netdev - Re: [RFC PATCH v2 net-next 05/17] net: bridge: implement unicast filtering for the bridge device

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Date:   Tue, 22 Feb 2022 13:21:53 +0200
From:   Vladimir Oltean <olteanv@...il.com>
To:     Ido Schimmel <idosch@...sch.org>
Cc:     netdev@...r.kernel.org, Andrew Lunn <andrew@...n.ch>,
        Florian Fainelli <f.fainelli@...il.com>,
        Vivien Didelot <vivien.didelot@...il.com>,
        Jiri Pirko <jiri@...nulli.us>,
        DENG Qingfang <dqfext@...il.com>,
        Tobias Waldekranz <tobias@...dekranz.com>,
        George McCollister <george.mccollister@...il.com>,
        Vlad Yasevich <vyasevich@...il.com>,
        Roopa Prabhu <roopa@...dia.com>,
        Nikolay Aleksandrov <nikolay@...dia.com>
Subject: Re: [RFC PATCH v2 net-next 05/17] net: bridge: implement unicast
 filtering for the bridge device

Hi Ido,

On Mon, 1 Mar 2021 at 17:22, Ido Schimmel <idosch@...sch.org> wrote:
>
> On Wed, Feb 24, 2021 at 01:43:38PM +0200, Vladimir Oltean wrote:
> > From: Vladimir Oltean <vladimir.oltean@....com>
> >
> > The bridge device currently goes into promiscuous mode when it has an
> > upper with a different MAC address than itself. But it could do better:
> > it could sync the MAC addresses of its uppers to the software FDB, as
> > local entries pointing to the bridge itself. This is compatible with
> > switchdev, since drivers are now instructed to trap these MAC addresses
> > to the CPU.
> >
> > Note that the dev_uc_add API does not propagate VLAN ID, so this only
> > works for VLAN-unaware bridges.
>
> IOW, it breaks VLAN-aware bridges...
>
> I understand that you do not want to track bridge uppers, but once you
> look beyond L2 you will need to do it anyway.
>
> Currently, you only care about getting packets with specific DMACs to
> the CPU. With L3 offload you will need to send these packets to your
> router block instead and track other attributes of these uppers such as
> their MTU so that the hardware will know to generate MTU exceptions. In
> addition, the hardware needs to know the MAC addresses of these uppers
> so that it will rewrite the SMAC of forwarded packets.

Ok, let's say I want to track bridge uppers. How can I track the changes to
those interfaces' secondary addresses, in a way that keeps the association
with their VLAN ID, if those uppers are VLAN interfaces?