phy_port is aimed at representing the various physical interfaces of a
net_device. They can be controlled by various components in the link,
such as the Ethernet PHY, the Ethernet MAC, and SFP module, etc.

Let's therefore make so we keep track of all the ports connected to a
netdev in phy_link_topology. The only ports added for now are phy-driven
ports.

Signed-off-by: Maxime Chevallier <maxime.chevallier@bootlin.com>
---
 drivers/net/phy/phy_link_topology.c | 53 +++++++++++++++++++++++++++++
 include/linux/phy_link_topology.h   | 18 ++++++++++
 include/linux/phy_port.h            |  2 ++
 net/core/dev.c                      |  1 +
 4 files changed, 74 insertions(+)

diff --git a/drivers/net/phy/phy_link_topology.c b/drivers/net/phy/phy_link_topology.c
index 7dc2ff10c74a..456f1144e83e 100644
--- a/drivers/net/phy/phy_link_topology.c
+++ b/drivers/net/phy/phy_link_topology.c
@@ -7,6 +7,7 @@
  */
 
 #include <linux/phy_link_topology.h>
+#include <linux/phy_port.h>
 #include <linux/phy.h>
 #include <linux/rtnetlink.h>
 #include <linux/xarray.h>
@@ -22,6 +23,9 @@ static int netdev_alloc_phy_link_topology(struct net_device *dev)
 	xa_init_flags(&topo->phys, XA_FLAGS_ALLOC1);
 	topo->next_phy_index = 1;
 
+	xa_init_flags(&topo->ports, XA_FLAGS_ALLOC1);
+	topo->next_port_index = 1;
+
 	dev->link_topo = topo;
 
 	return 0;
@@ -44,12 +48,45 @@ static struct phy_link_topology *phy_link_topo_get_or_alloc(struct net_device *d
 	return dev->link_topo;
 }
 
+int phy_link_topo_add_port(struct net_device *dev, struct phy_port *port)
+{
+	struct phy_link_topology *topo;
+	int ret;
+
+	topo = phy_link_topo_get_or_alloc(dev);
+	if (IS_ERR(topo))
+		return PTR_ERR(topo);
+
+	/* Attempt to re-use a previously allocated port_id */
+	if (port->id)
+		ret = xa_insert(&topo->ports, port->id, port, GFP_KERNEL);
+	else
+		ret = xa_alloc_cyclic(&topo->ports, &port->id, port,
+				      xa_limit_32b, &topo->next_port_index,
+				      GFP_KERNEL);
+
+	return ret;
+}
+EXPORT_SYMBOL_GPL(phy_link_topo_add_port);
+
+void phy_link_topo_del_port(struct net_device *dev, struct phy_port *port)
+{
+	struct phy_link_topology *topo = dev->link_topo;
+
+	if (!topo)
+		return;
+
+	xa_erase(&topo->ports, port->id);
+}
+EXPORT_SYMBOL_GPL(phy_link_topo_del_port);
+
 int phy_link_topo_add_phy(struct net_device *dev,
 			  struct phy_device *phy,
 			  enum phy_upstream upt, void *upstream)
 {
 	struct phy_link_topology *topo;
 	struct phy_device_node *pdn;
+	struct phy_port *port;
 	int ret;
 
 	topo = phy_link_topo_get_or_alloc(dev);
@@ -89,8 +126,20 @@ int phy_link_topo_add_phy(struct net_device *dev,
 	if (ret < 0)
 		goto err;
 
+	/* Add all the PHY's ports to the topology */
+	list_for_each_entry(port, &phy->ports, head) {
+		ret = phy_link_topo_add_port(dev, port);
+		if (ret)
+			goto del_ports;
+	}
+
 	return 0;
 
+del_ports:
+	list_for_each_entry_from_reverse(port, &phy->ports, head)
+		phy_link_topo_del_port(dev, port);
+
+	xa_erase(&topo->phys, phy->phyindex);
 err:
 	kfree(pdn);
 	return ret;
@@ -102,10 +151,14 @@ void phy_link_topo_del_phy(struct net_device *dev,
 {
 	struct phy_link_topology *topo = dev->link_topo;
 	struct phy_device_node *pdn;
+	struct phy_port *port;
 
 	if (!topo)
 		return;
 
+	list_for_each_entry(port, &phy->ports, head)
+		phy_link_topo_del_port(dev, port);
+
 	pdn = xa_erase(&topo->phys, phy->phyindex);
 
 	/* We delete the PHY from the topology, however we don't re-set the
diff --git a/include/linux/phy_link_topology.h b/include/linux/phy_link_topology.h
index 68a59e25821c..66bceff72b19 100644
--- a/include/linux/phy_link_topology.h
+++ b/include/linux/phy_link_topology.h
@@ -16,11 +16,15 @@
 
 struct xarray;
 struct phy_device;
+struct phy_port;
 struct sfp_bus;
 
 struct phy_link_topology {
 	struct xarray phys;
 	u32 next_phy_index;
+
+	struct xarray ports;
+	u32 next_port_index;
 };
 
 struct phy_device_node {
@@ -43,6 +47,9 @@ int phy_link_topo_add_phy(struct net_device *dev,
 
 void phy_link_topo_del_phy(struct net_device *dev, struct phy_device *phy);
 
