ipv6: Break up ip6_rt_copy()

This patch breaks up ip6_rt_copy() into ip6_rt_copy_init() and
ip6_rt_cache_alloc().

In the later patch, we need to create a percpu rt6_info copy. Hence,
refactor the common rt6_info init codes to ip6_rt_copy_init().
Signed-off-by: Martin KaFai Lau <kafai@fb.com>
Cc: Hannes Frederic Sowa <hannes@stressinduktion.org>
Cc: Steffen Klassert <steffen.klassert@secunet.com>
Cc: Julian Anastasov <ja@ssi.bg>
Signed-off-by: David S. Miller <davem@davemloft.net>

net/ipv6/route.c

@@ -72,8 +72,7 @@ enum rt6_nud_state {
 	RT6_NUD_SUCCEED = 1
 };
 
-static struct rt6_info *ip6_rt_copy(struct rt6_info *ort,
-				    const struct in6_addr *dest);
+static void ip6_rt_copy_init(struct rt6_info *rt, struct rt6_info *ort);
 static struct dst_entry	*ip6_dst_check(struct dst_entry *dst, u32 cookie);
 static unsigned int	 ip6_default_advmss(const struct dst_entry *dst);
 static unsigned int	 ip6_mtu(const struct dst_entry *dst);
@@ -913,10 +912,21 @@ static struct rt6_info *ip6_rt_cache_alloc(struct rt6_info *ort,
 	 *	Clone the route.
 	 */
 
-	rt = ip6_rt_copy(ort, daddr);
+	if (ort->rt6i_flags & RTF_CACHE)
+		ort = (struct rt6_info *)ort->dst.from;
 
-	if (rt) {
+	rt = ip6_dst_alloc(dev_net(ort->dst.dev), ort->dst.dev,
+			   0, ort->rt6i_table);
+
+	if (!rt)
+		return NULL;
+
+	ip6_rt_copy_init(rt, ort);
 	rt->rt6i_flags |= RTF_CACHE;
+	rt->rt6i_metric = 0;
+	rt->dst.flags |= DST_HOST;
+	rt->rt6i_dst.addr = *daddr;
+	rt->rt6i_dst.plen = 128;
 
 	if (!rt6_is_gw_or_nonexthop(ort)) {
 		if (ort->rt6i_dst.plen != 128 &&
@@ -929,7 +939,6 @@ static struct rt6_info *ip6_rt_cache_alloc(struct rt6_info *ort,
 		}
 #endif
 	}
-	}
 
 	return rt;
 }
@@ -1980,7 +1989,7 @@ static void rt6_do_redirect(struct dst_entry *dst, struct sock *sk, struct sk_bu
 				     NEIGH_UPDATE_F_ISROUTER))
 		     );
 
-	nrt = ip6_rt_copy(rt, &msg->dest);
+	nrt = ip6_rt_cache_alloc(rt, &msg->dest, NULL);
 	if (!nrt)
 		goto out;
 
@@ -2022,25 +2031,11 @@ static void rt6_set_from(struct rt6_info *rt, struct rt6_info *from)
 	dst_init_metrics(&rt->dst, dst_metrics_ptr(&from->dst), true);
 }
 
-static struct rt6_info *ip6_rt_copy(struct rt6_info *ort,
-				    const struct in6_addr *dest)
+static void ip6_rt_copy_init(struct rt6_info *rt, struct rt6_info *ort)
 {
-	struct net *net = dev_net(ort->dst.dev);
-	struct rt6_info *rt;
-
-	if (ort->rt6i_flags & RTF_CACHE)
-		ort = (struct rt6_info *)ort->dst.from;
-
-	rt = ip6_dst_alloc(net, ort->dst.dev, 0,
-			   ort->rt6i_table);
-
-	if (rt) {
 	rt->dst.input = ort->dst.input;
 	rt->dst.output = ort->dst.output;
-		rt->dst.flags |= DST_HOST;
-
-		rt->rt6i_dst.addr = *dest;
-		rt->rt6i_dst.plen = 128;
+	rt->rt6i_dst = ort->rt6i_dst;
 	rt->dst.error = ort->dst.error;
 	rt->rt6i_idev = ort->rt6i_idev;
 	if (rt->rt6i_idev)
@@ -2049,15 +2044,12 @@ static struct rt6_info *ip6_rt_copy(struct rt6_info *ort,
 	rt->rt6i_gateway = ort->rt6i_gateway;
 	rt->rt6i_flags = ort->rt6i_flags;
 	rt6_set_from(rt, ort);
-		rt->rt6i_metric = 0;
-
+	rt->rt6i_metric = ort->rt6i_metric;
 #ifdef CONFIG_IPV6_SUBTREES
-		memcpy(&rt->rt6i_src, &ort->rt6i_src, sizeof(struct rt6key));
+	rt->rt6i_src = ort->rt6i_src;
 #endif
-		memcpy(&rt->rt6i_prefsrc, &ort->rt6i_prefsrc, sizeof(struct rt6key));
+	rt->rt6i_prefsrc = ort->rt6i_prefsrc;
 	rt->rt6i_table = ort->rt6i_table;
-	}
-	return rt;
 }
 
 #ifdef CONFIG_IPV6_ROUTE_INFO