Re: [KVM PATCH v9 0/5] irqfd fixes and enhancements

From: Gregory Haskins
Date: Mon Jul 06 2009 - 14:49:01 EST


Michael S. Tsirkin wrote:
> On Mon, Jul 06, 2009 at 12:41:59PM -0400, Gregory Haskins wrote:
>
>> Michael S. Tsirkin wrote:
>>
>>>>
>>>>
>>> wouldn't it be cleaner to error out in the for each loop if we don't
>>> find an entry to deactivate? Might be helpful for apps to get an error
>>> if they didn't deassign anything.
>>>
>>>
>> Again, irqfds.init is somewhat orthogonal to whether the list is
>> populated or not. This check is for sanity (how can you deassign if you
>> didnt assign, etc). Normally this would be a simple BUG_ON() sanity
>> check, but I don't want a malicious/broken userspace to gain an easy
>> attack vector ;)
>>
>
> what I'm saying is that deassign should return an error if it's passed
> and entry that is not on the list.

This isn't an unreasonable request, and I believe this is actually the
way the original deassign logic worked before we yanked the feature a
few weeks ago. Its only slightly complicated by the fact that we may
match multiple irqfds, but I think we solved that before by returning
the number we matched.

If Avi answers the other mail stating he wants to still see the
on-demand work go in, lets use your suggestion.

Regards,
-Greg


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