ipv6: ip6_ptr rcu annotations

(struct net_device)->ip6_ptr is rcu protected :

add __rcu annotation and proper rcu primitives.
Signed-off-by: Eric Dumazet <eric.dumazet@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

include/linux/netdevice.h

@@ -952,7 +952,7 @@ struct net_device {
 	void 			*atalk_ptr;	/* AppleTalk link 	*/
 	struct in_device __rcu	*ip_ptr;	/* IPv4 specific data	*/
 	void                    *dn_ptr;        /* DECnet specific data */
-	void                    *ip6_ptr;       /* IPv6 specific data */
+	struct inet6_dev __rcu	*ip6_ptr;       /* IPv6 specific data */
 	void			*ec_ptr;	/* Econet specific data	*/
 	void			*ax25_ptr;	/* AX.25 specific data */
 	struct wireless_dev	*ieee80211_ptr;	/* IEEE 802.11 specific data,

net/core/dev.c

@@ -5416,7 +5416,7 @@ void netdev_run_todo(void)
 		/* paranoia */
 		BUG_ON(netdev_refcnt_read(dev));
 		WARN_ON(rcu_dereference_raw(dev->ip_ptr));
-		WARN_ON(dev->ip6_ptr);
+		WARN_ON(rcu_dereference_raw(dev->ip6_ptr));
 		WARN_ON(dev->dn_ptr);
 
 		if (dev->destructor)