Re: [RFC net-next 1/3] net: marvell: prestera: Add Switchdev driver for Prestera family ASIC device 98DX325x (AC3x)

From: Vadym Kochan
Date: Tue May 05 2020 - 00:01:57 EST


Hi Ido,

On Sat, May 02, 2020 at 06:20:49PM +0300, Vadym Kochan wrote:
> Hi Ido,
>
> On Thu, Mar 05, 2020 at 04:49:37PM +0200, Ido Schimmel wrote:
> > On Tue, Feb 25, 2020 at 04:30:54PM +0000, Vadym Kochan wrote:
> > > +int mvsw_pr_port_learning_set(struct mvsw_pr_port *port, bool learn)
> > > +{
> > > + return mvsw_pr_hw_port_learning_set(port, learn);
> > > +}
> > > +
> > > +int mvsw_pr_port_flood_set(struct mvsw_pr_port *port, bool flood)
> > > +{
> > > + return mvsw_pr_hw_port_flood_set(port, flood);
> > > +}
> >
> > Flooding and learning are per-port attributes? Not per-{port, VLAN} ?
> > If so, you need to have various restrictions in the driver in case
> > someone configures multiple vlan devices on top of a port and enslaves
> > them to different bridges.

Yes, and there is no support for vlan device on top of the port.

> >
> > > +
> > > +
> > > + INIT_LIST_HEAD(&port->vlans_list);
> > > + port->pvid = MVSW_PR_DEFAULT_VID;
> >
> > If you're using VID 1, then you need to make sure that user cannot
> > configure a VLAN device with with this VID. If possible, I suggest that
> > you use VID 4095, as it cannot be configured from user space.
> >
> > I'm actually not entirely sure why you need a default VID.
> >
>
> > > +mvsw_pr_port_vlan_bridge_join(struct mvsw_pr_port_vlan *port_vlan,
> > > + struct mvsw_pr_bridge_port *br_port,
> > > + struct netlink_ext_ack *extack)
> > > +{
> > > + struct mvsw_pr_port *port = port_vlan->mvsw_pr_port;
> > > + struct mvsw_pr_bridge_vlan *br_vlan;
> > > + u16 vid = port_vlan->vid;
> > > + int err;
> > > +
> > > + if (port_vlan->bridge_port)
> > > + return 0;
> > > +
> > > + err = mvsw_pr_port_flood_set(port, br_port->flags & BR_FLOOD);
> > > + if (err)
> > > + return err;
> > > +
> > > + err = mvsw_pr_port_learning_set(port, br_port->flags & BR_LEARNING);
> > > + if (err)
> > > + goto err_port_learning_set;
> >
> > It seems that learning and flooding are not per-{port, VLAN} attributes,
> > so I'm not sure why you have this here.
> >
> > The fact that you don't undo this in mvsw_pr_port_vlan_bridge_leave()
> > tells me it should not be here.
> >
>
> > +
> > > +void
> > > +mvsw_pr_port_vlan_bridge_leave(struct mvsw_pr_port_vlan *port_vlan)
> > > +{
> > > + struct mvsw_pr_port *port = port_vlan->mvsw_pr_port;
> > > + struct mvsw_pr_bridge_vlan *br_vlan;
> > > + struct mvsw_pr_bridge_port *br_port;
> > > + int port_count;
> > > + u16 vid = port_vlan->vid;
> > > + bool last_port, last_vlan;
> > > +
> > > + br_port = port_vlan->bridge_port;
> > > + last_vlan = list_is_singular(&br_port->vlan_list);
> > > + port_count =
> > > + mvsw_pr_bridge_vlan_port_count_get(br_port->bridge_device, vid);
> > > + br_vlan = mvsw_pr_bridge_vlan_find(br_port, vid);
> > > + last_port = port_count == 1;
> > > + if (last_vlan) {
> > > + mvsw_pr_fdb_flush_port(port, MVSW_PR_FDB_FLUSH_MODE_DYNAMIC);
> > > + } else if (last_port) {
> > > + mvsw_pr_fdb_flush_vlan(port->sw, vid,
> > > + MVSW_PR_FDB_FLUSH_MODE_DYNAMIC);
> > > + } else {
> > > + mvsw_pr_fdb_flush_port_vlan(port, vid,
> > > + MVSW_PR_FDB_FLUSH_MODE_DYNAMIC);
> >
> > If you always flush based on {port, VID}, then why do you need the other
> > two?
> >
>
> > +
> > > +static int mvsw_pr_port_obj_attr_set(struct net_device *dev,
> > > + const struct switchdev_attr *attr,
> > > + struct switchdev_trans *trans)
> > > +{
> > > + int err = 0;
> > > + struct mvsw_pr_port *port = netdev_priv(dev);
> > > +
> > > + switch (attr->id) {
> > > + case SWITCHDEV_ATTR_ID_PORT_STP_STATE:
> > > + err = -EOPNOTSUPP;
> >
> > You don't support STP?
>
> Not, yet. But it will be in the next submission or official patch.
> >
> > > + break;
>
> > > + default:
> > > + kfree(switchdev_work);
> > > + return NOTIFY_DONE;
> > > + }
> > > +
> > > + queue_work(mvsw_owq, &switchdev_work->work);
> >
> > Once you defer the operation you cannot return an error, which is
> > problematic. Do you have a way to know if the operation will succeed or
> > not? That is, if the hardware has enough space for this new FDB entry?
> >
> Right, fdb configuration on via fw is blocking operation I still need to
> think on it if it is possible by current design.
>
>
> >
> > Why do you need both 'struct mvsw_pr_switchdev' and 'struct
> > mvsw_pr_bridge'? I think the second is enough. Also, I assume
> > 'switchdev' naming is inspired by mlxsw, but 'bridge' is better.
> >
> I changed to use bridge for bridge object, because having bridge_device
> may confuse.
>
> Thank you for your comments they were very useful, sorry for so late
> answer, I decided to re-implement this version a bit. Regarding flooding
> and default vid I still need to check it.
>
> Regards,
> Vadym Kochan