net: Detect and ignore netif_stop_queue() calls before register_netdev()

After e6484930d7c73d324bccda7d43d131088da697b9: net: allocate tx queues in register_netdevice
These calls make net drivers oops at load time, so let's avoid people
git-bisect'ing known problems.

Signed-off-by: Guillaume Chazarain <guichaz@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/include/linux/netdevice.h b/include/linux/netdevice.h
index 072652d..d8fd2c2 100644
--- a/include/linux/netdevice.h
+++ b/include/linux/netdevice.h
@@ -1554,6 +1554,11 @@
 
 static inline void netif_tx_stop_queue(struct netdev_queue *dev_queue)
 {
+	if (WARN_ON(!dev_queue)) {
+		printk(KERN_INFO "netif_stop_queue() cannot be called before "
+		       "register_netdev()");
+		return;
+	}
 	set_bit(__QUEUE_STATE_XOFF, &dev_queue->state);
 }