[MPTCP next v3 00/12] mptcp: receive path improvement

[Paolo Abeni <pabeni@redhat.com>]

This series includes several changes to the MPTCP RX path.

The main goals are improving the RX performances _and_ increase the
long term maintainability.

Some changes reflects recent (or not so) improvements introduced in the
TCP stack: patch 1, 2 and 3 are the MPTCP counter part of skb deferral
free and auto-tuning improvements.

Note that patch 3 could possibly fix issues/574, and overall such patch
should protect from similar issues to arise in the future.

All the others patches are aimed at introducing the socket backlog usage
to process the packets received by the subflows while the msk socket is
owned. That (almost completely) replace the processing currently
happening in the mptcp_release_cb().

The actual job is done in patch 10, while the others are cleanups needed
to make the change tidy and more follow-up cleanups.

Sharing earlier with known issues (at least on fallback socket) to raise
awareness about this upcoming work.
---
v2 -> v3:
  - (hopefully) addressed CI failures
  - reordered to avoid trainsintly breaking fallback
  - refactor patch 3/12

v1 -> v2:
  - fix compile warn in patch 3
  - removed unneeded arg in patch 4
  - commit msg clarification and rebase

Paolo Abeni (12):
  mptcp: leverage skb deferral free
  tcp: make tcp_rcvbuf_grow() accessible to mptcp code
  mptcp: rcvbuf auto-tuning improvement
  mptcp: introduce the mptcp_init_skb helper.
  mptcp: remove unneeded mptcp_move_skb()
  mptcp: factor out a basic skb coalesce helper
  mptcp: minor move_skbs_to_msk() cleanup
  mptcp: cleanup fallback data fin reception
  mptcp: cleanup fallback dummy mapping generation.
  mptcp: leverage the sk backlog for RX packet processing.
  mptcp: prevernt __mptcp_move_skbs() interfering with the fastpath
  mptcp: borrow forward memory from subflow

 include/net/tcp.h    |   1 +
 net/ipv4/tcp_input.c |   2 +-
 net/mptcp/mib.c      |   2 +
 net/mptcp/mib.h      |   4 +
 net/mptcp/protocol.c | 343 ++++++++++++++++++++++++-------------------
 net/mptcp/protocol.h |   8 +-
 net/mptcp/subflow.c  |  12 +-
 7 files changed, 218 insertions(+), 154 deletions(-)

-- 
2.51.0