Messages in this thread Patch in this message | | | Date | Mon, 1 Dec 2008 13:55:01 +0100 | From | Ingo Molnar <> | Subject | Re: [PATCH v3] Fix dma_mapping_error for 32bit x86 |
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* FUJITA Tomonori <fujita.tomonori@lab.ntt.co.jp> wrote:
> On Mon, 1 Dec 2008 12:34:51 +0100 > Joerg Roedel <joro@8bytes.org> wrote: > > > On Sat, Nov 29, 2008 at 01:46:27PM +0100, Thomas Bogendoerfer wrote: > > > Devices like b44 ethernet can't dma from addresses above 1GB. The driver > > > handles this cases by falling back to GFP_DMA allocation. But for detecting > > > the problem it needs to get an indication from dma_mapping_error. > > > The bug is triggered by using a VMSPLIT option of 2G/2G. > > > > Looks like your system uses swiotlb as the dma_ops backend. Its the only > > implementation providing the ops->mapping_error callback and does not > > use bad_dma_address as the error value. > > I think that you misunderstand the problem. > > He uses X86_32 so swiotlb should not be used (which is available on > only X86_64 and IA64 for now). > > b44 needs an address under 1GB so it sets device->dma_mask to > DMA_30BIT_MASK. With VMSPLIT option of 2G/2G, I guess that b44 could > get addresses above 1GB from the networking subsystem. In such case, > nommu_map_single returns bad_dma_address properly, but on X86_32, > dma_mapping_error always returns 0 (success). So b44 wrongly thinks > that the address is under 1GB. > > This patch fixes dma_mapping_error() to check a passed address > properly (compares it with bad_dma_address). > > As I already wrote, the current git needs a patch modified slightly: > > http://marc.info/?l=linux-kernel&m=122797163405377&w=2
i have i queued up in x86/urgent, see below.
Ingo
--------------> From 7b1dedca42ac0d0d0be01e39d8461bb53a2389b3 Mon Sep 17 00:00:00 2001 From: Thomas Bogendoerfer <tsbogend@alpha.franken.de> Date: Sat, 29 Nov 2008 13:46:27 +0100 Subject: [PATCH] x86: fix dma_mapping_error for 32bit x86
Devices like b44 ethernet can't dma from addresses above 1GB. The driver handles this cases by falling back to GFP_DMA allocation. But for detecting the problem it needs to get an indication from dma_mapping_error. The bug is triggered by using a VMSPLIT option of 2G/2G.
Signed-off-by: Thomas Bogendoerfer <tsbogend@alpha.franken.de> Acked-by: FUJITA Tomonori <fujita.tomonori@lab.ntt.co.jp> Signed-off-by: Ingo Molnar <mingo@elte.hu> --- arch/x86/include/asm/dma-mapping.h | 6 ++---- 1 files changed, 2 insertions(+), 4 deletions(-)
diff --git a/arch/x86/include/asm/dma-mapping.h b/arch/x86/include/asm/dma-mapping.h index 7f225a4..097794f 100644 --- a/arch/x86/include/asm/dma-mapping.h +++ b/arch/x86/include/asm/dma-mapping.h @@ -71,15 +71,13 @@ static inline struct dma_mapping_ops *get_dma_ops(struct device *dev) /* Make sure we keep the same behaviour */ static inline int dma_mapping_error(struct device *dev, dma_addr_t dma_addr) { -#ifdef CONFIG_X86_32 - return 0; -#else +#ifdef CONFIG_X86_64 struct dma_mapping_ops *ops = get_dma_ops(dev); if (ops->mapping_error) return ops->mapping_error(dev, dma_addr); - return (dma_addr == bad_dma_address); #endif + return (dma_addr == bad_dma_address); } #define dma_alloc_noncoherent(d, s, h, f) dma_alloc_coherent(d, s, h, f)
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