nexthop: Replay nexthops when registering a notifier

When registering a new notifier to the nexthop notification chain,
replay all the existing nexthops to the new notifier so that it will
have a complete picture of the available nexthops.

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

diff --git a/net/ipv4/nexthop.c b/net/ipv4/nexthop.c
index 9a235d5c56701aa92ba7ddb8c9157d9b2e76899a..5e1b22d4f939f504371367b1c8543bbec9a0e71b 100644 (file)
--- a/net/ipv4/nexthop.c
+++ b/net/ipv4/nexthop.c
@@ -157,6 +157,27 @@ static int call_nexthop_notifiers(struct net *net,
        return notifier_to_errno(err);
 }
 
+static int call_nexthop_notifier(struct notifier_block *nb, struct net *net,
+                                enum nexthop_event_type event_type,
+                                struct nexthop *nh,
+                                struct netlink_ext_ack *extack)
+{
+       struct nh_notifier_info info = {
+               .net = net,
+               .extack = extack,
+       };
+       int err;
+
+       err = nh_notifier_info_init(&info, nh);
+       if (err)
+               return err;
+
+       err = nb->notifier_call(nb, event_type, &info);
+       nh_notifier_info_fini(&info);
+
+       return notifier_to_errno(err);
+}
+
 static unsigned int nh_dev_hashfn(unsigned int val)
 {
        unsigned int mask = NH_DEV_HASHSIZE - 1;
@@ -2118,11 +2139,40 @@ static struct notifier_block nh_netdev_notifier = {
        .notifier_call = nh_netdev_event,
 };
 
+static int nexthops_dump(struct net *net, struct notifier_block *nb,
+                        struct netlink_ext_ack *extack)
+{
+       struct rb_root *root = &net->nexthop.rb_root;
+       struct rb_node *node;
+       int err = 0;
+
+       for (node = rb_first(root); node; node = rb_next(node)) {
+               struct nexthop *nh;
+
+               nh = rb_entry(node, struct nexthop, rb_node);
+               err = call_nexthop_notifier(nb, net, NEXTHOP_EVENT_REPLACE, nh,
+                                           extack);
+               if (err)
+                       break;
+       }
+
+       return err;
+}
+
 int register_nexthop_notifier(struct net *net, struct notifier_block *nb,
                              struct netlink_ext_ack *extack)
 {
-       return blocking_notifier_chain_register(&net->nexthop.notifier_chain,
-                                               nb);
+       int err;
+
+       rtnl_lock();
+       err = nexthops_dump(net, nb, extack);
+       if (err)
+               goto unlock;
+       err = blocking_notifier_chain_register(&net->nexthop.notifier_chain,
+                                              nb);
+unlock:
+       rtnl_unlock();
+       return err;
 }
 EXPORT_SYMBOL(register_nexthop_notifier);