Re: [Xen-devel] [PATCH v3 20/24] xen/passthrough: Extend XEN_DOMCTL_assign_device to support DT device

[Stefano Stabellini <stefano.stabellini@xxxxxxxxxxxxx>]

On Thu, 29 Jan 2015, Julien Grall wrote:
> Hi Stefano,
> 
> On 29/01/15 10:29, Stefano Stabellini wrote:
> >> +static bool_t iommu_dt_device_is_assigned(const struct dt_device_node 
> >> *dev)
> >> +{
> >> +    bool_t assigned = 0;
> >> +
> >> +    if ( !dt_device_is_protected(dev) )
> >> +        return 1;
> > 
> > Why return true here?
> 
> Because any device not protected cannot be assigned to another guest.
> This could be used by the toolstack to know whether the device is
> assigned or not.

I understand that much.


> IHMO, returning 0 would be a false negative.

Why? Returning 0 means that the device is not assigned, that would be
correct. From this statement I think that actually you are thinking as
if this function actually returned whether a given device is assignable.

In that case you should rename the function to

iommu_dt_device_is_assignable


> Would a comment in the code suitable?

I think you should rename the function or be consistent with its name.

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