Re: [PATCH v4 01/14] iommufd/viommu: Introduce IOMMUFD_OBJ_VDEVICE and its related struct

On Fri, Oct 25, 2024 at 06:53:01PM +1100, Alexey Kardashevskiy wrote:

...

+#define iommufd_vdevice_alloc(ictx, drv_struct, member) \

• ({ \

• static_assert(                                                 \
  

• 	__same_type(struct iommufd_vdevice,                    \
  

• 		    ((struct drv_struct *)NULL)->member));     \
  

• static_assert(offsetof(struct drv_struct, member.obj) == 0);   \
  

• container_of(_iommufd_object_alloc(ictx,                       \
  

• 				   sizeof(struct drv_struct),  \
  

• 				   IOMMUFD_OBJ_VDEVICE),       \
  

• 	     struct drv_struct, member.obj);                   \
  

• }) #endif

A nit: it hurts eyes to read:

mock_vdev = iommufd_vdevice_alloc(viommu->ictx, mock_vdevice, core);

vs.

mock_vdev = iommufd_vdevice_alloc(viommu->ictx, struct mock_vdevice, core);

as for the former I go searching for a "mock_vdevice" variable and for the latter it is clear it is 1) a macro 2) which does some type checking.

also, it makes it impossible to pass things like typeof(..) or a type from typedef. Thanks,

Makes sense to me

And the container_of() should not be used in these macros, the point was to avoid it to make the PTR_ERR behavior cleraer. Just put a force type cast

Jason