| Message ID | 20200826063316.23486-3-m.szyprowski@samsung.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | DRM: fix struct sg_table nents vs. orig_nents misuse | expand |
On 2020-08-26 07:32, Marek Szyprowski wrote: > Replace the current hand-crafted code for extracting pages and DMA > addresses from the given scatterlist by the much more robust > code based on the generic scatterlist iterators and recently > introduced sg_table-based wrappers. The resulting code is simple and > easy to understand, so the comment describing the old code is no > longer needed. Is removing the WARN_ON()s intentional? It certainly seems like it would be a genuine driver bug if the caller asked for addresses but didn't allocate appropriately-sized arrays. Might be worth noting either way. I'm also assuming this isn't called in performance-critical paths with massive lists such that the two separate iterations might have a noticeable impact. Nits aside, Reviewed-by: Robin Murphy <robin.murphy@arm.com> > Signed-off-by: Marek Szyprowski <m.szyprowski@samsung.com> > Reviewed-by: Andrzej Hajda <a.hajda@samsung.com> > --- > drivers/gpu/drm/drm_prime.c | 49 ++++++++++++------------------------- > 1 file changed, 15 insertions(+), 34 deletions(-) > > diff --git a/drivers/gpu/drm/drm_prime.c b/drivers/gpu/drm/drm_prime.c > index 4ed5ed1f078c..5d181bf60a44 100644 > --- a/drivers/gpu/drm/drm_prime.c > +++ b/drivers/gpu/drm/drm_prime.c > @@ -990,45 +990,26 @@ EXPORT_SYMBOL(drm_gem_prime_import); > int drm_prime_sg_to_page_addr_arrays(struct sg_table *sgt, struct page **pages, > dma_addr_t *addrs, int max_entries) > { > - unsigned count; > - struct scatterlist *sg; > - struct page *page; > - u32 page_len, page_index; > - dma_addr_t addr; > - u32 dma_len, dma_index; > - > - /* > - * Scatterlist elements contains both pages and DMA addresses, but > - * one shoud not assume 1:1 relation between them. The sg->length is > - * the size of the physical memory chunk described by the sg->page, > - * while sg_dma_len(sg) is the size of the DMA (IO virtual) chunk > - * described by the sg_dma_address(sg). > - */ > - page_index = 0; > - dma_index = 0; > - for_each_sg(sgt->sgl, sg, sgt->nents, count) { > - page_len = sg->length; > - page = sg_page(sg); > - dma_len = sg_dma_len(sg); > - addr = sg_dma_address(sg); > - > - while (pages && page_len > 0) { > - if (WARN_ON(page_index >= max_entries)) > + struct sg_dma_page_iter dma_iter; > + struct sg_page_iter page_iter; > + struct page **p = pages; > + dma_addr_t *a = addrs; > + > + if (pages) { > + for_each_sgtable_page(sgt, &page_iter, 0) { > + if (p - pages >= max_entries) > return -1; > - pages[page_index] = page; > - page++; > - page_len -= PAGE_SIZE; > - page_index++; > + *p++ = sg_page_iter_page(&page_iter); > } > - while (addrs && dma_len > 0) { > - if (WARN_ON(dma_index >= max_entries)) > + } > + if (addrs) { > + for_each_sgtable_dma_page(sgt, &dma_iter, 0) { > + if (a - addrs >= max_entries) > return -1; > - addrs[dma_index] = addr; > - addr += PAGE_SIZE; > - dma_len -= PAGE_SIZE; > - dma_index++; > + *a++ = sg_page_iter_dma_address(&dma_iter); > } > } > + > return 0; > } > EXPORT_SYMBOL(drm_prime_sg_to_page_addr_arrays); >
diff --git a/drivers/gpu/drm/drm_prime.c b/drivers/gpu/drm/drm_prime.c index 4ed5ed1f078c..5d181bf60a44 100644 --- a/drivers/gpu/drm/drm_prime.c +++ b/drivers/gpu/drm/drm_prime.c @@ -990,45 +990,26 @@ EXPORT_SYMBOL(drm_gem_prime_import); int drm_prime_sg_to_page_addr_arrays(struct sg_table *sgt, struct page **pages, dma_addr_t *addrs, int max_entries) { - unsigned count; - struct scatterlist *sg; - struct page *page; - u32 page_len, page_index; - dma_addr_t addr; - u32 dma_len, dma_index; - - /* - * Scatterlist elements contains both pages and DMA addresses, but - * one shoud not assume 1:1 relation between them. The sg->length is - * the size of the physical memory chunk described by the sg->page, - * while sg_dma_len(sg) is the size of the DMA (IO virtual) chunk - * described by the sg_dma_address(sg). - */ - page_index = 0; - dma_index = 0; - for_each_sg(sgt->sgl, sg, sgt->nents, count) { - page_len = sg->length; - page = sg_page(sg); - dma_len = sg_dma_len(sg); - addr = sg_dma_address(sg); - - while (pages && page_len > 0) { - if (WARN_ON(page_index >= max_entries)) + struct sg_dma_page_iter dma_iter; + struct sg_page_iter page_iter; + struct page **p = pages; + dma_addr_t *a = addrs; + + if (pages) { + for_each_sgtable_page(sgt, &page_iter, 0) { + if (p - pages >= max_entries) return -1; - pages[page_index] = page; - page++; - page_len -= PAGE_SIZE; - page_index++; + *p++ = sg_page_iter_page(&page_iter); } - while (addrs && dma_len > 0) { - if (WARN_ON(dma_index >= max_entries)) + } + if (addrs) { + for_each_sgtable_dma_page(sgt, &dma_iter, 0) { + if (a - addrs >= max_entries) return -1; - addrs[dma_index] = addr; - addr += PAGE_SIZE; - dma_len -= PAGE_SIZE; - dma_index++; + *a++ = sg_page_iter_dma_address(&dma_iter); } } + return 0; } EXPORT_SYMBOL(drm_prime_sg_to_page_addr_arrays);