Re: [CI 15/19] drm/i915: Remove pinned check from madvise ioctl

[Daniel Vetter <daniel@ffwll.ch>]

On Fri, Aug 05, 2016 at 10:14:20AM +0100, Chris Wilson wrote:
> We don't need to incur the overhead of checking whether the object is
> pinned prior to changing its madvise. If the object is pinned, the
> madvise will not take effect until it is unpinned and so we cannot free
> the pages being pointed at by hardware. Marking a pinned object with
> allocated pages as DONTNEED will not trigger any undue warnings. The check
> is therefore superfluous, and by removing it we can remove a linear walk
> over all the vma the object has.
> 
> Still despite it being an overzealous check, that error code is part of
> the current ABI and so we must proceed with caution.
> 
> Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
> Cc: Daniel Vetter <daniel.vetter@ffwll.ch>
> Reviewed-by: Joonas Lahtinen <joonas.lahtinen@linux.intel.com>

fwiw Acked-by: Daniel Vetter <daniel.vetter@ffwll.ch>
> ---
>  drivers/gpu/drm/i915/i915_gem.c | 6 ------
>  1 file changed, 6 deletions(-)
> 
> diff --git a/drivers/gpu/drm/i915/i915_gem.c b/drivers/gpu/drm/i915/i915_gem.c
> index 063c56f5d6f8..7e6b7853f9d7 100644
> --- a/drivers/gpu/drm/i915/i915_gem.c
> +++ b/drivers/gpu/drm/i915/i915_gem.c
> @@ -3883,11 +3883,6 @@ i915_gem_madvise_ioctl(struct drm_device *dev, void *data,
>  		goto unlock;
>  	}
>  
> -	if (i915_gem_obj_is_pinned(obj)) {
> -		ret = -EINVAL;
> -		goto out;
> -	}
> -
>  	if (obj->pages &&
>  	    obj->tiling_mode != I915_TILING_NONE &&
>  	    dev_priv->quirks & QUIRK_PIN_SWIZZLED_PAGES) {
> @@ -3906,7 +3901,6 @@ i915_gem_madvise_ioctl(struct drm_device *dev, void *data,
>  
>  	args->retained = obj->madv != __I915_MADV_PURGED;
>  
> -out:
>  	i915_gem_object_put(obj);
>  unlock:
>  	mutex_unlock(&dev->struct_mutex);
> -- 
> 2.8.1
> 
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-- 
Daniel Vetter
Software Engineer, Intel Corporation
http://blog.ffwll.ch
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