Subject: Re: [PATCH V4 net-next 3/3] virtio-net: synchronize operstate with admin state on up/down

From: "Michael S. Tsirkin" <[email-masked]>
Date: Thu, 1 Aug 2024 02:05:54 -0400

On Wed, Jul 31, 2024 at 10:59:47AM +0800, Jason Wang wrote:
> This patch synchronize operstate with admin state per RFC2863.
> 
> This is done by trying to toggle the carrier upon open/close and
> synchronize with the config change work. This allows propagate status
> correctly to stacked devices like:
> 
> ip link add link enp0s3 macvlan0 type macvlan
> ip link set link enp0s3 down
> ip link show
> 
> Before this patch:
> 
> 3: enp0s3: <BROADCAST,MULTICAST> mtu 1500 qdisc pfifo_fast state DOWN mode DEFAULT group default qlen 1000
>     link/ether 00:00:05:00:00:09 brd ff:ff:ff:ff:ff:ff
> ......
> 5: macvlan0@enp0s3: <BROADCAST,MULTICAST,UP,LOWER_UP,M-DOWN> mtu 1500 qdisc noqueue state UP mode DEFAULT group default qlen 1000
>     link/ether b2:a9:c5:04:da:53 brd ff:ff:ff:ff:ff:ff
> 
> After this patch:
> 
> 3: enp0s3: <BROADCAST,MULTICAST> mtu 1500 qdisc pfifo_fast state DOWN mode DEFAULT group default qlen 1000
>     link/ether 00:00:05:00:00:09 brd ff:ff:ff:ff:ff:ff
> ...
> 5: macvlan0@enp0s3: <NO-CARRIER,BROADCAST,MULTICAST,UP,M-DOWN> mtu 1500 qdisc noqueue state LOWERLAYERDOWN mode DEFAULT group default qlen 1000
>     link/ether b2:a9:c5:04:da:53 brd ff:ff:ff:ff:ff:ff
> 
> Cc: Venkat Venkatsubra <[email-masked]>
> Cc: Gia-Khanh Nguyen <[email-masked]>
> Signed-off-by: Jason Wang <[email-masked]>
> ---
>  drivers/net/virtio_net.c | 84 ++++++++++++++++++++++++++--------------
>  1 file changed, 54 insertions(+), 30 deletions(-)
> 
> diff --git a/drivers/net/virtio_net.c b/drivers/net/virtio_net.c
> index 0383a3e136d6..0cb93261eba1 100644
> --- a/drivers/net/virtio_net.c
> +++ b/drivers/net/virtio_net.c
> @@ -2878,6 +2878,7 @@ static int virtnet_enable_queue_pair(struct virtnet_info *vi, int qp_index)
>  	return err;
>  }
>  
> +
>  static void virtnet_cancel_dim(struct virtnet_info *vi, struct dim *dim)
>  {
>  	if (!virtio_has_feature(vi->vdev, VIRTIO_NET_F_VQ_NOTF_COAL))
> @@ -2885,6 +2886,25 @@ static void virtnet_cancel_dim(struct virtnet_info *vi, struct dim *dim)
>  	net_dim_work_cancel(dim);
>  }
>  
> +static void virtnet_update_settings(struct virtnet_info *vi)
> +{
> +	u32 speed;
> +	u8 duplex;
> +
> +	if (!virtio_has_feature(vi->vdev, VIRTIO_NET_F_SPEED_DUPLEX))
> +		return;
> +
> +	virtio_cread_le(vi->vdev, struct virtio_net_config, speed, &speed);
> +
> +	if (ethtool_validate_speed(speed))
> +		vi->speed = speed;
> +
> +	virtio_cread_le(vi->vdev, struct virtio_net_config, duplex, &duplex);
> +
> +	if (ethtool_validate_duplex(duplex))
> +		vi->duplex = duplex;
> +}
> +
>  static int virtnet_open(struct net_device *dev)
>  {
>  	struct virtnet_info *vi = netdev_priv(dev);
> @@ -2903,6 +2923,16 @@ static int virtnet_open(struct net_device *dev)
>  			goto err_enable_qp;
>  	}
>  
> +	if (virtio_has_feature(vi->vdev, VIRTIO_NET_F_STATUS)) {
> +		if (vi->status & VIRTIO_NET_S_LINK_UP)
> +			netif_carrier_on(vi->dev);
> +		virtio_config_driver_enable(vi->vdev);
> +	} else {
> +		vi->status = VIRTIO_NET_S_LINK_UP;
> +		netif_carrier_on(dev);
> +		virtnet_update_settings(vi);
> +	}
> +
>  	return 0;
>  
>  err_enable_qp:
> @@ -3381,12 +3411,18 @@ static int virtnet_close(struct net_device *dev)
>  	disable_delayed_refill(vi);
>  	/* Make sure refill_work doesn't re-enable napi! */
>  	cancel_delayed_work_sync(&vi->refill);
> +	/* Make sure config notification doesn't schedule config work */
> +	virtio_config_driver_disable(vi->vdev);
> +	/* Make sure status updating is cancelled */
> +	cancel_work_sync(&vi->config_work);
>  
>  	for (i = 0; i < vi->max_queue_pairs; i++) {
>  		virtnet_disable_queue_pair(vi, i);
>  		virtnet_cancel_dim(vi, &vi->rq[i].dim);
>  	}
>  
> +	netif_carrier_off(dev);
> +
>  	return 0;
>  }
>  
> @@ -5085,25 +5121,6 @@ static void virtnet_init_settings(struct net_device *dev)
>  	vi->duplex = DUPLEX_UNKNOWN;
>  }
>  
> -static void virtnet_update_settings(struct virtnet_info *vi)
> -{
> -	u32 speed;
> -	u8 duplex;
> -
> -	if (!virtio_has_feature(vi->vdev, VIRTIO_NET_F_SPEED_DUPLEX))
> -		return;
> -
> -	virtio_cread_le(vi->vdev, struct virtio_net_config, speed, &speed);
> -
> -	if (ethtool_validate_speed(speed))
> -		vi->speed = speed;
> -
> -	virtio_cread_le(vi->vdev, struct virtio_net_config, duplex, &duplex);
> -
> -	if (ethtool_validate_duplex(duplex))
> -		vi->duplex = duplex;
> -}
> -
>  static u32 virtnet_get_rxfh_key_size(struct net_device *dev)
>  {
>  	return ((struct virtnet_info *)netdev_priv(dev))->rss_key_size;
> @@ -6514,6 +6531,11 @@ static int virtnet_probe(struct virtio_device *vdev)
>  		goto free_failover;
>  	}
>  
> +	/* Forbid config change notification until ndo_open. */
> +	virtio_config_driver_disable(vi->vdev);
> +	/* Make sure status updating work is done */

