> > +static __net_init int hwsim_init_net(struct net *net)
> > +{
> > + struct mac80211_hwsim_data *data;
> > + bool exists = true;
> > + int netgroup = 0;
> > +
> > + spin_lock_bh(&hwsim_radio_lock);
> > + while (exists) {
> > + exists = false;
> > + list_for_each_entry(data, &hwsim_radios, list) {
> > + if (netgroup == data->netgroup) {
> > + exists = true;
> > + netgroup++;
> > + break;
> > + }
> > + }
> > + }
> > + spin_unlock_bh(&hwsim_radio_lock);
> > +
> > + *(int *)net_generic(net, hwsim_net_id) = netgroup;
>
> This seems somewhat awkward. Why not just take the maximum of all the
> netgroup IDs + 1? We'd run out of memory and radio IDs long before
> netgroup IDs even that way
My intention was to reuse netgroups for the case many namespaces come
and go, but I agree that it is not optimal.
> consider a new netns that doesn't have any hwsim radios yet.
> Now you create *another* one, but it would get the same netgroup.
Correct, that is indeed broken if there are no radios.
> IOW, you should simply use a global counter. Surprising (net)
> namespaces don't have an index like that already, but I don't see
> one.
Ok, will do that in a v2.
> > +static void __net_exit hwsim_exit_net(struct net *net)
> > +{
> > + struct mac80211_hwsim_data *entry, *tmp;
> > +
> > + spin_lock_bh(&hwsim_radio_lock);
> > + list_for_each_entry_safe(entry, tmp, &hwsim_radios, list) {
> > + if (net_eq(wiphy_net(entry->hw->wiphy), net)) {
> > + list_del(&entry->list);
> > + INIT_WORK(&entry->destroy_work, destroy_radio);
> > + schedule_work(&entry->destroy_work);
> > + }
> > + }
> > + spin_unlock_bh(&hwsim_radio_lock);
> > +}
> This changes today's default behaviour of moving the wiphys to the
> default namespace. Did you intend to destroy them based on the
> netgroup, i.e. based on the namespace that created them? Actually,
> maybe they should move back to the namespace that created them, if
> the namespace they are in is destroyed? But that's difficult, I don't
> mind this behaviour, but I'm not sure it's what we want by default
> for radios created in the init_net.
With the proposed approach I destroy all radios if the owning namespace
gets deleted, because we probably don't want them landing in init_net
if they are created from a (unprivileged) userns process. I think this
is what other "virtual" interfaces do (gre tunnels, veth etc.). If we
think of hwsim radios as such a "virtual" device, that makes IMO sense
to delete them.
If we want to keep the existing behavior, we could move radios
belonging to the init_net-associated netgroup back to init_net, that
shouldn't be too difficult.
Moving the radio back to the creators namespace would be the most
consistent behavior, so I'll check how difficult such a reverse lookup
is. We then would delete the radio only if it is in the creators
namespace, or if the creators namespace is gone. Does that make sense?
Martin
