Re: [PATCH 0/3] fix alloc_coherent allocation issues (tip/x86/iommu)

FUJITA Tomonori
2008-09-08T18:07:38Z

On Mon, 8 Sep 2008 19:35:25 +0200
Ingo Molnar <mingo@elte.hu> wrote:

>
> btw., the build became very noisy - see the messages below.
>
> Ingo
>
> ---------->
> init/initramfs.c:517: warning: 'clean_rootfs' defined but not used
> In file included from include/linux/dma-mapping.h:53,
> from include/linux/dmaengine.h:30,
> from include/linux/skbuff.h:30,
> from include/linux/netlink.h:156,
> from include/linux/genetlink.h:5,
> from include/net/genetlink.h:5,
> from include/linux/taskstats_kern.h:13,
> from init/main.c:48:
> include/asm/dma-mapping.h: In function 'dma_alloc_coherent_gfp_flags':
> include/asm/dma-mapping.h:258: warning: unused variable 'dma_mask'
> In file included from include/linux/dma-mapping.h:53,
> from arch/x86/kernel/pci-dma.c:2:

Very sorry, I should have compile this on X86_32...

Can you replace the fourth patch with this?

=
From: FUJITA Tomonori <fujita.tomonori@lab.ntt.co.jp>
Subject: [PATCH] x86: dma_alloc_coherent sets gfp flags properly

Non real IOMMU implemenations (which doesn't do virtual mappings,
e.g. swiotlb, pci-nommu, etc) need to use proper gfp flags and
dma_mask to allocate pages in their own dma_alloc_coherent()
(allocated page need to be suitable for device's coherent_dma_mask).

This patch makes dma_alloc_coherent do this job so that IOMMUs don't
need to take care of it any more.

Real IOMMU implemenataions can simply ignore the gfp flags.

Signed-off-by: FUJITA Tomonori <fujita.tomonori@lab.ntt.co.jp>
---
arch/x86/kernel/pci-nommu.c | 19 ++-----------------
include/asm-x86/dma-mapping.h | 32 ++++++++++++++++++++++++++++----
2 files changed, 30 insertions(+), 21 deletions(-)

diff --git a/arch/x86/kernel/pci-nommu.c b/arch/x86/kernel/pci-nommu.c
index ada1c87..8e398b5 100644
--- a/arch/x86/kernel/pci-nommu.c
+++ b/arch/x86/kernel/pci-nommu.c
@@ -80,26 +80,11 @@ nommu_alloc_coherent(struct device *hwdev, size_t size,
int node;
struct page *page;

- gfp |= __GFP_ZERO;
-
- dma_mask = hwdev->coherent_dma_mask;
- if (!dma_mask)
- dma_mask = *(hwdev->dma_mask);
+ dma_mask = dma_alloc_coherent_mask(hwdev, gfp);

- if (dma_mask < DMA_24BIT_MASK)
- return NULL;
+ gfp |= __GFP_ZERO;

node = dev_to_node(hwdev);
-
-#ifdef CONFIG_X86_64
- if (dma_mask <= DMA_32BIT_MASK && !(gfp & GFP_DMA))
- gfp |= GFP_DMA32;
-#endif
-
- /* No alloc-free penalty for ISA devices */
- if (dma_mask == DMA_24BIT_MASK)
- gfp |= GFP_DMA;
-
again:
page = alloc_pages_node(node, gfp, get_order(size));
if (!page)
diff --git a/include/asm-x86/dma-mapping.h b/include/asm-x86/dma-mapping.h
index 9d6dcf4..8bb3108 100644
--- a/include/asm-x86/dma-mapping.h
+++ b/include/asm-x86/dma-mapping.h
@@ -241,6 +241,29 @@ static inline int dma_get_cache_alignment(void)
return boot_cpu_data.x86_clflush_size;
}

+static inline unsigned long dma_alloc_coherent_mask(struct device *dev,
+ gfp_t gfp)
+{
+ unsigned long dma_mask = 0;
+
+ dma_mask = dev->coherent_dma_mask;
+ if (!dma_mask)
+ dma_mask = (gfp & GFP_DMA) ? DMA_24BIT_MASK : DMA_32BIT_MASK;
+
+ return dma_mask;
+}
+
+static inline gfp_t dma_alloc_coherent_gfp_flags(struct device *dev, gfp_t gfp)
+{
+#ifdef CONFIG_X86_64
+ unsigned long dma_mask = dma_alloc_coherent_mask(dev, gfp);
+
+ if (dma_mask <= DMA_32BIT_MASK && !(gfp & GFP_DMA))
+ gfp |= GFP_DMA32;
+#endif
+ return gfp;
+}
+
static inline void *
dma_alloc_coherent(struct device *dev, size_t size, dma_addr_t *dma_handle,
gfp_t gfp)
@@ -261,10 +284,11 @@ dma_alloc_coherent(struct device *dev, size_t size, dma_addr_t *dma_handle,
if (!dev->dma_mask)
return NULL;

- if (ops->alloc_coherent)
- return ops->alloc_coherent(dev, size,
- dma_handle, gfp);
- return NULL;
+ if (!ops->alloc_coherent)
+ return NULL;
+
+ return ops->alloc_coherent(dev, size, dma_handle,
+ dma_alloc_coherent_gfp_flags(dev, gfp));
}

static inline void dma_free_coherent(struct device *dev, size_t size,
--
1.5.5.GIT