ipv6: Move common init code for rt6_info to a new function rt6_info_init()

Introduce rt6_info_init() to do the common init work for
'struct rt6_info' (after calling dst_alloc).

It is a prep work to fix the rt6_info init logic in the
ip6_blackhole_route().
Signed-off-by: Martin KaFai Lau <kafai@fb.com>
Cc: Hannes Frederic Sowa <hannes@stressinduktion.org>
Cc: Julian Anastasov <ja@ssi.bg>
Cc: Phil Sutter <phil@nwl.cc>
Cc: Steffen Klassert <steffen.klassert@secunet.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

net/ipv6/route.c

@@ -319,6 +319,15 @@ static const struct rt6_info ip6_blk_hole_entry_template = {
 
 #endif
 
+static void rt6_info_init(struct rt6_info *rt)
+{
+	struct dst_entry *dst = &rt->dst;
+
+	memset(dst + 1, 0, sizeof(*rt) - sizeof(*dst));
+	INIT_LIST_HEAD(&rt->rt6i_siblings);
+	INIT_LIST_HEAD(&rt->rt6i_uncached);
+}
+
 /* allocate dst with ip6_dst_ops */
 static struct rt6_info *__ip6_dst_alloc(struct net *net,
 					struct net_device *dev,
@@ -327,13 +336,9 @@ static struct rt6_info *__ip6_dst_alloc(struct net *net,
 	struct rt6_info *rt = dst_alloc(&net->ipv6.ip6_dst_ops, dev,
 					0, DST_OBSOLETE_FORCE_CHK, flags);
 
-	if (rt) {
-		struct dst_entry *dst = &rt->dst;
+	if (rt)
+		rt6_info_init(rt);
 
-		memset(dst + 1, 0, sizeof(*rt) - sizeof(*dst));
-		INIT_LIST_HEAD(&rt->rt6i_siblings);
-		INIT_LIST_HEAD(&rt->rt6i_uncached);
-	}
 	return rt;
 }