2 files changed, 60 insertions, 0 deletions

diff --git a/include/linux/netdevice.h b/include/linux/netdevice.h
index 20e99efb1ca6..fb912e8e5c7f 100644
--- a/include/linux/netdevice.h
+++ b/include/linux/netdevice.h
@@ -3077,6 +3077,14 @@ void *netdev_lower_get_next_private_rcu(struct net_device *dev,
              priv; \
              priv = netdev_lower_get_next_private_rcu(dev, &(iter)))
 
+void *netdev_lower_get_next(struct net_device *dev,
+                                struct list_head **iter);
+#define netdev_for_each_lower_dev(dev, ldev, iter) \
+        for (iter = &(dev)->adj_list.lower, \
+             ldev = netdev_lower_get_next(dev, &(iter)); \
+             ldev; \
+             ldev = netdev_lower_get_next(dev, &(iter)))
+
 void *netdev_adjacent_get_private(struct list_head *adj_list);
 void *netdev_lower_get_first_private_rcu(struct net_device *dev);
 struct net_device *netdev_master_upper_dev_get(struct net_device *dev);
@@ -3092,6 +3100,8 @@ void netdev_upper_dev_unlink(struct net_device *dev,
 void netdev_adjacent_rename_links(struct net_device *dev, char *oldname);
 void *netdev_lower_dev_get_private(struct net_device *dev,
                                    struct net_device *lower_dev);
+int dev_get_nest_level(struct net_device *dev,
+                       bool (*type_check)(struct net_device *dev));
 int skb_checksum_help(struct sk_buff *skb);
 struct sk_buff *__skb_gso_segment(struct sk_buff *skb,
                                   netdev_features_t features, bool tx_path);
diff --git a/net/core/dev.c b/net/core/dev.c
index ed928e846559..6ee3ac25ed72 100644
--- a/net/core/dev.c
+++ b/net/core/dev.c
@@ -4623,6 +4623,32 @@ void *netdev_lower_get_next_private_rcu(struct net_device *dev,
 EXPORT_SYMBOL(netdev_lower_get_next_private_rcu);
 
 /**
+ * netdev_lower_get_next - Get the next device from the lower neighbour
+ *                         list
+ * @dev: device
+ * @iter: list_head ** of the current position
+ *
+ * Gets the next netdev_adjacent from the dev's lower neighbour
+ * list, starting from iter position. The caller must hold RTNL lock or
+ * its own locking that guarantees that the neighbour lower
+ * list will remain unchainged.
+ */
+void *netdev_lower_get_next(struct net_device *dev, struct list_head **iter)
+{
+        struct netdev_adjacent *lower;
+
+        lower = list_entry((*iter)->next, struct netdev_adjacent, list);
+
+        if (&lower->list == &dev->adj_list.lower)
+                return NULL;
+
+        *iter = &lower->list;
+
+        return lower->dev;
+}
+EXPORT_SYMBOL(netdev_lower_get_next);
+
+/**
  * netdev_lower_get_first_private_rcu - Get the first ->private from the
  *                                     lower neighbour list, RCU
  *                                     variant
@@ -5072,6 +5098,30 @@ void *netdev_lower_dev_get_private(struct net_device *dev,
 }
 EXPORT_SYMBOL(netdev_lower_dev_get_private);
 
+
+int dev_get_nest_level(struct net_device *dev,
+                       bool (*type_check)(struct net_device *dev))
+{
+        struct net_device *lower = NULL;
+        struct list_head *iter;
+        int max_nest = -1;
+        int nest;
+
+        ASSERT_RTNL();
+
+        netdev_for_each_lower_dev(dev, lower, iter) {
+                nest = dev_get_nest_level(lower, type_check);
+                if (max_nest < nest)
+                        max_nest = nest;
+        }
+
+        if (type_check(dev))
+                max_nest++;
+
+        return max_nest;
+}
+EXPORT_SYMBOL(dev_get_nest_level);
+
 static void dev_change_rx_flags(struct net_device *dev, int flags)
 {
         const struct net_device_ops *ops = dev->netdev_ops;