Re: [PATCH for-next 1/4] RDMA/core: Add Completion Counters support

[Jason Gunthorpe <jgg@nvidia.com>]

On Tue, Apr 07, 2026 at 11:54:21AM +0000, Michael Margolin wrote:
> +static int UVERBS_HANDLER(UVERBS_METHOD_COMP_CNTR_CREATE)(
> +	struct uverbs_attr_bundle *attrs)
> +{
> +	struct ib_uobject *uobj = uverbs_attr_get_uobject(
> +		attrs, UVERBS_ATTR_CREATE_COMP_CNTR_HANDLE);
> +	struct ib_device *ib_dev = attrs->context->device;
> +	struct ib_comp_cntr *cc;
> +	int ret;
> +
> +	if (!ib_dev->ops.create_comp_cntr ||
> +	    !ib_dev->ops.destroy_comp_cntr ||
> +	    !ib_dev->ops.qp_attach_comp_cntr)
> +		return -EOPNOTSUPP;
> +
> +	cc = rdma_zalloc_drv_obj(ib_dev, ib_comp_cntr);
> +	if (!cc)
> +		return -ENOMEM;
> +
> +	cc->device = ib_dev;
> +	cc->uobject = uobj;
> +
> +	ret = comp_cntr_get_umem(ib_dev, attrs,
> +				 UVERBS_ATTR_CREATE_COMP_CNTR_BUFFER_VA,
> +				 UVERBS_ATTR_CREATE_COMP_CNTR_BUFFER_FD,
> +				 UVERBS_ATTR_CREATE_COMP_CNTR_BUFFER_OFFSET,
> +				 &cc->comp_umem);
> +	if (ret)
> +		goto err_free;
> +
> +	ret = comp_cntr_get_umem(ib_dev, attrs,
> +				 UVERBS_ATTR_CREATE_COMP_CNTR_ERR_BUFFER_VA,
> +				 UVERBS_ATTR_CREATE_COMP_CNTR_ERR_BUFFER_FD,
> +				 UVERBS_ATTR_CREATE_COMP_CNTR_ERR_BUFFER_OFFSET,
> +				 &cc->err_umem);
> +	if (ret)
> +		goto err_comp_umem;

Seems a bit weird to have two things inside the object? Why not have
the counter support all events and if userspace wants two it can just
create two? There is alot of code to support this err/not err split..

Did any spec define the API this way?

Jason