Re: [PATCH net-next] bridge: Let bridge not age 'externally' learnt FDB entries, they are removed when 'external' entity notifies the aging

On Wed, Feb 4, 2015 at 8:19 AM, roopa [off-list ref] wrote:

On 2/4/15, 12:02 AM, Siva Mannem wrote:

quoted

On Tue, Feb 3, 2015 at 8:41 PM, roopa [off-list ref] wrote:

quoted

On 2/2/15, 9:21 AM, Siva Mannem wrote:

quoted

   When 'learned_sync' flag is turned on, the offloaded switch
   port syncs learned MAC addresses to bridge's FDB via switchdev
notifier
   (NETDEV_SWITCH_FDB_ADD). Currently, FDB entries learnt via this
mechanism are
   wrongly being deleted by bridge aging logic. This patch ensures that
FDB
   entries synced from offloaded switch ports are not deleted by
bridging
logic.
   Such entries can only be deleted via switchdev notifier
   (NETDEV_SWITCH_FDB_DEL).

Your patch seems right and maintains symmetry for fdb add/del of
externally
learnt entries.
However, this could be made configurable. I think some drivers may rely
on
bridge driver aging these entries (The default setting needs more
thought).
I am not sure what rocker does (CC'ed rocker maintainers). But, our
driver
does rely on the bridge driver aging these entries by default.

added_by_external_learn flag is only set for entries learned via
switchdev notifier
(NETDEV_SWITCH_FDB_ADD) and rocker is the only driver using these
notifiers.
  I see that rocker is deleting the entries via switchdev notifier
(NETDEV_SWITCH_FDB_DEL).
This mechanism is only used by drivers when learned_sync is turned on by
user.

$ sudo bridge link set dev swp1 learning_sync on self

Am I missing something here?

I know that its enabled by an external flag. I wasn't sure rocker was doing
a del
or was relying on the bridge driver to age those entries (hence the CC to
rocker maintainers).
And, my only point was its valid in some cases for the switch driver to rely
on bridge driver ageing those entries.
For symmetry, your patch seems right.

No, not right.  Drats, email was sent to the wrong address for me.
Thanks Roopa for trying to keep me in the loop.

We want the bridge's aging logic to age out these externally learned
entries, just like it would age out internally learned entries.

I'd like to see this patch reverted so we can have a more
comprehensive discussion/solution.  With this patch applied, the only
user (rocker) of NETDEV_SWITCH_FDB_ADD is broken.  So please undo this
patch so rocker isn't broken and let's work on a knob to suit both
modes: 1) let bridge manage aging, 2) let device manage aging.

-scott