fib: introduce FIB notification infrastructure

This allows to pass information about added/deleted FIB entries/rules to
whoever is interested. This is done in a very similar way as devinet
notifies address additions/removals.

Signed-off-by: Jiri Pirko <jiri@mellanox.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/net/ipv4/fib_rules.c b/net/ipv4/fib_rules.c
index 770bebe..ebadf6b 100644
--- a/net/ipv4/fib_rules.c
+++ b/net/ipv4/fib_rules.c
@@ -164,6 +164,14 @@
 	return NULL;
 }
 
+static int call_fib_rule_notifiers(struct net *net,
+				   enum fib_event_type event_type)
+{
+	struct fib_notifier_info info;
+
+	return call_fib_notifiers(net, event_type, &info);
+}
+
 static const struct nla_policy fib4_rule_policy[FRA_MAX+1] = {
 	FRA_GENERIC_POLICY,
 	[FRA_FLOW]	= { .type = NLA_U32 },
@@ -221,6 +229,7 @@
 
 	net->ipv4.fib_has_custom_rules = true;
 	fib_flush_external(rule->fr_net);
+	call_fib_rule_notifiers(net, FIB_EVENT_RULE_ADD);
 
 	err = 0;
 errout:
@@ -243,6 +252,7 @@
 #endif
 	net->ipv4.fib_has_custom_rules = true;
 	fib_flush_external(rule->fr_net);
+	call_fib_rule_notifiers(net, FIB_EVENT_RULE_DEL);
 errout:
 	return err;
 }