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Date: Sun, 12 May 2024 19:35:32 -0700
From: Nicolin Chen <nicolinc@nvidia.com>
To: Jason Gunthorpe <jgg@nvidia.com>
CC: <will@kernel.org>, <robin.murphy@arm.com>, <kevin.tian@intel.com>,
	<suravee.suthikulpanit@amd.com>, <joro@8bytes.org>,
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Subject: Re: [PATCH RFCv1 03/14] iommufd: Prepare for viommu structures and
 functions
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On Sun, May 12, 2024 at 10:42:12AM -0300, Jason Gunthorpe wrote:
> On Fri, Apr 12, 2024 at 08:47:00PM -0700, Nicolin Chen wrote:
> 
> > +static inline struct iommufd_object *___iommufd_object_alloc(size_t size)
> > +{
> > +	struct iommufd_object *obj;
> > +
> > +	obj = kzalloc(size, GFP_KERNEL_ACCOUNT);
> > +	if (!obj)
> > +		return ERR_PTR(-ENOMEM);
> > +
> > +	/* Starts out bias'd by 1 until it is removed from the xarray */
> > +	refcount_set(&obj->shortterm_users, 1);
> > +	refcount_set(&obj->users, 1);
> > +
> > +	/*
> > +	 * The allocation of an obj->id needs an ictx, so it has to be done
> > +	 * after this ___iommufd_object_alloc() callback.
> > +	 */
> > +
> > +	return obj;
> > +}
> 
> It is probably cleaner to just make the existing allocation work with
> a NULL ictx for this case? Then we can use the existing alloc
> functions.
> 
> > +#define viommu_struct_alloc(name)                                              \
> > +	struct iommufd_##name *_iommufd_##name##_alloc(size_t size)            \
> > +	{                                                                      \
> > +		struct iommufd_object *obj;                                    \
> > +		if (WARN_ON(size < sizeof(struct iommufd_##name)))             \
> > +			return NULL;                                           \
> 
> Then here you'd just use the exisint container_of based flow with the
> driver sub struct name passed as the 'obj'

Yes. And then we can probably unwrap this macro too since it's
no long that verbose to duplicate in viommu/vqueue allocators.

Thanks
Nicolin