Re: [PATCH net-next 4/6] net: dsa: sja1105: support flow-based redirection via virtual links

[Vivien Didelot <vivien.didelot@gmail.com>]

Hi Vladimir,

On Mon, 4 May 2020 21:38:26 +0300, Vladimir Oltean <olteanv@gmail.com> wrote:
> Hi Vivien,
> 
> On Mon, 4 May 2020 at 21:23, Vivien Didelot <vivien.didelot@gmail.com> wrote:
> >
> > On Mon, 4 May 2020 14:19:13 -0400, Vivien Didelot <vivien.didelot@gmail.com> wrote:
> > > Hi Vladimir,
> > >
> > > On Mon,  4 May 2020 00:10:33 +0300, Vladimir Oltean <olteanv@gmail.com> wrote:
> > > > +           case FLOW_ACTION_REDIRECT: {
> > > > +                   struct dsa_port *to_dp;
> > > > +
> > > > +                   if (!dsa_slave_dev_check(act->dev)) {
> > > > +                           NL_SET_ERR_MSG_MOD(extack,
> > > > +                                              "Destination not a switch port");
> > > > +                           return -EOPNOTSUPP;
> > > > +                   }
> > > > +
> > > > +                   to_dp = dsa_slave_to_port(act->dev);
> > >
> > > Instead of exporting two DSA core internal functions, I would rather expose
> > > a new helper for drivers, such as this one:
> > >
> > >     struct dsa_port *dsa_dev_to_port(struct net_device *dev)
> > >     {
> > >         if (!dsa_slave_dev_check(dev))
> > >             return -EOPNOTSUPP;
> >
> > Oops, NULL, not an integer error code, but you get the idea of public helpers.
> >
> > >
> > >         return dsa_slave_to_port(dev);
> > >     }
> > >
> > > The naming might not be the best, this helper could even be mirroring-specific,
> > > I didn't really check the requirements for this functionality yet.
> > >
> > >
> > > Thank you,
> > >
> > >       Vivien
> 
> How about
> 
> int dsa_slave_get_port_index(struct net_device *dev)
> {
>     if (!dsa_slave_dev_check(dev))
>         return -EINVAL;
> 
>     return dsa_slave_to_port(dev)->index;
> }
> EXPORT_SYMBOL_GPL(dsa_slave_get_port_index);
> 
> also, where to put it? slave.c I suppose?

dsa.c is the place for private implementation of public functions. "slave"
is a core term, no need to expose it. Public helpers exposed in dsa.h usually
scope the dsa_switch structure and an optional port index. mv88e6xxx allows
mirroring an external device port, so dsa_port would be preferred, but this
can wait. So I'm thinking about implementing the following:

net/dsa/dsa.c:

int dsa_to_port_index(struct dsa_switch *ds, struct net_device *dev)
{
    struct dsa_port *dp;

    if (!dsa_slave_dev_check(dev))
        return -ENODEV;

    dp = dsa_slave_to_port(dev);

    if (dp->ds != ds)
        return -EINVAL;

    return dp->index;
}

include/net/dsa.h:

int dsa_to_port_index(struct dsa_switch *ds, struct net_device *dev);


What do you think?

	Vivien