[PATCH] x86_64: Fallback to swiotlb for dma_alloc_coherent

From: Suresh B Siddha

Coresponding change to IA64 code is in, so this can be merged too.

- fallback to swiotlb for consistent DMA mappings
- fix a memory leak in dma_alloc_coherent
Signed-off-by: Suresh Siddha <suresh.b.siddha@intel.com>
Signed-off-by: Andi Kleen <ak@suse.de>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

arch/x86_64/kernel/pci-gart.c

@@ -236,11 +236,21 @@ dma_alloc_coherent(struct device *dev, size_t size, dma_addr_t *dma_handle,
 			mmu = 1;
 		if (no_iommu || dma_mask < 0xffffffffUL) { 
 			if (high) {
+				free_pages((unsigned long)memory,
+					   get_order(size));
+
+				if (swiotlb) {
+					return
+					swiotlb_alloc_coherent(dev, size,
+							       dma_handle,
+							       gfp);
+				}
+
 				if (!(gfp & GFP_DMA)) { 
 					gfp |= GFP_DMA; 
 					goto again;
 				}
-				goto free;
+				return NULL;
 			}
 			mmu = 0; 
 		} 	
@@ -260,9 +270,7 @@ dma_alloc_coherent(struct device *dev, size_t size, dma_addr_t *dma_handle,
 error:
 	if (panic_on_overflow)
 		panic("dma_alloc_coherent: IOMMU overflow by %lu bytes\n", size);
-free:
 	free_pages((unsigned long)memory, get_order(size)); 
-	/* XXX Could use the swiotlb pool here too */
 	return NULL; 
 }
 
@@ -273,6 +281,11 @@ dma_alloc_coherent(struct device *dev, size_t size, dma_addr_t *dma_handle,
 void dma_free_coherent(struct device *dev, size_t size,
 			 void *vaddr, dma_addr_t bus)
 {
+	if (swiotlb) {
+		swiotlb_free_coherent(dev, size, vaddr, bus);
+		return;
+	}
+
 	dma_unmap_single(dev, bus, size, 0);
 	free_pages((unsigned long)vaddr, get_order(size)); 		
 }

include/asm-x86_64/swiotlb.h

@@ -26,6 +26,10 @@ extern int swiotlb_map_sg(struct device *hwdev, struct scatterlist *sg,
 extern void swiotlb_unmap_sg(struct device *hwdev, struct scatterlist *sg,
 			 int nents, int direction);
 extern int swiotlb_dma_mapping_error(dma_addr_t dma_addr);
+extern void *swiotlb_alloc_coherent (struct device *hwdev, size_t size,
+				     dma_addr_t *dma_handle, int flags);
+extern void swiotlb_free_coherent (struct device *hwdev, size_t size,
+				   void *vaddr, dma_addr_t dma_handle);
 
 #ifdef CONFIG_SWIOTLB
 extern int swiotlb;