The Documentation/DMA-API-HOWTO.txt states that dma_map_sg returns the numer of the created entries in the DMA address space. However the subsequent calls to dma_sync_sg_for_{device,cpu} and dma_unmap_sg must be called with the original number of entries passed to dma_map_sg. The sg_table->nents in turn holds the result of the dma_map_sg call as stated in include/linux/scatterlist.h. Adapt the code to obey those rules.
Signed-off-by: Marek Szyprowski m.szyprowski@samsung.com --- For more information, see '[PATCH v2 00/21] DRM: fix struct sg_table nents vs. orig_nents misuse' thread: https://lkml.org/lkml/2020/5/4/373 --- drivers/gpu/drm/tegra/gem.c | 25 +++++++++++++------------ drivers/gpu/drm/tegra/plane.c | 13 +++++++------ 2 files changed, 20 insertions(+), 18 deletions(-)
diff --git a/drivers/gpu/drm/tegra/gem.c b/drivers/gpu/drm/tegra/gem.c index 6237681..5710ab4 100644 --- a/drivers/gpu/drm/tegra/gem.c +++ b/drivers/gpu/drm/tegra/gem.c @@ -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 { @@ -197,7 +197,7 @@ 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->sgt->orig_nents, prot); if (!bo->size) { dev_err(tegra->drm->dev, "failed to map buffer\n"); err = -ENOMEM; @@ -264,7 +264,7 @@ 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_unmap_sg(drm->dev, bo->sgt->sgl, bo->sgt->orig_nents, DMA_FROM_DEVICE); drm_gem_put_pages(&bo->gem, bo->pages, true, true); sg_free_table(bo->sgt); @@ -290,9 +290,9 @@ 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) { + bo->sgt->nents = dma_map_sg(drm->dev, bo->sgt->sgl, bo->sgt->orig_nents, + DMA_FROM_DEVICE); + if (bo->sgt->nents == 0) { err = -EFAULT; goto free_sgt; } @@ -571,7 +571,8 @@ 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) + sgt->nents = dma_map_sg(attach->dev, sgt->sgl, sgt->orig_nents, dir); + if (sgt->nents == 0) goto free;
return sgt; @@ -590,7 +591,7 @@ 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_sg(attach->dev, sgt->sgl, sgt->orig_nents, dir);
sg_free_table(sgt); kfree(sgt); @@ -609,7 +610,7 @@ 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_sync_sg_for_cpu(drm->dev, bo->sgt->sgl, bo->sgt->orig_nents, DMA_FROM_DEVICE);
return 0; @@ -623,8 +624,8 @@ 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_sg_for_device(drm->dev, bo->sgt->sgl, + bo->sgt->orig_nents, DMA_TO_DEVICE);
return 0; } diff --git a/drivers/gpu/drm/tegra/plane.c b/drivers/gpu/drm/tegra/plane.c index 9ccfb56..3982bf8 100644 --- a/drivers/gpu/drm/tegra/plane.c +++ b/drivers/gpu/drm/tegra/plane.c @@ -130,9 +130,10 @@ 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) { + sgt->nents = dma_map_sg(dc->dev, sgt->sgl, + sgt->orig_nents, + DMA_TO_DEVICE); + if (sgt->nents == 0) { err = -ENOMEM; goto unpin; } @@ -143,7 +144,7 @@ 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; } @@ -165,7 +166,7 @@ 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_unmap_sg(dc->dev, sgt->sgl, sgt->orig_nents, DMA_TO_DEVICE);
host1x_bo_unpin(dc->dev, &bo->base, sgt); @@ -185,7 +186,7 @@ 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_unmap_sg(dc->dev, sgt->sgl, sgt->orig_nents, DMA_TO_DEVICE);
host1x_bo_unpin(dc->dev, &bo->base, sgt);