From: David Miller <davem@davemloft.net>
To: arei.gonglei@huawei.com
Cc: netdev@vger.kernel.org, xen-devel@lists.xenproject.org,
linux-kernel@vger.kernel.org, peter.huangpeng@huawei.com
Subject: Re: [PATCH] xen-netfront: set real_num_tx_queues to zreo avoid to trigger BUG_ON
Date: Fri, 19 Feb 2016 23:36:43 -0500 (EST) [thread overview]
Message-ID: <20160219.233643.95383657086552033.davem@davemloft.net> (raw)
In-Reply-To: <1455931646-5672-1-git-send-email-arei.gonglei@huawei.com>
From: Gonglei <arei.gonglei@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.
next prev parent reply other threads:[~2016-02-20 4:36 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-02-20 1:27 [PATCH] xen-netfront: set real_num_tx_queues to zreo avoid to trigger BUG_ON Gonglei
2016-02-20 4:36 ` David Miller [this message]
2016-02-20 6:00 ` Gonglei (Arei)
2016-02-22 13:33 ` [Xen-devel] " David Vrabel
2016-02-20 15:50 ` Sergei Shtylyov
2016-02-22 14:10 ` [Xen-devel] " David Vrabel
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