Re: [PATCH 04/11] io_uring: setup ZC for an RX queue when registering an ifq

[David Ahern <dsahern@kernel.org>]

On 8/25/23 6:19 PM, David Wei wrote:
> diff --git a/io_uring/zc_rx.c b/io_uring/zc_rx.c
> index 6c57c9b06e05..8cc66731af5b 100644
> --- a/io_uring/zc_rx.c
> +++ b/io_uring/zc_rx.c
> @@ -10,6 +11,35 @@
>  #include "kbuf.h"
>  #include "zc_rx.h"
>  
> +typedef int (*bpf_op_t)(struct net_device *dev, struct netdev_bpf *bpf);
> +
> +static int __io_queue_mgmt(struct net_device *dev, struct io_zc_rx_ifq *ifq,
> +			   u16 queue_id)
> +{
> +	struct netdev_bpf cmd;
> +	bpf_op_t ndo_bpf;
> +
> +	ndo_bpf = dev->netdev_ops->ndo_bpf;

This is not bpf related, so it seems wrong to be overloading this ndo.


> +	if (!ndo_bpf)
> +		return -EINVAL;
> +
> +	cmd.command = XDP_SETUP_ZC_RX;
> +	cmd.zc_rx.ifq = ifq;
> +	cmd.zc_rx.queue_id = queue_id;
> +
> +	return ndo_bpf(dev, &cmd);
> +}
> +
> +static int io_open_zc_rxq(struct io_zc_rx_ifq *ifq)
> +{
> +	return __io_queue_mgmt(ifq->dev, ifq, ifq->if_rxq_id);
> +}
> +
> +static int io_close_zc_rxq(struct io_zc_rx_ifq *ifq)
> +{
> +	return __io_queue_mgmt(ifq->dev, NULL, ifq->if_rxq_id);
> +}
> +
>  static struct io_zc_rx_ifq *io_zc_rx_ifq_alloc(struct io_ring_ctx *ctx)
>  {
>  	struct io_zc_rx_ifq *ifq;
> @@ -19,12 +49,17 @@ static struct io_zc_rx_ifq *io_zc_rx_ifq_alloc(struct io_ring_ctx *ctx)
>  		return NULL;
>  
>  	ifq->ctx = ctx;
> +	ifq->if_rxq_id = -1;
>  
>  	return ifq;
>  }
>  
>  static void io_zc_rx_ifq_free(struct io_zc_rx_ifq *ifq)
>  {
> +	if (ifq->if_rxq_id != -1)
> +		io_close_zc_rxq(ifq);
> +	if (ifq->dev)
> +		dev_put(ifq->dev);
>  	io_free_rbuf_ring(ifq);
>  	kfree(ifq);
>  }
> @@ -41,17 +76,22 @@ int io_register_zc_rx_ifq(struct io_ring_ctx *ctx,
>  		return -EFAULT;
>  	if (ctx->ifq)
>  		return -EBUSY;
> +	if (reg.if_rxq_id == -1)
> +		return -EINVAL;
>  
>  	ifq = io_zc_rx_ifq_alloc(ctx);
>  	if (!ifq)
>  		return -ENOMEM;
>  
> -	/* TODO: initialise network interface */
> -
>  	ret = io_allocate_rbuf_ring(ifq, &reg);
>  	if (ret)
>  		goto err;
>  
> +	ret = -ENODEV;
> +	ifq->dev = dev_get_by_index(&init_net, reg.if_idx);

What's the plan for other namespaces? Ideally the device bind comes from
a socket and that gives you the namespace.

> +	if (!ifq->dev)
> +		goto err;
> +
>  	/* TODO: map zc region and initialise zc pool */
>  
>  	ifq->rq_entries = reg.rq_entries;