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 02:42:52 -0400

On Thu, Aug 01, 2024 at 02:13:49PM +0800, Jason Wang wrote:
> On Thu, Aug 1, 2024 at 2:06 PM Michael S. Tsirkin <[email-masked]> wrote:
> >
> > 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.
> 
> For buggy devices.

buggy or not, virtio core will not invoke callbacks until
after probe and scan.

> >
> > > +     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.
> 
> Only if we have a good device.

not if you read the core code.

> >
> > > +                virtnet_config_changed_work(&vi->config_work);
> >
> >
> >
> 
> Thanks
> 
> 
> >
> > > +        } 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
> >