Re: [PATCH net-next 2/2] net: bridge: switchdev: include local flag in FDB notifications

From: Vladimir Oltean <olteanv@gmail.com>
To: Andrew Lunn <andrew@lunn.ch>
Cc: Jakub Kicinski <kuba@kernel.org>,
	"David S. Miller" <davem@davemloft.net>,
	netdev@vger.kernel.org, Ioana Ciornei <ioana.ciornei@nxp.com>,
	Vadym Kochan <vkochan@marvell.com>,
	Taras Chornyi <tchornyi@marvell.com>,
	Jiri Pirko <jiri@nvidia.com>, Ido Schimmel <idosch@nvidia.com>,
	Grygorii Strashko <grygorii.strashko@ti.com>,
	Ivan Vecera <ivecera@redhat.com>, Roopa Prabhu <roopa@nvidia.com>,
	Nikolay Aleksandrov <nikolay@nvidia.com>,
	Vivien Didelot <vivien.didelot@gmail.com>,
	Florian Fainelli <f.fainelli@gmail.com>,
	Vignesh Raghavendra <vigneshr@ti.com>,
	Linus Walleij <linus.walleij@linaro.org>,
	linux-omap@vger.kernel.org,
	Vladimir Oltean <vladimir.oltean@nxp.com>,
	Tobias Waldekranz <tobias@waldekranz.com>
Subject: Re: [PATCH net-next 2/2] net: bridge: switchdev: include local flag in FDB notifications
Date: Wed, 14 Apr 2021 19:05:10 +0300	[thread overview]
Message-ID: <20210414160510.zcif6liazjltd2cz@skbuf> (raw)
In-Reply-To: <YHcRNIgI9lVs6MDj@lunn.ch>

On Wed, Apr 14, 2021 at 05:58:44PM +0200, Andrew Lunn wrote:
> > Let us now add the 'is_local' bit to bridge FDB entries, and make all
> > drivers ignore these entries by their own choice.
> 
> Hi Vladimir
> 
> This goes to the question about the missing cover letter. Why should
> drivers get to ignore them, rather than the core? It feels like there
> should be another patch in the series, where a driver does not
> actually ignore them, but does something?

Hi Andrew,

Bridge fdb entries with the is_local flag are entries which are
terminated locally and not forwarded. Switchdev drivers might want to be
notified of these addresses so they can trap them (otherwise, if they
don't program these entries to hardware, there is no guarantee that they
will do the right thing with these entries, and they won't be, let's
say, flooded). Of course, ideally none of the switchdev drivers should
ignore them, but having access to the is_local bit is the bare minimum
change that should be done in the bridge layer, before this is even
possible.

These 2 changes are actually part of a larger group of changes that
together form the "RX filtering for DSA" series. I haven't had a lot of
success with that, so I thought a better approach would be to take it
step by step. DSA will need to be notified of local FDB entries. For
now, it ignores them like everybody else. This is supposed to be a
non-functional patch series because I don't want to spam every switchdev
maintainer with 15+ DSA RX filtering patches.