On Thu, 23 Jun 2022 22:50:30 -0300 Jason Gunthorpe <jgg@xxxxxxxxxx> wrote: > On Thu, Jun 23, 2022 at 05:00:44PM -0600, Alex Williamson wrote: > > > > >> +struct vfio_device *vfio_device_get_from_iommu(struct iommu_group *iommu_group) > > > >> +{ > > > >> + struct vfio_group *group = vfio_group_get_from_iommu(iommu_group); > > > >> + struct vfio_device *device; > > > > > > > > Check group for NULL. > > > > > > OK - FWIW in context this should only ever make sense to call with an > > > iommu_group which has already been derived from a vfio_group, and I did > > > initially consider a check with a WARN_ON(), but then decided that the > > > unguarded dereference would be a sufficiently strong message. No problem > > > with bringing that back to make it more defensive if that's what you prefer. > > > > A while down the road, that's a bit too much implicit knowledge of the > > intent and single purpose of this function just to simply avoid a test. > > I think we should just pass the 'struct vfio_group *' into the > attach_group op and have this API take that type in and forget the > vfio_group_get_from_iommu(). That's essentially what I'm suggesting, the vfio_group is passed as an opaque pointer which type1 can use for a vfio_group_for_each_vfio_device() type call. Thanks, Alex