[PATCH] Bug Fix arch/ia64/kernel/pci-dma.c: fix recursive dma_supported() call in iommu_dma_supporte

[PATCH] Bug Fix arch/ia64/kernel/pci-dma.c: fix recursive dma_supported() call in iommu_dma_supporte

[Fenghua Yu]

In commit dfb805e831cc5306b14eacd64e0b36d0d973ee0d,
dma_ops->dma_supported = iommu_dma_supported;

This dma_ops->dma_supported is first called in platform_dma_init() during kernel
boot. Then dma_ops->dma_supported will be called recursively in
iommu_dma_supported.

Kernel can not boot because kernel can not get out of iommu_dma_supported until
it runs out of stack memory.

Signed-off-by: Fenghua Yu <fenghua.yu@intel.com>

---

 arch/ia64/kernel/pci-dma.c |    5 -----
 1 files changed, 5 deletions(-)

diff --git a/arch/ia64/kernel/pci-dma.c b/arch/ia64/kernel/pci-dma.c
index 0569596..f6b1ff0 100644
--- a/arch/ia64/kernel/pci-dma.c
+++ b/arch/ia64/kernel/pci-dma.c
@@ -69,11 +69,6 @@ iommu_dma_init(void)
 
 int iommu_dma_supported(struct device *dev, u64 mask)
 {
-	struct dma_map_ops *ops = platform_dma_get_ops(dev);
-
-	if (ops->dma_supported)
-		return ops->dma_supported(dev, mask);
-
 	/* Copied from i386. Doesn't make much sense, because it will
 	   only work for pci_alloc_coherent.
 	   The caller just has to use GFP_DMA in this case. */

Re: [PATCH] Bug Fix arch/ia64/kernel/pci-dma.c: fix recursive

[FUJITA Tomonori]

On Tue, 4 Aug 2009 15:35:26 -0700
Fenghua Yu <fenghua.yu@intel.com> wrote:

> In commit dfb805e831cc5306b14eacd64e0b36d0d973ee0d,
> dma_ops->dma_supported = iommu_dma_supported;

Hmm, the dfb805e831cc5306b14eacd64e0b36d0d973ee0d commit touches only
dma_ops->mapping_error. It doesn't like like that this commit is
related with the bug.

I guess that I added the bug when I rewrote IA64 dma operations.


> This dma_ops->dma_supported is first called in platform_dma_init() during kernel
> boot. Then dma_ops->dma_supported will be called recursively in
> iommu_dma_supported.
> 
> Kernel can not boot because kernel can not get out of iommu_dma_supported until
> it runs out of stack memory.

The patch looks correct.

Reviewed-by: FUJITA Tomonori <fujita.tomonori@lab.ntt.co.jp>


Thanks!

> 
> Signed-off-by: Fenghua Yu <fenghua.yu@intel.com>
> 
> ---
> 
>  arch/ia64/kernel/pci-dma.c |    5 -----
>  1 files changed, 5 deletions(-)
> 
> diff --git a/arch/ia64/kernel/pci-dma.c b/arch/ia64/kernel/pci-dma.c
> index 0569596..f6b1ff0 100644
> --- a/arch/ia64/kernel/pci-dma.c
> +++ b/arch/ia64/kernel/pci-dma.c
> @@ -69,11 +69,6 @@ iommu_dma_init(void)
>  
>  int iommu_dma_supported(struct device *dev, u64 mask)
>  {
> -	struct dma_map_ops *ops = platform_dma_get_ops(dev);
> -
> -	if (ops->dma_supported)
> -		return ops->dma_supported(dev, mask);
> -
>  	/* Copied from i386. Doesn't make much sense, because it will
>  	   only work for pci_alloc_coherent.
>  	   The caller just has to use GFP_DMA in this case. */
> --
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RE: [PATCH] Bug Fix arch/ia64/kernel/pci-dma.c: fix recursive

[Yu, Fenghua]

>On Tue, 4 Aug 2009 15:35:26 -0700
>Fenghua Yu <fenghua.yu@intel.com> wrote:
>
>> In commit dfb805e831cc5306b14eacd64e0b36d0d973ee0d,
>> dma_ops->dma_supported = iommu_dma_supported;
>
>Hmm, the dfb805e831cc5306b14eacd64e0b36d0d973ee0d commit touches only
>dma_ops->mapping_error. It doesn't like like that this commit is
>related with the bug.
>
>I guess that I added the bug when I rewrote IA64 dma operations.

My bad. The commit I refer to should be 160c1d8e40866edfeae7d68816b7005d70acf391
which added the statement:
dma_ops->dma_supported = iommu_dma_supported;

I will change to this commit# in comment when push the patch to upstream.

Thanks.

-Fenghua