From 39913934e67cab214480cc95a3632696aeb8e71a Mon Sep 17 00:00:00 2001 From: Marek Szyprowski Date: Fri, 19 Jun 2020 12:36:04 +0200 Subject: drm: amdgpu: fix common struct sg_table related issues MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit The Documentation/DMA-API-HOWTO.txt states that the dma_map_sg() function returns the number of the created entries in the DMA address space. However the subsequent calls to the dma_sync_sg_for_{device,cpu}() and dma_unmap_sg must be called with the original number of the entries passed to the dma_map_sg(). struct sg_table is a common structure used for describing a non-contiguous memory buffer, used commonly in the DRM and graphics subsystems. It consists of a scatterlist with memory pages and DMA addresses (sgl entry), as well as the number of scatterlist entries: CPU pages (orig_nents entry) and DMA mapped pages (nents entry). It turned out that it was a common mistake to misuse nents and orig_nents entries, calling DMA-mapping functions with a wrong number of entries or ignoring the number of mapped entries returned by the dma_map_sg() function. To avoid such issues, lets use a common dma-mapping wrappers operating directly on the struct sg_table objects and use scatterlist page iterators where possible. This, almost always, hides references to the nents and orig_nents entries, making the code robust, easier to follow and copy/paste safe. Signed-off-by: Marek Szyprowski Reviewed-by: Christian König Link: https://patchwork.freedesktop.org/patch/371142/ Signed-off-by: Christian König --- drivers/gpu/drm/amd/amdgpu/amdgpu_vram_mgr.c | 8 ++++---- 1 file changed, 4 insertions(+), 4 deletions(-) (limited to 'drivers/gpu/drm/amd/amdgpu/amdgpu_vram_mgr.c') diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_vram_mgr.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_vram_mgr.c index ad5732f8d4d2..d4f626d9bec1 100644 --- a/drivers/gpu/drm/amd/amdgpu/amdgpu_vram_mgr.c +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_vram_mgr.c @@ -476,11 +476,11 @@ int amdgpu_vram_mgr_alloc_sgt(struct amdgpu_device *adev, if (r) goto error_free; - for_each_sg((*sgt)->sgl, sg, num_entries, i) + for_each_sgtable_sg((*sgt), sg, i) sg->length = 0; node = mem->mm_node; - for_each_sg((*sgt)->sgl, sg, num_entries, i) { + for_each_sgtable_sg((*sgt), sg, i) { phys_addr_t phys = (node->start << PAGE_SHIFT) + adev->gmc.aper_base; size_t size = node->size << PAGE_SHIFT; @@ -500,7 +500,7 @@ int amdgpu_vram_mgr_alloc_sgt(struct amdgpu_device *adev, return 0; error_unmap: - for_each_sg((*sgt)->sgl, sg, num_entries, i) { + for_each_sgtable_sg((*sgt), sg, i) { if (!sg->length) continue; @@ -531,7 +531,7 @@ void amdgpu_vram_mgr_free_sgt(struct amdgpu_device *adev, struct scatterlist *sg; int i; - for_each_sg(sgt->sgl, sg, sgt->nents, i) + for_each_sgtable_sg(sgt, sg, i) dma_unmap_resource(dev, sg->dma_address, sg->length, dir, DMA_ATTR_SKIP_CPU_SYNC); -- cgit v1.2.3-70-g09d2