vlan: rcu annotations

(struct net_device)->vlgrp is rcu protected :

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

include/linux/netdevice.h

@@ -944,7 +944,7 @@ struct net_device {
 	/* Protocol specific pointers */
 
 #if defined(CONFIG_VLAN_8021Q) || defined(CONFIG_VLAN_8021Q_MODULE)
-	struct vlan_group	*vlgrp;		/* VLAN group */
+	struct vlan_group __rcu	*vlgrp;		/* VLAN group */
 #endif
 #ifdef CONFIG_NET_DSA
 	void			*dsa_ptr;	/* dsa specific data */

net/8021q/vlan.c

@@ -112,7 +112,7 @@ void unregister_vlan_dev(struct net_device *dev, struct list_head *head)
 
 	ASSERT_RTNL();
 
-	grp = real_dev->vlgrp;
+	grp = rtnl_dereference(real_dev->vlgrp);
 	BUG_ON(!grp);
 
 	/* Take it out of our own structures, but be sure to interlock with
@@ -177,7 +177,7 @@ int register_vlan_dev(struct net_device *dev)
 	struct vlan_group *grp, *ngrp = NULL;
 	int err;
 
-	grp = real_dev->vlgrp;
+	grp = rtnl_dereference(real_dev->vlgrp);
 	if (!grp) {
 		ngrp = grp = vlan_group_alloc(real_dev);
 		if (!grp)
@@ -385,7 +385,7 @@ static int vlan_device_event(struct notifier_block *unused, unsigned long event,
 		dev->netdev_ops->ndo_vlan_rx_add_vid(dev, 0);
 	}
 
-	grp = dev->vlgrp;
+	grp = rtnl_dereference(dev->vlgrp);
 	if (!grp)
 		goto out;