[PATCH v5 14/38] drm: mediatek: use common helper for a scatterlist contiguity check

From: Marek Szyprowski
Date: Wed May 13 2020 - 09:34:27 EST


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@xxxxxxxxxxx>
---
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@xxxxxxxxxxx/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