[PATCH 1/3] x86: remove the NULL device hack in dma-mapping.h

[FUJITA Tomonori]

dma_alloc_coherent in dma-mapping.h has a hack to use
x86_dma_fallback_dev if a pointer to a device is NULL. Some of IOMMUs
don't need such hack. The hack also makes it difficult for IOMMUs to
make a proper decision because the hack hides the information.

Signed-off-by: FUJITA Tomonori <fujita.tomonori@xxxxxxxxxxxxx>
---
 arch/x86/kernel/pci-swiotlb_64.c |   15 ++++++++++++++-
 include/asm-x86/dma-mapping.h    |    9 +--------
 2 files changed, 15 insertions(+), 9 deletions(-)

diff --git a/arch/x86/kernel/pci-swiotlb_64.c b/arch/x86/kernel/pci-swiotlb_64.c
index c4ce033..f3d8d0e 100644
--- a/arch/x86/kernel/pci-swiotlb_64.c
+++ b/arch/x86/kernel/pci-swiotlb_64.c
@@ -11,6 +11,8 @@
 
 int swiotlb __read_mostly;
 
+extern struct device x86_dma_fallback_dev;
+
 static dma_addr_t
 swiotlb_map_single_phys(struct device *hwdev, phys_addr_t paddr, size_t size,
 			int direction)
@@ -18,9 +20,20 @@ swiotlb_map_single_phys(struct device *hwdev, phys_addr_t paddr, size_t size,
 	return swiotlb_map_single(hwdev, phys_to_virt(paddr), size, direction);
 }
 
+static void *x86_swiotlb_alloc_coherent(struct device *dev, size_t size,
+					dma_addr_t *dma_handle, gfp_t gfp)
+{
+	if (!dev) {
+		dev = &x86_dma_fallback_dev;
+		gfp |= GFP_DMA;
+	}
+
+	return swiotlb_alloc_coherent(dev, size, dma_handle, gfp);
+}
+
 struct dma_mapping_ops swiotlb_dma_ops = {
 	.mapping_error = swiotlb_dma_mapping_error,
-	.alloc_coherent = swiotlb_alloc_coherent,
+	.alloc_coherent = x86_swiotlb_alloc_coherent,
 	.free_coherent = swiotlb_free_coherent,
 	.map_single = swiotlb_map_single_phys,
 	.unmap_single = swiotlb_unmap_single,
diff --git a/include/asm-x86/dma-mapping.h b/include/asm-x86/dma-mapping.h
index bc6c8df..3463702 100644
--- a/include/asm-x86/dma-mapping.h
+++ b/include/asm-x86/dma-mapping.h
@@ -14,7 +14,6 @@
 
 extern dma_addr_t bad_dma_address;
 extern int iommu_merge;
-extern struct device x86_dma_fallback_dev;
 extern int panic_on_overflow;
 extern int force_iommu;
 
@@ -251,14 +250,8 @@ dma_alloc_coherent(struct device *dev, size_t size, dma_addr_t *dma_handle,
 	if (dma_alloc_from_coherent(dev, size, dma_handle, &memory))
 		return memory;
 
-	if (!dev) {
-		dev = &x86_dma_fallback_dev;
-		gfp |= GFP_DMA;
-	}
-
 	if (ops->alloc_coherent)
-		return ops->alloc_coherent(dev, size,
-				dma_handle, gfp);
+		return ops->alloc_coherent(dev, size, dma_handle, gfp);
 	return NULL;
 }
 
-- 
1.5.5.GIT

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