netdev - Re: [RFC PATCH 02/10] net: dsa: b53: prevent FAST

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Message-ID: <20250603101931.fgj3p46wkupjdrn4@skbuf>
Date: Tue, 3 Jun 2025 13:19:31 +0300
From: Vladimir Oltean <olteanv@...il.com>
To: Florian Fainelli <florian.fainelli@...adcom.com>
Cc: Álvaro Fernández Rojas <noltari@...il.com>,
	jonas.gorski@...il.com, andrew@...n.ch, davem@...emloft.net,
	edumazet@...gle.com, kuba@...nel.org, pabeni@...hat.com,
	vivien.didelot@...il.com, netdev@...r.kernel.org,
	linux-kernel@...r.kernel.org, dgcbueu@...il.com
Subject: Re: [RFC PATCH 02/10] net: dsa: b53: prevent FAST_AGE access on
 BCM5325

On Mon, Jun 02, 2025 at 11:01:40AM -0700, Florian Fainelli wrote:
> On 6/2/25 02:37, Vladimir Oltean wrote:
> > Hello,
> > 
> > On Sat, May 31, 2025 at 12:13:00PM +0200, Álvaro Fernández Rojas wrote:
> > > BCM5325 doesn't implement FAST_AGE registers so we should avoid reading or
> > > writing them.
> > > 
> > > Fixes: 967dd82ffc52 ("net: dsa: b53: Add support for Broadcom RoboSwitch")
> > > Signed-off-by: Álvaro Fernández Rojas <noltari@...il.com>
> > > ---
> > 
> > How about implementing a "slow age" procedure instead? Walk through the
> > FDB, and delete the dynamically learned entries for the port?
> > 
> > Address aging is important for STP state transitions.
> 
> That's a good suggestion, I suppose for now this can be b53 specific until
> we encounter another 20 year old switch and then we move that logic within
> the DSA framework?
> -- 
> Florian

Hmm, thank you for saying that, I didn't even consider consolidating the
logic in the DSA framework, but it sure makes sense and we already have
almost all API required to do that.

So I now have a WIP patch attached, but the consolidation into the
framework is definitely a net-next activity, since it will also affect
mt7530, hellcreek and vsc73xx, and those need testing. Also, for b53 it
further requires changing the port_fast_age() prototype.

The question further becomes whether for stable kernels we should
implement a local slow age procedure in b53 like the one from sja1105,
only to delete it in net-next, or to skip it altogether, go with
Álvaro's patch as is and concentrate on the net-next implementation
directly. I'm ok both ways.

View attachment "0001-net-dsa-centralize-the-slow-aging-procedure-from-sja.patch" of type "text/x-diff" (7259 bytes)