net: Add info for NETDEV_CHANGEUPPER event

Some consumers of NETDEV_CHANGEUPPER event would like to know which
upper device was linked/unlinked and what operation was carried.

Add information in the notifier info block for that purpose.
Signed-off-by: Matan Barak <matanb@mellanox.com>
Signed-off-by: Doug Ledford <dledford@redhat.com>

include/linux/netdevice.h

@@ -3556,6 +3556,20 @@ struct sk_buff *__skb_gso_segment(struct sk_buff *skb,
 struct sk_buff *skb_mac_gso_segment(struct sk_buff *skb,
 				    netdev_features_t features);
 
+enum netdev_changeupper_event {
+	NETDEV_CHANGEUPPER_LINK,
+	NETDEV_CHANGEUPPER_UNLINK,
+};
+
+struct netdev_changeupper_info {
+	struct netdev_notifier_info	info; /* must be first */
+	enum netdev_changeupper_event	event;
+	struct net_device		*upper;
+};
+
+void netdev_changeupper_info_change(struct net_device *dev,
+				    struct netdev_changeupper_info *info);
+
 struct netdev_bonding_info {
 	ifslave	slave;
 	ifbond	master;

net/core/dev.c

@@ -5302,6 +5302,7 @@ static int __netdev_upper_dev_link(struct net_device *dev,
 				   void *private)
 {
 	struct netdev_adjacent *i, *j, *to_i, *to_j;
+	struct netdev_changeupper_info changeupper_info;
 	int ret = 0;
 
 	ASSERT_RTNL();
@@ -5357,7 +5358,10 @@ static int __netdev_upper_dev_link(struct net_device *dev,
 			goto rollback_lower_mesh;
 	}
 
-	call_netdevice_notifiers(NETDEV_CHANGEUPPER, dev);
+	changeupper_info.event = NETDEV_CHANGEUPPER_LINK;
+	changeupper_info.upper = upper_dev;
+	call_netdevice_notifiers_info(NETDEV_CHANGEUPPER, dev,
+				      &changeupper_info.info);
 	return 0;
 
 rollback_lower_mesh:
@@ -5453,6 +5457,7 @@ void netdev_upper_dev_unlink(struct net_device *dev,
 			     struct net_device *upper_dev)
 {
 	struct netdev_adjacent *i, *j;
+	struct netdev_changeupper_info changeupper_info;
 	ASSERT_RTNL();
 
 	__netdev_adjacent_dev_unlink_neighbour(dev, upper_dev);
@@ -5474,7 +5479,10 @@ void netdev_upper_dev_unlink(struct net_device *dev,
 	list_for_each_entry(i, &upper_dev->all_adj_list.upper, list)
 		__netdev_adjacent_dev_unlink(dev, i->dev);
 
-	call_netdevice_notifiers(NETDEV_CHANGEUPPER, dev);
+	changeupper_info.event = NETDEV_CHANGEUPPER_UNLINK;
+	changeupper_info.upper = upper_dev;
+	call_netdevice_notifiers_info(NETDEV_CHANGEUPPER, dev,
+				      &changeupper_info.info);
 }
 EXPORT_SYMBOL(netdev_upper_dev_unlink);