On Wed, May 04, 2011 at 07:33:19PM +0530, Krishna Kumar wrote:
> Introduce virtqueue_get_capacity() to help bail out of transmit
> path early. Also remove notification when we run out of space (I
> am not sure if this should be under a feature bit).
>
> Signed-off-by: Krishna Kumar <krkumar2@xxxxxxxxxx>
> ---
> drivers/virtio/virtio_ring.c | 13 ++++++++-----
> include/linux/virtio.h | 5 +++++
> 2 files changed, 13 insertions(+), 5 deletions(-)
>
> diff -ruNp org/include/linux/virtio.h new/include/linux/virtio.h
> --- org/include/linux/virtio.h 2011-05-04 18:57:06.000000000 +0530
> +++ new/include/linux/virtio.h 2011-05-04 18:57:09.000000000 +0530
> @@ -27,6 +27,9 @@ struct virtqueue {
>
> /**
> * operations for virtqueue
> + * virtqueue_get_capacity: Get vq capacity
> + * vq: the struct virtqueue we're talking about.
> + * Returns remaining capacity of queue
> * virtqueue_add_buf: expose buffer to other end
> * vq: the struct virtqueue we're talking about.
> * sg: the description of the buffer(s).
> @@ -62,6 +65,8 @@ struct virtqueue {
> * All operations can be called in any context.
> */
>
> +int virtqueue_get_capacity(struct virtqueue *vq);
> +
> int virtqueue_add_buf_gfp(struct virtqueue *vq,
> struct scatterlist sg[],
> unsigned int out_num,
This is same as Shirley sent?
Maybe split and attribute ...
> diff -ruNp org/drivers/virtio/virtio_ring.c new/drivers/virtio/virtio_ring.c
> --- org/drivers/virtio/virtio_ring.c 2011-05-04 18:57:06.000000000 +0530
> +++ new/drivers/virtio/virtio_ring.c 2011-05-04 18:57:09.000000000 +0530
> @@ -156,6 +156,14 @@ static int vring_add_indirect(struct vri
> return head;
> }
>
> +int virtqueue_get_capacity(struct virtqueue *_vq)
> +{
> + struct vring_virtqueue *vq = to_vvq(_vq);
> +
> + return vq->num_free;
> +}
> +EXPORT_SYMBOL_GPL(virtqueue_get_capacity);
> +
> int virtqueue_add_buf_gfp(struct virtqueue *_vq,
> struct scatterlist sg[],
> unsigned int out,
> @@ -185,11 +193,6 @@ int virtqueue_add_buf_gfp(struct virtque
> if (vq->num_free < out + in) {
> pr_debug("Can't add buf len %i - avail = %i\n",
> out + in, vq->num_free);
> - /* FIXME: for historical reasons, we force a notify here if
> - * there are outgoing parts to the buffer. Presumably the
> - * host should service the ring ASAP. */
> - if (out)
> - vq->notify(&vq->vq);
> END_USE(vq);
> return -ENOSPC;
> }
This will break qemu versions 0.13 and back.
I'm adding some new virtio ring flags, we'll be
able to reuse one of these to mean 'no need for
work around', I think.
--
MST
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