Re: [PATCH 2/3] drm/i915: Refactor duplicate object vmap functions

["Ville Syrjälä" <ville.syrjala@linux.intel.com>]

On Thu, Oct 08, 2015 at 01:39:55PM +0100, Chris Wilson wrote:
> We now have two implementations for vmapping a whole object, one for
> dma-buf and one for the ringbuffer. If we couple the vmapping into the
> obj->pages lifetime, then we can reuse an obj->vmapping for both and at
> the same time couple it into the shrinker.
> 
> Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
> ---
>  drivers/gpu/drm/i915/i915_drv.h         | 12 ++++---
>  drivers/gpu/drm/i915/i915_gem.c         | 41 ++++++++++++++++++++++++
>  drivers/gpu/drm/i915/i915_gem_dmabuf.c  | 55 +++++----------------------------
>  drivers/gpu/drm/i915/intel_ringbuffer.c | 53 ++++++++++---------------------
>  4 files changed, 72 insertions(+), 89 deletions(-)
> 
> diff --git a/drivers/gpu/drm/i915/i915_drv.h b/drivers/gpu/drm/i915/i915_drv.h
> index 4093eedfd664..343a0a723d2c 100644
> --- a/drivers/gpu/drm/i915/i915_drv.h
> +++ b/drivers/gpu/drm/i915/i915_drv.h
> @@ -2089,10 +2089,7 @@ struct drm_i915_gem_object {
>  		struct scatterlist *sg;
>  		int last;
>  	} get_page;
> -
> -	/* prime dma-buf support */
> -	void *dma_buf_vmapping;
> -	int vmapping_count;
> +	void *vmapping;
>  
>  	/** Breadcrumb of last rendering to the buffer.
>  	 * There can only be one writer, but we allow for multiple readers.
> @@ -2840,12 +2837,19 @@ static inline void i915_gem_object_pin_pages(struct drm_i915_gem_object *obj)
>  	BUG_ON(obj->pages == NULL);
>  	obj->pages_pin_count++;
>  }
> +
>  static inline void i915_gem_object_unpin_pages(struct drm_i915_gem_object *obj)
>  {
>  	BUG_ON(obj->pages_pin_count == 0);
>  	obj->pages_pin_count--;
>  }
>  
> +void *__must_check i915_gem_object_pin_vmap(struct drm_i915_gem_object *obj);
> +static inline void i915_gem_object_unpin_vmap(struct drm_i915_gem_object *obj)
> +{
> +	i915_gem_object_unpin_pages(obj);
> +}
> +
>  int __must_check i915_mutex_lock_interruptible(struct drm_device *dev);
>  int i915_gem_object_sync(struct drm_i915_gem_object *obj,
>  			 struct intel_engine_cs *to,
> diff --git a/drivers/gpu/drm/i915/i915_gem.c b/drivers/gpu/drm/i915/i915_gem.c
> index 78640aecf86d..446cf0662a38 100644
> --- a/drivers/gpu/drm/i915/i915_gem.c
> +++ b/drivers/gpu/drm/i915/i915_gem.c
> @@ -2159,6 +2159,11 @@ i915_gem_object_put_pages(struct drm_i915_gem_object *obj)
>  	ops->put_pages(obj);
>  	obj->pages = NULL;
>  
> +	if (obj->vmapping) {
> +		vunmap(obj->vmapping);
> +		obj->vmapping = NULL;
> +	}
> +
>  	i915_gem_object_invalidate(obj);
>  
>  	return 0;
> @@ -2325,6 +2330,42 @@ i915_gem_object_get_pages(struct drm_i915_gem_object *obj)
>  	return 0;
>  }
>  
> +void *i915_gem_object_pin_vmap(struct drm_i915_gem_object *obj)
> +{
> +	int ret;
> +
> +	ret = i915_gem_object_get_pages(obj);
> +	if (ret)
> +		return ERR_PTR(ret);
> +
> +	i915_gem_object_pin_pages(obj);
> +
> +	if (obj->vmapping == NULL) {
> +		struct sg_page_iter sg_iter;
> +		struct page **pages;
> +		int n;
> +
> +		n = obj->base.size >> PAGE_SHIFT;
> +		pages = kmalloc(n*sizeof(*pages), GFP_TEMPORARY);

Random driveby: kmalloc_array()

Also __GFP_NOWARN?

I wonder if the drm_malloc stuff should do the kmalloc attempt
regardless fo the size, so we wouldn't have to do it here?

> +		if (pages == NULL)
> +			pages = drm_malloc_ab(n, sizeof(*pages));
> +		if (pages != NULL) {
> +			n = 0;
> +			for_each_sg_page(obj->pages->sgl, &sg_iter, obj->pages->nents, 0)
> +				pages[n++] = sg_page_iter_page(&sg_iter);
> +
> +			obj->vmapping = vmap(pages, n, 0, PAGE_KERNEL);
> +			drm_free_large(pages);
> +		}
> +		if (obj->vmapping == NULL) {
> +			i915_gem_object_unpin_pages(obj);
> +			return ERR_PTR(-ENOMEM);
> +		}
> +	}
> +
> +	return obj->vmapping;
> +}
> +
>  void i915_vma_move_to_active(struct i915_vma *vma,
>  			     struct drm_i915_gem_request *req)
>  {
<snip>

-- 
Ville Syrjälä
Intel OTC
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