Re: [PATCH net-next v2 05/13] virtio_ring: introduce add api for premapped

Jason Wang
2024-11-05T04:28:34Z

On Wed, Oct 30, 2024 at 4:25 PM Xuan Zhuo <xuanzhuo@linux.alibaba.com> wrote:
>
> Two APIs are introduced to submit premapped per-buffers.
>
> int virtqueue_add_inbuf_premapped(struct virtqueue *vq,
> struct scatterlist *sg, unsigned int num,
> void *data,
> void *ctx,
> bool premapped,
> gfp_t gfp);
>
> int virtqueue_add_outbuf_premapped(struct virtqueue *vq,
> struct scatterlist *sg, unsigned int num,
> void *data,
> bool premapped,
> gfp_t gfp);
>
> Signed-off-by: Xuan Zhuo <xuanzhuo@linux.alibaba.com>
> ---
> drivers/virtio/virtio_ring.c | 48 ++++++++++++++++++++++++++++++++++++
> include/linux/virtio.h | 13 ++++++++++
> 2 files changed, 61 insertions(+)
>
> diff --git a/drivers/virtio/virtio_ring.c b/drivers/virtio/virtio_ring.c
> index a89295b79e66..525308d82728 100644
> --- a/drivers/virtio/virtio_ring.c
> +++ b/drivers/virtio/virtio_ring.c
> @@ -2272,6 +2272,29 @@ int virtqueue_add_outbuf(struct virtqueue *vq,
> }
> EXPORT_SYMBOL_GPL(virtqueue_add_outbuf);
>
> +/**
> + * virtqueue_add_outbuf_premapped - expose output buffers to other end
> + * @vq: the struct virtqueue we're talking about.
> + * @sg: scatterlist (must be well-formed and terminated!)
> + * @num: the number of entries in @sg readable by other side
> + * @data: the token identifying the buffer.
> + * @gfp: how to do memory allocations (if necessary).
> + *
> + * Caller must ensure we don't call this with other virtqueue operations
> + * at the same time (except where noted).
> + *
> + * Returns zero or a negative error (ie. ENOSPC, ENOMEM, EIO).
> + */
> +int virtqueue_add_outbuf_premapped(struct virtqueue *vq,
> + struct scatterlist *sg, unsigned int num,
> + void *data,
> + bool premapped,

We don't need this parameter consider:

1) we've already had virtqueue_add_outbuf() which implies the buf has
been mapped
2) no explanation for "premapped" in the function doc

Thanks

> + gfp_t gfp)
> +{
> + return virtqueue_add(vq, &sg, num, 1, 0, data, NULL, premapped, gfp);
> +}
> +EXPORT_SYMBOL_GPL(virtqueue_add_outbuf_premapped);
> +
> /**
> * virtqueue_add_inbuf - expose input buffers to other end
> * @vq: the struct virtqueue we're talking about.
> @@ -2318,6 +2341,31 @@ int virtqueue_add_inbuf_ctx(struct virtqueue *vq,
> }
> EXPORT_SYMBOL_GPL(virtqueue_add_inbuf_ctx);
>
> +/**
> + * virtqueue_add_inbuf_premapped - expose input buffers to other end
> + * @vq: the struct virtqueue we're talking about.
> + * @sg: scatterlist (must be well-formed and terminated!)
> + * @num: the number of entries in @sg writable by other side
> + * @data: the token identifying the buffer.
> + * @ctx: extra context for the token
> + * @gfp: how to do memory allocations (if necessary).
> + *
> + * Caller must ensure we don't call this with other virtqueue operations
> + * at the same time (except where noted).
> + *
> + * Returns zero or a negative error (ie. ENOSPC, ENOMEM, EIO).
> + */
> +int virtqueue_add_inbuf_premapped(struct virtqueue *vq,
> + struct scatterlist *sg, unsigned int num,
> + void *data,
> + void *ctx,
> + bool premapped,
> + gfp_t gfp)
> +{
> + return virtqueue_add(vq, &sg, num, 0, 1, data, ctx, premapped, gfp);
> +}
> +EXPORT_SYMBOL_GPL(virtqueue_add_inbuf_premapped);
> +
> /**
> * virtqueue_dma_dev - get the dma dev
> * @_vq: the struct virtqueue we're talking about.
> diff --git a/include/linux/virtio.h b/include/linux/virtio.h
> index 306137a15d07..19afa49b92d0 100644
> --- a/include/linux/virtio.h
> +++ b/include/linux/virtio.h
> @@ -56,6 +56,19 @@ int virtqueue_add_inbuf_ctx(struct virtqueue *vq,
> void *ctx,
> gfp_t gfp);
>
> +int virtqueue_add_inbuf_premapped(struct virtqueue *vq,
> + struct scatterlist *sg, unsigned int num,
> + void *data,
> + void *ctx,
> + bool premapped,
> + gfp_t gfp);
> +
> +int virtqueue_add_outbuf_premapped(struct virtqueue *vq,
> + struct scatterlist *sg, unsigned int num,
> + void *data,
> + bool premapped,
> + gfp_t gfp);
> +
> int virtqueue_add_sgs(struct virtqueue *vq,
> struct scatterlist *sgs[],
> unsigned int out_sgs,
> --
> 2.32.0.3.g01195cf9f
>