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 <[email protected]> > > > Sent: Wednesday, February 22, 2023 3:40 PM > > > > > > > From: Liu, Yi L <[email protected]> > > > > 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
