nexthop: Emit a notification when a nexthop is added

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.

A 'REPLACE' notification is emitted instead of 'ADD' as the distinction
between the two is not important for in-kernel listeners. In case the
listener is not familiar with the encoded nexthop ID, it can simply
treat it as a new one. This is also consistent with the route offload
API.

Changes since RFC:
* Reword commit message

Signed-off-by: Ido Schimmel <idosch@nvidia.com>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

diff --git a/include/net/nexthop.h b/include/net/nexthop.h
index aa7ac12c35e246035e69b37174dde70426cbd89d..9c85199b826efd0e4629c82af6f829d9403cbf85 100644 (file)
--- a/include/net/nexthop.h
+++ b/include/net/nexthop.h
@@ -105,7 +105,8 @@ struct nexthop {
 };
 
 enum nexthop_event_type {
-       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 d1a1600aee18df773384e04efb25d7346ff4d89d..4e9d0395f959b0d270a454c2ccf2b4d6843a5244 100644 (file)
--- a/net/ipv4/nexthop.c
+++ b/net/ipv4/nexthop.c
@@ -1278,7 +1278,11 @@ 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);