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drm: core: 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> Reviewed-by: Andrzej Hajda <a.hajda@samsung.com> Reviewed-by: Robin Murphy <robin.murphy@arm.com>
This commit is contained in:
parent
0552daac2d
commit
6c6fa39ca9
3 changed files with 16 additions and 11 deletions
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@ -127,7 +127,7 @@ drm_clflush_sg(struct sg_table *st)
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struct sg_page_iter sg_iter;
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mb(); /*CLFLUSH is ordered only by using memory barriers*/
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for_each_sg_page(st->sgl, &sg_iter, st->nents, 0)
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for_each_sgtable_page(st, &sg_iter, 0)
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drm_clflush_page(sg_page_iter_page(&sg_iter));
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mb(); /*Make sure that all cache line entry is flushed*/
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@ -126,8 +126,8 @@ void drm_gem_shmem_free_object(struct drm_gem_object *obj)
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drm_prime_gem_destroy(obj, shmem->sgt);
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} else {
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if (shmem->sgt) {
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dma_unmap_sg(obj->dev->dev, shmem->sgt->sgl,
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shmem->sgt->nents, DMA_BIDIRECTIONAL);
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dma_unmap_sgtable(obj->dev->dev, shmem->sgt,
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DMA_BIDIRECTIONAL, 0);
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sg_free_table(shmem->sgt);
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kfree(shmem->sgt);
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}
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@ -424,8 +424,7 @@ void drm_gem_shmem_purge_locked(struct drm_gem_object *obj)
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WARN_ON(!drm_gem_shmem_is_purgeable(shmem));
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dma_unmap_sg(obj->dev->dev, shmem->sgt->sgl,
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shmem->sgt->nents, DMA_BIDIRECTIONAL);
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dma_unmap_sgtable(obj->dev->dev, shmem->sgt, DMA_BIDIRECTIONAL, 0);
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sg_free_table(shmem->sgt);
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kfree(shmem->sgt);
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shmem->sgt = NULL;
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@ -697,12 +696,17 @@ struct sg_table *drm_gem_shmem_get_pages_sgt(struct drm_gem_object *obj)
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goto err_put_pages;
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}
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/* Map the pages for use by the h/w. */
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dma_map_sg(obj->dev->dev, sgt->sgl, sgt->nents, DMA_BIDIRECTIONAL);
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ret = dma_map_sgtable(obj->dev->dev, sgt, DMA_BIDIRECTIONAL, 0);
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if (ret)
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goto err_free_sgt;
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shmem->sgt = sgt;
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return sgt;
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err_free_sgt:
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sg_free_table(sgt);
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kfree(sgt);
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err_put_pages:
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drm_gem_shmem_put_pages(shmem);
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return ERR_PTR(ret);
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@ -617,6 +617,7 @@ struct sg_table *drm_gem_map_dma_buf(struct dma_buf_attachment *attach,
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{
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struct drm_gem_object *obj = attach->dmabuf->priv;
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struct sg_table *sgt;
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int ret;
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if (WARN_ON(dir == DMA_NONE))
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return ERR_PTR(-EINVAL);
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@ -626,11 +627,12 @@ struct sg_table *drm_gem_map_dma_buf(struct dma_buf_attachment *attach,
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else
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sgt = obj->dev->driver->gem_prime_get_sg_table(obj);
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if (!dma_map_sg_attrs(attach->dev, sgt->sgl, sgt->nents, dir,
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DMA_ATTR_SKIP_CPU_SYNC)) {
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ret = dma_map_sgtable(attach->dev, sgt, dir,
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DMA_ATTR_SKIP_CPU_SYNC);
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if (ret) {
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sg_free_table(sgt);
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kfree(sgt);
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sgt = ERR_PTR(-ENOMEM);
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sgt = ERR_PTR(ret);
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}
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return sgt;
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@ -652,8 +654,7 @@ void drm_gem_unmap_dma_buf(struct dma_buf_attachment *attach,
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if (!sgt)
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return;
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dma_unmap_sg_attrs(attach->dev, sgt->sgl, sgt->nents, dir,
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DMA_ATTR_SKIP_CPU_SYNC);
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dma_unmap_sgtable(attach->dev, sgt, dir, DMA_ATTR_SKIP_CPU_SYNC);
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sg_free_table(sgt);
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kfree(sgt);
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}
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