[PATCH 2/3] x86: set gfp flag properly for swiotlb_alloc_coherent

[FUJITA Tomonori]

This tries to avoid GFP_DMA zone unless absolutely needed (and set gfp
flag to use GFP_DMA zone properly if necessary).

Signed-off-by: FUJITA Tomonori <fujita.tomonori@xxxxxxxxxxxxx>
---
 arch/x86/kernel/pci-swiotlb_64.c |   18 ++++++++++++++++++
 1 files changed, 18 insertions(+), 0 deletions(-)

diff --git a/arch/x86/kernel/pci-swiotlb_64.c b/arch/x86/kernel/pci-swiotlb_64.c
index f3d8d0e..3f4d9b4 100644
--- a/arch/x86/kernel/pci-swiotlb_64.c
+++ b/arch/x86/kernel/pci-swiotlb_64.c
@@ -23,11 +23,29 @@ swiotlb_map_single_phys(struct device *hwdev, phys_addr_t paddr, size_t size,
 static void *x86_swiotlb_alloc_coherent(struct device *dev, size_t size,
 					dma_addr_t *dma_handle, gfp_t gfp)
 {
+	unsigned long dma_mask;
+
+	gfp &= ~(__GFP_DMA | __GFP_HIGHMEM | __GFP_DMA32);
+
 	if (!dev) {
 		dev = &x86_dma_fallback_dev;
 		gfp |= GFP_DMA;
 	}
 
+	if (!dev->dma_mask)
+		return NULL;
+
+	dma_mask = dev->coherent_dma_mask;
+	if (!dma_mask)
+		dma_mask = gfp & GFP_DMA ? DMA_24BIT_MASK : DMA_32BIT_MASK;
+
+	if (!(gfp & GFP_DMA)) {
+		if (dma_mask <= DMA_24BIT_MASK)
+			gfp |= GFP_DMA;
+		else if (dma_mask <= DMA_32BIT_MASK)
+			gfp |= GFP_DMA32;
+	}
+
 	return swiotlb_alloc_coherent(dev, size, dma_handle, gfp);
 }
 
-- 
1.5.5.GIT

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