> From: Jason Gunthorpe <jgg@xxxxxxxxxx>
> Sent: Thursday, January 5, 2023 2:25 AM
>
> 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.
>
You are right.
