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/lima/lima_gem.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-)
diff --git a/drivers/gpu/drm/lima/lima_gem.c b/drivers/gpu/drm/lima/lima_gem.c index 5404e0d..3edd2ff 100644 --- a/drivers/gpu/drm/lima/lima_gem.c +++ b/drivers/gpu/drm/lima/lima_gem.c @@ -70,7 +70,7 @@ int lima_heap_alloc(struct lima_bo *bo, struct lima_vm *vm)
if (bo->base.sgt) { dma_unmap_sg(dev, bo->base.sgt->sgl, - bo->base.sgt->nents, DMA_BIDIRECTIONAL); + bo->base.sgt->orig_nents, DMA_BIDIRECTIONAL); sg_free_table(bo->base.sgt); } else { bo->base.sgt = kmalloc(sizeof(*bo->base.sgt), GFP_KERNEL); @@ -80,7 +80,7 @@ int lima_heap_alloc(struct lima_bo *bo, struct lima_vm *vm) } }
- dma_map_sg(dev, sgt.sgl, sgt.nents, DMA_BIDIRECTIONAL); + sgt.nents = dma_map_sg(dev, sgt.sgl, sgt.orig_nents, DMA_BIDIRECTIONAL);
*bo->base.sgt = sgt;