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/staging/media/tegra-vde/iommu.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-)
diff --git a/drivers/staging/media/tegra-vde/iommu.c b/drivers/staging/media/tegra-vde/iommu.c index 6af863d..adf8dc7 100644 --- a/drivers/staging/media/tegra-vde/iommu.c +++ b/drivers/staging/media/tegra-vde/iommu.c @@ -36,8 +36,8 @@ int tegra_vde_iommu_map(struct tegra_vde *vde,
addr = iova_dma_addr(&vde->iova, iova);
- size = iommu_map_sg(vde->domain, addr, sgt->sgl, sgt->nents, - IOMMU_READ | IOMMU_WRITE); + size = iommu_map_sgtable(vde->domain, addr, sgt, + IOMMU_READ | IOMMU_WRITE); if (!size) { __free_iova(&vde->iova, iova); return -ENXIO;