On Mon, Oct 21, 2024 at 07:11:47PM +1100, Alexey Kardashevskiy wrote:
> > + hwpt_paging = iommufd_get_hwpt_paging(ucmd, cmd->hwpt_id);
> > + if (IS_ERR(hwpt_paging)) {
> > + rc = PTR_ERR(hwpt_paging);
>
>
> iommufd_get_hwpt_paging() is container_of() which does not test for the
> value and just does a simple math so the actual error value from
> iommufd_get_object() is ... lost?
>
> Oh well, not really lost, as "obj" and "common.obj" seem to be forced to be
> at the beginning of iommufd object structs so container_of() is no-op or is
> not it?
Yes, it is just a type check, the revised code I suggested doesn't
rely on this. Jonathon remarked on the same for fwctl and we came up
with something different.
> If something needs to be guaranteed to stay alive, may be just call
> device_get(viommu->dev), with the comment above? Or it is some different
> refcounting which is missing? Thanks,
device_get is different, it just makes sure the struct device memory
is around, it doesn't prevent iommu unplug
Jason
