Messages in this thread |  | | Subject | Re: [PATCH v2 1/1] block: blk-merge: don't merge the pages with non-contiguous descriptors | From | James Bottomley <> | Date | Thu, 17 Jan 2013 09:11:20 +0000 |
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On Wed, 2013-01-16 at 15:18 -0800, Tejun Heo wrote: > On Wed, Jan 16, 2013 at 10:32:35AM +0000, James Bottomley wrote: > > diff --git a/arch/arm/mm/dma-mapping.c b/arch/arm/mm/dma-mapping.c > > index 6b2fb87..ab88c5b 100644 > > --- a/arch/arm/mm/dma-mapping.c > > +++ b/arch/arm/mm/dma-mapping.c > > @@ -809,7 +809,7 @@ static void dma_cache_maint_page(struct page *page, unsigned long offset, > > op(vaddr, len, dir); > > } > > offset = 0; > > - page++; > > + page = pfn_to_page(page_to_pfn(page) + 1); > > Probably page = nth_page(page, 1) is the better form.
It's the same thing.
I'd actually prefer page = pfn_to_page(page_to_pfn(page) + 1); because it makes the code look like the hack it is. The preferred form for all iterators like this should be to iterate over the pfn instead of a pointer into the page arrays, because that will always work correctly no matter how many weird and wonderful memory schemes we come up with.
James
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