ipv6: Add rt6_get_cookie() function

Instead of doing the rt6->rt6i_node check whenever we need
to get the route's cookie.  Refactor it into rt6_get_cookie().
It is a prep work to handle FLOWI_FLAG_KNOWN_NH and also
percpu rt6_info later.
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>

include/net/ip6_fib.h

@@ -159,6 +159,11 @@ static inline void rt6_update_expires(struct rt6_info *rt0, int timeout)
 	rt0->rt6i_flags |= RTF_EXPIRES;
 }
 
+static inline u32 rt6_get_cookie(const struct rt6_info *rt)
+{
+	return rt->rt6i_node ? rt->rt6i_node->fn_sernum : 0;
+}
+
 static inline void ip6_rt_put(struct rt6_info *rt)
 {
 	/* dst_release() accepts a NULL parameter.

include/net/ip6_route.h

@@ -145,7 +145,7 @@ static inline void __ip6_dst_store(struct sock *sk, struct dst_entry *dst,
 #ifdef CONFIG_IPV6_SUBTREES
 	np->saddr_cache = saddr;
 #endif
-	np->dst_cookie = rt->rt6i_node ? rt->rt6i_node->fn_sernum : 0;
+	np->dst_cookie = rt6_get_cookie(rt);
 }
 
 static inline void ip6_dst_store(struct sock *sk, struct dst_entry *dst,

net/ipv6/ip6_tunnel.c

@@ -151,7 +151,7 @@ EXPORT_SYMBOL_GPL(ip6_tnl_dst_reset);
 void ip6_tnl_dst_store(struct ip6_tnl *t, struct dst_entry *dst)
 {
 	struct rt6_info *rt = (struct rt6_info *) dst;
-	t->dst_cookie = rt->rt6i_node ? rt->rt6i_node->fn_sernum : 0;
+	t->dst_cookie = rt6_get_cookie(rt);
 	dst_release(t->dst_cache);
 	t->dst_cache = dst;
 }

net/ipv6/tcp_ipv6.c

@@ -99,8 +99,7 @@ static void inet6_sk_rx_dst_set(struct sock *sk, const struct sk_buff *skb)
 		dst_hold(dst);
 		sk->sk_rx_dst = dst;
 		inet_sk(sk)->rx_dst_ifindex = skb->skb_iif;
-		if (rt->rt6i_node)
-			inet6_sk(sk)->rx_dst_cookie = rt->rt6i_node->fn_sernum;
+		inet6_sk(sk)->rx_dst_cookie = rt6_get_cookie(rt);
 	}
 }
 

net/ipv6/xfrm6_policy.c

@@ -76,8 +76,7 @@ static int xfrm6_init_path(struct xfrm_dst *path, struct dst_entry *dst,
 {
 	if (dst->ops->family == AF_INET6) {
 		struct rt6_info *rt = (struct rt6_info *)dst;
-		if (rt->rt6i_node)
-			path->path_cookie = rt->rt6i_node->fn_sernum;
+		path->path_cookie = rt6_get_cookie(rt);
 	}
 
 	path->u.rt6.rt6i_nfheader_len = nfheader_len;
@@ -105,8 +104,7 @@ static int xfrm6_fill_dst(struct xfrm_dst *xdst, struct net_device *dev,
 						   RTF_LOCAL);
 	xdst->u.rt6.rt6i_metric = rt->rt6i_metric;
 	xdst->u.rt6.rt6i_node = rt->rt6i_node;
-	if (rt->rt6i_node)
-		xdst->route_cookie = rt->rt6i_node->fn_sernum;
+	xdst->route_cookie = rt6_get_cookie(rt);
 	xdst->u.rt6.rt6i_gateway = rt->rt6i_gateway;
 	xdst->u.rt6.rt6i_dst = rt->rt6i_dst;
 	xdst->u.rt6.rt6i_src = rt->rt6i_src;

net/netfilter/ipvs/ip_vs_xmit.c

@@ -435,7 +435,7 @@ __ip_vs_get_out_rt_v6(int skb_af, struct sk_buff *skb, struct ip_vs_dest *dest,
 				goto err_unreach;
 			}
 			rt = (struct rt6_info *) dst;
-			cookie = rt->rt6i_node ? rt->rt6i_node->fn_sernum : 0;
+			cookie = rt6_get_cookie(rt);
 			__ip_vs_dst_set(dest, dest_dst, &rt->dst, cookie);
 			spin_unlock_bh(&dest->dst_lock);
 			IP_VS_DBG(10, "new dst %pI6, src %pI6, refcnt=%d\n",

net/sctp/ipv6.c

@@ -331,7 +331,7 @@ static void sctp_v6_get_dst(struct sctp_transport *t, union sctp_addr *saddr,
 
 		rt = (struct rt6_info *)dst;
 		t->dst = dst;
-		t->dst_cookie = rt->rt6i_node ? rt->rt6i_node->fn_sernum : 0;
+		t->dst_cookie = rt6_get_cookie(rt);
 		pr_debug("rt6_dst:%pI6/%d rt6_src:%pI6\n",
 			 &rt->rt6i_dst.addr, rt->rt6i_dst.plen,
 			 &fl6->saddr);