net: Lock netdevices during dev_shutdown

__qdisc_destroy() calls into various qdiscs .destroy() op, which in turn
can call .ndo_setup_tc(), which requires the netdev instance lock.

This commit extends the critical section in
unregister_netdevice_many_notify() to cover dev_shutdown() (and
dev_tcx_uninstall() as a side-effect) and acquires the netdev instance
lock in __dev_change_net_namespace() for the other dev_shutdown() call.

This should now guarantee that for all qdisc ops, the netdev instance
lock is held during .ndo_setup_tc().

Fixes: a0527ee ("net: hold netdev instance lock during qdisc ndo_setup_tc")
Signed-off-by: Cosmin Ratiu <[email protected]>
Acked-by: Stanislav Fomichev <[email protected]>
Link: https://patch.msgid.link/[email protected]
Signed-off-by: Jakub Kicinski <[email protected]>

Author: Cosmin Ratiu

net/core/dev.c

@@ -11966,9 +11966,9 @@ void unregister_netdevice_many_notify(struct list_head *head,
 		struct sk_buff *skb = NULL;
 
 		/* Shutdown queueing discipline. */
+		netdev_lock_ops(dev);
 		dev_shutdown(dev);
 		dev_tcx_uninstall(dev);
-		netdev_lock_ops(dev);
 		dev_xdp_uninstall(dev);
 		dev_memory_provider_uninstall(dev);
 		netdev_unlock_ops(dev);
@@ -12161,7 +12161,9 @@ int __dev_change_net_namespace(struct net_device *dev, struct net *net,
 	synchronize_net();
 
 	/* Shutdown queueing discipline. */
+	netdev_lock_ops(dev);
 	dev_shutdown(dev);
+	netdev_unlock_ops(dev);
 
 	/* Notify protocols, that we are about to destroy
 	 * this device. They should clean all the things.