netdev - Re: [PATCH v3 net-next 08/10] net: mscc: ocelot: register devlink ports

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Date:   Mon, 11 Jan 2021 19:13:44 +0200
From:   Vladimir Oltean <olteanv@...il.com>
To:     Jakub Kicinski <kuba@...nel.org>
Cc:     netdev@...r.kernel.org, alexandre.belloni@...tlin.com,
        andrew@...n.ch, f.fainelli@...il.com, vivien.didelot@...il.com,
        alexandru.marginean@....com, claudiu.manoil@....com,
        xiaoliang.yang_1@....com, hongbo.wang@....com, jiri@...nulli.us,
        idosch@...sch.org, UNGLinuxDriver@...rochip.com
Subject: Re: [PATCH v3 net-next 08/10] net: mscc: ocelot: register devlink
 ports

On Sat, Jan 09, 2021 at 05:44:39PM -0800, Jakub Kicinski wrote:
> On Fri,  8 Jan 2021 19:59:48 +0200 Vladimir Oltean wrote:
> > From: Vladimir Oltean <vladimir.oltean@....com>
> > 
> > Add devlink integration into the mscc_ocelot switchdev driver. Only the
> > probed interfaces are registered with devlink, because for convenience,
> > struct devlink_port was included into struct ocelot_port_private, which
> > is only initialized for the ports that are used.
> > 
> > Since we use devlink_port_type_eth_set to link the devlink port to the
> > net_device, we can as well remove the .ndo_get_phys_port_name and
> > .ndo_get_port_parent_id implementations, since devlink takes care of
> > retrieving the port name and number automatically, once
> > .ndo_get_devlink_port is implemented.
> > 
> > Note that the felix DSA driver is already integrated with devlink by
> > default, since that is a thing that the DSA core takes care of. This is
> > the reason why these devlink stubs were put in ocelot_net.c and not in
> > the common library.
> > 
> > Signed-off-by: Vladimir Oltean <vladimir.oltean@....com>
> 
> > diff --git a/drivers/net/ethernet/mscc/ocelot_net.c b/drivers/net/ethernet/mscc/ocelot_net.c
> > index 2bd2840d88bd..d0d98c6adea8 100644
> > --- a/drivers/net/ethernet/mscc/ocelot_net.c
> > +++ b/drivers/net/ethernet/mscc/ocelot_net.c
> > @@ -8,6 +8,116 @@
> >  #include "ocelot.h"
> >  #include "ocelot_vcap.h"
> >  
> > +struct ocelot_devlink_private {
> > +	struct ocelot *ocelot;
> > +};
> 
> Why not make struct ocelot part of devlink_priv?

I am not sure what you mean.

> > +static const struct devlink_ops ocelot_devlink_ops = {
> > +};
> > +
> > +static int ocelot_port_devlink_init(struct ocelot *ocelot, int port)
> > +{
> > +	struct ocelot_port *ocelot_port = ocelot->ports[port];
> > +	int id_len = sizeof(ocelot->base_mac);
> > +	struct devlink *dl = ocelot->devlink;
> > +	struct devlink_port_attrs attrs = {};
> > +	struct ocelot_port_private *priv;
> > +	struct devlink_port *dlp;
> > +	int err;
> > +
> > +	if (!ocelot_port)
> > +		return 0;
> > +
> > +	priv = container_of(ocelot_port, struct ocelot_port_private, port);
> > +	dlp = &priv->devlink_port;
> > +
> > +	memcpy(attrs.switch_id.id, &ocelot->base_mac, id_len);
> > +	attrs.switch_id.id_len = id_len;
> > +	attrs.phys.port_number = port;
> > +
> > +	if (priv->dev)
> > +		attrs.flavour = DEVLINK_PORT_FLAVOUR_PHYSICAL;
> > +	else
> > +		attrs.flavour = DEVLINK_PORT_FLAVOUR_UNUSED;
> > +
> > +	devlink_port_attrs_set(dlp, &attrs);
> > +
> > +	err = devlink_port_register(dl, dlp, port);
> > +	if (err)
> > +		return err;
> > +
> > +	if (priv->dev)
> > +		devlink_port_type_eth_set(dlp, priv->dev);
> 
> devlink_port_attrs_set() should be called before netdev is registered,
> and devlink_port_type_eth_set() after. So this sequence makes me a tad
> suspicious.
> 
> In particular IIRC devlink's .ndo_get_phys_port_name depends on it,
> because udev event needs to carry the right info for interface renaming
> to work reliably. No?
> 

If I change the driver's Kconfig from tristate to bool, all is fine,
isn't it?

> > +	return 0;
> > +}
> > +
> > +static void ocelot_port_devlink_teardown(struct ocelot *ocelot, int port)
> > +{
> > +	struct ocelot_port *ocelot_port = ocelot->ports[port];
> > +	struct ocelot_port_private *priv;
> > +	struct devlink_port *dlp;
> > +
> > +	if (!ocelot_port)
> > +		return;
> > +
> > +	priv = container_of(ocelot_port, struct ocelot_port_private, port);
> > +	dlp = &priv->devlink_port;
> > +
> > +	devlink_port_unregister(dlp);
> > +}
> > +
> > +int ocelot_devlink_init(struct ocelot *ocelot)
> > +{
> > +	struct ocelot_devlink_private *dl_priv;
> > +	int port, err;
> > +
> > +	ocelot->devlink = devlink_alloc(&ocelot_devlink_ops, sizeof(*dl_priv));
> > +	if (!ocelot->devlink)
> > +		return -ENOMEM;
> > +	dl_priv = devlink_priv(ocelot->devlink);
> > +	dl_priv->ocelot = ocelot;
> > +
> > +	err = devlink_register(ocelot->devlink, ocelot->dev);
> > +	if (err)
> > +		goto free_devlink;
> > +
> > +	for (port = 0; port < ocelot->num_phys_ports; port++) {
> > +		err = ocelot_port_devlink_init(ocelot, port);
> > +		if (err) {
> > +			while (port-- > 0)
> > +				ocelot_port_devlink_teardown(ocelot, port);
> > +			goto unregister_devlink;
> 
> nit: should this also be on the error path below?
> 
> > +		}
> > +	}
> > +
> > +	return 0;
> > +
> > +unregister_devlink:
> > +	devlink_unregister(ocelot->devlink);
> > +free_devlink:
> > +	devlink_free(ocelot->devlink);
> > +	return err;
> > +}
> 
> > --- a/drivers/net/ethernet/mscc/ocelot_vsc7514.c
> > +++ b/drivers/net/ethernet/mscc/ocelot_vsc7514.c
> > @@ -1293,6 +1293,12 @@ static int mscc_ocelot_probe(struct platform_device *pdev)
> >  		}
> >  	}
> >  
> > +	err = ocelot_devlink_init(ocelot);
> > +	if (err) {
> > +		mscc_ocelot_release_ports(ocelot);
> > +		goto out_ocelot_deinit;
> 
> No need to add ocelot_deinit_timestamp(ocelot); to the error path?

Yes, the error handling could be better.