[PATCH] virtio: fix size computation according to the definition of struct vring_used in vring_size

[Wang Sheng-Hui <shhuiw@gmail.com>]

The patch is against 3.1-rc3.

struct vring_used has two __u16 fields plus array of struct vring_used_elem.
Current vring_size counts the __u16 fields to 3. Fix it to 2 in the patch.

Signed-off-by: Wang Sheng-Hui <shhuiw@gmail.com>
---
 include/linux/virtio_ring.h |    2 +-
 1 files changed, 1 insertions(+), 1 deletions(-)

diff --git a/include/linux/virtio_ring.h b/include/linux/virtio_ring.h
index 4a32cb6..fcda152 100644
--- a/include/linux/virtio_ring.h
+++ b/include/linux/virtio_ring.h
@@ -143,7 +143,7 @@ static inline unsigned vring_size(unsigned int num, unsigned long align)
 {
 	return ((sizeof(struct vring_desc) * num + sizeof(__u16) * (2 + num)
 		 + align - 1) & ~(align - 1))
-		+ sizeof(__u16) * 3 + sizeof(struct vring_used_elem) * num;
+		+ sizeof(__u16) * 2 + sizeof(struct vring_used_elem) * num;
 }
 
 /* The following is used with USED_EVENT_IDX and AVAIL_EVENT_IDX */
-- 
1.7.1

crossover@crossover-plinux:~/dev/patchwork$