[PATCH v7 04/36] drm: amdgpu: fix common struct sg_table related issues
From: Marek Szyprowski <m.szyprowski@samsung.com>
Date: 2020-06-19 10:37:52
Also in:
amd-gfx, dri-devel, linux-iommu, lkml
Subsystem:
drm drivers, radeon and amdgpu drm drivers, the rest · Maintainers:
David Airlie, Simona Vetter, Alex Deucher, Christian König, Linus Torvalds
Possibly related (same subject, not in this thread)
- 2020-07-07 · Re: [PATCH v7 04/36] drm: amdgpu: fix common struct sg_table related issues · Marek Szyprowski <m.szyprowski@samsung.com>
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: Christian König <christian.koenig@amd.com>
---
drivers/gpu/drm/amd/amdgpu/amdgpu_dma_buf.c | 6 +++---
drivers/gpu/drm/amd/amdgpu/amdgpu_ttm.c | 9 +++------
drivers/gpu/drm/amd/amdgpu/amdgpu_vram_mgr.c | 8 ++++----
3 files changed, 10 insertions(+), 13 deletions(-)
diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_dma_buf.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_dma_buf.c
index 43d8ed7dbd00..519ce4427fce 100644
--- a/drivers/gpu/drm/amd/amdgpu/amdgpu_dma_buf.c
+++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_dma_buf.c@@ -307,8 +307,8 @@ static struct sg_table *amdgpu_dma_buf_map(struct dma_buf_attachment *attach, if (IS_ERR(sgt)) return sgt; - if (!dma_map_sg_attrs(attach->dev, sgt->sgl, sgt->nents, dir, - DMA_ATTR_SKIP_CPU_SYNC)) + if (dma_map_sgtable(attach->dev, sgt, dir, + DMA_ATTR_SKIP_CPU_SYNC)) goto error_free; break;
@@ -349,7 +349,7 @@ static void amdgpu_dma_buf_unmap(struct dma_buf_attachment *attach, struct amdgpu_device *adev = amdgpu_ttm_adev(bo->tbo.bdev); if (sgt->sgl->page_link) { - dma_unmap_sg(attach->dev, sgt->sgl, sgt->nents, dir); + dma_unmap_sgtable(attach->dev, sgt, dir, 0); sg_free_table(sgt); kfree(sgt); } else {
diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_ttm.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_ttm.c
index 5129a996e941..97fb73e5a6ae 100644
--- a/drivers/gpu/drm/amd/amdgpu/amdgpu_ttm.c
+++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_ttm.c@@ -1025,7 +1025,6 @@ static int amdgpu_ttm_tt_pin_userptr(struct ttm_tt *ttm) { struct amdgpu_device *adev = amdgpu_ttm_adev(ttm->bdev); struct amdgpu_ttm_tt *gtt = (void *)ttm; - unsigned nents; int r; int write = !(gtt->userflags & AMDGPU_GEM_USERPTR_READONLY);
@@ -1040,9 +1039,8 @@ static int amdgpu_ttm_tt_pin_userptr(struct ttm_tt *ttm) goto release_sg; /* Map SG to device */ - r = -ENOMEM; - nents = dma_map_sg(adev->dev, ttm->sg->sgl, ttm->sg->nents, direction); - if (nents == 0) + r = dma_map_sgtable(adev->dev, ttm->sg, direction, 0); + if (r) goto release_sg; /* convert SG to linear array of pages and dma addresses */
@@ -1073,8 +1071,7 @@ static void amdgpu_ttm_tt_unpin_userptr(struct ttm_tt *ttm) return; /* unmap the pages mapped to the device */ - dma_unmap_sg(adev->dev, ttm->sg->sgl, ttm->sg->nents, direction); - + dma_unmap_sgtable(adev->dev, ttm->sg, direction, 0); sg_free_table(ttm->sg); #if IS_ENABLED(CONFIG_DRM_AMDGPU_USERPTR)
diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_vram_mgr.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_vram_mgr.c
index d399e5893170..c281aa13f5ec 100644
--- a/drivers/gpu/drm/amd/amdgpu/amdgpu_vram_mgr.c
+++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_vram_mgr.c@@ -477,11 +477,11 @@ 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;
@@ -501,7 +501,7 @@ 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;
@@ -532,7 +532,7 @@ 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);
--
2.17.1
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