[PATCH 4.9 22/86] virtio_ring: fix num_free handling in error case

[Greg Kroah-Hartman]

4.9-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Tiwei Bie <tiwei.bie@xxxxxxxxx>

commit e82df670235138575b37ff0ec24412a471efd97f upstream.

The vq->vq.num_free hasn't been changed when error happens,
so it shouldn't be changed when handling the error.

Fixes: 780bc7903a32 ("virtio_ring: Support DMA APIs")
Cc: Andy Lutomirski <luto@xxxxxxxxxx>
Cc: Michael S. Tsirkin <mst@xxxxxxxxxx>
Cc: stable@xxxxxxxxxxxxxxx
Signed-off-by: Tiwei Bie <tiwei.bie@xxxxxxxxx>
Signed-off-by: Michael S. Tsirkin <mst@xxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>

---
 drivers/virtio/virtio_ring.c |    2 --
 1 file changed, 2 deletions(-)

--- a/drivers/virtio/virtio_ring.c
+++ b/drivers/virtio/virtio_ring.c
@@ -423,8 +423,6 @@ unmap_release:
 		i = vq->vring.desc[i].next;
 	}
 
-	vq->vq.num_free += total_sg;
-
 	if (indirect)
 		kfree(desc);