From d901b2760dc6cd5fbbf2eac31d71d94baa6c4aef Mon Sep 17 00:00:00 2001 From: Jason Gunthorpe Date: Fri, 4 Jan 2019 11:40:21 -0700 Subject: lib/scatterlist: Provide a DMA page iterator Commit 2db76d7c3c6d ("lib/scatterlist: sg_page_iter: support sg lists w/o backing pages") introduced the sg_page_iter_dma_address() function without providing a way to use it in the general case. If the sg_dma_len() is not equal to the sg length callers cannot safely use the for_each_sg_page/sg_page_iter_dma_address combination. Resolve this API mistake by providing a DMA specific iterator, for_each_sg_dma_page(), that uses the right length so sg_page_iter_dma_address() works as expected with all sglists. A new iterator type is introduced to provide compile-time safety against wrongly mixing accessors and iterators. Acked-by: Christoph Hellwig (for scatterlist) Acked-by: Thomas Hellstrom Acked-by: Sakari Ailus (ipu3-cio2) Signed-off-by: Jason Gunthorpe --- drivers/gpu/drm/vmwgfx/vmwgfx_ttm_buffer.c | 8 +++++++- 1 file changed, 7 insertions(+), 1 deletion(-) (limited to 'drivers/gpu/drm/vmwgfx') diff --git a/drivers/gpu/drm/vmwgfx/vmwgfx_ttm_buffer.c b/drivers/gpu/drm/vmwgfx/vmwgfx_ttm_buffer.c index 31786b200afc..a3357ff7540d 100644 --- a/drivers/gpu/drm/vmwgfx/vmwgfx_ttm_buffer.c +++ b/drivers/gpu/drm/vmwgfx/vmwgfx_ttm_buffer.c @@ -311,7 +311,13 @@ static dma_addr_t __vmw_piter_dma_addr(struct vmw_piter *viter) static dma_addr_t __vmw_piter_sg_addr(struct vmw_piter *viter) { - return sg_page_iter_dma_address(&viter->iter); + /* + * FIXME: This driver wrongly mixes DMA and CPU SG list iteration and + * needs revision. See + * https://lore.kernel.org/lkml/20190104223531.GA1705@ziepe.ca/ + */ + return sg_page_iter_dma_address( + container_of(&viter->iter, struct sg_dma_page_iter, base)); } -- cgit v1.2.3