Messages in this thread | | | Subject | Re: [PATCH v9 18/32] drm: tegra: fix common struct sg_table related issues | From | Robin Murphy <> | Date | Tue, 1 Sep 2020 21:11:36 +0100 |
| |
On 2020-08-26 07:33, Marek Szyprowski wrote: > 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.
Reviewed-by: Robin Murphy <robin.murphy@arm.com>
> Signed-off-by: Marek Szyprowski <m.szyprowski@samsung.com> > --- > drivers/gpu/drm/tegra/gem.c | 27 ++++++++++----------------- > drivers/gpu/drm/tegra/plane.c | 15 +++++---------- > 2 files changed, 15 insertions(+), 27 deletions(-) > > diff --git a/drivers/gpu/drm/tegra/gem.c b/drivers/gpu/drm/tegra/gem.c > index 723df142a981..01d94befab11 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 { > @@ -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 @@ tegra_gem_prime_map_dma_buf(struct dma_buf_attachment *attach, > 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; > } > diff --git a/drivers/gpu/drm/tegra/plane.c b/drivers/gpu/drm/tegra/plane.c > index 4cd0461cc508..539d14935728 100644 > --- a/drivers/gpu/drm/tegra/plane.c > +++ b/drivers/gpu/drm/tegra/plane.c > @@ -131,12 +131,9 @@ 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 > @@ -144,7 +141,7 @@ 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; > } > @@ -166,8 +163,7 @@ 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; > @@ -186,8 +182,7 @@ 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; >
| |