netdev - [PATCH net-next 07/18] nexthop: Emit a notification when a nexthop is added

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Date:   Wed,  4 Nov 2020 15:30:29 +0200
From:   Ido Schimmel <idosch@...sch.org>
To:     netdev@...r.kernel.org
Cc:     davem@...emloft.net, kuba@...nel.org, dsahern@...il.com,
        jiri@...dia.com, mlxsw@...dia.com, Ido Schimmel <idosch@...dia.com>
Subject: [PATCH net-next 07/18] nexthop: Emit a notification when a nexthop is added

From: Ido Schimmel <idosch@...dia.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.

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@...dia.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 aa7ac12c35e2..9c85199b826e 100644
--- 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 d1a1600aee18..4e9d0395f959 100644
--- 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);
-- 
2.26.2