neighbour: send netlink notification if NTF_ROUTER changes

send netlink notification if neigh_update results in NTF_ROUTER
change and if NEIGH_UPDATE_F_ISROUTER is on. Also move the
NTF_ROUTER change function into a helper.
Signed-off-by: Roopa Prabhu <roopa@cumulusnetworks.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

include/net/neighbour.h

@@ -544,4 +544,19 @@ static inline void neigh_update_ext_learned(struct neighbour *neigh, u32 flags,
 		*notify = 1;
 	}
 }
+
+static inline void neigh_update_is_router(struct neighbour *neigh, u32 flags,
+					  int *notify)
+{
+	u8 ndm_flags = 0;
+
+	ndm_flags |= (flags & NEIGH_UPDATE_F_ISROUTER) ? NTF_ROUTER : 0;
+	if ((neigh->flags ^ ndm_flags) & NTF_ROUTER) {
+		if (ndm_flags & NTF_ROUTER)
+			neigh->flags |= NTF_ROUTER;
+		else
+			neigh->flags &= ~NTF_ROUTER;
+		*notify = 1;
+	}
+}
 #endif

net/core/neighbour.c

@@ -1280,11 +1280,8 @@ int neigh_update(struct neighbour *neigh, const u8 *lladdr, u8 new,
 		neigh->arp_queue_len_bytes = 0;
 	}
 out:
-	if (update_isrouter) {
-		neigh->flags = (flags & NEIGH_UPDATE_F_ISROUTER) ?
-			(neigh->flags | NTF_ROUTER) :
-			(neigh->flags & ~NTF_ROUTER);
-	}
+	if (update_isrouter)
+		neigh_update_is_router(neigh, flags, &notify);
 	write_unlock_bh(&neigh->lock);
 
 	if (notify)