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Date: Mon, 14 Mar 2022 19:55:56 +0200
From: Vladimir Oltean <olteanv@gmail.com>
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Subject: Re: [Bridge] [PATCH v3 net-next 09/14] net: dsa: Validate hardware
 support for MST
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To: Tobias Waldekranz <tobias@waldekranz.com>
Cc: Ivan Vecera <ivecera@redhat.com>, Andrew Lunn <andrew@lunn.ch>, Florian Fainelli <f.fainelli@gmail.com>, Jiri Pirko <jiri@resnulli.us>, bridge@lists.linux-foundation.org, Ido Schimmel <idosch@nvidia.com>, Nikolay Aleksandrov <razor@blackwall.org>, Petr Machata <petrm@nvidia.com>, Russell King <linux@armlinux.org.uk>, Vivien Didelot <vivien.didelot@gmail.com>, netdev@vger.kernel.org, Cooper Lees <me@cooperlees.com>, Roopa Prabhu <roopa@nvidia.com>, kuba@kernel.org, Matt Johnston <matt@codeconstruct.com.au>, davem@davemloft.net, linux-kernel@vger.kernel.org

On Mon, Mar 14, 2022 at 06:56:49PM +0200, Vladimir Oltean wrote:
> > diff --git a/net/dsa/port.c b/net/dsa/port.c
> > index 58291df14cdb..1a17a0efa2fa 100644
> > --- a/net/dsa/port.c
> > +++ b/net/dsa/port.c
> > @@ -240,6 +240,10 @@ static int dsa_port_switchdev_sync_attrs(struct dsa_port *dp,
> >  	if (err && err != -EOPNOTSUPP)
> >  		return err;
> >  
> > +	err = dsa_port_mst_enable(dp, br_mst_enabled(br), extack);
> > +	if (err && err != -EOPNOTSUPP)
> > +		return err;
> 
> Sadly this will break down because we don't have unwinding on error in
> place (sorry). We'd end up with an unoffloaded bridge port with
> partially synced bridge port attributes. Could you please add a patch
> previous to this one that handles this, and unoffloads those on error?

Actually I would rather rename the entire dsa_port_mst_enable() function
to dsa_port_mst_validate() and move it to the beginning of dsa_port_bridge_join().
This simplifies the unwinding that needs to take place quite a bit.