netdev - Re: [PATCH] net: tun: fix tun_xdp_one() for IFF

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Date:   Tue, 22 Jun 2021 15:51:43 +0800
From:   Jason Wang <jasowang@...hat.com>
To:     David Woodhouse <dwmw2@...radead.org>,
        netdev <netdev@...r.kernel.org>
Cc:     Eugenio Pérez <eperezma@...hat.com>
Subject: Re: [PATCH] net: tun: fix tun_xdp_one() for IFF_TUN mode


在 2021/6/22 下午3:24, David Woodhouse 写道:
> On Tue, 2021-06-22 at 12:52 +0800, Jason Wang wrote:
>>
>> I cook two patches. Please see and check if they fix the problem.
>> (compile test only for me).
> I did the second one slightly differently (below) but those are what I
> came up with too, which seems to be working.
>
> @@ -2331,7 +2344,7 @@ static int tun_xdp_one(struct tun_struct *tun,
>   {
>          unsigned int datasize = xdp->data_end - xdp->data;
>          struct tun_xdp_hdr *hdr = xdp->data_hard_start;
> -       struct virtio_net_hdr *gso = &hdr->gso;
> +       struct virtio_net_hdr *gso = NULL;
>          struct bpf_prog *xdp_prog;
>          struct sk_buff *skb = NULL;
>          u32 rxhash = 0, act;
> @@ -2340,9 +2353,12 @@ static int tun_xdp_one(struct tun_struct *tun,
>          bool skb_xdp = false;
>          struct page *page;
>   
> +       if (tun->flags & IFF_VNET_HDR)
> +               gso = &hdr->gso;
> +
>          xdp_prog = rcu_dereference(tun->xdp_prog);
>          if (xdp_prog) {
> -               if (gso->gso_type) {
> +               if (gso && gso->gso_type) {
>                          skb_xdp = true;
>                          goto build;
>                  }
> @@ -2388,14 +2406,18 @@ static int tun_xdp_one(struct tun_struct *tun,
>          skb_reserve(skb, xdp->data - xdp->data_hard_start);
>          skb_put(skb, xdp->data_end - xdp->data);
>   
> -       if (virtio_net_hdr_to_skb(skb, gso, tun_is_little_endian(tun))) {
> +       if (!gso)
> +               skb_reset_mac_header(skb);
> +       else if (virtio_net_hdr_to_skb(skb, gso, tun_is_little_endian(tun))) {
>                  atomic_long_inc(&tun->rx_frame_errors);
>                  kfree_skb(skb);


This should work as well.

Thanks