Re: [PATCH] cma: use unsigned type for count argument
From: Andrew Morton <akpm@linux-foundation.org>
Date: 2012-12-20 23:35:30
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On Wed, 19 Dec 2012 18:44:40 +0100 Michal Nazarewicz [off-list ref] wrote:
quoted hunk ↗ jump to hunk
From: Michal Nazarewicz <redacted> Specifying negative size of buffer makes no sense and thus this commit changes the type of the count argument to unsigned.--- a/arch/arm/mm/dma-mapping.c +++ b/arch/arm/mm/dma-mapping.c@@ -1038,9 +1038,9 @@ static struct page **__iommu_alloc_buffer(struct device *dev, size_t size, gfp_t gfp, struct dma_attrs *attrs) { struct page **pages; - int count = size >> PAGE_SHIFT; - int array_size = count * sizeof(struct page *); - int i = 0; + unsigned int count = size >> PAGE_SHIFT; + unsigned int array_size = count * sizeof(struct page *); + unsigned int i = 0;
C programmers expect a variable called `i' to have type `int'. It would be clearer to find a new name for this. `idx', perhaps. Also, we later do int j; .. pages[i + j] ... So `j' should also be converted to unsigned. And perhaps renamed, but `j' isn't as egregious as `i'.
quoted hunk ↗ jump to hunk
if (array_size <= PAGE_SIZE) pages = kzalloc(array_size, gfp);@@ -1102,9 +1102,9 @@ error: static int __iommu_free_buffer(struct device *dev, struct page **pages, size_t size, struct dma_attrs *attrs) { - int count = size >> PAGE_SHIFT; - int array_size = count * sizeof(struct page *); - int i; + unsigned int count = size >> PAGE_SHIFT; + unsigned int array_size = count * sizeof(struct page *); + unsigned int i;
ditto.
--- a/arch/arm/mm/dma-mapping.c~cma-use-unsigned-type-for-count-argument-fix
+++ a/arch/arm/mm/dma-mapping.c@@ -1040,7 +1040,7 @@ static struct page **__iommu_alloc_buffe struct page **pages; unsigned int count = size >> PAGE_SHIFT; unsigned int array_size = count * sizeof(struct page *); - unsigned int i = 0; + unsigned int idx = 0; if (array_size <= PAGE_SIZE) pages = kzalloc(array_size, gfp);
@@ -1049,8 +1049,7 @@ static struct page **__iommu_alloc_buffe if (!pages) return NULL; - if (dma_get_attr(DMA_ATTR_FORCE_CONTIGUOUS, attrs)) - { + if (dma_get_attr(DMA_ATTR_FORCE_CONTIGUOUS, attrs)) { unsigned long order = get_order(size); struct page *page;
@@ -1060,38 +1059,39 @@ static struct page **__iommu_alloc_buffe __dma_clear_buffer(page, size); - for (i = 0; i < count; i++) - pages[i] = page + i; + for (idx = 0; idx < count; idx++) + pages[i] = page + idx; return pages; } while (count) { - int j, order = __fls(count); + unsigned int j; + unnsigned int order = __fls(count); - pages[i] = alloc_pages(gfp | __GFP_NOWARN, order); - while (!pages[i] && order) - pages[i] = alloc_pages(gfp | __GFP_NOWARN, --order); - if (!pages[i]) + pages[idx] = alloc_pages(gfp | __GFP_NOWARN, order); + while (!pages[idx] && order) + pages[idx] = alloc_pages(gfp | __GFP_NOWARN, --order); + if (!pages[idx]) goto error; if (order) { - split_page(pages[i], order); + split_page(pages[idx], order); j = 1 << order; while (--j) - pages[i + j] = pages[i] + j; + pages[idx + j] = pages[idx] + j; } - __dma_clear_buffer(pages[i], PAGE_SIZE << order); - i += 1 << order; + __dma_clear_buffer(pages[idx], PAGE_SIZE << order); + idx += 1 << order; count -= 1 << order; } return pages; error: - while (i--) - if (pages[i]) - __free_pages(pages[i], 0); + while (idx--) + if (pages[idx]) + __free_pages(pages[idx], 0); if (array_size <= PAGE_SIZE) kfree(pages); else
@@ -1104,14 +1104,15 @@ static int __iommu_free_buffer(struct de { unsigned int count = size >> PAGE_SHIFT; unsigned int array_size = count * sizeof(struct page *); - unsigned int i; if (dma_get_attr(DMA_ATTR_FORCE_CONTIGUOUS, attrs)) { dma_release_from_contiguous(dev, pages[0], count); } else { - for (i = 0; i < count; i++) - if (pages[i]) - __free_pages(pages[i], 0); + unsigned int idx; + + for (idx = 0; idx < count; idx++) + if (pages[idx]) + __free_pages(pages[idx], 0); } if (array_size <= PAGE_SIZE)
diff -puN drivers/base/dma-contiguous.c~cma-use-unsigned-type-for-count-argument-fix drivers/base/dma-contiguous.c diff -puN include/linux/dma-contiguous.h~cma-use-unsigned-type-for-count-argument-fix include/linux/dma-contiguous.h _ -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: <a href=mailto:"dont@kvack.org"> email@kvack.org </a>