Re: [PATCH net 2/3] vhost_net: keep private_data and rx_ring synced

[Michael S. Tsirkin]

On Fri, Mar 09, 2018 at 02:50:33PM +0800, Jason Wang wrote:
> We get pointer ring from the exported sock, this means we should keep
> rx_ring and vq->private synced during both vq stop and backend set,
> otherwise we may see stale rx_ring.
> 
> Fixes: c67df11f6e480 ("vhost_net: try batch dequing from skb array")
> Signed-off-by: Michael S. Tsirkin <mst@xxxxxxxxxx>
> Signed-off-by: Jason Wang <jasowang@xxxxxxxxxx>

Acked-by: Michael S. Tsirkin <mst@xxxxxxxxxx>

> ---
>  drivers/vhost/net.c | 5 +++--
>  1 file changed, 3 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/vhost/net.c b/drivers/vhost/net.c
> index 60f1080..efb9306 100644
> --- a/drivers/vhost/net.c
> +++ b/drivers/vhost/net.c
> @@ -973,6 +973,7 @@ static struct socket *vhost_net_stop_vq(struct vhost_net *n,
>  	vhost_net_disable_vq(n, vq);
>  	vq->private_data = NULL;
>  	vhost_net_buf_unproduce(nvq);
> +	nvq->rx_ring = NULL;
>  	mutex_unlock(&vq->mutex);
>  	return sock;
>  }
> @@ -1162,14 +1163,14 @@ static long vhost_net_set_backend(struct vhost_net *n, unsigned index, int fd)
>  		vhost_net_disable_vq(n, vq);
>  		vq->private_data = sock;
>  		vhost_net_buf_unproduce(nvq);
> -		if (index == VHOST_NET_VQ_RX)
> -			nvq->rx_ring = get_tap_ptr_ring(fd);
>  		r = vhost_vq_init_access(vq);
>  		if (r)
>  			goto err_used;
>  		r = vhost_net_enable_vq(n, vq);
>  		if (r)
>  			goto err_used;
> +		if (index == VHOST_NET_VQ_RX)
> +			nvq->rx_ring = get_tap_ptr_ring(fd);
>  
>  		oldubufs = nvq->ubufs;
>  		nvq->ubufs = ubufs;
> -- 
> 2.7.4