Re: [PATCH net-next 3/3] virtio-net: support XDP_REDIRECT

From: John Fastabend
Date: Wed Sep 20 2017 - 18:03:06 EST


On 09/19/2017 02:42 AM, Jason Wang wrote:
> This patch tries to add XDP_REDIRECT for virtio-net. The changes are
> not complex as we could use exist XDP_TX helpers for most of the
> work. The rest is passing the XDP_TX to NAPI handler for implementing
> batching.
>
> Cc: John Fastabend <john.fastabend@xxxxxxxxx>
> Signed-off-by: Jason Wang <jasowang@xxxxxxxxxx>
> ---

[...]

> @@ -678,12 +711,20 @@ static struct sk_buff *receive_mergeable(struct net_device *dev,
> }
> break;
> case XDP_TX:
> - if (unlikely(!virtnet_xdp_xmit(vi, &xdp)))
> + if (unlikely(!__virtnet_xdp_xmit(vi, &xdp)))
> trace_xdp_exception(vi->dev, xdp_prog, act);
> + else
> + *xdp_xmit = true;
> if (unlikely(xdp_page != page))
> goto err_xdp;
> rcu_read_unlock();
> goto xdp_xmit;
> + case XDP_REDIRECT:
> + err = xdp_do_redirect(dev, &xdp, xdp_prog);
> + if (err)
> + *xdp_xmit = true;

Is this a typo? Should above be

if (!err)
*xdp_xmit = true;

this would match the pattern in receive_small and also make more sense.

> + rcu_read_unlock();
> + goto xdp_xmit;
> default:
> bpf_warn_invalid_xdp_action(act);
> case XDP_ABORTED:
> @@ -788,7 +829,7 @@ static struct sk_buff *receive_mergeable(struct net_device *dev,
> }
>

[...]

Otherwise looks good to me thanks for doing this.

.John