Re: [Intel-gfx] [PATCH v2 4/4] drm/vgem: use shmem helpers

From: Andi Shyti <andi.shyti@intel.com>
To: Daniel Vetter <daniel.vetter@ffwll.ch>
Cc: "Christian König" <christian.koenig@amd.com>,
	"Intel Graphics Development" <intel-gfx@lists.freedesktop.org>,
	"DRI Development" <dri-devel@lists.freedesktop.org>,
	"Chris Wilson" <chris@chris-wilson.co.uk>,
	"Melissa Wen" <melissa.srw@gmail.com>,
	"Thomas Zimmermann" <tzimmermann@suse.de>,
	"Daniel Vetter" <daniel.vetter@intel.com>
Subject: Re: [Intel-gfx] [PATCH v2 4/4] drm/vgem: use shmem helpers
Date: Thu, 3 Jun 2021 21:42:00 +0300	[thread overview]
Message-ID: <YLkieISPHgzmUnD4@intel.intel> (raw)
In-Reply-To: <20210603150326.1326658-5-daniel.vetter@ffwll.ch>

Hi Daniel,

> +/*
> + * This just sets wc mode for shmem helpers. vgem doesn't have any begin/end cpu
> + * access ioctls, there must use coherent memory or dma-buf sharing just wont
> + * work.
> + */
> +static struct drm_gem_object *vgem_gem_create_object(struct drm_device *dev, size_t size)
>  {
> -	struct drm_vgem_gem_object *obj;
> -	int npages;
> +	struct drm_gem_shmem_object *obj;
>  
> -	obj = __vgem_gem_create(dev, attach->dmabuf->size);
> -	if (IS_ERR(obj))
> -		return ERR_CAST(obj);
> -
> -	npages = PAGE_ALIGN(attach->dmabuf->size) / PAGE_SIZE;
> +	obj = kzalloc(sizeof(*obj), GFP_KERNEL);
> +	if (!obj)
> +		return NULL;
>  
> -	obj->table = sg;
> -	obj->pages = kvmalloc_array(npages, sizeof(struct page *), GFP_KERNEL);
> -	if (!obj->pages) {
> -		__vgem_gem_destroy(obj);
> -		return ERR_PTR(-ENOMEM);
> -	}
> +	obj->base.funcs = &drm_gem_shmem_funcs;
> +	obj->map_wc = true;
>  
> -	obj->pages_pin_count++; /* perma-pinned */
> -	drm_prime_sg_to_page_array(obj->table, obj->pages, npages);
>  	return &obj->base;

here you are allocating a bigger object than what you are
returning, in size. How does it get freed?

Andi