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 Reviewed-by: Christian König christian.koenig@amd.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/radeon/radeon_ttm.c | 11 ++++++----- 1 file changed, 6 insertions(+), 5 deletions(-)
diff --git a/drivers/gpu/drm/radeon/radeon_ttm.c b/drivers/gpu/drm/radeon/radeon_ttm.c index 5d50c9e..f8275c8 100644 --- a/drivers/gpu/drm/radeon/radeon_ttm.c +++ b/drivers/gpu/drm/radeon/radeon_ttm.c @@ -481,7 +481,7 @@ static int radeon_ttm_tt_pin_userptr(struct ttm_tt *ttm) { struct radeon_device *rdev = radeon_get_rdev(ttm->bdev); struct radeon_ttm_tt *gtt = (void *)ttm; - unsigned pinned = 0, nents; + unsigned pinned = 0; int r;
int write = !(gtt->userflags & RADEON_GEM_USERPTR_READONLY); @@ -522,8 +522,9 @@ static int radeon_ttm_tt_pin_userptr(struct ttm_tt *ttm) goto release_sg;
r = -ENOMEM; - nents = dma_map_sg(rdev->dev, ttm->sg->sgl, ttm->sg->nents, direction); - if (nents == 0) + ttm->sg->nents = dma_map_sg(rdev->dev, ttm->sg->sgl, + ttm->sg->orig_nents, direction); + if (ttm->sg->nents == 0) goto release_sg;
drm_prime_sg_to_page_addr_arrays(ttm->sg, ttm->pages, @@ -554,9 +555,9 @@ static void radeon_ttm_tt_unpin_userptr(struct ttm_tt *ttm) return;
/* free the sg table and pages again */ - dma_unmap_sg(rdev->dev, ttm->sg->sgl, ttm->sg->nents, direction); + dma_unmap_sg(rdev->dev, ttm->sg->sgl, ttm->sg->orig_nents, direction);
- for_each_sg_page(ttm->sg->sgl, &sg_iter, ttm->sg->nents, 0) { + for_each_sg_page(ttm->sg->sgl, &sg_iter, ttm->sg->orig_nents, 0) { struct page *page = sg_page_iter_page(&sg_iter); if (!(gtt->userflags & RADEON_GEM_USERPTR_READONLY)) set_page_dirty(page);