On Wed, 27 Feb 2019 23:47:33 -0500, Michael S. Tsirkin wrote:
> On Wed, Feb 27, 2019 at 05:52:18PM -0800, Jakub Kicinski wrote:
> > > > Can the users who care about the naming put net_failover into
> > > > "user space will do the bond enslavement" mode, and do the bond
> > > > creation/management themselves from user space (in systemd/
> > > > Network Manager) based on the failover flag?
> > >
> > > Putting issues of compatibility aside (userspace tends to be confused if
> > > you give it two devices with same MAC), how would you have it work in
> > > practice? Timer based hacks like netvsc where if userspace didn't
> > > respond within X seconds we assume it won't and do everything ourselves?
> >
> > Well, what I'm saying is basically if user space knows how to deal with
> > the auto-bonding, we can put aside net_failover for the most part. It
> > can either be blacklisted or it can have some knob which will
> > effectively disable the auto-enslavement.
>
> OK I guess we could add a module parameter to skip this.
> Is this what you mean?
Yup.
> > Auto-bonding capable user space can do the renames, spawn the bond,
> > etc. all by itself. I'm basically going back to my initial proposal
> > here :) There is a RedHat bugzilla for the NetworkManager team to do
> > this, but we merged net_failover before those folks got around to
> > implementing it.
>
> In particular because there's no policy involved whatsoever
> here so it's just mechanism being pushed up to userspace.
>
> > IOW if NM/systemd is capable of doing the auto-bonding itself it can
> > disable the kernel mechanism and take care of it all. If kernel is
> > booted with an old user space which doesn't have capable NM/systemd -
> > net_failover will kick in and do its best.
>
> Sure - it's just 2 lines of code, see below.
>
> Signed-off-by: Michael S. Tsirkin <m...@redhat.com>
>
> But I don't intend to bother until there's actual interest from
> userspace developers to bother. In particular it is not just NM/systemd
> even on Fedora - e.g. you will need to teach dracut to somehow detect
> and handle this - right now it gets confused if there are two devices
> with same MAC addresses.
It is a bit of a the chicken or the egg situation ;) But users can
just blacklist, too. Anyway, I think this is far better than module
parameters for twiddling kernel-based interface naming policy.. :S
> diff --git a/drivers/net/virtio_net.c b/drivers/net/virtio_net.c
> index 955b3e76eb8d..dd2b2c370003 100644
> --- a/drivers/net/virtio_net.c
> +++ b/drivers/net/virtio_net.c
> @@ -43,6 +43,7 @@ static bool csum = true, gso = true, napi_tx;
> module_param(csum, bool, 0444);
> module_param(gso, bool, 0444);
> module_param(napi_tx, bool, 0644);
> +module_param(disable_failover, bool, 0644);
>
> /* FIXME: MTU in config. */
> #define GOOD_PACKET_LEN (ETH_HLEN + VLAN_HLEN + ETH_DATA_LEN)
> @@ -3163,6 +3164,7 @@ static int virtnet_probe(struct virtio_device *vdev)
> virtnet_init_settings(dev);
>
> - if (virtio_has_feature(vdev, VIRTIO_NET_F_STANDBY)) {
> + if (virtio_has_feature(vdev, VIRTIO_NET_F_STANDBY) &&
> + !disable_failover) {
> vi->failover = net_failover_create(vi->dev);
> if (IS_ERR(vi->failover)) {
> err = PTR_ERR(vi->failover);
>
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