[Intel-gfx] [PATCH 53/55] drm/i915: Release vma when the handle is closed

[Joonas Lahtinen]

On ma, 2016-07-25 at 18:32 +0100, Chris Wilson wrote:
>  /**
>   * i915_gem_wait_ioctl - implements DRM_IOCTL_I915_GEM_WAIT
>   * @dev: drm device pointer
> @@ -2810,26 +2823,32 @@ static int __i915_vma_unbind(struct i915_vma *vma, bool wait)
>  	if (active && wait) {
>  		int idx;
>  
> +		/* When a closed VMA is retired, it is unbound - eek.
> +		 * In order to prevent it from being recursively closed,
> +		 * take a pin on the vma so that the second unbind is
> +		 * aborted.
> +		 */
> +		vma->pin_count++;

Always smells fishy. But an extra variable probably not worthy.

> diff --git a/drivers/gpu/drm/i915/i915_gem_gtt.c b/drivers/gpu/drm/i915/i915_gem_gtt.c
> index ef0dc7131808..bfac2448ba04 100644
> --- a/drivers/gpu/drm/i915/i915_gem_gtt.c
> +++ b/drivers/gpu/drm/i915/i915_gem_gtt.c
> @@ -3339,6 +3339,31 @@ i915_vma_retire(struct i915_gem_active *active,
>  		return;
>  
>  	list_move_tail(&vma->vm_link, &vma->vm->inactive_list);
> +	if (unlikely(vma->closed && !vma->pin_count))
> +		WARN_ON(i915_vma_unbind(vma));

So this is just an optimization to get rid of the VMA ASAP if we're
lucky?

> +
> +void i915_vma_close(struct i915_vma *vma)
> +{
> +	GEM_BUG_ON(vma->closed);
> +	vma->closed = true;
> +
> +	list_del_init(&vma->obj_link);
> +	if (!i915_vma_is_active(vma) && !vma->pin_count)
> +		WARN_ON(__i915_vma_unbind_no_wait(vma));

Same here, an optimization?

Somebody from the original CC list probably should give it a look too.

Regards, Joonas
-- 
Joonas Lahtinen
Open Source Technology Center
Intel Corporation