Small fix to the error-return path after calling

__copy_to_user in the swiotlb sync function. We cannot
immediately exit the sync function as there may be tail work
to do (e.g., kunmap_atomic). In fact, doing nothing is the
right thing to do and is sufficient to avoid compiler
warnings about not checking the __copy_to_user return value.

Signed-off-by: Keir Fraser <keir@xensource.com>

linux-2.6-xen-sparse/arch/xen/i386/kernel/swiotlb.c

@@ -223,7 +223,7 @@ __sync_single(struct phys_addr buffer, char *dma_addr, size_t size, int dir)
 			host = kmp + buffer.offset;
 			if (dir == DMA_FROM_DEVICE) {
 				if (__copy_to_user(host, dev, bytes))
-					return; /* inaccessible */
+					/* inaccessible */;
 			} else
 				memcpy(dev, host, bytes);
 			kunmap_atomic(kmp, KM_SWIOTLB);
@@ -236,7 +236,7 @@ __sync_single(struct phys_addr buffer, char *dma_addr, size_t size, int dir)
 			page_to_pseudophys(buffer.page)) + buffer.offset;
 		if (dir == DMA_FROM_DEVICE) {
 			if (__copy_to_user(host, dma_addr, size))
-				return; /* inaccessible */
+				/* inaccessible */;
 		} else if (dir == DMA_TO_DEVICE)
 			memcpy(dma_addr, host, size);
 	}