Subject: fix swiotlb sync functions to properly deal with DMA_BIDIRECTIONAL

This change was left out from a merge somewhere between 2.6.12 and 2.6.16.

Signed-off-by: Jan Beulich <jbeulich@xxxxxxxxxx>
Cc: Dominic Curran <dominic.curran@xxxxxxxxxx>

--- a/lib/swiotlb-xen.c
+++ b/lib/swiotlb-xen.c
@@ -47,6 +47,14 @@ EXPORT_SYMBOL(swiotlb);
  */
 #define IO_TLB_SHIFT 11
 
+/*
+ * Enumeration for sync targets
+ */
+enum dma_sync_target {
+	SYNC_FOR_CPU = 0,
+	SYNC_FOR_DEVICE = 1,
+};
+
 int swiotlb_force;
 
 static char *iotlb_virt_start;
@@ -444,11 +452,26 @@ unmap_single(struct device *hwdev, char 
 }
 
 static void
-sync_single(struct device *hwdev, char *dma_addr, size_t size, int dir)
+sync_single(struct device *hwdev, char *dma_addr, size_t size,
+	    int dir, int target)
 {
 	struct phys_addr buffer = dma_addr_to_phys_addr(dma_addr);
-	BUG_ON((dir != DMA_FROM_DEVICE) && (dir != DMA_TO_DEVICE));
-	__sync_single(buffer, dma_addr, size, dir);
+	switch (target) {
+	case SYNC_FOR_CPU:
+		if (likely(dir == DMA_FROM_DEVICE || dir == DMA_BIDIRECTIONAL))
+			__sync_single(buffer, dma_addr, size, DMA_FROM_DEVICE);
+		else
+			BUG_ON(dir != DMA_TO_DEVICE);
+		break;
+	case SYNC_FOR_DEVICE:
+		if (likely(dir == DMA_TO_DEVICE || dir == DMA_BIDIRECTIONAL))
+			__sync_single(buffer, dma_addr, size, DMA_TO_DEVICE);
+		else
+			BUG_ON(dir != DMA_FROM_DEVICE);
+		break;
+	default:
+		BUG();
+	}
 }
 
 static void
@@ -543,22 +566,27 @@ swiotlb_unmap_single(struct device *hwde
  * address back to the card, you must first perform a
  * swiotlb_dma_sync_for_device, and then the device again owns the buffer
  */
+static inline void
+swiotlb_sync_single(struct device *hwdev, dma_addr_t dev_addr,
+		    size_t size, int dir, int target)
+{
+	BUG_ON(dir == DMA_NONE);
+	if (in_swiotlb_aperture(dev_addr))
+		sync_single(hwdev, bus_to_virt(dev_addr), size, dir, target);
+}
+
 void
 swiotlb_sync_single_for_cpu(struct device *hwdev, dma_addr_t dev_addr,
 			    size_t size, int dir)
 {
-	BUG_ON(dir == DMA_NONE);
-	if (in_swiotlb_aperture(dev_addr))
-		sync_single(hwdev, bus_to_virt(dev_addr), size, dir);
+	swiotlb_sync_single(hwdev, dev_addr, size, dir, SYNC_FOR_CPU);
 }
 
 void
 swiotlb_sync_single_for_device(struct device *hwdev, dma_addr_t dev_addr,
 			       size_t size, int dir)
 {
-	BUG_ON(dir == DMA_NONE);
-	if (in_swiotlb_aperture(dev_addr))
-		sync_single(hwdev, bus_to_virt(dev_addr), size, dir);
+	swiotlb_sync_single(hwdev, dev_addr, size, dir, SYNC_FOR_DEVICE);
 }
 
 /*
@@ -642,9 +670,9 @@ swiotlb_unmap_sg(struct device *hwdev, s
  * The same as swiotlb_sync_single_* but for a scatter-gather list, same rules
  * and usage.
  */
-void
-swiotlb_sync_sg_for_cpu(struct device *hwdev, struct scatterlist *sg,
-			int nelems, int dir)
+static inline void
+swiotlb_sync_sg(struct device *hwdev, struct scatterlist *sg,
+		int nelems, int dir, int target)
 {
 	int i;
 
@@ -652,24 +680,22 @@ swiotlb_sync_sg_for_cpu(struct device *h
 
 	for (i = 0; i < nelems; i++, sg++)
 		if (in_swiotlb_aperture(sg->dma_address))
-			sync_single(hwdev,
-				    (void *)bus_to_virt(sg->dma_address),
-				    sg->dma_length, dir);
+			sync_single(hwdev, bus_to_virt(sg->dma_address),
+				    sg->dma_length, dir, target);
+}
+
+void
+swiotlb_sync_sg_for_cpu(struct device *hwdev, struct scatterlist *sg,
+			int nelems, int dir)
+{
+	swiotlb_sync_sg(hwdev, sg, nelems, dir, SYNC_FOR_CPU);
 }
 
 void
 swiotlb_sync_sg_for_device(struct device *hwdev, struct scatterlist *sg,
 			   int nelems, int dir)
 {
-	int i;
-
-	BUG_ON(dir == DMA_NONE);
-
-	for (i = 0; i < nelems; i++, sg++)
-		if (in_swiotlb_aperture(sg->dma_address))
-			sync_single(hwdev,
-				    (void *)bus_to_virt(sg->dma_address),
-				    sg->dma_length, dir);
+	swiotlb_sync_sg(hwdev, sg, nelems, dir, SYNC_FOR_DEVICE);
 }
 
 #ifdef CONFIG_HIGHMEM