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author | Marek Szyprowski <m.szyprowski@samsung.com> | 2020-05-04 13:12:07 +0200 |
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committer | Marek Szyprowski <m.szyprowski@samsung.com> | 2020-09-10 08:18:35 +0200 |
commit | b827e3ac4185a6091b90263b6516b54a766c109e (patch) | |
tree | 623092327a6f3cfba201c0fb9f175bd5fc69de09 /drivers/gpu | |
parent | 84404614167b829f7b58189cd24b6c0c74897171 (diff) |
drm: i915: fix common struct sg_table related issues
The Documentation/DMA-API-HOWTO.txt states that the dma_map_sg() function
returns the number of the created entries in the DMA address space.
However the subsequent calls to the dma_sync_sg_for_{device,cpu}() and
dma_unmap_sg must be called with the original number of the entries
passed to the dma_map_sg().
struct sg_table is a common structure used for describing a non-contiguous
memory buffer, used commonly in the DRM and graphics subsystems. It
consists of a scatterlist with memory pages and DMA addresses (sgl entry),
as well as the number of scatterlist entries: CPU pages (orig_nents entry)
and DMA mapped pages (nents entry).
It turned out that it was a common mistake to misuse nents and orig_nents
entries, calling DMA-mapping functions with a wrong number of entries or
ignoring the number of mapped entries returned by the dma_map_sg()
function.
This driver creatively uses sg_table->orig_nents to store the size of the
allocated scatterlist and ignores the number of the entries returned by
dma_map_sg function. The sg_table->orig_nents is (mis)used to properly
free the (over)allocated scatterlist.
This patch only introduces the common DMA-mapping wrappers operating
directly on the struct sg_table objects to the dmabuf related functions,
so the other drivers, which might share buffers with i915 could rely on
the properly set nents and orig_nents values.
Signed-off-by: Marek Szyprowski <m.szyprowski@samsung.com>
Reviewed-by: Robin Murphy <robin.murphy@arm.com>
Reviewed-by: Michael J. Ruhl <michael.j.ruhl@intel.com>
Diffstat (limited to 'drivers/gpu')
-rw-r--r-- | drivers/gpu/drm/i915/gem/i915_gem_dmabuf.c | 11 | ||||
-rw-r--r-- | drivers/gpu/drm/i915/gem/selftests/mock_dmabuf.c | 7 |
2 files changed, 6 insertions, 12 deletions
diff --git a/drivers/gpu/drm/i915/gem/i915_gem_dmabuf.c b/drivers/gpu/drm/i915/gem/i915_gem_dmabuf.c index 2679380159fc..8a988592715b 100644 --- a/drivers/gpu/drm/i915/gem/i915_gem_dmabuf.c +++ b/drivers/gpu/drm/i915/gem/i915_gem_dmabuf.c @@ -48,12 +48,9 @@ static struct sg_table *i915_gem_map_dma_buf(struct dma_buf_attachment *attachme src = sg_next(src); } - if (!dma_map_sg_attrs(attachment->dev, - st->sgl, st->nents, dir, - DMA_ATTR_SKIP_CPU_SYNC)) { - ret = -ENOMEM; + ret = dma_map_sgtable(attachment->dev, st, dir, DMA_ATTR_SKIP_CPU_SYNC); + if (ret) goto err_free_sg; - } return st; @@ -73,9 +70,7 @@ static void i915_gem_unmap_dma_buf(struct dma_buf_attachment *attachment, { struct drm_i915_gem_object *obj = dma_buf_to_obj(attachment->dmabuf); - dma_unmap_sg_attrs(attachment->dev, - sg->sgl, sg->nents, dir, - DMA_ATTR_SKIP_CPU_SYNC); + dma_unmap_sgtable(attachment->dev, sg, dir, DMA_ATTR_SKIP_CPU_SYNC); sg_free_table(sg); kfree(sg); diff --git a/drivers/gpu/drm/i915/gem/selftests/mock_dmabuf.c b/drivers/gpu/drm/i915/gem/selftests/mock_dmabuf.c index debaf7b18ab5..be30b27e2926 100644 --- a/drivers/gpu/drm/i915/gem/selftests/mock_dmabuf.c +++ b/drivers/gpu/drm/i915/gem/selftests/mock_dmabuf.c @@ -28,10 +28,9 @@ static struct sg_table *mock_map_dma_buf(struct dma_buf_attachment *attachment, sg = sg_next(sg); } - if (!dma_map_sg(attachment->dev, st->sgl, st->nents, dir)) { - err = -ENOMEM; + err = dma_map_sgtable(attachment->dev, st, dir, 0); + if (err) goto err_st; - } return st; @@ -46,7 +45,7 @@ static void mock_unmap_dma_buf(struct dma_buf_attachment *attachment, struct sg_table *st, enum dma_data_direction dir) { - dma_unmap_sg(attachment->dev, st->sgl, st->nents, dir); + dma_unmap_sgtable(attachment->dev, st, dir, 0); sg_free_table(st); kfree(st); } |