Merge branch 'mptcp-features-and-fixes-for-v6-7'

Mat Martineau says:

====================
mptcp: Features and fixes for v6.7

Patch 1 adds a configurable timeout for the MPTCP connection when all
subflows are closed, to support break-before-make use cases.

Patch 2 is a fix for a 1-byte error in rx data counters with MPTCP
fastopen connections.

Patch 3 is a minor code cleanup.

Patches 4 & 5 add handling of rcvlowat for MPTCP sockets, with a
prerequisite patch to use a common scaling ratio between TCP and MPTCP.

Patch 6 improves efficiency of memory copying in MPTCP transmit code.

Patch 7 refactors syncing of socket options from the MPTCP socket to
its subflows.

Patches 8 & 9 help the MPTCP packet scheduler perform well by changing
the handling of notsent_lowat in subflows and how available buffer space
is calculated for MPTCP-level sends.
====================

Link: https://lore.kernel.org/r/20231023-send-net-next-20231023-2-v1-0-9dc60939d371@kernel.org
Signed-off-by: Jakub Kicinski <kuba@kernel.org>