From 482bd84f1fab20ac6c4d112945ae2d1bdb36839f Mon Sep 17 00:00:00 2001 From: "Michael S. Tsirkin" Date: Tue, 27 May 2025 10:26:29 -0400 Subject: [PATCH] virtio: document ENOSPC drivers handle ENOSPC specially since it's an error one can get from a working VQ. Document the semantics. Message-Id: <2e6ec46b8d5e6755be291cec8e2ec57ef286e97b.1748356035.git.mst@redhat.com> Reported-by: Parav Pandit Signed-off-by: Michael S. Tsirkin Reviewed-by: Stefan Hajnoczi Reviewed-by: Parav Pandit --- drivers/virtio/virtio_ring.c | 4 ++++ 1 file changed, 4 insertions(+) diff --git a/drivers/virtio/virtio_ring.c b/drivers/virtio/virtio_ring.c index 4397392bfef00..f5062061c4084 100644 --- a/drivers/virtio/virtio_ring.c +++ b/drivers/virtio/virtio_ring.c @@ -2296,6 +2296,10 @@ static inline int virtqueue_add(struct virtqueue *_vq, * at the same time (except where noted). * * Returns zero or a negative error (ie. ENOSPC, ENOMEM, EIO). + * + * NB: ENOSPC is a special code that is only returned on an attempt to add a + * buffer to a full VQ. It indicates that some buffers are outstanding and that + * the operation can be retried after some buffers have been used. */ int virtqueue_add_sgs(struct virtqueue *_vq, struct scatterlist *sgs[], -- 2.47.2