[RFC PATCH net-next 11/22] nexthop: Emit a notification when a nexthop is added

[Ido Schimmel <idosch@idosch.org>]

From: Ido Schimmel <idosch@nvidia.com>

Emit a notification in the nexthop notification chain when a new nexthop
is added (not replaced). The nexthop can either be a new group or a
single nexthop.

The notification is sent after the nexthop is inserted into the
red-black tree, as listeners might need to callback into the nexthop
code with the nexthop ID in order to mark the nexthop as offloaded.

Signed-off-by: Ido Schimmel <idosch@nvidia.com>
---
 include/net/nexthop.h | 3 ++-
 net/ipv4/nexthop.c    | 6 +++++-
 2 files changed, 7 insertions(+), 2 deletions(-)

diff --git a/include/net/nexthop.h b/include/net/nexthop.h
index 4147681e86d2..6431ff8cdb89 100644
--- a/include/net/nexthop.h
+++ b/include/net/nexthop.h
@@ -106,7 +106,8 @@ struct nexthop {
 
 enum nexthop_event_type {
 	NEXTHOP_EVENT_ADD,
-	NEXTHOP_EVENT_DEL
+	NEXTHOP_EVENT_DEL,
+	NEXTHOP_EVENT_REPLACE,
 };
 
 struct nh_notifier_single_info {
diff --git a/net/ipv4/nexthop.c b/net/ipv4/nexthop.c
index 71605c612458..1fa249facd46 100644
--- a/net/ipv4/nexthop.c
+++ b/net/ipv4/nexthop.c
@@ -1277,7 +1277,11 @@ static int insert_nexthop(struct net *net, struct nexthop *new_nh,
 
 	rb_link_node_rcu(&new_nh->rb_node, parent, pp);
 	rb_insert_color(&new_nh->rb_node, root);
-	rc = 0;
+
+	rc = call_nexthop_notifiers(net, NEXTHOP_EVENT_REPLACE, new_nh, extack);
+	if (rc)
+		rb_erase(&new_nh->rb_node, &net->nexthop.rb_root);
+
 out:
 	if (!rc) {
 		nh_base_seq_inc(net);
-- 
2.26.2