[PATCHv2 RFC 4/4] Revert "virtio: make add_buf return capacity remaining:

["Michael S. Tsirkin" <mst@redhat.com>]

This reverts commit 3c1b27d5043086a485f8526353ae9fe37bfa1065.
The only user was virtio_net, and it switched to
min_capacity instead.

Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
---
 drivers/virtio/virtio_ring.c |    2 +-
 include/linux/virtio.h       |    2 +-
 2 files changed, 2 insertions(+), 2 deletions(-)

diff --git a/drivers/virtio/virtio_ring.c b/drivers/virtio/virtio_ring.c
index 23422f1..a6c21eb 100644
--- a/drivers/virtio/virtio_ring.c
+++ b/drivers/virtio/virtio_ring.c
@@ -233,7 +233,7 @@ add_head:
 	pr_debug("Added buffer head %i to %p\n", head, vq);
 	END_USE(vq);
 
-	return vq->num_free;
+	return 0;
 }
 EXPORT_SYMBOL_GPL(virtqueue_add_buf_gfp);
 
diff --git a/include/linux/virtio.h b/include/linux/virtio.h
index 209220d..63c4908 100644
--- a/include/linux/virtio.h
+++ b/include/linux/virtio.h
@@ -34,7 +34,7 @@ struct virtqueue {
  *	in_num: the number of sg which are writable (after readable ones)
  *	data: the token identifying the buffer.
  *	gfp: how to do memory allocations (if necessary).
- *      Returns remaining capacity of queue (sg segments) or a negative error.
+ *      Returns 0 on success or a negative error.
  * virtqueue_kick: update after add_buf
  *	vq: the struct virtqueue
  *	After one or more add_buf calls, invoke this to kick the other side.
-- 
1.7.5.53.gc233e