Subject: Re: [PATCH net] virtio-net: fix race between set queues and probe

From: "Michael S. Tsirkin" <[email-masked]>
Date: Tue, 25 Jul 2023 03:53:09 -0400

On Tue, Jul 25, 2023 at 03:20:49AM -0400, Jason Wang wrote:
> A race were found where set_channels could be called after registering
> but before virtnet_set_queues() in virtnet_probe(). Fixing this by
> moving the virtnet_set_queues() before netdevice registering. While at
> it, use _virtnet_set_queues() to avoid holding rtnl as the device is
> not even registered at that time.
> 
> Fixes: a220871be66f ("virtio-net: correctly enable multiqueue")
> Signed-off-by: Jason Wang <[email-masked]>

Acked-by: Michael S. Tsirkin <[email-masked]>

stable material I guess?

> ---
>  drivers/net/virtio_net.c | 4 ++--
>  1 file changed, 2 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/net/virtio_net.c b/drivers/net/virtio_net.c
> index 0db14f6b87d3..1270c8d23463 100644
> --- a/drivers/net/virtio_net.c
> +++ b/drivers/net/virtio_net.c
> @@ -4219,6 +4219,8 @@ static int virtnet_probe(struct virtio_device *vdev)
>  	if (vi->has_rss || vi->has_rss_hash_report)
>  		virtnet_init_default_rss(vi);
>  
> +	_virtnet_set_queues(vi, vi->curr_queue_pairs);
> +
>  	/* serialize netdev register + virtio_device_ready() with ndo_open() */
>  	rtnl_lock();
>  
> @@ -4257,8 +4259,6 @@ static int virtnet_probe(struct virtio_device *vdev)
>  		goto free_unregister_netdev;
>  	}
>  
> -	virtnet_set_queues(vi, vi->curr_queue_pairs);
> -
>  	/* Assume link up if device can't report link status,
>  	   otherwise get link status from config. */
>  	netif_carrier_off(dev);
> -- 
> 2.39.3