On Fri, Dec 05, 2025 at 01:51:05AM +0100, Stefano Brivio wrote:

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

Reviewed-by: David Gibson

--- 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

-- David Gibson (he or they) | I'll have my music baroque, and my code david AT gibson.dropbear.id.au | minimalist, thank you, not the other way | around. http://www.ozlabs.org/~dgibson