ipv4: add __rcu annotations to ip_ra_chain

Add __rcu annotations to :
        (struct ip_ra_chain)->next
	struct ip_ra_chain *ip_ra_chain;

And use appropriate rcu primitives.

Signed-off-by: Eric Dumazet <eric.dumazet@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/include/net/ip.h b/include/net/ip.h
index dbee3fe..86e2b18 100644
--- a/include/net/ip.h
+++ b/include/net/ip.h
@@ -59,7 +59,7 @@
 #define IPCB(skb) ((struct inet_skb_parm*)((skb)->cb))
 
 struct ip_ra_chain {
-	struct ip_ra_chain	*next;
+	struct ip_ra_chain __rcu *next;
 	struct sock		*sk;
 	union {
 		void			(*destructor)(struct sock *);
@@ -68,7 +68,7 @@
 	struct rcu_head		rcu;
 };
 
-extern struct ip_ra_chain *ip_ra_chain;
+extern struct ip_ra_chain __rcu *ip_ra_chain;
 
 /* IP flags. */
 #define IP_CE		0x8000		/* Flag: "Congestion"		*/