+int phy_link_topo_add_port(struct net_device *dev, struct phy_port *port);
+void phy_link_topo_del_port(struct net_device *dev, struct phy_port *port);
+
 static inline struct phy_device *
 phy_link_topo_get_phy(struct net_device *dev, u32 phyindex)
 {
@@ -72,6 +79,17 @@ static inline void phy_link_topo_del_phy(struct net_device *dev,
 {
 }
 
+static inline int phy_link_topo_add_port(struct net_device *dev,
+					 struct phy_port *port)
+{
+	return 0;
+}
+
+static inline void phy_link_topo_del_port(struct net_device *dev,
+					  struct phy_port *port)
+{
+}
+
 static inline struct phy_device *
 phy_link_topo_get_phy(struct net_device *dev, u32 phyindex)
 {
diff --git a/include/linux/phy_port.h b/include/linux/phy_port.h
index 0ef0f5ce4709..4e2a3fdd2f2e 100644
--- a/include/linux/phy_port.h
+++ b/include/linux/phy_port.h
@@ -36,6 +36,7 @@ struct phy_port_ops {
 /**
  * struct phy_port - A representation of a network device physical interface
  *
+ * @id: Unique identifier for the port within the topology
  * @head: Used by the port's parent to list ports
  * @parent_type: The type of device this port is directly connected to
  * @phy: If the parent is PHY_PORT_PHYDEV, the PHY controlling that port
@@ -52,6 +53,7 @@ struct phy_port_ops {
  * @is_sfp: Indicates if this port drives an SFP cage.
  */
 struct phy_port {
+	u32 id;
 	struct list_head head;
 	enum phy_port_parent parent_type;
 	union {
diff --git a/net/core/dev.c b/net/core/dev.c
index 43de5af0d6ec..fe2dfcc95400 100644
--- a/net/core/dev.c
+++ b/net/core/dev.c
@@ -11277,6 +11277,7 @@ static void netdev_free_phy_link_topology(struct net_device *dev)
 
 	if (IS_ENABLED(CONFIG_PHYLIB) && topo) {
 		xa_destroy(&topo->phys);
+		xa_destroy(&topo->ports);
 		kfree(topo);
 		dev->link_topo = NULL;
 	}
-- 
2.49.0

This is an AI-generated review of your patch. The human sending this
email has considered the AI review valid, or at least plausible.

For local reproduction steps see https://netdev-ai.bots.linux.dev/ai-local.html
---
net: phy: phy_link_topology: Track ports in phy_link_topology

This commit adds port tracking to phy_link_topology, keeping track of all
ports connected to a netdev. Ports are added when a PHY is attached and
removed when it is detached.

> diff --git a/drivers/net/phy/phy_link_topology.c b/drivers/net/phy/phy_link_topology.c
> index 7dc2ff10c74a..456f1144e83e 100644
> --- a/drivers/net/phy/phy_link_topology.c
> +++ b/drivers/net/phy/phy_link_topology.c

[ ... ]

> +int phy_link_topo_add_port(struct net_device *dev, struct phy_port *port)
> +{
> +	struct phy_link_topology *topo;
> +	int ret;
> +
> +	topo = phy_link_topo_get_or_alloc(dev);
> +	if (IS_ERR(topo))
> +		return PTR_ERR(topo);
> +
> +	/* Attempt to re-use a previously allocated port_id */
> +	if (port->id)
> +		ret = xa_insert(&topo->ports, port->id, port, GFP_KERNEL);
> +	else
> +		ret = xa_alloc_cyclic(&topo->ports, &port->id, port,
> +				      xa_limit_32b, &topo->next_port_index,
> +				      GFP_KERNEL);
> +
> +	return ret;
> +}

[ ... ]

> @@ -89,8 +126,20 @@ int phy_link_topo_add_phy(struct net_device *dev,
>  	if (ret < 0)
>  		goto err;
> +
> +	/* Add all the PHY's ports to the topology */
> +	list_for_each_entry(port, &phy->ports, head) {
> +		ret = phy_link_topo_add_port(dev, port);
> +		if (ret)
> +			goto del_ports;
                   ^^^

xa_alloc_cyclic() returns 1 when ID allocation wraps around, which is still a
successful allocation. The check at line 126 above correctly uses `if (ret < 0)`
for the phyindex allocation:

    ret = xa_alloc_cyclic(&topo->phys, &phy->phyindex, pdn, ...);
    if (ret < 0)
        goto err;

Should this use `if (ret < 0)` as well for consistency? With the current code,
when the port ID wraps around, the PHY attachment will fail and trigger rollback
of all successfully added ports even though the allocation succeeded.

Hi Simon,

On 03/02/2026 19:02, Simon Horman wrote:
> This is an AI-generated review of your patch. The human sending this
> email has considered the AI review valid, or at least plausible.

> 
> xa_alloc_cyclic() returns 1 when ID allocation wraps around, which is still a
> successful allocation. The check at line 126 above correctly uses `if (ret < 0)`
> for the phyindex allocation:

I already reported that to Chris, this review is incorrect.

xa_alloc_cyclic() doesn't return 1 upon wraparound. __xa_alloc_cyclic()
does :)

Maxime