On Tue, Apr 10, 2018 at 8:43 AM, Jiri Pirko <jiri@xxxxxxxxxxx> wrote:
> Tue, Apr 10, 2018 at 05:27:48PM CEST, sridhar.samudrala@xxxxxxxxx wrote:
>>On 4/10/2018 8:22 AM, Jiri Pirko wrote:
>>> Tue, Apr 10, 2018 at 05:13:40PM CEST, sridhar.samudrala@xxxxxxxxx wrote:
>>> > On 4/10/2018 3:55 AM, Jiri Pirko wrote:
>>> > > Mon, Apr 09, 2018 at 08:47:06PM CEST, sridhar.samudrala@xxxxxxxxx wrote:
>>> > > > On 4/9/2018 1:07 AM, Jiri Pirko wrote:
>>> > > > > Sat, Apr 07, 2018 at 12:59:14AM CEST, sridhar.samudrala@xxxxxxxxx wrote:
>>> > > > > > On 4/6/2018 5:48 AM, Jiri Pirko wrote:
>>> > > > > > > Thu, Apr 05, 2018 at 11:08:22PM CEST, sridhar.samudrala@xxxxxxxxx wrote:
>>> > > > > [...]
>>> > > > >
>>> > > > > > > > +static int virtnet_bypass_join_child(struct net_device *bypass_netdev,
>>> > > > > > > > + struct net_device *child_netdev)
>>> > > > > > > > +{
>>> > > > > > > > + struct virtnet_bypass_info *vbi;
>>> > > > > > > > + bool backup;
>>> > > > > > > > +
>>> > > > > > > > + vbi = netdev_priv(bypass_netdev);
>>> > > > > > > > + backup = (child_netdev->dev.parent == bypass_netdev->dev.parent);
>>> > > > > > > > + if (backup ? rtnl_dereference(vbi->backup_netdev) :
>>> > > > > > > > + rtnl_dereference(vbi->active_netdev)) {
>>> > > > > > > > + netdev_info(bypass_netdev,
>>> > > > > > > > + "%s attempting to join bypass dev when %s already present\n",
>>> > > > > > > > + child_netdev->name, backup ? "backup" : "active");
>>> > > > > > > Bypass module should check if there is already some other netdev
>>> > > > > > > enslaved and refuse right there.
>>> > > > > > This will work for virtio-net with 3 netdev model, but this check has to be done by netvsc
>>> > > > > > as its bypass_netdev is same as the backup_netdev.
>>> > > > > > Will add a flag while registering with the bypass module to indicate if the driver is doing
>>> > > > > > a 2 netdev or 3 netdev model and based on that flag this check can be done in bypass module
>>> > > > > > for 3 netdev scenario.
>>> > > > > Just let me undestand it clearly. What I expect the difference would be
>>> > > > > between 2netdev and3 netdev model is this:
>>> > > > > 2netdev:
>>> > > > > bypass_master
>>> > > > > /
>>> > > > > /
>>> > > > > VF_slave
>>> > > > >
>>> > > > > 3netdev:
>>> > > > > bypass_master
>>> > > > > / \
>>> > > > > / \
>>> > > > > VF_slave backup_slave
>>> > > > >
>>> > > > > Is that correct? If not, how does it look like?
>>> > > > >
>>> > > > >
>>> > > > Looks correct.
>>> > > > VF_slave and backup_slave are the original netdevs and are present in both the models.
>>> > > > In the 3 netdev model, bypass_master netdev is created and VF_slave and backup_slave are
>>> > > > marked as the 2 slaves of this new netdev.
>>> > > You say it looks correct and in another sentence you provide completely
>>> > > different description. Could you please look again?
>>> > >
>>> > To be exact, 2 netdev model with netvsc looks like this.
>>> >
>>> > netvsc_netdev
>>> > /
>>> > /
>>> > VF_slave
>>> >
>>> > With virtio_net, 3 netdev model
>>> >
>>> > bypass_netdev
>>> > / \
>>> > / \
>>> > VF_slave virtio_net netdev
>>> Could you also mark the original netdev which is there now? is it
>>> bypass_netdev or virtio_net_netdev ?
>>
>> bypass_netdev
>> / \
>> / \
>>VF_slave virtio_net netdev (original)
>
> That does not make sense.
> 1) You diverge from the behaviour of the netvsc, where the original
> netdev is a master of the VF
> 2) If the original netdev is a slave, you cannot have any IP address
> configured on it (well you could, but the rx_handler would eat every
> incoming packet). So you will break the user bacause he would have to
> move the configuration to the new master device.
That's exactly the point why I need to hide the lower netdev slaves
and trying the align the naming of the bypass with where IP was
configured on the original netdev. The current 3-netdev model is not
"transparent" by any means.
-Siwei
> This only makes sense that the original netdev becomes the master for both
> netvsc and virtio_net.
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