Commit b26aa481 authored by Heng Qi's avatar Heng Qi Committed by David S. Miller
Browse files

virtio-net: build skb from multi-buffer xdp 



This converts the xdp_buff directly to a skb, including
multi-buffer and single buffer xdp. We'll isolate the
construction of skb based on xdp from page_to_skb().

Signed-off-by: default avatarHeng Qi <hengqi@linux.alibaba.com>
Reviewed-by: default avatarXuan Zhuo <xuanzhuo@linux.alibaba.com>
Acked-by: default avatarJason Wang <jasowang@redhat.com>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent 97717e8d

drivers/net/virtio_net.c

+49 −0
Original line number Diff line number Diff line
@@ -959,6 +959,55 @@ static struct sk_buff *receive_big(struct net_device *dev, 
	return NULL;

}



/* Why not use xdp_build_skb_from_frame() ?

 * XDP core assumes that xdp frags are PAGE_SIZE in length, while in

 * virtio-net there are 2 points that do not match its requirements:

 *  1. The size of the prefilled buffer is not fixed before xdp is set.

 *  2. xdp_build_skb_from_frame() does more checks that we don't need,

 *     like eth_type_trans() (which virtio-net does in receive_buf()).

 */

static struct sk_buff *build_skb_from_xdp_buff(struct net_device *dev,

					       struct virtnet_info *vi,

					       struct xdp_buff *xdp,

					       unsigned int xdp_frags_truesz)

{

	struct skb_shared_info *sinfo = xdp_get_shared_info_from_buff(xdp);

	unsigned int headroom, data_len;

	struct sk_buff *skb;

	int metasize;

	u8 nr_frags;



	if (unlikely(xdp->data_end > xdp_data_hard_end(xdp))) {

		pr_debug("Error building skb as missing reserved tailroom for xdp");

		return NULL;

	}



	if (unlikely(xdp_buff_has_frags(xdp)))

		nr_frags = sinfo->nr_frags;



	skb = build_skb(xdp->data_hard_start, xdp->frame_sz);

	if (unlikely(!skb))

		return NULL;



	headroom = xdp->data - xdp->data_hard_start;

	data_len = xdp->data_end - xdp->data;

	skb_reserve(skb, headroom);

	__skb_put(skb, data_len);



	metasize = xdp->data - xdp->data_meta;

	metasize = metasize > 0 ? metasize : 0;

	if (metasize)

		skb_metadata_set(skb, metasize);



	if (unlikely(xdp_buff_has_frags(xdp)))

		xdp_update_skb_shared_info(skb, nr_frags,

					   sinfo->xdp_frags_size,

					   xdp_frags_truesz,

					   xdp_buff_is_frag_pfmemalloc(xdp));



	return skb;

}



/* TODO: build xdp in big mode */

static int virtnet_build_xdp_buff_mrg(struct net_device *dev,

				      struct virtnet_info *vi,