From: Gonglei <arei.gong...@huawei.com> Date: Sat, 20 Feb 2016 09:27:26 +0800
> It's possible for a race condition to exist between xennet_open() and > talk_to_netback(). After invoking netfront_probe() then other > threads or processes invoke xennet_open (such as NetworkManager) > immediately may trigger BUG_ON(). Besides, we also should reset > real_num_tx_queues in xennet_destroy_queues(). One should really never invoke register_netdev() until the device is %100 fully initialized. This means you cannot call register_netdev() until it is completely legal to invoke your ->open() method. And I think that is what the real problem is here. If you follow the correct rules for ordering wrt. register_netdev() there are no "races". Because ->open() must be legally invokable from the exact moment you call register_netdev(). I'm not applying this, as it really sounds like the fundamental issue is the order in which the xen-netfront private data is initialized or setup before being registered.