| From 7a639046ccbb1b6bbf84318acadfc9abf18e630d Mon Sep 17 00:00:00 2001 |
| From: Sasha Levin <sashal@kernel.org> |
| Date: Fri, 8 May 2020 16:07:13 +0200 |
| Subject: xen: gntdev: fix common struct sg_table related issues |
| |
| From: Marek Szyprowski <m.szyprowski@samsung.com> |
| |
| [ Upstream commit d1749eb1ab85e04e58c29e58900e3abebbdd6e82 ] |
| |
| 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> |
| Acked-by: Juergen Gross <jgross@suse.com> |
| Signed-off-by: Sasha Levin <sashal@kernel.org> |
| --- |
| drivers/xen/gntdev-dmabuf.c | 13 ++++++------- |
| 1 file changed, 6 insertions(+), 7 deletions(-) |
| |
| diff --git a/drivers/xen/gntdev-dmabuf.c b/drivers/xen/gntdev-dmabuf.c |
| index b1b6eebafd5de..4c13cbc99896a 100644 |
| --- a/drivers/xen/gntdev-dmabuf.c |
| +++ b/drivers/xen/gntdev-dmabuf.c |
| @@ -247,10 +247,9 @@ static void dmabuf_exp_ops_detach(struct dma_buf *dma_buf, |
| |
| if (sgt) { |
| if (gntdev_dmabuf_attach->dir != DMA_NONE) |
| - dma_unmap_sg_attrs(attach->dev, sgt->sgl, |
| - sgt->nents, |
| - gntdev_dmabuf_attach->dir, |
| - DMA_ATTR_SKIP_CPU_SYNC); |
| + dma_unmap_sgtable(attach->dev, sgt, |
| + gntdev_dmabuf_attach->dir, |
| + DMA_ATTR_SKIP_CPU_SYNC); |
| sg_free_table(sgt); |
| } |
| |
| @@ -288,8 +287,8 @@ dmabuf_exp_ops_map_dma_buf(struct dma_buf_attachment *attach, |
| sgt = dmabuf_pages_to_sgt(gntdev_dmabuf->pages, |
| gntdev_dmabuf->nr_pages); |
| if (!IS_ERR(sgt)) { |
| - if (!dma_map_sg_attrs(attach->dev, sgt->sgl, sgt->nents, dir, |
| - DMA_ATTR_SKIP_CPU_SYNC)) { |
| + if (dma_map_sgtable(attach->dev, sgt, dir, |
| + DMA_ATTR_SKIP_CPU_SYNC)) { |
| sg_free_table(sgt); |
| kfree(sgt); |
| sgt = ERR_PTR(-ENOMEM); |
| @@ -633,7 +632,7 @@ dmabuf_imp_to_refs(struct gntdev_dmabuf_priv *priv, struct device *dev, |
| |
| /* Now convert sgt to array of pages and check for page validity. */ |
| i = 0; |
| - for_each_sg_page(sgt->sgl, &sg_iter, sgt->nents, 0) { |
| + for_each_sgtable_page(sgt, &sg_iter, 0) { |
| struct page *page = sg_page_iter_page(&sg_iter); |
| /* |
| * Check if page is valid: this can happen if we are given |
| -- |
| 2.27.0 |
| |