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Subject[PATCH 21/28] x86: retry allocation if failed
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This patch puts in the code to retry allocation in case it fails. By its
own, it does not make much sense but making the code look like x86_64.
But later patches in this series will make we try to allocate from
zones other than DMA first, which will possibly fail.

Signed-off-by: Glauber Costa <gcosta@redhat.com>
---
arch/x86/kernel/pci-dma_32.c | 34 +++++++++++++++++++++++++++++-----
1 files changed, 29 insertions(+), 5 deletions(-)
diff --git a/arch/x86/kernel/pci-dma_32.c b/arch/x86/kernel/pci-dma_32.c
index 0d630ae..f6cf434 100644
--- a/arch/x86/kernel/pci-dma_32.c
+++ b/arch/x86/kernel/pci-dma_32.c
@@ -66,6 +66,8 @@ void *dma_alloc_coherent(struct device *dev, size_t size,
struct page *page;
dma_addr_t bus;
int order = get_order(size);
+ unsigned long dma_mask = 0;
+
/* ignore region specifiers */
gfp &= ~(__GFP_DMA | __GFP_HIGHMEM);

@@ -75,15 +77,37 @@ void *dma_alloc_coherent(struct device *dev, size_t size,
if (dev == NULL || (dev->coherent_dma_mask < 0xffffffff))
gfp |= GFP_DMA;

+ dma_mask = dev->coherent_dma_mask;
+ if (dma_mask == 0)
+ dma_mask = DMA_32BIT_MASK;
+
+ again:
page = dma_alloc_pages(dev, gfp, order);
if (page == NULL)
return NULL;

- ret = page_address(page);
- bus = page_to_phys(page);
-
- memset(ret, 0, size);
- *dma_handle = bus;
+ {
+ int high, mmu;
+ bus = page_to_phys(page);
+ ret = page_address(page);
+ high = (bus + size) >= dma_mask;
+ mmu = high;
+ if (force_iommu && !(gfp & GFP_DMA))
+ mmu = 1;
+ else if (high) {
+ free_pages((unsigned long)ret,
+ get_order(size));
+
+ /* Don't use the 16MB ZONE_DMA unless absolutely
+ needed. It's better to use remapping first. */
+ if (dma_mask < DMA_32BIT_MASK && !(gfp & GFP_DMA)) {
+ gfp = (gfp & ~GFP_DMA32) | GFP_DMA;
+ goto again;
+ }
+ }
+ memset(ret, 0, size);
+ *dma_handle = bus;
+ }

return ret;
}
--
1.5.0.6


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