net: use hlist_del_rcu() in dev_change_name()

Using plain hlist_del() in dev_change_name() is wrong since a
concurrent reader can crash trying to dereference LIST_POISON1.

Bug introduced in commit 72c9528b (net: Introduce
dev_get_by_name_rcu())
Signed-off-by: Eric Dumazet <eric.dumazet@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

net/core/dev.c

@@ -1007,7 +1007,7 @@ int dev_change_name(struct net_device *dev, const char *newname)
 	}
 
 	write_lock_bh(&dev_base_lock);
-	hlist_del(&dev->name_hlist);
+	hlist_del_rcu(&dev->name_hlist);
 	write_unlock_bh(&dev_base_lock);
 
 	synchronize_rcu();