Re: [PATCH v3 03/11] iommufd: Introduce IOMMUFD_OBJ_VIOMMU and its related struct

[Jason Gunthorpe <jgg@nvidia.com>]

On Wed, Oct 09, 2024 at 09:38:03AM -0700, Nicolin Chen wrote:
> +	struct iommufd_viommu *(*viommu_alloc)(struct iommu_device *iommu_dev,
> +					       struct iommu_domain *domain,

Let's call this parent_domain ie nesting parent

> +/*
> + * Helpers for IOMMU driver to allocate driver structures that will be freed by
> + * the iommufd core. Yet, a driver is responsible for its own
> struct cleanup.

'own struct cleanup via the free callback'

> diff --git a/drivers/iommu/iommufd/viommu_api.c b/drivers/iommu/iommufd/viommu_api.c
> new file mode 100644
> index 000000000000..c1731f080d6b
> --- /dev/null
> +++ b/drivers/iommu/iommufd/viommu_api.c

Let's call this file driver.c to match CONFIG_IOMMUFD_DRIVER

> +struct iommufd_viommu *
> +__iommufd_viommu_alloc(struct iommufd_ctx *ictx, size_t size,
> +		       const struct iommufd_viommu_ops *ops)
> +{
> +	struct iommufd_viommu *viommu;
> +	struct iommufd_object *obj;
> +
> +	if (WARN_ON(size < sizeof(*viommu)))
> +		return ERR_PTR(-EINVAL);

The macro does this already

> +	obj = iommufd_object_alloc_elm(ictx, size, IOMMUFD_OBJ_VIOMMU);
> +	if (IS_ERR(obj))
> +		return ERR_CAST(obj);
> +	viommu = container_of(obj, struct iommufd_viommu, obj);

And this too..

> +	if (ops)
> +		viommu->ops = ops;

No need for an if...

It could just be in the macro which is a bit appealing given we want
this linked into the drivers..

/*
 * Helpers for IOMMU driver to allocate driver structures that will be freed by
 * the iommufd core. The free op will be called prior to freeing the memory.
 */
#define iommufd_viommu_alloc(ictx, drv_struct, member, viommu_ops)            \
	({                                                                    \
		struct drv_struct *ret;                                       \
                                                                              \
		static_assert(                                                \
			__same_type(struct iommufd_viommu,                    \
				    ((struct drv_struct *)NULL)->member));    \
		static_assert(offsetof(struct drv_struct, member.obj) == 0);  \
		ret = (struct drv_struct *)iommufd_object_alloc_elm(          \
			ictx, sizeof(struct drv_struct), IOMMUFD_OBJ_VIOMMU); \
		ret->member.ops = viommu_ops;                                 \
		ret;                                                          \
	})

Jason