The mptcp protocol maintains an additional struct socket per connection,
mainly to be able to use easily tcp-level struct socket operations.

That lead to several ill side effects, beyond the quite unfortunate/
confusing field name
- active and passive sockets behavior is incosistent, as only active
  ones have not NULL msk->subflow, leading to different error handling
  (and different error code returned to the user-space) in several
  places.
- active sockets uses an unneeded, larger amount of memory
- passive sockets can't successfully go through accept()/disconnect()
  accept()

This series address all the above finally getting rid of the blamed
field. The first 2 patches are minor cleanups, in the next 11 patches
msk->subflow usage is sistematically removed from the mptcp protocol,
replacing it with direct msk->first usage, eventually introducing new
core helpers as needed.

The final patch finally dispose the field, and it's the only patch in
the series intened to produce functional changes.

Paolo Abeni (14):
  mptcp: more accurate NL event generation.
  mptcp: avoid unneeded mptcp_token_destroy() calls
  mptcp: avoid additional __inet_stream_connect() call
  mptcp: avoid subflow socket usage in mptcp_get_port()
  net: factor out inet{,6}_bind_sk helpers
  mptcp: mptcp: avoid additional indirection in mptcp_bind()
  net: factor out __inet_listen_sk() helper
  mptcp: avoid additional indirection in mptcp_listen()
  mptcp: avoid additional indirection in mptcp_poll()
  mptcp: avoid unneeded indirection in mptcp_stream_accept()
  mptcp: avoid additional indirection in sockopt
  mptcp: avoid ssock usage in mptcp_pm_nl_create_listen_socket()
  mptcp: change the mpc check helper to return a sk
  mptcp: get rid of msk->subflow

 include/net/inet_common.h |   2 +
 include/net/ipv6.h        |   1 +
 net/ipv4/af_inet.c        |  47 ++++++-----
 net/ipv6/af_inet6.c       |  10 ++-
 net/mptcp/pm_netlink.c    |  30 ++++---
 net/mptcp/protocol.c      | 161 +++++++++++++++++++-------------------
 net/mptcp/protocol.h      |  15 ++--
 net/mptcp/sockopt.c       |  65 ++++++++-------
 8 files changed, 174 insertions(+), 157 deletions(-)

-- 
2.41.0