Re: [PATCH drm-misc-next v2 5/7] drm/gpuvm: add an abstraction for a VM / BO combination

[Danilo Krummrich]

On 9/7/23 10:42, Boris Brezillon wrote:
> On Wed,  6 Sep 2023 23:47:13 +0200
> Danilo Krummrich <dakr@xxxxxxxxxx> wrote:
>
> > +void drm_gpuvm_bo_destroy(struct kref *kref);
>
> I usually keep kref's release functions private so people are not
> tempted to use them.

I think I did that because drm_gpuvm_bo_put() needs it.

> > +
> > +/**
> > + * drm_gpuvm_bo_get() - acquire a struct drm_gpuvm_bo reference
> > + * @vm_bo: the &drm_gpuvm_bo to acquire the reference of
> > + *
> > + * This function acquires an additional reference to @vm_bo. It is illegal to
> > + * call this without already holding a reference. No locks required.
> > + */
> > +static inline struct drm_gpuvm_bo *
> > +drm_gpuvm_bo_get(struct drm_gpuvm_bo *vm_bo)
> > +{
> > +	kref_get(&vm_bo->kref);
> > +	return vm_bo;
> > +}
> > +
> > +/**
> > + * drm_gpuvm_bo_put() - drop a struct drm_gpuvm_bo reference
> > + * @vm_bo: the &drm_gpuvm_bo to release the reference of
> > + *
> > + * This releases a reference to @vm_bo.
> > + */
> > +static inline void
> > +drm_gpuvm_bo_put(struct drm_gpuvm_bo *vm_bo)
> > +{
> > +	kref_put(&vm_bo->kref, drm_gpuvm_bo_destroy);
>
> nit: can we have
>
> 	if (vm_bo)
> 		kref_put(&vm_bo->kref, drm_gpuvm_bo_destroy);
>
> so we don't have to bother testing the vm_bo value in the error/cleanup
> paths?
>
> > +}
> > +