linux-kernel - Re: [PATCH v9 13/32] drm: omapdrm: use common helper for extracting pages array

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Date:   Tue, 1 Sep 2020 20:17:19 +0100
From:   Robin Murphy <robin.murphy@....com>
To:     Marek Szyprowski <m.szyprowski@...sung.com>,
        dri-devel@...ts.freedesktop.org, iommu@...ts.linux-foundation.org,
        linaro-mm-sig@...ts.linaro.org, linux-kernel@...r.kernel.org
Cc:     Christoph Hellwig <hch@....de>,
        Bartlomiej Zolnierkiewicz <b.zolnierkie@...sung.com>,
        linux-arm-kernel@...ts.infradead.org,
        David Airlie <airlied@...ux.ie>,
        Daniel Vetter <daniel@...ll.ch>,
        Tomi Valkeinen <tomi.valkeinen@...com>
Subject: Re: [PATCH v9 13/32] drm: omapdrm: use common helper for extracting
 pages array

On 2020-08-26 07:32, Marek Szyprowski wrote:
> Use common helper for converting a sg_table object into struct
> page pointer array.
> 
> Signed-off-by: Marek Szyprowski <m.szyprowski@...sung.com>
> ---
>   drivers/gpu/drm/omapdrm/omap_gem.c | 14 ++++----------
>   1 file changed, 4 insertions(+), 10 deletions(-)
> 
> diff --git a/drivers/gpu/drm/omapdrm/omap_gem.c b/drivers/gpu/drm/omapdrm/omap_gem.c
> index d0d12d5dd76c..ff0c4b0c3fd0 100644
> --- a/drivers/gpu/drm/omapdrm/omap_gem.c
> +++ b/drivers/gpu/drm/omapdrm/omap_gem.c
> @@ -1297,10 +1297,9 @@ struct drm_gem_object *omap_gem_new_dmabuf(struct drm_device *dev, size_t size,
>   		omap_obj->dma_addr = sg_dma_address(sgt->sgl);
>   	} else {
>   		/* Create pages list from sgt */
> -		struct sg_page_iter iter;
>   		struct page **pages;
>   		unsigned int npages;
> -		unsigned int i = 0;
> +		unsigned int ret;
>   
>   		npages = DIV_ROUND_UP(size, PAGE_SIZE);
>   		pages = kcalloc(npages, sizeof(*pages), GFP_KERNEL);
> @@ -1311,14 +1310,9 @@ struct drm_gem_object *omap_gem_new_dmabuf(struct drm_device *dev, size_t size,
>   		}
>   
>   		omap_obj->pages = pages;
> -
> -		for_each_sg_page(sgt->sgl, &iter, sgt->orig_nents, 0) {
> -			pages[i++] = sg_page_iter_page(&iter);
> -			if (i > npages)
> -				break;
> -		}
> -
> -		if (WARN_ON(i != npages)) {
> +		ret = drm_prime_sg_to_page_addr_arrays(sgt, pages, NULL,
> +						       npages);
> +		if (WARN_ON(ret)) {

Again, I'm inclined to think the WARN_ON should remain in 
drm_prime_sg_to_page_addr_arrays() itself such that it could be removed 
here, but either way,

Reviewed-by: Robin Murphy <robin.murphy@....com>

>   			omap_gem_free_object(obj);
>   			obj = ERR_PTR(-ENOMEM);
>   			goto done;
>