[libvirt] [PATCH] interface: Check for interface (in-)activity on some operations

[Michal Privoznik]

On 15.07.2011 16:29, Eric Blake wrote:
> On 07/15/2011 07:58 AM, Michal Privoznik wrote:
>> Right now it is possible to undefine an active interface, or
>> destroy inactive. This patch add some checking to these operations
>> to prevent this. Also fix test driver.
>
> I'm inclined to NACK this on design principles (I haven't read the patch
> itself, though).  Given the discussion about domains and undefine, the
> ability to undefine an active interface is a feature, provided we
> support the concept of a transient interface like we do for transient
> domains.
>
> That is, we have the following transitions:
>
> nothing ->  transient/running via Create
> nothing ->  persistent/inactive via Define
>
> persistent/inactive ->  persistent/active via Start
> persistent/inactive ->  gone via Undefine
>
> persistent/running ->  persistent/inactive via Destroy
> persistent/running ->  transient/running via Undefine
>
> transient/running ->  gone via Destroy
> transient/running ->  persistent/running via Define
>
> and rejecting Undefine on a running interface would prevent the ability
> to transistion a persistent over to a transient interface.
>
> On the other hand, if we don't support transient interfaces, then the
> above analysis which works for domains would have to be adjusted for
> interfaces, so you may have something to patch after all.
>
Well, although we have function interfaceCreate, it is actually (from 
semantic POV) interfaceStart, because it just start inactive but defined 
interface. So we do not support transient interfaces. Therefore 
transitions for interfaces are slightly different from transitions for 
domains. That's why I think we do need this patch.

Michal