Merge branch 'mptcp-misc-fixes-for-v7-1-rc7'

Matthieu Baerts says:

====================
mptcp: misc fixes for v7.1-rc7

Here are various unrelated fixes:

- Patch 1: fix missing wakeups when multiple threads are reading from
  the same fd. A fix for v5.7.

- Patch 2: fix retransmission loop when MPTCP checksum is enabled. A fix
  for v5.14.

- Patch 3: fix a TOCTOU race while computing rcv_wnd. A fix for v5.11.

- Patch 4: allow subflows receive window to shrink if needed. A fix for
  v5.19.

- Patches 5-6: avoid 'extra_subflows' to underflow with the userspace
  PM. A fix for v5.19.

- Patch 7: report errors if one subflow cannot set SO_TIMESTAMPING. A
  fix for v5.14.

- Patch 8: try to set TCP_MAXSEG on all subflows, before reporting
  errors, if any. A fix for v6.17.

- Patch 9: check desc->count in read_sock, to act as expected. A fix
  for v7.0.

- Patch 10: fix an uninit value in mptcp_established_options, reported
  by syzbot. A fix for v7.1-rc1.

- Patch 11: fix a similar issue than the previous patch, exposed by the
  same modification from v7.1-rc1, but was already causing issues since
  v5.15.
====================

Link: https://patch.msgid.link/20260602-net-mptcp-misc-fixes-7-1-rc7-v2-0-856831229976@kernel.org
Signed-off-by: Jakub Kicinski <kuba@kernel.org>