Re: [net PATCH v5 4/6] virtio_net: remove duplicate queue pair binding in XDP

["Michael S. Tsirkin" <mst@redhat.com>]

On Tue, Jan 17, 2017 at 02:21:44PM -0800, John Fastabend wrote:
> Factor out qp assignment.
> 
> Signed-off-by: John Fastabend <john.r.fastabend@intel.com>

Acked-by: Michael S. Tsirkin <mst@redhat.com>

> ---
>  drivers/net/virtio_net.c |   18 +++++++-----------
>  1 file changed, 7 insertions(+), 11 deletions(-)
> 
> diff --git a/drivers/net/virtio_net.c b/drivers/net/virtio_net.c
> index 6de0cbe..922ca66 100644
> --- a/drivers/net/virtio_net.c
> +++ b/drivers/net/virtio_net.c
> @@ -332,15 +332,19 @@ static struct sk_buff *page_to_skb(struct virtnet_info *vi,
>  
>  static void virtnet_xdp_xmit(struct virtnet_info *vi,
>  			     struct receive_queue *rq,
> -			     struct send_queue *sq,
>  			     struct xdp_buff *xdp,
>  			     void *data)
>  {
>  	struct virtio_net_hdr_mrg_rxbuf *hdr;
>  	unsigned int num_sg, len;
> +	struct send_queue *sq;
> +	unsigned int qp;
>  	void *xdp_sent;
>  	int err;
>  
> +	qp = vi->curr_queue_pairs - vi->xdp_queue_pairs + smp_processor_id();
> +	sq = &vi->sq[qp];
> +
>  	/* Free up any pending old buffers before queueing new ones. */
>  	while ((xdp_sent = virtqueue_get_buf(sq->vq, &len)) != NULL) {
>  		if (vi->mergeable_rx_bufs) {
> @@ -404,7 +408,6 @@ static struct sk_buff *receive_small(struct net_device *dev,
>  	if (xdp_prog) {
>  		struct virtio_net_hdr_mrg_rxbuf *hdr = buf;
>  		struct xdp_buff xdp;
> -		unsigned int qp;
>  		u32 act;
>  
>  		if (unlikely(hdr->hdr.gso_type || hdr->hdr.flags))
> @@ -417,10 +420,7 @@ static struct sk_buff *receive_small(struct net_device *dev,
>  		case XDP_PASS:
>  			break;
>  		case XDP_TX:
> -			qp = vi->curr_queue_pairs -
> -				vi->xdp_queue_pairs +
> -				smp_processor_id();
> -			virtnet_xdp_xmit(vi, rq, &vi->sq[qp], &xdp, skb);
> +			virtnet_xdp_xmit(vi, rq, &xdp, skb);
>  			rcu_read_unlock();
>  			goto xdp_xmit;
>  		default:
> @@ -545,7 +545,6 @@ static struct sk_buff *receive_mergeable(struct net_device *dev,
>  	if (xdp_prog) {
>  		struct page *xdp_page;
>  		struct xdp_buff xdp;
> -		unsigned int qp;
>  		void *data;
>  		u32 act;
>  
> @@ -586,10 +585,7 @@ static struct sk_buff *receive_mergeable(struct net_device *dev,
>  			}
>  			break;
>  		case XDP_TX:
> -			qp = vi->curr_queue_pairs -
> -				vi->xdp_queue_pairs +
> -				smp_processor_id();
> -			virtnet_xdp_xmit(vi, rq, &vi->sq[qp], &xdp, data);
> +			virtnet_xdp_xmit(vi, rq, &xdp, data);
>  			ewma_pkt_len_add(&rq->mrg_avg_pkt_len, len);
>  			if (unlikely(xdp_page != page))
>  				goto err_xdp;