82a678e22d
Tobias Waldekranz says:
====================
net: bridge: switchdev: Ensure MDB events are delivered exactly once
When a device is attached to a bridge, drivers will request a replay
of objects that were created before the device joined the bridge, that
are still of interest to the joining port. Typical examples include
FDB entries and MDB memberships on other ports ("foreign interfaces")
or on the bridge itself.
Conversely when a device is detached, the bridge will synthesize
deletion events for all those objects that are still live, but no
longer applicable to the device in question.
This series eliminates two races related to the synching and
unsynching phases of a bridge's MDB with a joining or leaving device,
that would cause notifications of such objects to be either delivered
twice (1/2), or not at all (2/2).
A similar race to the one solved by 1/2 still remains for the
FDB. This is much harder to solve, due to the lockless operation of
the FDB's rhashtable, and is therefore knowingly left out of this
series.
v1 -> v2:
- Squash the previously separate addition of
switchdev_port_obj_act_is_deferred into first consumer.
- Use ether_addr_equal to compare MAC addresses.
- Document switchdev_port_obj_act_is_deferred (renamed from
switchdev_port_obj_is_deferred in v1, to indicate that we also match
on the action).
- Delay allocations of MDB objects until we know they're needed.
- Use non-RCU version of the hash list iterator, now that the MDB is
not scanned while holding the RCU read lock.
- Add Fixes tag to commit message
v2 -> v3:
- Fix unlocking in error paths
- Access RCU protected port list via mlock_dereference, since MDB is
guaranteed to remain constant for the duration of the scan.
v3 -> v4:
- Limit the search for exiting deferred events in 1/2 to only apply to
additions, since the problem does not exist in the deletion case.
- Add 2/2, to plug a related race when unoffloading an indirectly
associated device.
v4 -> v5:
- Fix grammatical errors in kerneldoc of
switchdev_port_obj_act_is_deferred
====================
Signed-off-by: David S. Miller <davem@davemloft.net>
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README
Linux kernel
============
There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.
In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``. The formatted documentation can also be read online at:
https://www.kernel.org/doc/html/latest/
There are various text files in the Documentation/ subdirectory,
several of them using the Restructured Text markup notation.
Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.