netdev - Re: [PATCH net-next 6/6] net: dsa: tag_8021q: Restore bridge pvid when enabling vlan

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Date:   Tue, 20 Aug 2019 13:28:51 +0300
From:   Vladimir Oltean <olteanv@...il.com>
To:     Florian Fainelli <f.fainelli@...il.com>
Cc:     Vivien Didelot <vivien.didelot@...il.com>,
        Andrew Lunn <andrew@...n.ch>, Ido Schimmel <idosch@...sch.org>,
        Roopa Prabhu <roopa@...ulusnetworks.com>,
        nikolay@...ulusnetworks.com,
        "David S. Miller" <davem@...emloft.net>,
        netdev <netdev@...r.kernel.org>
Subject: Re: [PATCH net-next 6/6] net: dsa: tag_8021q: Restore bridge pvid
 when enabling vlan_filtering

Hi Florian,

On Tue, 20 Aug 2019 at 06:33, Florian Fainelli <f.fainelli@...il.com> wrote:
>
>
>
> On 8/19/2019 5:00 PM, Vladimir Oltean wrote:
> > The bridge core assumes that enabling/disabling vlan_filtering will
> > translate into the simple toggling of a flag for switchdev drivers.
> >
> > That is clearly not the case for sja1105, which alters the VLAN table
> > and the pvids in order to obtain port separation in standalone mode.
> >
> > So, since the bridge will not call any vlan operation through switchdev
> > after enabling vlan_filtering, we need to ensure we're in a functional
> > state ourselves.
> >
> > Hence read the pvid that the bridge is aware of, and program that into
> > our ports.
>
> That is arguably applicable with DSA at large and not just specifically
> for tag_8021q.c no? Is there a reason why you are not seeking to solve
> this on a more global scale?
>

Perhaps because I don't have a good feel for what are other DSA
drivers' struggles with restoring the pvid, even after re-reading the
"What to do when a bridge port gets its pvid deleted?" thread.
I understand b53 has a similar need, and for that purpose maybe you
can EXPORT_SYMBOL_GPL(dsa_port_restore_pvid) and use it, but
otherwise, what is the more global scale?

> >
> > Signed-off-by: Vladimir Oltean <olteanv@...il.com>
> > ---
> >  net/dsa/tag_8021q.c | 32 +++++++++++++++++++++++++++++++-
> >  1 file changed, 31 insertions(+), 1 deletion(-)
> >
> > diff --git a/net/dsa/tag_8021q.c b/net/dsa/tag_8021q.c
> > index 67a1bc635a7b..6423beb1efcd 100644
> > --- a/net/dsa/tag_8021q.c
> > +++ b/net/dsa/tag_8021q.c
> > @@ -93,6 +93,33 @@ int dsa_8021q_rx_source_port(u16 vid)
> >  }
> >  EXPORT_SYMBOL_GPL(dsa_8021q_rx_source_port);
> >
> > +static int dsa_port_restore_pvid(struct dsa_switch *ds, int port)
> > +{
> > +     struct bridge_vlan_info vinfo;
> > +     struct net_device *slave;
> > +     u16 pvid;
> > +     int err;
> > +
> > +     if (!dsa_is_user_port(ds, port))
> > +             return 0;
> > +
> > +     slave = ds->ports[port].slave;
> > +
> > +     err = br_vlan_get_pvid(slave, &pvid);
> > +     if (err < 0) {
> > +             dev_err(ds->dev, "Couldn't determine bridge PVID\n");
> > +             return err;
> > +     }
> > +
> > +     err = br_vlan_get_info(slave, pvid, &vinfo);
> > +     if (err < 0) {
> > +             dev_err(ds->dev, "Couldn't determine PVID attributes\n");
> > +             return err;
> > +     }
> > +
> > +     return dsa_port_vid_add(&ds->ports[port], pvid, vinfo.flags);
> > +}
> > +
> >  /* RX VLAN tagging (left) and TX VLAN tagging (right) setup shown for a single
> >   * front-panel switch port (here swp0).
> >   *
> > @@ -223,7 +250,10 @@ int dsa_port_setup_8021q_tagging(struct dsa_switch *ds, int port, bool enabled)
> >               return err;
> >       }
> >
> > -     return 0;
> > +     if (!enabled)
> > +             err = dsa_port_restore_pvid(ds, port);
> > +
> > +     return err;
> >  }
> >  EXPORT_SYMBOL_GPL(dsa_port_setup_8021q_tagging);
> >
> >
>
> --
> Florian

Regards,
-Vladimir