Re: [PATCH net-next v2 3/7] net: dsa: Register devlink ports before calling DSA driver setup()

Andrew Lunn
2020-09-27T00:45:19Z

> > +static int dsa_port_devlink_setup(struct dsa_port *dp)
> > {
> > struct devlink_port *dlp = &dp->devlink_port;
> > + struct dsa_switch_tree *dst = dp->ds->dst;
> > + struct devlink_port_attrs attrs = {};
> > + struct devlink *dl = dp->ds->devlink;
> > + const unsigned char *id;
> > + unsigned char len;
> > + int err;
> > +
> > + id = (const unsigned char *)&dst->index;
> > + len = sizeof(dst->index);
> > +
> > + attrs.phys.port_number = dp->index;
> > + memcpy(attrs.switch_id.id, id, len);
> > + attrs.switch_id.id_len = len;
> > +
> > + if (dp->setup)
> > + return 0;
> >
>
> I wonder what this is protecting against? I ran on a multi-switch tree
> without these 2 lines and I didn't get anything like multiple
> registration or things like that. What is the call path that would call
> dsa_port_devlink_setup twice?

I made a duplicate copy of dsa_port_setup() and trimmed out what was
not needed to give the new dsa_port_setup() and
dsa_port_devlink_setup(). I did not trim enough...

>
> > + switch (dp->type) {
> > + case DSA_PORT_TYPE_UNUSED:
> > + memset(dlp, 0, sizeof(*dlp));
> > + attrs.flavour = DEVLINK_PORT_FLAVOUR_UNUSED;
>
> > + devlink_port_attrs_set(dlp, &attrs);
> > + err = devlink_port_register(dl, dlp, dp->index);
>
> These 2 lines are common everywhere. Could you move them out of the
> switch-case statement?

Yes, that makes sense. Too much blind copy/paste without actually
reviewing the code afterwards.

Andrew