Merge tag 'batadv-net-pullrequest-20250509' of git://git.open-mesh.org/linux-merge

Simon Wunderlich says:

====================
Here is a batman-adv bugfix:

 - fix duplicate MAC address check, by Matthias Schiffer

* tag 'batadv-net-pullrequest-20250509' of git://git.open-mesh.org/linux-merge:
  batman-adv: fix duplicate MAC address check
====================

Link: https://patch.msgid.link/20250509090240.107796-1-sw@simonwunderlich.de
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

Author: kuba-moo

net/batman-adv/hard-interface.c

@@ -506,28 +506,32 @@ batadv_hardif_is_iface_up(const struct batadv_hard_iface *hard_iface)
 	return false;
 }
 
-static void batadv_check_known_mac_addr(const struct net_device *net_dev)
+static void batadv_check_known_mac_addr(const struct batadv_hard_iface *hard_iface)
 {
-	const struct batadv_hard_iface *hard_iface;
+	const struct net_device *mesh_iface = hard_iface->mesh_iface;
+	const struct batadv_hard_iface *tmp_hard_iface;
 
-	rcu_read_lock();
-	list_for_each_entry_rcu(hard_iface, &batadv_hardif_list, list) {
-		if (hard_iface->if_status != BATADV_IF_ACTIVE &&
-		    hard_iface->if_status != BATADV_IF_TO_BE_ACTIVATED)
+	if (!mesh_iface)
+		return;
+
+	list_for_each_entry(tmp_hard_iface, &batadv_hardif_list, list) {
+		if (tmp_hard_iface == hard_iface)
+			continue;
+
+		if (tmp_hard_iface->mesh_iface != mesh_iface)
 			continue;
 
-		if (hard_iface->net_dev == net_dev)
+		if (tmp_hard_iface->if_status == BATADV_IF_NOT_IN_USE)
 			continue;
 
-		if (!batadv_compare_eth(hard_iface->net_dev->dev_addr,
-					net_dev->dev_addr))
+		if (!batadv_compare_eth(tmp_hard_iface->net_dev->dev_addr,
+					hard_iface->net_dev->dev_addr))
 			continue;
 
 		pr_warn("The newly added mac address (%pM) already exists on: %s\n",
-			net_dev->dev_addr, hard_iface->net_dev->name);
+			hard_iface->net_dev->dev_addr, tmp_hard_iface->net_dev->name);
 		pr_warn("It is strongly recommended to keep mac addresses unique to avoid problems!\n");
 	}
-	rcu_read_unlock();
 }
 
 /**
@@ -763,6 +767,8 @@ int batadv_hardif_enable_interface(struct batadv_hard_iface *hard_iface,
 			    hard_iface->net_dev->name, hardif_mtu,
 			    required_mtu);
 
+	batadv_check_known_mac_addr(hard_iface);
+
 	if (batadv_hardif_is_iface_up(hard_iface))
 		batadv_hardif_activate_interface(hard_iface);
 	else
@@ -901,7 +907,6 @@ batadv_hardif_add_interface(struct net_device *net_dev)
 
 	batadv_v_hardif_init(hard_iface);
 
-	batadv_check_known_mac_addr(hard_iface->net_dev);
 	kref_get(&hard_iface->refcount);
 	list_add_tail_rcu(&hard_iface->list, &batadv_hardif_list);
 	batadv_hardif_generation++;
@@ -988,7 +993,7 @@ static int batadv_hard_if_event(struct notifier_block *this,
 		if (hard_iface->if_status == BATADV_IF_NOT_IN_USE)
 			goto hardif_put;
 
-		batadv_check_known_mac_addr(hard_iface->net_dev);
+		batadv_check_known_mac_addr(hard_iface);
 
 		bat_priv = netdev_priv(hard_iface->mesh_iface);
 		bat_priv->algo_ops->iface.update_mac(hard_iface);