Wait a second, how can anything run here, this is probe,
config change callbacks are never invoked at all.

> +	cancel_work_sync(&vi->config_work);
> +

this is pointless, too.

>  	virtio_device_ready(vdev);
>  
>  	virtnet_set_queues(vi, vi->curr_queue_pairs);
> @@ -6563,6 +6585,19 @@ static int virtnet_probe(struct virtio_device *vdev)
>  		vi->device_stats_cap = le64_to_cpu(v);
>  	}
>  
> +	/* Assume link up if device can't report link status,
> +           otherwise get link status from config. */
> +        netif_carrier_off(dev);
> +        if (virtio_has_feature(vi->vdev, VIRTIO_NET_F_STATUS)) {
> +		/* This is safe as config notification change has been
> +		   disabled. */

What "this"? pls explain what this does: get config data from
device.

Actually not because it was disabled. probe can poke at
config with impunity no change callbacks trigger during probe.

> +                virtnet_config_changed_work(&vi->config_work);

> +        } else {
> +                vi->status = VIRTIO_NET_S_LINK_UP;
> +                virtnet_update_settings(vi);
> +                netif_carrier_on(dev);
> +        }
> +
>  	rtnl_unlock();
>  
>  	err = virtnet_cpu_notif_add(vi);
> @@ -6571,17 +6606,6 @@ static int virtnet_probe(struct virtio_device *vdev)
>  		goto free_unregister_netdev;
>  	}
>  
> -	/* Assume link up if device can't report link status,
> -	   otherwise get link status from config. */
> -	netif_carrier_off(dev);
> -	if (virtio_has_feature(vi->vdev, VIRTIO_NET_F_STATUS)) {
> -		schedule_work(&vi->config_work);
> -	} else {
> -		vi->status = VIRTIO_NET_S_LINK_UP;
> -		virtnet_update_settings(vi);
> -		netif_carrier_on(dev);
> -	}
> -
>  	for (i = 0; i < ARRAY_SIZE(guest_offloads); i++)
>  		if (virtio_has_feature(vi->vdev, guest_offloads[i]))
>  			set_bit(guest_offloads[i], &vi->guest_offloads);
> -- 
> 2.31.1