[PATCH 4/4] drm/i915: Use CPU mapping for userspace dma-buf mmap()

[Chris Wilson]

On Tue, Aug 11, 2015 at 05:59:23PM -0300, Tiago Vignatti wrote:
> Userspace is the one in charge of flush CPU by wrapping mmap with
> begin{,end}_cpu_access.
> 
> v2: Remove LLC check cause we have dma-buf sync providers now. Also, fix return
> before transferring ownership when mmap fails.
> v3: Fix return values.
> 
> Signed-off-by: Tiago Vignatti <tiago.vignatti at intel.com>
> ---
>  drivers/gpu/drm/i915/i915_gem_dmabuf.c | 18 +++++++++++++++++-
>  1 file changed, 17 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/gpu/drm/i915/i915_gem_dmabuf.c b/drivers/gpu/drm/i915/i915_gem_dmabuf.c
> index 8447ba4..8b87c86 100644
> --- a/drivers/gpu/drm/i915/i915_gem_dmabuf.c
> +++ b/drivers/gpu/drm/i915/i915_gem_dmabuf.c
> @@ -193,7 +193,23 @@ static void i915_gem_dmabuf_kunmap(struct dma_buf *dma_buf, unsigned long page_n
>  
>  static int i915_gem_dmabuf_mmap(struct dma_buf *dma_buf, struct vm_area_struct *vma)
>  {
> -	return -EINVAL;
> +	struct drm_i915_gem_object *obj = dma_buf_to_obj(dma_buf);
> +	int ret;
> +
> +	if (obj->base.size < vma->vm_end - vma->vm_start)
> +		return -EINVAL;
> +
> +	if (WARN_ON(!obj->base.filp))
> +		return -ENODEV;

That's user triggerable, mmap(dma_buf_export(userptr)), so remove the
WARN.
-Chris

-- 
Chris Wilson, Intel Open Source Technology Centre