On Mon, 23 Jul 2018 00:13:02 +0900, Toshiaki Makita wrote:
> From: Toshiaki Makita <makita.toshi...@lab.ntt.co.jp>
>
> This is the basic implementation of veth driver XDP.
>
> Incoming packets are sent from the peer veth device in the form of skb,
> so this is generally doing the same thing as generic XDP.
>
> This itself is not so useful, but a starting point to implement other
> useful veth XDP features like TX and REDIRECT.
>
> This introduces NAPI when XDP is enabled, because XDP is now heavily
> relies on NAPI context. Use ptr_ring to emulate NIC ring. Tx function
> enqueues packets to the ring and peer NAPI handler drains the ring.
>
> Currently only one ring is allocated for each veth device, so it does
> not scale on multiqueue env. This can be resolved by allocating rings
> on the per-queue basis later.
>
> Note that NAPI is not used but netif_rx is used when XDP is not loaded,
> so this does not change the default behaviour.
>
> v3:
> - Fix race on closing the device.
> - Add extack messages in ndo_bpf.
>
> v2:
> - Squashed with the patch adding NAPI.
> - Implement adjust_tail.
> - Don't acquire consumer lock because it is guarded by NAPI.
> - Make poll_controller noop since it is unnecessary.
> - Register rxq_info on enabling XDP rather than on opening the device.
>
> Signed-off-by: Toshiaki Makita <makita.toshi...@lab.ntt.co.jp>
> +static struct sk_buff *veth_xdp_rcv_skb(struct veth_priv *priv,
> + struct sk_buff *skb)
> +{
> + u32 pktlen, headroom, act, metalen;
> + void *orig_data, *orig_data_end;
> + int size, mac_len, delta, off;
> + struct bpf_prog *xdp_prog;
> + struct xdp_buff xdp;
> +
> + rcu_read_lock();
> + xdp_prog = rcu_dereference(priv->xdp_prog);
> + if (unlikely(!xdp_prog)) {
> + rcu_read_unlock();
> + goto out;
> + }
> +
> + mac_len = skb->data - skb_mac_header(skb);
> + pktlen = skb->len + mac_len;
> + size = SKB_DATA_ALIGN(VETH_XDP_HEADROOM + pktlen) +
> + SKB_DATA_ALIGN(sizeof(struct skb_shared_info));
> + if (size > PAGE_SIZE)
> + goto drop;
> +
> + headroom = skb_headroom(skb) - mac_len;
> + if (skb_shared(skb) || skb_head_is_locked(skb) ||
> + skb_is_nonlinear(skb) || headroom < XDP_PACKET_HEADROOM) {
> + struct sk_buff *nskb;
> + void *head, *start;
> + struct page *page;
> + int head_off;
> +
> + page = alloc_page(GFP_ATOMIC);
> + if (!page)
> + goto drop;
> +
> + head = page_address(page);
> + start = head + VETH_XDP_HEADROOM;
> + if (skb_copy_bits(skb, -mac_len, start, pktlen)) {
> + page_frag_free(head);
> + goto drop;
> + }
> +
> + nskb = veth_build_skb(head,
> + VETH_XDP_HEADROOM + mac_len, skb->len,
> + PAGE_SIZE);
> + if (!nskb) {
> + page_frag_free(head);
> + goto drop;
> + }
> +static int veth_enable_xdp(struct net_device *dev)
> +{
> + struct veth_priv *priv = netdev_priv(dev);
> + int err;
> +
> + if (!xdp_rxq_info_is_reg(&priv->xdp_rxq)) {
> + err = xdp_rxq_info_reg(&priv->xdp_rxq, dev, 0);
> + if (err < 0)
> + return err;
> +
> + err = xdp_rxq_info_reg_mem_model(&priv->xdp_rxq,
> + MEM_TYPE_PAGE_SHARED, NULL);
nit: doesn't matter much but looks like a mix of MEM_TYPE_PAGE_SHARED
and MEM_TYPE_PAGE_ORDER0
