On Wed, Feb 22, 2023 at 08:59:51AM -0400, Jason Gunthorpe wrote:
> On Wed, Feb 22, 2023 at 07:44:12AM +0000, Liu, Yi L wrote:
> > > From: Tian, Kevin <kevin.tian@xxxxxxxxx>
> > > Sent: Wednesday, February 22, 2023 3:40 PM
> > >
> > > > From: Liu, Yi L <yi.l.liu@xxxxxxxxx>
> > > > Sent: Tuesday, February 21, 2023 11:48 AM
> > > >
> > > > +
> > > > +void vfio_device_cdev_close(struct vfio_device_file *df)
> > > > +{
> > > > + struct vfio_device *device = df->device;
> > > > +
> > > > + mutex_lock(&device->dev_set->lock);
> > > > + if (!smp_load_acquire(&df->access_granted)) {
> > >
> > > there is no contention with another one changing this flag at this
> > > point so directly accessing it is fine.
> >
> > make sense.
>
> Have to use READ_ONCE though
>
Just a curious question:
given df->access_granted is now written with device->dev_set->lock held and
also read with this lock held in vfio_device_cdev_close(), is READ_ONCE
still required? And what about df->iommufd ?
Thanks
Yan
