Messages in this thread Patch in this message | | | Subject | [PATCH] ppc highmem fix | From | Paolo Galtieri <> | Date | Mon, 10 Oct 2005 16:20:27 -0700 |
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I've noticed that the calculations for seg_size and nr_segs in __dma_sync_page_highmem() (arch/ppc/kernel/dma-mapping.c) are wrong. The incorrect calculations can result in either an oops or a panic when running fsck depending on the size of the partition. The problem with the seg_size calculation is that it can result in a negative number if size is offset > size. The problem with the nr_segs caculation is returns the wrong number of segments, e.g. it returns 1 when size is 200 and offset is 4095, when it should return 2 or more.
Here is the patch to fix the problem.
--- linux-2.6.14-rc3-git8/arch/ppc/kernel/dma-mapping.c 2005-10-10 13:55:37.000000000 -0700 +++ linux-2.6.14/arch/ppc/kernel/dma-mapping.c 2005-10-10 13:57:51.000000000 -0700 @@ -401,10 +401,10 @@ static inline void __dma_sync_page_highmem(struct page *page, unsigned long offset, size_t size, int direction) { - size_t seg_size = min((size_t)PAGE_SIZE, size) - offset; + size_t seg_size = min((size_t)(PAGE_SIZE - offset), size); size_t cur_size = seg_size; unsigned long flags, start, seg_offset = offset; - int nr_segs = PAGE_ALIGN(size + (PAGE_SIZE - offset))/PAGE_SIZE; + int nr_segs = 1 + ((size - seg_size) + PAGE_SIZE - 1)/PAGE_SIZE; int seg_nr = 0;
local_irq_save(flags);
Paolo Galtieri (pgaltieri@mvista.com)
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