[PATCH net-next] net: phy: phy_link_topology: Handle NULL topologies

[Maxime Chevallier <maxime.chevallier@bootlin.com>]

In situations where phylib is a module, the topology can be NULL as it's
not initialized at netdev creation.

Allow passing a NULL topology pointer to phy_link_topo helpers.

Signed-off-by: Maxime Chevallier <maxime.chevallier@bootlin.com>
Closes: https://lore.kernel.org/netdev/2e11b89d-100f-49e7-9c9a-834cc0b82f97@gmail.com/
Closes: https://lore.kernel.org/netdev/20240409201553.GA4124869@dev-arch.thelio-3990X/
---

Hi,

This patch fixes a commit that is in net-next, hence the net-next tag and the
lack of "Fixes" tag.

Nathan, Heiner, can you confirm this solves what you're seeing ?

I think we can improve on this solution by moving the topology init at
the first PHY insertion and clearing it at netdev destruction.

Maxime

 drivers/net/phy/phy_link_topology.c | 10 +++++++++-
 include/linux/phy_link_topology.h   |  7 ++++++-
 2 files changed, 15 insertions(+), 2 deletions(-)

diff --git a/drivers/net/phy/phy_link_topology.c b/drivers/net/phy/phy_link_topology.c
index 985941c5c558..0f3973f07fac 100644
--- a/drivers/net/phy/phy_link_topology.c
+++ b/drivers/net/phy/phy_link_topology.c
@@ -42,6 +42,9 @@ int phy_link_topo_add_phy(struct phy_link_topology *topo,
 	struct phy_device_node *pdn;
 	int ret;
 
+	if (!topo)
+		return 0;
+
 	pdn = kzalloc(sizeof(*pdn), GFP_KERNEL);
 	if (!pdn)
 		return -ENOMEM;
@@ -93,7 +96,12 @@ EXPORT_SYMBOL_GPL(phy_link_topo_add_phy);
 void phy_link_topo_del_phy(struct phy_link_topology *topo,
 			   struct phy_device *phy)
 {
-	struct phy_device_node *pdn = xa_erase(&topo->phys, phy->phyindex);
+	struct phy_device_node *pdn;
+
+	if (!topo)
+		return;
+
+	pdn = xa_erase(&topo->phys, phy->phyindex);
 
 	/* We delete the PHY from the topology, however we don't re-set the
 	 * phy->phyindex field. If the PHY isn't gone, we can re-assign it the
diff --git a/include/linux/phy_link_topology.h b/include/linux/phy_link_topology.h
index 6b79feb607e7..21ca78127d0f 100644
--- a/include/linux/phy_link_topology.h
+++ b/include/linux/phy_link_topology.h
@@ -40,7 +40,12 @@ struct phy_link_topology {
 static inline struct phy_device *
 phy_link_topo_get_phy(struct phy_link_topology *topo, u32 phyindex)
 {
-	struct phy_device_node *pdn = xa_load(&topo->phys, phyindex);
+	struct phy_device_node *pdn;
+
+	if (!topo)
+		return NULL;
+
+	pdn = xa_load(&topo->phys, phyindex);
 
 	if (pdn)
 		return pdn->phy;
-- 
2.44.0