Merge tag 'batadv-net-pullrequest-20220302' of git://git.open-mesh.org/linux-merge

Simon Wunderlich says:

====================
Here are some batman-adv bugfixes:

 - Remove redundant iflink requests, by Sven Eckelmann (2 patches)

 - Don't expect inter-netns unique iflink indices, by Sven Eckelmann

* tag 'batadv-net-pullrequest-20220302' of git://git.open-mesh.org/linux-merge:
  batman-adv: Don't expect inter-netns unique iflink indices
  batman-adv: Request iflink once in batadv_get_real_netdevice
  batman-adv: Request iflink once in batadv-on-batadv check
====================

Link: https://lore.kernel.org/r/20220302163049.101957-1-sw@simonwunderlich.de
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

Author: kuba-moo

net/batman-adv/hard-interface.c

@@ -149,22 +149,25 @@ static bool batadv_is_on_batman_iface(const struct net_device *net_dev)
 	struct net *net = dev_net(net_dev);
 	struct net_device *parent_dev;
 	struct net *parent_net;
+	int iflink;
 	bool ret;
 
 	/* check if this is a batman-adv mesh interface */
 	if (batadv_softif_is_valid(net_dev))
 		return true;
 
-	/* no more parents..stop recursion */
-	if (dev_get_iflink(net_dev) == 0 ||
-	    dev_get_iflink(net_dev) == net_dev->ifindex)
+	iflink = dev_get_iflink(net_dev);
+	if (iflink == 0)
 		return false;
 
 	parent_net = batadv_getlink_net(net_dev, net);
 
+	/* iflink to itself, most likely physical device */
+	if (net == parent_net && iflink == net_dev->ifindex)
+		return false;
+
 	/* recurse over the parent device */
-	parent_dev = __dev_get_by_index((struct net *)parent_net,
-					dev_get_iflink(net_dev));
+	parent_dev = __dev_get_by_index((struct net *)parent_net, iflink);
 	/* if we got a NULL parent_dev there is something broken.. */
 	if (!parent_dev) {
 		pr_err("Cannot find parent device\n");
@@ -214,14 +217,15 @@ static struct net_device *batadv_get_real_netdevice(struct net_device *netdev)
 	struct net_device *real_netdev = NULL;
 	struct net *real_net;
 	struct net *net;
-	int ifindex;
+	int iflink;
 
 	ASSERT_RTNL();
 
 	if (!netdev)
 		return NULL;
 
-	if (netdev->ifindex == dev_get_iflink(netdev)) {
+	iflink = dev_get_iflink(netdev);
+	if (iflink == 0) {
 		dev_hold(netdev);
 		return netdev;
 	}
@@ -231,9 +235,16 @@ static struct net_device *batadv_get_real_netdevice(struct net_device *netdev)
 		goto out;
 
 	net = dev_net(hard_iface->soft_iface);
-	ifindex = dev_get_iflink(netdev);
 	real_net = batadv_getlink_net(netdev, net);
-	real_netdev = dev_get_by_index(real_net, ifindex);
+
+	/* iflink to itself, most likely physical device */
+	if (net == real_net && netdev->ifindex == iflink) {
+		real_netdev = netdev;
+		dev_hold(real_netdev);
+		goto out;
+	}
+
+	real_netdev = dev_get_by_index(real_net, iflink);
 
 out:
 	batadv_hardif_put(hard_iface);