mptcp-avoid-dup-nl-events-and-propagate-error'

Matthieu Baerts says:

====================
mptcp: avoid dup NL events and propagate error

Here are two fixes affecting the MPTCP Netlink events with their tests:

- Patches 1 & 2: a subflow closed NL event was visible multiple times in
  some specific conditions. A fix for v5.12.

- Patches 3 & 4: subflow closed NL events never contained the error
  code, even when expected. A fix for v5.11.

Plus an extra fix:

- Patch 5: fix a false positive with the "signal addresses race test"
  subtest when validating the MPTCP Join selftest on a v5.15.y stable
  kernel.
====================

Link: https://patch.msgid.link/20260127-net-mptcp-dup-nl-events-v1-0-7f71e1bc4feb@kernel.org
Signed-off-by: Jakub Kicinski <kuba@kernel.org>