Re: [RFC PATCH net-next v2 01/10] net: phy: Introduce ethernet link topology representation

From: Maxime Chevallier
Date: Thu Nov 23 2023 - 08:34:21 EST


Hello Andrew,

On Tue, 21 Nov 2023 01:24:47 +0100
Andrew Lunn <andrew@xxxxxxx> wrote:

> > +int link_topo_add_phy(struct link_topology *lt, struct phy_device *phy,
> > + enum phy_upstream upt, void *upstream)
> > +{
> > + ret = xa_alloc_cyclic(&lt->phys, &phy->phyindex, pdn, xa_limit_32b,
> > + &lt->next_phy_index, GFP_KERNEL);
> > + if (ret)
> > + goto err;
> > +
> > + return 0;
>
> It looks like that could be just return xa_alloc_cyclic(...);

Indeed, nice catch

>
> > diff --git a/include/linux/link_topology.h b/include/linux/link_topology.h
>
> I think this filename is too generic. Maybe phy_link_topology.h, or
> move it into include/net.
>
> > +struct phy_device *link_topo_get_phy(struct link_topology *lt, int phyindex);
> > +int link_topo_add_phy(struct link_topology *lt, struct phy_device *phy,
> > + enum phy_upstream upt, void *upstream);
> > +
> > +void link_topo_del_phy(struct link_topology *lt, struct phy_device *phy);
>
> What is the locking for these functions? Are you assuming RTNL? Maybe
> add ASSERT_RTNL(); into them to make this clear.

Indeed I assume it, I'll add an assert and document that clearly then.

>
> > diff --git a/include/linux/link_topology_core.h b/include/linux/link_topology_core.h
>
> Again, i think this filename is too generic.
>
> > diff --git a/include/linux/netdevice.h b/include/linux/netdevice.h
> > index a16c9cc063fe..7021a0d3d982 100644
> > --- a/include/linux/netdevice.h
> > +++ b/include/linux/netdevice.h
> > @@ -40,7 +40,6 @@
> > #include <net/dcbnl.h>
> > #endif
> > #include <net/netprio_cgroup.h>
> > -
> > #include <linux/netdev_features.h>
>
> Whitespace change.
>
> > #include <linux/neighbour.h>
> > #include <uapi/linux/netdevice.h>
> > @@ -52,6 +51,7 @@
> > #include <net/net_trackers.h>
> > #include <net/net_debug.h>
> > #include <net/dropreason-core.h>
> > +#include <linux/link_topology_core.h>
> >
> > struct netpoll_info;
> > struct device;
> > @@ -2405,6 +2405,7 @@ struct net_device {
> > #if IS_ENABLED(CONFIG_CGROUP_NET_PRIO)
> > struct netprio_map __rcu *priomap;
> > #endif
> > + struct link_topology link_topo;
> > struct phy_device *phydev;
> > struct sfp_bus *sfp_bus;
> > struct lock_class_key *qdisc_tx_busylock;
> > diff --git a/include/linux/phy.h b/include/linux/phy.h
> > index 3cc52826f18e..d698180b1df0 100644
> > --- a/include/linux/phy.h
> > +++ b/include/linux/phy.h
> > @@ -543,6 +543,8 @@ struct macsec_ops;
> > * @drv: Pointer to the driver for this PHY instance
> > * @devlink: Create a link between phy dev and mac dev, if the external phy
> > * used by current mac interface is managed by another mac interface.
> > + * @phyindex: Unique id across the phy's parent tree of phys to address the PHY
> > + * from userspace, similar to ifindex. It's never recycled.
> > * @phy_id: UID for this device found during discovery
> > * @c45_ids: 802.3-c45 Device Identifiers if is_c45.
> > * @is_c45: Set to true if this PHY uses clause 45 addressing.
> > @@ -640,6 +642,7 @@ struct phy_device {
> >
> > struct device_link *devlink;
> >
> > + int phyindex;
>
> Is this int, or unsigned int? Is a negative value possible and legal?

You're right this should be unsigned. I've also missed properly
documenting correct values and their meaning (like phyindex 0 would be
no index assigned).

>
> > +enum phy_upstream {
> > + PHY_UPSTREAM_MAC,
> > + PHY_UPSTREAM_SFP,
> > + PHY_UPSTREAM_PHY,
> > +};
>
> Please document what these actually mean.

I'll do this as well.

Thank you for reviewing,

Maxime

>
> Andrew