Merge branch 'mptcp-prereq'

Merge branch 'mptcp-prereq'

Mat Martineau says:

====================
Multipath TCP: Prerequisites

v6 -> v7: Rename/move ULP clone helper to make inline-friendly (patch 5)

v5 -> v6: Fix BPF accessors for sk_type and sk_protocol (patch 2), fix
the width of an __unused bitfield (patch 6), and add some commit message
and comment text (patches 5 & 7).

v4 -> v5: Cover letter subject fix. No changes to commits.

v3 -> v4: Update coalesce/collapse of incoming MPTCP skbs (patch 7)

v2 -> v3: Ensure sk_type alignment in struct sock (patch 2)

v1 -> v2: sk_pacing_shift left as a regular struct member (patch 2), and
modified SACK space check based on recent -net fix (patch 9).

The MPTCP upstreaming community has been collaborating on an
upstreamable MPTCP implementation that complies with RFC 8684. A minimal
set of features to comply with the specification involves a sizeable set
of code changes, so David requested that we split this work in to
multiple, smaller patch sets to build up MPTCP infrastructure.

The minimal MPTCP feature set we are proposing for review in the v5.6
timeframe begins with these three parts:

Part 1 (this patch set): MPTCP prerequisites. Introduce some MPTCP
definitions, additional ULP and skb extension features, TCP option space
checking, and a few exported symbols.

Part 2: Single subflow implementation and self tests.

Part 3: Switch from MPTCP v0 (RFC 6824) to MPTCP v1 (new RFC 8684,
publication expected in the next few days).

Additional patches for multiple subflow support, path management, active
backup, and other features are in the pipeline for submission after
making progress with the above reviews.

Clone/fetch:
https://github.com/multipath-tcp/mptcp_net-next.git (tag: netdev-v7-part1)

Browse:
https://github.com/multipath-tcp/mptcp_net-next/tree/netdev-v7-part1

Thank you for your review. You can find us at mptcp@lists.01.org and
https://is.gd/mptcp_upstream
====================

Signed-off-by: David S. Miller <davem@davemloft.net>