Re: [PATCH v2 3/3] iommufd/vdevice: add TSM guest request ioctl

[Jason Gunthorpe]

On Wed, Mar 11, 2026 at 09:43:43PM +0000, Jonathan Cameron wrote:
> > +	vdev = container_of(iommufd_get_object(ucmd->ictx, cmd->vdevice_id,
> > +					       IOMMUFD_OBJ_VDEVICE),
> 
> As in previous, can the object be PTR_ERR()?  Maybe not, but I'd
> be surprised if the static analysis tools are convinced.
> This might work for now if obj is first element but that's not
> elegant or matainable.

The compiler enforces first element:

#define __iommufd_object_alloc(ictx, ptr, type, obj)                           \
        container_of(_iommufd_object_alloc(                                    \
                             ictx,                                             \
                             sizeof(*(ptr)) + BUILD_BUG_ON_ZERO(               \
                                                      offsetof(typeof(*(ptr)), \
                                                               obj) != 0),     \
                             type),                                            \
                     typeof(*(ptr)), obj)

I have a lovely little series 

https://github.com/jgunthorpe/linux/commits/container_of/

For this that I keep meaning to send but then never do

Jason