[PATCH] vu_common: Clarify prototype of vu_collect()

[Stefano Brivio <sbrivio@redhat.com>]

The last argument of vu_collect() can't exceed @size, but this isn't
documented and it wasn't obvious to me, to the point that I actually
proposed a change to "fix" callers so that they wouldn't overrun input
buffers.

Rename @frame_size to @collected, and clarify that it can only be up
to @size bytes.

Signed-off-by: Stefano Brivio <sbrivio@redhat.com>
---
 vu_common.c | 8 ++++----
 vu_common.h | 2 +-
 2 files changed, 5 insertions(+), 5 deletions(-)

diff --git a/vu_common.c b/vu_common.c
index b13b7c3..ce61fa6 100644
--- a/vu_common.c
+++ b/vu_common.c
@@ -76,13 +76,13 @@ void vu_init_elem(struct vu_virtq_element *elem, struct iovec *iov, int elem_cnt
  * 			in the in_sg array.
  * @max_elem:		Number of virtqueue elements in the array
  * @size:		Maximum size of the data in the frame
- * @frame_size:		The total size of the buffers (output)
+ * @collected:		Collected buffer length, up to @size, set on return
  *
  * Return: number of elements used to contain the frame
  */
 int vu_collect(const struct vu_dev *vdev, struct vu_virtq *vq,
 	       struct vu_virtq_element *elem, int max_elem,
-	       size_t size, size_t *frame_size)
+	       size_t size, size_t *collected)
 {
 	size_t current_size = 0;
 	int elem_cnt = 0;
@@ -113,8 +113,8 @@ int vu_collect(const struct vu_dev *vdev, struct vu_virtq *vq,
 			break;
 	}
 
-	if (frame_size)
-		*frame_size = current_size;
+	if (collected)
+		*collected = current_size;
 
 	return elem_cnt;
 }
diff --git a/vu_common.h b/vu_common.h
index f538f23..c0883b2 100644
--- a/vu_common.h
+++ b/vu_common.h
@@ -48,7 +48,7 @@ void vu_init_elem(struct vu_virtq_element *elem, struct iovec *iov,
 		  int elem_cnt);
 int vu_collect(const struct vu_dev *vdev, struct vu_virtq *vq,
 	       struct vu_virtq_element *elem, int max_elem, size_t size,
-	       size_t *frame_size);
+	       size_t *collected);
 void vu_set_vnethdr(const struct vu_dev *vdev,
 		    struct virtio_net_hdr_mrg_rxbuf *vnethdr,
                     int num_buffers);
-- 
2.43.0