On Thu, Feb 28, 2019 at 10:13:56AM -0800, Jakub Kicinski wrote:

On Wed, 27 Feb 2019 23:47:33 -0500, Michael S. Tsirkin wrote:

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On Wed, Feb 27, 2019 at 05:52:18PM -0800, Jakub Kicinski wrote:

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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.

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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.

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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 <mst@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

Sorry I'm a bit confused. What is better than what?

for twiddling kernel-based interface naming policy.. :S

I see your point. But my point is slave names don't really matter, only
master name matters.  So I am not sure there's any policy worth talking
about here.

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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);