On 2019/4/25 上午1:40, David Ahern wrote:
On 4/24/19 11:37 AM, Michael S. Tsirkin wrote:diff --git a/drivers/net/virtio_net.c b/drivers/net/virtio_net.c index 9010938e2d71..ccc1bdd1bb1f 100644 --- a/drivers/net/virtio_net.c +++ b/drivers/net/virtio_net.c @@ -495,8 +495,8 @@ static struct send_queue *virtnet_xdp_sq(struct virtnet_info *vi) return &vi->sq[qp]; }-static int virtnet_xdp_xmit(struct net_device *dev,- int n, struct xdp_frame **frames, u32 flags) +static int __virtnet_xdp_xmit(struct net_device *dev, + int n, struct xdp_frame **frames, u32 flags) { struct virtnet_info *vi = netdev_priv(dev); struct receive_queue *rq = vi->rq; @@ -569,6 +569,17 @@ static int virtnet_xdp_xmit(struct net_device *dev, return ret; }+static int virtnet_xdp_xmit(struct net_device *dev,+ int n, struct xdp_frame **frames, u32 flags) +{ + int r; + + rcu_read_lock_bh(); + r = __virtnet_xdp_xmit(dev, n, frames, flags); + rcu_read_unlock_bh(); + return r; +} + static unsigned int virtnet_get_headroom(struct virtnet_info *vi) { return vi->xdp_queue_pairs ? VIRTIO_XDP_HEADROOM : 0; @@ -714,7 +725,7 @@ static struct sk_buff *receive_small(struct net_device *dev,receive_small takes the rcu lock at the beginning.
Yes, so the code call __virtnet_xdp_xmit() that won't try to take rcu lock. Thanks
xdpf = convert_to_xdp_frame(&xdp); if (unlikely(!xdpf)) goto err_xdp; - err = virtnet_xdp_xmit(dev, 1, &xdpf, 0); + err = __virtnet_xdp_xmit(dev, 1, &xdpf, 0); if (unlikely(err < 0)) { trace_xdp_exception(vi->dev, xdp_prog, act); goto err_xdp; @@ -887,7 +898,7 @@ static struct sk_buff *receive_mergeable(struct net_device *dev,same here.xdpf = convert_to_xdp_frame(&xdp); if (unlikely(!xdpf)) goto err_xdp; - err = virtnet_xdp_xmit(dev, 1, &xdpf, 0); + err = __virtnet_xdp_xmit(dev, 1, &xdpf, 0); if (unlikely(err < 0)) { trace_xdp_exception(vi->dev, xdp_prog, act); if (unlikely(xdp_page != page))bq_xmit_all is invoking the xdp_xmit callback without taking the rcu lock, but from the git history does not appear to have any recent changes.
