[net,0/2] net: bridge: switchdev: Skip MDB replays of pending events

Message

Tobias Waldekranz Jan. 31, 2024, 12:35 p.m. UTC

Prevent the MDB replay logic from racing with the IGMP/MLD snooping
logic, which can otherwise cause the bridge to generate replays of
events that will also be delivered as regular events. The log message
of 2/2 has all the details.

We choose to preserve events in the deferred queue, eliding the
corresponding replay instead of the opposite. This is important
because purging the deferred event instead, would rob other listeners
of of that event entirely. I.e., regular events are "broadcast" to all
listeners, while replays are "unicast" only to the port joining or
leaving the bridge.

        br0
       /   \
  sw1p0     sw2p0
(hwdom 1) (hwdom 2)

In a setup like above, it is vital that sw1p0 learns about all group
memberships on sw2p0, since it may want to translate such memberships
to host equivalents, in order to let the bridge sofware forward them
to ports in other hardware domains.

Tobias Waldekranz (2):
  net: switchdev: Add helper to check if an object event is pending
  net: bridge: switchdev: Skip MDB replays of pending events

 include/net/switchdev.h   |  3 ++
 net/bridge/br_switchdev.c | 44 +++++++++++++++++-----------
 net/switchdev/switchdev.c | 61 +++++++++++++++++++++++++++++++++++++++
 3 files changed, 91 insertions(+), 17 deletions(-)