From 70e4cb9aafb3caa9e5eb25614a5bc40b0ffa9ffd Mon Sep 17 00:00:00 2001
From: "Michael S. Tsirkin" <mst@redhat.com>
Date: Thu, 1 Nov 2012 09:16:37 +0000
Subject: vhost-net: cleanup macros for DMA status tracking

Better document macros for DMA tracking. Add an
explicit one for DMA in progress instead of
relying on user supplying len != 1.

Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
---
 drivers/vhost/vhost.h | 12 +++++++++---
 1 file changed, 9 insertions(+), 3 deletions(-)

(limited to 'drivers/vhost/vhost.h')

diff --git a/drivers/vhost/vhost.h b/drivers/vhost/vhost.h
index 2de4ce2fec4..b6538eef746 100644
--- a/drivers/vhost/vhost.h
+++ b/drivers/vhost/vhost.h
@@ -13,9 +13,15 @@
 #include <linux/virtio_ring.h>
 #include <linux/atomic.h>
 
-/* This is for zerocopy, used buffer len is set to 1 when lower device DMA
- * done */
-#define VHOST_DMA_DONE_LEN	1
+/*
+ * For transmit, used buffer len is unused; we override it to track buffer
+ * status internally; used for zerocopy tx only.
+ */
+/* Lower device DMA done */
+#define VHOST_DMA_DONE_LEN	2
+/* Lower device DMA in progress */
+#define VHOST_DMA_IN_PROGRESS	1
+/* Buffer unused */
 #define VHOST_DMA_CLEAR_LEN	0
 
 struct vhost_device;
-- 
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