| From 61f616a34c2625b0f41dcb6cb4c77b795edef039 Mon Sep 17 00:00:00 2001 |
| From: Sasha Levin <sashal@kernel.org> |
| Date: Tue, 28 Apr 2020 13:09:11 +0200 |
| Subject: drm: lima: fix common struct sg_table related issues |
| |
| From: Marek Szyprowski <m.szyprowski@samsung.com> |
| |
| [ Upstream commit c3d9c17f486d5c54940487dc31a54ebfdeeb371a ] |
| |
| 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 <m.szyprowski@samsung.com> |
| Reviewed-by: Qiang Yu <yuq825@gmail.com> |
| Signed-off-by: Sasha Levin <sashal@kernel.org> |
| --- |
| drivers/gpu/drm/lima/lima_gem.c | 11 ++++++++--- |
| drivers/gpu/drm/lima/lima_vm.c | 5 ++--- |
| 2 files changed, 10 insertions(+), 6 deletions(-) |
| |
| diff --git a/drivers/gpu/drm/lima/lima_gem.c b/drivers/gpu/drm/lima/lima_gem.c |
| index 155f2b4b4030a..11223fe348dfe 100644 |
| --- a/drivers/gpu/drm/lima/lima_gem.c |
| +++ b/drivers/gpu/drm/lima/lima_gem.c |
| @@ -69,8 +69,7 @@ int lima_heap_alloc(struct lima_bo *bo, struct lima_vm *vm) |
| return ret; |
| |
| if (bo->base.sgt) { |
| - dma_unmap_sg(dev, bo->base.sgt->sgl, |
| - bo->base.sgt->nents, DMA_BIDIRECTIONAL); |
| + dma_unmap_sgtable(dev, bo->base.sgt, DMA_BIDIRECTIONAL, 0); |
| sg_free_table(bo->base.sgt); |
| } else { |
| bo->base.sgt = kmalloc(sizeof(*bo->base.sgt), GFP_KERNEL); |
| @@ -80,7 +79,13 @@ int lima_heap_alloc(struct lima_bo *bo, struct lima_vm *vm) |
| } |
| } |
| |
| - dma_map_sg(dev, sgt.sgl, sgt.nents, DMA_BIDIRECTIONAL); |
| + ret = dma_map_sgtable(dev, &sgt, DMA_BIDIRECTIONAL, 0); |
| + if (ret) { |
| + sg_free_table(&sgt); |
| + kfree(bo->base.sgt); |
| + bo->base.sgt = NULL; |
| + return ret; |
| + } |
| |
| *bo->base.sgt = sgt; |
| |
| diff --git a/drivers/gpu/drm/lima/lima_vm.c b/drivers/gpu/drm/lima/lima_vm.c |
| index 5b92fb82674a9..2b2739adc7f53 100644 |
| --- a/drivers/gpu/drm/lima/lima_vm.c |
| +++ b/drivers/gpu/drm/lima/lima_vm.c |
| @@ -124,7 +124,7 @@ int lima_vm_bo_add(struct lima_vm *vm, struct lima_bo *bo, bool create) |
| if (err) |
| goto err_out1; |
| |
| - for_each_sg_dma_page(bo->base.sgt->sgl, &sg_iter, bo->base.sgt->nents, 0) { |
| + for_each_sgtable_dma_page(bo->base.sgt, &sg_iter, 0) { |
| err = lima_vm_map_page(vm, sg_page_iter_dma_address(&sg_iter), |
| bo_va->node.start + offset); |
| if (err) |
| @@ -298,8 +298,7 @@ int lima_vm_map_bo(struct lima_vm *vm, struct lima_bo *bo, int pageoff) |
| mutex_lock(&vm->lock); |
| |
| base = bo_va->node.start + (pageoff << PAGE_SHIFT); |
| - for_each_sg_dma_page(bo->base.sgt->sgl, &sg_iter, |
| - bo->base.sgt->nents, pageoff) { |
| + for_each_sgtable_dma_page(bo->base.sgt, &sg_iter, pageoff) { |
| err = lima_vm_map_page(vm, sg_page_iter_dma_address(&sg_iter), |
| base + offset); |
| if (err) |
| -- |
| 2.27.0 |
| |