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: Xuan Zhuo <xuanzhuo@xxxxxxxxxxxxxxxxx>
---
drivers/net/virtio_net.c | 19 +++++++------------
1 file changed, 7 insertions(+), 12 deletions(-)
diff --git a/drivers/net/virtio_net.c b/drivers/net/virtio_net.c
index e2560b6f7980..42435e762d72 100644
--- a/drivers/net/virtio_net.c
+++ b/drivers/net/virtio_net.c
@@ -1245,6 +1245,9 @@ 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));
@@ -1259,11 +1262,12 @@ 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))
@@ -1278,8 +1282,6 @@ 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:
@@ -1297,8 +1299,6 @@ 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:
@@ -1307,8 +1307,6 @@ 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:
@@ -1321,9 +1319,6 @@ 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++) {
--
2.32.0.3.g01195cf9f
