| Message ID | 20200505084614.30424-10-m.szyprowski@samsung.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | DRM: fix struct sg_table nents vs. orig_nents misuse | expand |
On 05/05/2020 09:45, Marek Szyprowski wrote: > 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 the 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. A common mistake was to ignore a result > of the dma_map_sg function and don't use the sg_table->orig_nents at all. > > To avoid such issues, lets use common dma-mapping wrappers operating > directly on the struct sg_table objects and adjust references to the > nents and orig_nents respectively. > > Signed-off-by: Marek Szyprowski <m.szyprowski@samsung.com> The change looks good to me: Reviewed-by: Steven Price <steven.price@arm.com> Although I would have appreciated the commit message being modified to match the specifics of Panfrost - the return of dma_mpa_sg() wasn't being ignored, but the use of orig_nents/nents was indeed wrong. Steve > --- > For more information, see '[PATCH v3 00/25] DRM: fix struct sg_table nents > vs. orig_nents misuse' thread: https://lkml.org/lkml/2020/5/5/187 > --- > drivers/gpu/drm/panfrost/panfrost_gem.c | 4 ++-- > drivers/gpu/drm/panfrost/panfrost_mmu.c | 5 ++--- > 2 files changed, 4 insertions(+), 5 deletions(-) > > diff --git a/drivers/gpu/drm/panfrost/panfrost_gem.c b/drivers/gpu/drm/panfrost/panfrost_gem.c > index 17b654e..95d7e80 100644 > --- a/drivers/gpu/drm/panfrost/panfrost_gem.c > +++ b/drivers/gpu/drm/panfrost/panfrost_gem.c > @@ -41,8 +41,8 @@ static void panfrost_gem_free_object(struct drm_gem_object *obj) > > for (i = 0; i < n_sgt; i++) { > if (bo->sgts[i].sgl) { > - dma_unmap_sg(pfdev->dev, bo->sgts[i].sgl, > - bo->sgts[i].nents, DMA_BIDIRECTIONAL); > + dma_unmap_sgtable(pfdev->dev, &bo->sgts[i], > + DMA_BIDIRECTIONAL); > sg_free_table(&bo->sgts[i]); > } > } > diff --git a/drivers/gpu/drm/panfrost/panfrost_mmu.c b/drivers/gpu/drm/panfrost/panfrost_mmu.c > index ed28aeb..9926111 100644 > --- a/drivers/gpu/drm/panfrost/panfrost_mmu.c > +++ b/drivers/gpu/drm/panfrost/panfrost_mmu.c > @@ -517,10 +517,9 @@ static int panfrost_mmu_map_fault_addr(struct panfrost_device *pfdev, int as, > if (ret) > goto err_pages; > > - if (!dma_map_sg(pfdev->dev, sgt->sgl, sgt->nents, DMA_BIDIRECTIONAL)) { > - ret = -EINVAL; > + ret = dma_map_sgtable(pfdev->dev, sgt, DMA_BIDIRECTIONAL); > + if (ret) > goto err_map; > - } > > mmu_map_sg(pfdev, bomapping->mmu, addr, > IOMMU_WRITE | IOMMU_READ | IOMMU_NOEXEC, sgt); >
diff --git a/drivers/gpu/drm/panfrost/panfrost_gem.c b/drivers/gpu/drm/panfrost/panfrost_gem.c index 17b654e..95d7e80 100644 --- a/drivers/gpu/drm/panfrost/panfrost_gem.c +++ b/drivers/gpu/drm/panfrost/panfrost_gem.c @@ -41,8 +41,8 @@ static void panfrost_gem_free_object(struct drm_gem_object *obj) for (i = 0; i < n_sgt; i++) { if (bo->sgts[i].sgl) { - dma_unmap_sg(pfdev->dev, bo->sgts[i].sgl, - bo->sgts[i].nents, DMA_BIDIRECTIONAL); + dma_unmap_sgtable(pfdev->dev, &bo->sgts[i], + DMA_BIDIRECTIONAL); sg_free_table(&bo->sgts[i]); } } diff --git a/drivers/gpu/drm/panfrost/panfrost_mmu.c b/drivers/gpu/drm/panfrost/panfrost_mmu.c index ed28aeb..9926111 100644 --- a/drivers/gpu/drm/panfrost/panfrost_mmu.c +++ b/drivers/gpu/drm/panfrost/panfrost_mmu.c @@ -517,10 +517,9 @@ static int panfrost_mmu_map_fault_addr(struct panfrost_device *pfdev, int as, if (ret) goto err_pages; - if (!dma_map_sg(pfdev->dev, sgt->sgl, sgt->nents, DMA_BIDIRECTIONAL)) { - ret = -EINVAL; + ret = dma_map_sgtable(pfdev->dev, sgt, DMA_BIDIRECTIONAL); + if (ret) goto err_map; - } mmu_map_sg(pfdev, bomapping->mmu, addr, IOMMU_WRITE | IOMMU_READ | IOMMU_NOEXEC, sgt);
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 the 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. A common mistake was to ignore a result of the dma_map_sg function and don't use the sg_table->orig_nents at all. To avoid such issues, lets use common dma-mapping wrappers operating directly on the struct sg_table objects and adjust references to the nents and orig_nents respectively. Signed-off-by: Marek Szyprowski <m.szyprowski@samsung.com> --- For more information, see '[PATCH v3 00/25] DRM: fix struct sg_table nents vs. orig_nents misuse' thread: https://lkml.org/lkml/2020/5/5/187 --- drivers/gpu/drm/panfrost/panfrost_gem.c | 4 ++-- drivers/gpu/drm/panfrost/panfrost_mmu.c | 5 ++--- 2 files changed, 4 insertions(+), 5 deletions(-)