Commit 363d8ce4 authored by Xuan Zhuo's avatar Xuan Zhuo Committed by Jakub Kicinski
Browse files

virtio_net: mergeable xdp: put old page immediately 



In the xdp implementation of virtio-net mergeable, it always checks
whether two page is used and a page is selected to release. This is
complicated for the processing of action, and be careful.

In the entire process, we have such principles:
* If xdp_page is used (PASS, TX, Redirect), then we release the old
  page.
* If it is a drop case, we will release two. The old page obtained from
  buf is release inside err_xdp, and xdp_page needs be relased by us.

But in fact, when we allocate a new page, we can release the old page
immediately. Then just one is using, we just need to release the new
page for drop case. On the drop path, err_xdp will release the variable
"page", so we only need to let "page" point to the new xdp_page in
advance.

Signed-off-by: default avatarXuan Zhuo <xuanzhuo@linux.alibaba.com>
Acked-by: default avatarJason Wang <jasowang@redhat.com>
Signed-off-by: default avatarJakub Kicinski <kuba@kernel.org>
parent 559ae55c

drivers/net/virtio_net.c

+7 −12
Original line number Diff line number Diff line
@@ -1249,6 +1249,9 @@ static struct sk_buff *receive_mergeable(struct net_device *dev, 
			if (!xdp_page)

				goto err_xdp;

			offset = VIRTIO_XDP_HEADROOM;



			put_page(page);

			page = xdp_page;

		} else if (unlikely(headroom < virtnet_get_headroom(vi))) {

			xdp_room = SKB_DATA_ALIGN(VIRTIO_XDP_HEADROOM +

						  sizeof(struct skb_shared_info));
@@ -1263,11 +1266,12 @@ static struct sk_buff *receive_mergeable(struct net_device *dev, 
			       page_address(page) + offset, len);

			frame_sz = PAGE_SIZE;

			offset = VIRTIO_XDP_HEADROOM;

		} else {

			xdp_page = page;



			put_page(page);

			page = xdp_page;

		}



		data = page_address(xdp_page) + offset;

		data = page_address(page) + offset;

		err = virtnet_build_xdp_buff_mrg(dev, vi, rq, &xdp, data, len, frame_sz,

						 &num_buf, &xdp_frags_truesz, stats);

		if (unlikely(err))
@@ -1282,8 +1286,6 @@ static struct sk_buff *receive_mergeable(struct net_device *dev, 
			if (unlikely(!head_skb))

				goto err_xdp_frags;



			if (unlikely(xdp_page != page))

				put_page(page);

			rcu_read_unlock();

			return head_skb;

		case XDP_TX:
@@ -1301,8 +1303,6 @@ static struct sk_buff *receive_mergeable(struct net_device *dev, 
				goto err_xdp_frags;

			}

			*xdp_xmit |= VIRTIO_XDP_TX;

			if (unlikely(xdp_page != page))

				put_page(page);

			rcu_read_unlock();

			goto xdp_xmit;

		case XDP_REDIRECT:
@@ -1311,8 +1311,6 @@ static struct sk_buff *receive_mergeable(struct net_device *dev, 
			if (err)

				goto err_xdp_frags;

			*xdp_xmit |= VIRTIO_XDP_REDIR;

			if (unlikely(xdp_page != page))

				put_page(page);

			rcu_read_unlock();

			goto xdp_xmit;

		default:
@@ -1325,9 +1323,6 @@ static struct sk_buff *receive_mergeable(struct net_device *dev, 
			goto err_xdp_frags;

		}

err_xdp_frags:

		if (unlikely(xdp_page != page))

			__free_pages(xdp_page, 0);



		if (xdp_buff_has_frags(&xdp)) {

			shinfo = xdp_get_shared_info_from_buff(&xdp);

			for (i = 0; i < shinfo->nr_frags; i++) {