netdev - [PATCH net-next 4/5] nexthop: Only emit a notification when nexthop is actually deleted

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Date:   Tue, 15 Sep 2020 14:41:02 +0300
From:   Ido Schimmel <idosch@...sch.org>
To:     netdev@...r.kernel.org
Cc:     davem@...emloft.net, kuba@...nel.org, dsahern@...il.com,
        mlxsw@...dia.com, Ido Schimmel <idosch@...dia.com>
Subject: [PATCH net-next 4/5] nexthop: Only emit a notification when nexthop is actually deleted

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

Currently, the in-kernel delete notification is emitted from the error
path of nexthop_add() and replace_nexthop(), which can be confusing to
in-kernel listeners as they are not familiar with the nexthop.

Instead, only emit the notification when the nexthop is actually
deleted. The following sub-cases are covered:

1. User space deletes the nexthop
2. The nexthop is deleted by the kernel due to a netdev event (e.g.,
   nexthop device going down)
3. A group is deleted because its last nexthop is being deleted
4. The network namespace of the nexthop device is deleted

Signed-off-by: Ido Schimmel <idosch@...dia.com>
Reviewed-by: David Ahern <dsahern@...il.com>
---
 net/ipv4/nexthop.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/net/ipv4/nexthop.c b/net/ipv4/nexthop.c
index 13d9219a9aa1..8c0f17c6863c 100644
--- a/net/ipv4/nexthop.c
+++ b/net/ipv4/nexthop.c
@@ -870,8 +870,6 @@ static void __remove_nexthop_fib(struct net *net, struct nexthop *nh)
 	bool do_flush = false;
 	struct fib_info *fi;
 
-	call_nexthop_notifiers(net, NEXTHOP_EVENT_DEL, nh);
-
 	list_for_each_entry(fi, &nh->fi_list, nh_list) {
 		fi->fib_flags |= RTNH_F_DEAD;
 		do_flush = true;
@@ -909,6 +907,8 @@ static void __remove_nexthop(struct net *net, struct nexthop *nh,
 static void remove_nexthop(struct net *net, struct nexthop *nh,
 			   struct nl_info *nlinfo)
 {
+	call_nexthop_notifiers(net, NEXTHOP_EVENT_DEL, nh);
+
 	/* remove from the tree */
 	rb_erase(&nh->rb_node, &net->nexthop.rb_root);
 
-- 
2.26.2