On Wed, Dec 21, 2022 at 04:07:42AM +0000, Tian, Kevin wrote:
> > From: Liu, Yi L <yi.l.liu@xxxxxxxxx>
> > Sent: Monday, December 19, 2022 4:47 PM
> >
> > +static bool vfio_device_enforced_coherent(struct vfio_device *device)
> > +{
> > + bool ret;
> > +
> > + if (!vfio_device_try_get_registration(device))
> > + return true;
> > +
> > + ret = device_iommu_capable(device->dev,
> > +
> > IOMMU_CAP_ENFORCE_CACHE_COHERENCY);
> > +
> > + vfio_device_put_registration(device);
> > + return ret;
> > +}
>
> This probably needs an explanation that recounting is required because
> this might be called before vfio_device_open() is called to hold the
> count.
How does that happen? The only call site already has a struct file and
the struct file implicitly holds the registration. This should be
removed.
Just inline the whole thing and make it clear:
device = vfio_device_from_file(file);
if (device)
return device_iommu_capable(device->dev,
IOMMU_CAP_ENFORCE_CACHE_COHERENCY);
Jason
