From: Danny Feng <dfeng@redhat.com>
Date: Tue, 25 Aug 2009 06:44:17 -0400
Subject: [net] use netlink notifications to track neighbour states
Message-id: <20090825064428.28685.34140.sendpatchset@danny>
Patchwork-id: 20796
O-Subject: [PATCH RHEL5.5 2/2] [NETLINK]: Netlink notifications
Bugzilla: 516589
RH-Acked-by: David S. Miller <davem@redhat.com>
RH-Acked-by: Thomas Graf <tgraf@redhat.com>
RH-Acked-by: Jiri Pirko <jpirko@redhat.com>

RHBZ#:
https://bugzilla.redhat.com/show_bug.cgi?id=516589

Description:
Currently neighbour event notifications are limited to update
notifications and only sent if the ARP daemon is enabled. This
patch extends the existing notification code by also reporting
neighbours being removed due to gc or administratively and
removes the dependency on the ARP daemon. This allows to keep
track of neighbour states without periodically fetching the
complete neighbour table.

Upstream status:
http://git.kernel.org/?p=linux/kernel/git/stable/linux-2.6-stable.git;a=commitdiff;h=d961db358f41033a8fc7b62948bc7cff1b4bb1fe

diff --git a/net/core/neighbour.c b/net/core/neighbour.c
index 96841cc..bf9121e 100644
--- a/net/core/neighbour.c
+++ b/net/core/neighbour.c
@@ -54,9 +54,8 @@
 #define PNEIGH_HASHMASK		0xF
 
 static void neigh_timer_handler(unsigned long arg);
-#ifdef CONFIG_ARPD
-static void neigh_app_notify(struct neighbour *n);
-#endif
+static void __neigh_notify(struct neighbour *n, int type, int flags);
+static void neigh_update_notify(struct neighbour *neigh);
 static int pneigh_ifdown(struct neigh_table *tbl, struct net_device *dev);
 void neigh_changeaddr(struct neigh_table *tbl, struct net_device *dev);
 
@@ -109,6 +108,7 @@ static void neigh_cleanup_and_release(struct neighbour *neigh)
 	if (neigh->parms->neigh_destructor)
 		neigh->parms->neigh_destructor(neigh);
 
+	__neigh_notify(neigh, RTM_DELNEIGH, 0);
 	neigh_release(neigh);
 }
 
@@ -829,12 +829,8 @@ out:
 		write_unlock(&neigh->lock);
 	}
 	if (notify)
-		call_netevent_notifiers(NETEVENT_NEIGH_UPDATE, neigh);
+		neigh_update_notify(neigh);
 
-#ifdef CONFIG_ARPD
-	if (notify && neigh->parms->app_probes)
-		neigh_app_notify(neigh);
-#endif
 	neigh_release(neigh);
 }
 
@@ -1064,11 +1060,8 @@ out:
 	write_unlock_bh(&neigh->lock);
 
 	if (notify)
-		call_netevent_notifiers(NETEVENT_NEIGH_UPDATE, neigh);
-#ifdef CONFIG_ARPD
-	if (notify && neigh->parms->app_probes)
-		neigh_app_notify(neigh);
-#endif
+		neigh_update_notify(neigh);
+
 	return err;
 }
 
@@ -1925,6 +1918,11 @@ rtattr_failure:
 	return -1;
 }
 
+static void neigh_update_notify(struct neighbour *neigh)
+{
+	call_netevent_notifiers(NETEVENT_NEIGH_UPDATE, neigh);
+	__neigh_notify(neigh, RTM_NEWNEIGH, 0);
+}
 
 static int neigh_dump_table(struct neigh_table *tbl, struct sk_buff *skb,
 			    struct netlink_callback *cb)
@@ -2370,11 +2368,6 @@ void neigh_app_ns(struct neighbour *n)
 	__neigh_notify(n, RTM_GETNEIGH, NLM_F_REQUEST);
 }
 
-static void neigh_app_notify(struct neighbour *n)
-{
-	__neigh_notify(n, RTM_NEWNEIGH, 0);
-}
-
 #endif /* CONFIG_ARPD */
 
 #ifdef CONFIG_SYSCTL