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From:   Marek Szyprowski <m.szyprowski@samsung.com>
To:     dri-devel@lists.freedesktop.org, iommu@lists.linux-foundation.org,
        linaro-mm-sig@lists.linaro.org, linux-kernel@vger.kernel.org
Cc:     Marek Szyprowski <m.szyprowski@samsung.com>,
        Christoph Hellwig <hch@lst.de>,
        Robin Murphy <robin.murphy@arm.com>,
        Bartlomiej Zolnierkiewicz <b.zolnierkie@samsung.com>,
        linux-arm-kernel@lists.infradead.org,
        David Airlie <airlied@linux.ie>,
        Daniel Vetter <daniel@ffwll.ch>,
        Matthias Brugger <matthias.bgg@gmail.com>,
        Chun-Kuang Hu <chunkuang.hu@kernel.org>,
        Philipp Zabel <p.zabel@pengutronix.de>,
        linux-mediatek@lists.infradead.org
Subject: [PATCH v5 14/38] drm: mediatek: use common helper for a scatterlist
 contiguity check
Date:   Wed, 13 May 2020 15:32:21 +0200
Message-Id: <20200513133245.6408-14-m.szyprowski@samsung.com>
In-Reply-To: <20200513133245.6408-1-m.szyprowski@samsung.com>
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References: <20200513132114.6046-1-m.szyprowski@samsung.com>
        <20200513133245.6408-1-m.szyprowski@samsung.com>
        <CGME20200513133306eucas1p1ab15386cc4bbcf09052a8175d3660997@eucas1p1.samsung.com>
Sender: linux-kernel-owner@vger.kernel.org
Precedence: bulk

Use common helper for checking the contiguity of the imported dma-buf and
do this check before allocating resources, so the error path is simpler.

Signed-off-by: Marek Szyprowski <m.szyprowski@samsung.com>
---
For more information, see '[PATCH v5 00/38] DRM: fix struct sg_table nents
vs. orig_nents misuse' thread:
https://lore.kernel.org/linux-iommu/20200513132114.6046-1-m.szyprowski@samsung.com/T/
---
 drivers/gpu/drm/mediatek/mtk_drm_gem.c | 25 ++++++-------------------
 1 file changed, 6 insertions(+), 19 deletions(-)

diff --git a/drivers/gpu/drm/mediatek/mtk_drm_gem.c b/drivers/gpu/drm/mediatek/mtk_drm_gem.c
index b04a3c2..6c34c06 100644
--- a/drivers/gpu/drm/mediatek/mtk_drm_gem.c
+++ b/drivers/gpu/drm/mediatek/mtk_drm_gem.c
@@ -212,34 +212,21 @@ struct drm_gem_object *mtk_gem_prime_import_sg_table(struct drm_device *dev,
 			struct dma_buf_attachment *attach, struct sg_table *sg)
 {
 	struct mtk_drm_gem_obj *mtk_gem;
-	int ret;
-	struct scatterlist *s;
-	unsigned int i;
-	dma_addr_t expected;
 
-	mtk_gem = mtk_drm_gem_init(dev, attach->dmabuf->size);
+	/* check if the entries in the sg_table are contiguous */
+	if (drm_prime_get_contiguous_size(sg) < attach->dmabuf->size) {
+		DRM_ERROR("sg_table is not contiguous");
+		return ERR_PTR(-EINVAL);
+	}
 
+	mtk_gem = mtk_drm_gem_init(dev, attach->dmabuf->size);
 	if (IS_ERR(mtk_gem))
 		return ERR_CAST(mtk_gem);
 
-	expected = sg_dma_address(sg->sgl);
-	for_each_sg(sg->sgl, s, sg->nents, i) {
-		if (sg_dma_address(s) != expected) {
-			DRM_ERROR("sg_table is not contiguous");
-			ret = -EINVAL;
-			goto err_gem_free;
-		}
-		expected = sg_dma_address(s) + sg_dma_len(s);
-	}
-
 	mtk_gem->dma_addr = sg_dma_address(sg->sgl);
 	mtk_gem->sg = sg;
 
 	return &mtk_gem->base;
-
-err_gem_free:
-	kfree(mtk_gem);
-	return ERR_PTR(ret);
 }
 
 void *mtk_drm_gem_prime_vmap(struct drm_gem_object *obj)
-- 
1.9.1