@@ -98,8 +98,8 @@ static struct sg_table *tegra_bo_pin(struct device *dev, struct host1x_bo *bo,
* the SG table needs to be copied to avoid overwriting any
* other potential users of the original SG table.
*/
- err = sg_alloc_table_from_sg(sgt, obj->sgt->sgl, obj->sgt->nents,
- GFP_KERNEL);
+ err = sg_alloc_table_from_sg(sgt, obj->sgt->sgl,
+ obj->sgt->orig_nents, GFP_KERNEL);
if (err < 0)
goto free;
} else {
@@ -196,8 +196,7 @@ static int tegra_bo_iommu_map(struct tegra_drm *tegra, struct tegra_bo *bo)
bo->iova = bo->mm->start;
- bo->size = iommu_map_sg(tegra->domain, bo->iova, bo->sgt->sgl,
- bo->sgt->nents, prot);
+ bo->size = iommu_map_sgtable(tegra->domain, bo->iova, bo->sgt, prot);
if (!bo->size) {
dev_err(tegra->drm->dev, "failed to map buffer\n");
err = -ENOMEM;
@@ -264,8 +263,7 @@ static struct tegra_bo *tegra_bo_alloc_object(struct drm_device *drm,
static void tegra_bo_free(struct drm_device *drm, struct tegra_bo *bo)
{
if (bo->pages) {
- dma_unmap_sg(drm->dev, bo->sgt->sgl, bo->sgt->nents,
- DMA_FROM_DEVICE);
+ dma_unmap_sgtable(drm->dev, bo->sgt, DMA_FROM_DEVICE, 0);
drm_gem_put_pages(&bo->gem, bo->pages, true, true);
sg_free_table(bo->sgt);
kfree(bo->sgt);
@@ -290,12 +288,9 @@ static int tegra_bo_get_pages(struct drm_device *drm, struct tegra_bo *bo)
goto put_pages;
}
- err = dma_map_sg(drm->dev, bo->sgt->sgl, bo->sgt->nents,
- DMA_FROM_DEVICE);
- if (err == 0) {
- err = -EFAULT;
+ err = dma_map_sgtable(drm->dev, bo->sgt, DMA_FROM_DEVICE, 0);
+ if (err)
goto free_sgt;
- }
return 0;
@@ -571,7 +566,7 @@ int tegra_drm_mmap(struct file *file, struct vm_area_struct *vma)
goto free;
}
- if (dma_map_sg(attach->dev, sgt->sgl, sgt->nents, dir) == 0)
+ if (dma_map_sgtable(attach->dev, sgt, dir, 0))
goto free;
return sgt;
@@ -590,7 +585,7 @@ static void tegra_gem_prime_unmap_dma_buf(struct dma_buf_attachment *attach,
struct tegra_bo *bo = to_tegra_bo(gem);
if (bo->pages)
- dma_unmap_sg(attach->dev, sgt->sgl, sgt->nents, dir);
+ dma_unmap_sgtable(attach->dev, sgt, dir, 0);
sg_free_table(sgt);
kfree(sgt);
@@ -609,8 +604,7 @@ static int tegra_gem_prime_begin_cpu_access(struct dma_buf *buf,
struct drm_device *drm = gem->dev;
if (bo->pages)
- dma_sync_sg_for_cpu(drm->dev, bo->sgt->sgl, bo->sgt->nents,
- DMA_FROM_DEVICE);
+ dma_sync_sgtable_for_cpu(drm->dev, bo->sgt, DMA_FROM_DEVICE);
return 0;
}
@@ -623,8 +617,7 @@ static int tegra_gem_prime_end_cpu_access(struct dma_buf *buf,
struct drm_device *drm = gem->dev;
if (bo->pages)
- dma_sync_sg_for_device(drm->dev, bo->sgt->sgl, bo->sgt->nents,
- DMA_TO_DEVICE);
+ dma_sync_sgtable_for_device(drm->dev, bo->sgt, DMA_TO_DEVICE);
return 0;
}
@@ -130,12 +130,9 @@ static int tegra_dc_pin(struct tegra_dc *dc, struct tegra_plane_state *state)
}
if (sgt) {
- err = dma_map_sg(dc->dev, sgt->sgl, sgt->nents,
- DMA_TO_DEVICE);
- if (err == 0) {
- err = -ENOMEM;
+ err = dma_map_sgtable(dc->dev, sgt, DMA_TO_DEVICE, 0);
+ if (err)
goto unpin;
- }
/*
* The display controller needs contiguous memory, so
@@ -143,7 +140,7 @@ static int tegra_dc_pin(struct tegra_dc *dc, struct tegra_plane_state *state)
* map its SG table to a single contiguous chunk of
* I/O virtual memory.
*/
- if (err > 1) {
+ if (sgt->nents > 1) {
err = -EINVAL;
goto unpin;
}
@@ -165,8 +162,7 @@ static int tegra_dc_pin(struct tegra_dc *dc, struct tegra_plane_state *state)
struct sg_table *sgt = state->sgt[i];
if (sgt)
- dma_unmap_sg(dc->dev, sgt->sgl, sgt->nents,
- DMA_TO_DEVICE);
+ dma_unmap_sgtable(dc->dev, sgt, DMA_TO_DEVICE, 0);
host1x_bo_unpin(dc->dev, &bo->base, sgt);
state->iova[i] = DMA_MAPPING_ERROR;
@@ -185,8 +181,7 @@ static void tegra_dc_unpin(struct tegra_dc *dc, struct tegra_plane_state *state)
struct sg_table *sgt = state->sgt[i];
if (sgt)
- dma_unmap_sg(dc->dev, sgt->sgl, sgt->nents,
- DMA_TO_DEVICE);
+ dma_unmap_sgtable(dc->dev, sgt, DMA_TO_DEVICE, 0);
host1x_bo_unpin(dc->dev, &bo->base, sgt);
state->iova[i] = DMA_MAPPING_ERROR;
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> --- 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/tegra/gem.c | 27 ++++++++++----------------- drivers/gpu/drm/tegra/plane.c | 15 +++++---------- 2 files changed, 15 insertions(+), 27 deletions(-)