nexthop: Add nexthop notification data structures

Add data structures that will be used for nexthop replace and delete
notifications in the previously introduced nexthop notification chain.

New data structures are added instead of passing the existing nexthop
code structures directly for several reasons.

First, the existing structures encode a lot of bookkeeping information
which is irrelevant for listeners of the notification chain.

Second, the existing structures can be changed without worrying about
introducing regressions in listeners since they are not accessed
directly by them.

Third, listeners of the notification chain do not need to each parse the
relatively complex nexthop code structures. They are passing the
required information in a simplified way.

Note that a single 'has_encap' bit is added instead of the actual
encapsulation information since current listeners do not support such
nexthops.

Changes since RFC:
* s/is_encap/has_encap/
Signed-off-by: Ido Schimmel <idosch@nvidia.com>
Reviewed-by: David Ahern <dsahern@gmail.com>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

include/net/nexthop.h

@@ -108,6 +108,41 @@ enum nexthop_event_type {
 	NEXTHOP_EVENT_DEL
 };
 
+struct nh_notifier_single_info {
+	struct net_device *dev;
+	u8 gw_family;
+	union {
+		__be32 ipv4;
+		struct in6_addr ipv6;
+	};
+	u8 is_reject:1,
+	   is_fdb:1,
+	   has_encap:1;
+};
+
+struct nh_notifier_grp_entry_info {
+	u8 weight;
+	u32 id;
+	struct nh_notifier_single_info nh;
+};
+
+struct nh_notifier_grp_info {
+	u16 num_nh;
+	bool is_fdb;
+	struct nh_notifier_grp_entry_info nh_entries[];
+};
+
+struct nh_notifier_info {
+	struct net *net;
+	struct netlink_ext_ack *extack;
+	u32 id;
+	bool is_grp;
+	union {
+		struct nh_notifier_single_info *nh;
+		struct nh_notifier_grp_info *nh_grp;
+	};
+};
+
 int register_nexthop_notifier(struct net *net, struct notifier_block *nb);
 int unregister_nexthop_notifier(struct net *net, struct notifier_block *nb);