[PATCH v2 03/21] drm: armada: fix sg_table nents vs. orig_nents misuse
From: Marek Szyprowski <m.szyprowski@samsung.com>
Date: 2020-05-04 12:55:56
Also in:
dri-devel, linux-iommu, lkml
Subsystem:
drm drivers, marvell armada drm support, the rest · Maintainers:
David Airlie, Simona Vetter, Russell King, Linus Torvalds
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/armada/armada_gem.c | 14 +++++++++-----
1 file changed, 9 insertions(+), 5 deletions(-)
diff --git a/drivers/gpu/drm/armada/armada_gem.c b/drivers/gpu/drm/armada/armada_gem.c
index 976685f..749647f 100644
--- a/drivers/gpu/drm/armada/armada_gem.c
+++ b/drivers/gpu/drm/armada/armada_gem.c@@ -407,8 +407,10 @@ int armada_gem_pwrite_ioctl(struct drm_device *dev, void *data, sg_set_page(sg, page, PAGE_SIZE, 0); } - if (dma_map_sg(attach->dev, sgt->sgl, sgt->nents, dir) == 0) { - num = sgt->nents; + sgt->nents = dma_map_sg(attach->dev, sgt->sgl, sgt->orig_nents, + dir); + if (sgt->nents == 0) { + num = sgt->orig_nents; goto release; } } else if (dobj->page) {
@@ -418,7 +420,9 @@ int armada_gem_pwrite_ioctl(struct drm_device *dev, void *data, sg_set_page(sgt->sgl, dobj->page, dobj->obj.size, 0); - if (dma_map_sg(attach->dev, sgt->sgl, sgt->nents, dir) == 0) + sgt->nents = dma_map_sg(attach->dev, sgt->sgl, sgt->orig_nents, + dir); + if (sgt->nents == 0) goto free_table; } else if (dobj->linear) { /* Single contiguous physical region - no struct page */
@@ -449,11 +453,11 @@ static void armada_gem_prime_unmap_dma_buf(struct dma_buf_attachment *attach, int i; if (!dobj->linear) - dma_unmap_sg(attach->dev, sgt->sgl, sgt->nents, dir); + dma_unmap_sg(attach->dev, sgt->sgl, sgt->orig_nents, dir); if (dobj->obj.filp) { struct scatterlist *sg; - for_each_sg(sgt->sgl, sg, sgt->nents, i) + for_each_sg(sgt->sgl, sg, sgt->orig_nents, i) put_page(sg_page(sg)); }
--
1.9.1
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