Re: [PATCH 4/5] lguest: use KVM hypercalls

[ebiederm-aS9lmoZGLiVWk0Htik3J/w@public.gmane.org (Eric W. Biederman)]

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