[PATCH mptcp-net v2 0/5] mptcp: fix fallback-related races

[Paolo Abeni <pabeni@redhat.com>]

This series contains 3 fixes somewhat related to various races we have
while handling fallback and 2 small follow-up likely more suited for
net-next.

The root cause of the issues addressed here is that the check for
"we can fallback to tcp now" and the related action are not atomic. That
also applies to fallback due to MP_FAIL - where the window race is even
wider.

Address the issue introducing an additional spinlock to bundle together
all the relevant events, as per patch 1 and 2.

Note that mptcp_disconnect() unconditionally
clears the fallback status (zeroing msk->flags) and that may race with
operation still running on the (closing) subflows.

Such race is addressed in patch 3.

Patch 4 cleans up a bit the fallback code, introducing specific MIB for
each FB reason, and patch 5 drops the, hopefully now redundandt
pr_fallback().

Paolo Abeni (5):
  mptcp: make fallback action and fallback decision atomic
  mptcp: plug races between subflow fail and subflow creation
  mptcp: fix status reset on disconnect()
  mptcp: track fallbacks accurately via mibs
  mptcp: remove pr_fallback()

 net/mptcp/ctrl.c     |   4 +-
 net/mptcp/mib.c      |   5 ++
 net/mptcp/mib.h      |   7 +++
 net/mptcp/options.c  |   4 +-
 net/mptcp/pm.c       |   8 ++-
 net/mptcp/protocol.c | 126 +++++++++++++++++++++++++++++++++++--------
 net/mptcp/protocol.h |  35 ++++++------
 net/mptcp/subflow.c  |  35 ++++++------
 8 files changed, 164 insertions(+), 60 deletions(-)

-- 
2.49.0