On Sep 27, 2007, 18:46 +0200, FUJITA Tomonori <[email protected]> wrote:
> On Fri, 28 Sep 2007 01:38:27 +0900
> FUJITA Tomonori <[email protected]> wrote:
>
>> This patch is for Jens' block tree (sg chaining branch).
>>
>> I don't have the hardware but this looks like a bug.
>>
>> ---
>> From: FUJITA Tomonori <[email protected]>
>> Subject: [PATCH] x86-64: pci-gart iommu sg chaining zeroes a wrong sg's dma_length
>>
>> Needs to zero the end of the list.
>>
>> Signed-off-by: FUJITA Tomonori <[email protected]>
>> ---
>> arch/x86_64/kernel/pci-gart.c | 3 ++-
>> 1 files changed, 2 insertions(+), 1 deletions(-)
>>
>> diff --git a/arch/x86_64/kernel/pci-gart.c b/arch/x86_64/kernel/pci-gart.c
>> index 27b7db4..a4151a7 100644
>> --- a/arch/x86_64/kernel/pci-gart.c
>> +++ b/arch/x86_64/kernel/pci-gart.c
>> @@ -425,9 +425,10 @@ int gart_map_sg(struct device *dev, struct scatterlist *sg, int nents, int dir)
>> if (dma_map_cont(start_sg, i - start, sgmap, pages, need) < 0)
>> goto error;
>> out++;
>> + sgmap = sg_next(sgmap);
>> flush_gart();
>> if (out < nents)
>> - ps->dma_length = 0;
>> + sgmap->dma_length = 0;
>> return out;
>
> Sorry, it should be:
>
>
> diff --git a/arch/x86_64/kernel/pci-gart.c b/arch/x86_64/kernel/pci-gart.c
> index 27b7db4..cfcc84e 100644
> --- a/arch/x86_64/kernel/pci-gart.c
> +++ b/arch/x86_64/kernel/pci-gart.c
> @@ -426,8 +426,10 @@ int gart_map_sg(struct device *dev, struct scatterlist *sg, int nents, int dir)
> goto error;
> out++;
> flush_gart();
> - if (out < nents)
> - ps->dma_length = 0;
> + if (out < nents) {
> + sgmap = sg_next(sgmap);
> + sgmap->dma_length = 0;
> + }
looks correct to me.
ps points at the previous "scanned" sg entry while you want to zero out
dma_length at the entry immediately following the last entry mapped
(if (out < nents))
the original code before 62296749bd421904dace1e6b0fc3c4538aac7111 was:
- if (out < nents)
- sg[out].dma_length = 0;
Benny
> return out;
>
> error:
> -
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