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/vmwgfx/vmwgfx_ttm_buffer.c | 6 +++--- 1 file changed, 3 insertions(+), 3 deletions(-)
diff --git a/drivers/gpu/drm/vmwgfx/vmwgfx_ttm_buffer.c b/drivers/gpu/drm/vmwgfx/vmwgfx_ttm_buffer.c index bf0bc46..a5fd128 100644 --- a/drivers/gpu/drm/vmwgfx/vmwgfx_ttm_buffer.c +++ b/drivers/gpu/drm/vmwgfx/vmwgfx_ttm_buffer.c @@ -362,7 +362,7 @@ static void vmw_ttm_unmap_from_dma(struct vmw_ttm_tt *vmw_tt) { struct device *dev = vmw_tt->dev_priv->dev->dev;
- dma_unmap_sg(dev, vmw_tt->sgt.sgl, vmw_tt->sgt.nents, + dma_unmap_sg(dev, vmw_tt->sgt.sgl, vmw_tt->sgt.orig_nents, DMA_BIDIRECTIONAL); vmw_tt->sgt.nents = vmw_tt->sgt.orig_nents; } @@ -449,10 +449,10 @@ static int vmw_ttm_map_dma(struct vmw_ttm_tt *vmw_tt) if (unlikely(ret != 0)) goto out_sg_alloc_fail;
- if (vsgt->num_pages > vmw_tt->sgt.nents) { + if (vsgt->num_pages > vmw_tt->sgt.orig_nents) { uint64_t over_alloc = sgl_size * (vsgt->num_pages - - vmw_tt->sgt.nents); + vmw_tt->sgt.orig_nents);
ttm_mem_global_free(glob, over_alloc); vmw_tt->sg_alloc_size -= over_alloc;