From mboxrd@z Thu Jan  1 00:00:00 1970
From: ebiederm-aS9lmoZGLiVWk0Htik3J/w@public.gmane.org (Eric W. Biederman)
Subject: Re: [PATCH 4/5] lguest: use KVM hypercalls
Date: Wed, 15 Apr 2009 07:10:32 -0700
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Cc: lguest-mnsaURCQ41sdnm+yROfE0A@public.gmane.org, Christian Borntraeger <borntraeger-tA70FqPdS9bQT0dZR+AlfA@public.gmane.org>,
	"David S. Miller" <davem-fT/PcQaiUtIeIZ0/mPfg9Q@public.gmane.org>, virtualization-qjLDD68F18O7TbgM5vRIOg@public.gmane.org,
	Matias Zabaljauregui <zabaljauregui-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>,
	netdev-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, Patrick McHardy <kaber-dcUjhNyLwpNeoWH0uzbU5w@public.gmane.org>
To: Herbert Xu <herbert-lOAM2aK0SrRLBo1qDEOMRrpzq4S04n8Q@public.gmane.org>
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	message of "Wed\, 15 Apr 2009 21\:55\:02 +0800")
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Herbert Xu <herbert-lOAM2aK0SrRLBo1qDEOMRrpzq4S04n8Q@public.gmane.org> writes:

> On Wed, Apr 15, 2009 at 09:46:10PM +0800, Herbert Xu wrote:
>>
>> Does anything actually rely on this behaviour?
>
> I doubt it :)
>
>> If not we should just change it to not do that.
>
> It appears that this was introduced in
>
> commit c70f182940f988448f3c12a209d18b1edc276e33
> Author: Eric W. Biederman <ebiederm-aS9lmoZGLiVWk0Htik3J/w@public.gmane.org>
> Date:   Tue Jan 20 11:07:17 2009 +0000
>
>     tun: Fix races between tun_net_close and free_netdev.
>
> Presumably in order to fix the problem of trying to unregister
> the same device twice.
>
> I what we should do is to mark the device as dead instead of
> detaching if a third party deletes it.  That's all you need
> to know to stop close(2) from trying the unregister a device
> that's already been unregistered.
>
> What else am I missing?

Hopefully my earlier explanation helps.  I will get back to
you as soon as I can.  But I am off on vacation for the
rest of the week.

Eric