This is a refresh and rebase of an already shared work:

https://lore.kernel.org/mptcp/cover.1621963632.git.pabeni@redhat.com/
[1]

The motiviation for refreshing this is:

https://lore.kernel.org/mptcp/YtVhyGSsv1CWvPz4@xsang-OptiPlex-9020/

specifically it looks like that properly attaching mem_cg to the
msk socket would be (much?) easier if the RX path and the fwd memory
allocation would be under msk socket lock protection.

The first 2 patches are proably worthy even without the refactor,
but specifically the 2nd one is required to get a good mptcp-level
acking behavior when we move the rx under the socket lock.

The 3rd patch does the real work, and the 4th is a follow-up cleanup.

Back at [1], I measured relevant performance regressions in some
specific cases. I've done the same test here and I now see little to
noise changes. I guess that is mostly due to the better acking
strategy already introduce with commit 949dfdcf343c ("Merge branch 
'mptcp-improve-mptcp-level-window-tracking'") and refined here.

v1 -> v2:
 - fix build issue in patch 3/4 due to PEBKAC
 - added missing commit messages(!!!) in patch 3/4 & 4/4

Paolo Abeni (4):
  mptcp: move RCVPRUNE event later
  mptcp: more accurate receive buffer updates
  mptcp: move msk input path under full msk socket lock
  mptcp: use common helper for rmem memory accounting

 include/net/mptcp.h  |   2 +
 net/ipv4/tcp.c       |   3 +
 net/mptcp/options.c  |   1 -
 net/mptcp/protocol.c | 219 +++++++++++--------------------------------
 net/mptcp/protocol.h |  12 ++-
 5 files changed, 68 insertions(+), 169 deletions(-)

-- 
2.35.3