Revert "8021q: fix a potential use-after-free"

This reverts commit 9829fe9 which is
upstream commit 4a7df34 

It turns out this causes problems on the 3.0-stable release.

Reported-by: Thomas Voegtle <tv@lio96.de>
Acked-by: Cong Wang <amwang@redhat.com>
Cc: Patrick McHardy <kaber@trash.net>
Cc: "David S. Miller" <davem@davemloft.net>
Cc: Eric Dumazet <edumazet@google.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

net/8021q/vlan.c

@@ -108,6 +108,13 @@ void unregister_vlan_dev(struct net_device *dev, struct list_head *head)
 	grp = rtnl_dereference(real_dev->vlgrp);
 	BUG_ON(!grp);
 
+	/* Take it out of our own structures, but be sure to interlock with
+	 * HW accelerating devices or SW vlan input packet processing if
+	 * VLAN is not 0 (leave it there for 802.1p).
+	 */
+	if (vlan_id && (real_dev->features & NETIF_F_HW_VLAN_FILTER))
+		ops->ndo_vlan_rx_kill_vid(real_dev, vlan_id);
+
 	grp->nr_vlans--;
 
 	if (vlan->flags & VLAN_FLAG_GVRP)
@@ -132,13 +139,6 @@ void unregister_vlan_dev(struct net_device *dev, struct list_head *head)
 		call_rcu(&grp->rcu, vlan_rcu_free);
 	}
 
-	/* Take it out of our own structures, but be sure to interlock with
-	 * HW accelerating devices or SW vlan input packet processing if
-	 * VLAN is not 0 (leave it there for 802.1p).
-	 */
-	if (vlan_id && (real_dev->features & NETIF_F_HW_VLAN_FILTER))
-		ops->ndo_vlan_rx_kill_vid(real_dev, vlan_id);
-
 	/* Get rid of the vlan's reference to real_dev */
 	dev_put(real_dev);
 }