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drm: armada: 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. To avoid such issues, lets use a common dma-mapping wrappers operating directly on the struct sg_table objects and use scatterlist page iterators where possible. This, almost always, hides references to the nents and orig_nents entries, making the code robust, easier to follow and copy/paste safe. Signed-off-by: Marek Szyprowski <m.szyprowski@samsung.com>
This commit is contained in:
parent
6c6fa39ca9
commit
efcb3730ef
1 changed files with 11 additions and 13 deletions
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@ -379,7 +379,7 @@ armada_gem_prime_map_dma_buf(struct dma_buf_attachment *attach,
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struct armada_gem_object *dobj = drm_to_armada_gem(obj);
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struct armada_gem_object *dobj = drm_to_armada_gem(obj);
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struct scatterlist *sg;
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struct scatterlist *sg;
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struct sg_table *sgt;
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struct sg_table *sgt;
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int i, num;
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int i;
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sgt = kmalloc(sizeof(*sgt), GFP_KERNEL);
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sgt = kmalloc(sizeof(*sgt), GFP_KERNEL);
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if (!sgt)
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if (!sgt)
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@ -395,22 +395,18 @@ armada_gem_prime_map_dma_buf(struct dma_buf_attachment *attach,
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mapping = dobj->obj.filp->f_mapping;
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mapping = dobj->obj.filp->f_mapping;
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for_each_sg(sgt->sgl, sg, count, i) {
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for_each_sgtable_sg(sgt, sg, i) {
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struct page *page;
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struct page *page;
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page = shmem_read_mapping_page(mapping, i);
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page = shmem_read_mapping_page(mapping, i);
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if (IS_ERR(page)) {
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if (IS_ERR(page))
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num = i;
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goto release;
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goto release;
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}
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sg_set_page(sg, page, PAGE_SIZE, 0);
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sg_set_page(sg, page, PAGE_SIZE, 0);
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}
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}
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if (dma_map_sg(attach->dev, sgt->sgl, sgt->nents, dir) == 0) {
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if (dma_map_sgtable(attach->dev, sgt, dir, 0))
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num = sgt->nents;
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goto release;
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goto release;
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}
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} else if (dobj->page) {
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} else if (dobj->page) {
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/* Single contiguous page */
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/* Single contiguous page */
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if (sg_alloc_table(sgt, 1, GFP_KERNEL))
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if (sg_alloc_table(sgt, 1, GFP_KERNEL))
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@ -418,7 +414,7 @@ armada_gem_prime_map_dma_buf(struct dma_buf_attachment *attach,
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sg_set_page(sgt->sgl, dobj->page, dobj->obj.size, 0);
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sg_set_page(sgt->sgl, dobj->page, dobj->obj.size, 0);
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if (dma_map_sg(attach->dev, sgt->sgl, sgt->nents, dir) == 0)
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if (dma_map_sgtable(attach->dev, sgt, dir, 0))
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goto free_table;
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goto free_table;
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} else if (dobj->linear) {
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} else if (dobj->linear) {
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/* Single contiguous physical region - no struct page */
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/* Single contiguous physical region - no struct page */
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@ -432,8 +428,9 @@ armada_gem_prime_map_dma_buf(struct dma_buf_attachment *attach,
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return sgt;
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return sgt;
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release:
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release:
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for_each_sg(sgt->sgl, sg, num, i)
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for_each_sgtable_sg(sgt, sg, i)
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put_page(sg_page(sg));
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if (sg_page(sg))
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put_page(sg_page(sg));
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free_table:
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free_table:
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sg_free_table(sgt);
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sg_free_table(sgt);
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free_sgt:
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free_sgt:
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@ -449,11 +446,12 @@ static void armada_gem_prime_unmap_dma_buf(struct dma_buf_attachment *attach,
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int i;
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int i;
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if (!dobj->linear)
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if (!dobj->linear)
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dma_unmap_sg(attach->dev, sgt->sgl, sgt->nents, dir);
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dma_unmap_sgtable(attach->dev, sgt, dir, 0);
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if (dobj->obj.filp) {
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if (dobj->obj.filp) {
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struct scatterlist *sg;
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struct scatterlist *sg;
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for_each_sg(sgt->sgl, sg, sgt->nents, i)
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for_each_sgtable_sg(sgt, sg, i)
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put_page(sg_page(sg));
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put_page(sg_page(sg));
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}
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}
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