[PATCH net-next v2 2/3] vhost_net: Call peek_len when using xdp

[Yunjian Wang]

If TUN supports AF_XDP TX zero-copy, the XDP program will enqueue
packets to the XDP ring and wake up the vhost worker. This requires
the vhost worker to call peek_len(), which can be used to consume
XDP descriptors.

Signed-off-by: Yunjian Wang <wangyunj...@huawei.com>
---
 drivers/vhost/net.c | 17 ++++++++++++-----
 1 file changed, 12 insertions(+), 5 deletions(-)

diff --git a/drivers/vhost/net.c b/drivers/vhost/net.c
index f2ed7167c848..077e74421558 100644
--- a/drivers/vhost/net.c
+++ b/drivers/vhost/net.c
@@ -207,6 +207,11 @@ static int vhost_net_buf_peek_len(void *ptr)
        return __skb_array_len_with_tag(ptr);
 }
 
+static bool vhost_sock_xdp(struct socket *sock)
+{
+       return sock_flag(sock->sk, SOCK_XDP);
+}
+
 static int vhost_net_buf_peek(struct vhost_net_virtqueue *nvq)
 {
        struct vhost_net_buf *rxq = &nvq->rxq;
@@ -214,6 +219,13 @@ static int vhost_net_buf_peek(struct vhost_net_virtqueue 
*nvq)
        if (!vhost_net_buf_is_empty(rxq))
                goto out;
 
+       if (ptr_ring_empty(nvq->rx_ring)) {
+               struct socket *sock = vhost_vq_get_backend(&nvq->vq);
+               /* Call peek_len to consume XSK descriptors, when using xdp */
+               if (vhost_sock_xdp(sock) && sock->ops->peek_len)
+                       sock->ops->peek_len(sock);
+       }
+
        if (!vhost_net_buf_produce(nvq))
                return 0;
 
@@ -346,11 +358,6 @@ static bool vhost_sock_zcopy(struct socket *sock)
                sock_flag(sock->sk, SOCK_ZEROCOPY);
 }
 
-static bool vhost_sock_xdp(struct socket *sock)
-{
-       return sock_flag(sock->sk, SOCK_XDP);
-}
-
 /* In case of DMA done not in order in lower device driver for some reason.
  * upend_idx is used to track end of used idx, done_idx is used to track head
  * of used idx. Once lower device DMA done contiguously, we will signal KVM
-- 
2.41.0