[PATCH] arm: mm: fix DMA pool affiliation check
From: m.szyprowski@samsung.com (Marek Szyprowski)
Date: 2012-09-07 05:58:31
Hello, On Monday, September 03, 2012 2:44 PM Thomas Petazzoni wrote:
The __free_from_pool() function was changed in e9da6e9905e639b0f842a244bc770b48ad0523e9. Unfortunately, the test that checks whether the provided (start,size) is within the DMA pool has been improperly modified. It used to be: if (start < coherent_head.vm_start || end > coherent_head.vm_end) Where coherent_head.vm_end was non-inclusive (i.e, it did not include the first byte after the pool). The test has been changed to: if (start < pool->vaddr || start > pool->vaddr + pool->size) So now pool->vaddr + pool->size is inclusive (i.e, it includes the first byte after the pool), so the test should be >= instead of >. This bug causes the following message when freeing the *first* DMA coherent buffer that has been allocated, because its virtual address is exactly equal to pool->vaddr + pool->size : WARNING: at /home/thomas/projets/linux-2.6/arch/arm/mm/dma-mapping.c:463 __free_from_pool+0xa4/0xc0() freeing wrong coherent size from pool Signed-off-by: Thomas Petazzoni <redacted> Cc: Marek Szyprowski <m.szyprowski@samsung.com> Cc: Russell King <redacted> Cc: Lior Amsalem <redacted> Cc: Maen Suleiman <redacted> Cc: Tawfik Bayouk <redacted> Cc: Shadi Ammouri <redacted> Cc: Eran Ben-Avi <redacted> Cc: Yehuda Yitschak <redacted> Cc: Nadav Haklai <redacted>
Thanks for spotting this issue and providing a fix. I will add it to my dma-mapping fixes branch for v3.6 kernels.
quoted hunk ↗ jump to hunk
--- arch/arm/mm/dma-mapping.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)diff --git a/arch/arm/mm/dma-mapping.c b/arch/arm/mm/dma-mapping.c index 4e7d118..59d9062 100644 --- a/arch/arm/mm/dma-mapping.c +++ b/arch/arm/mm/dma-mapping.c@@ -456,7 +456,7 @@ static int __free_from_pool(void *start, size_t size) unsigned long pageno, count; unsigned long flags; - if (start < pool->vaddr || start > pool->vaddr + pool->size) + if (start < pool->vaddr || start >= pool->vaddr + pool->size) return 0; if (start + size > pool->vaddr + pool->size) { --1.7.9.5
Best regards -- Marek Szyprowski Samsung Poland R&D Center