Re: [PATCH v1 net-next 3/3] geneve: Support per-netns netdev unregistration.

On Tue, Aug 4, 2026 at 6:47 AM Paolo Abeni <[email protected]> wrote:
>
> On 7/31/26 6:45 PM, Kuniyuki Iwashima wrote:
> > geneve_exit_rtnl_net() iterates geneve devices whose sockets
> > are in the dying netns and queues them for destruction.
> >
> > So the devices may reside in different netns.
> >
> > Let's use unregister_netdevice_queue_net() to support per-netns
> > device unregistration.
> >
> > list_del() is changed to list_del_init() to avoid queueing the
> > same device twice.
> >
> > Even after geneve_exit_rtnl_net() queues a cross-netns geneve
> > device, geneve_dellink() can be called concurrently for it.
> > In such a case, __rtnl_net_unlock() will perform the unregistration.
> >
> > Note that geneve uses register_pernet_subsys() instead of _device(),
> > so default_device_exit_batch() guarantees that the async per-netns
> > works are flushed before ->exit().
> >
> > Tested:
> >
> > 1. Create geneve device across two netns.
> >
> >   # ip netns add ns1
> >   # ip netns add ns2
> >   # ip -n ns1 link add geneve0 link-netns ns2 type geneve external
> >
> > 2. Run bpftrace to check that geneve_uninit() is called between
> >    ->exit_rtnl() and ->exit().
> >
> >   # bpftrace -e '#include <linux/netdevice.h>
> >   kprobe:geneve_uninit {
> >       $dev = (struct net_device *)arg0;
> >       printf("PID: %d | DEV: %s%s\n", pid, $dev->name, kstack());
> >   }
> >   kprobe:geneve_exit_rtnl_net,
> >   kprobe:geneve_exit_net {
> >       printf("PID: %d%s\n", pid, kstack());
> >   }'
> >
> > 3. Remove the netns where the geneve socket resides
> >
> >   # ip netns del ns2
> >
> > Now, we can see geneve0 is unregistered by per-netns work
> > instead of cleanup_net() and it finishes before ->exit() to
> > avoid WARN_ON_ONCE(!list_empty(&gn->sock_list)) there.
> >
> >   PID: 571
> >           geneve_exit_rtnl_net+5
> >           ops_undo_list+702
> >           cleanup_net+1122
> >           process_scheduled_works+2538
> >   ...
> >   PID: 1047 | DEV: geneve0
> >           geneve_uninit+5
> >           unregister_netdevice_many_notify+7129
> >           unregister_netdevice_many_net+1050
> >           rtnl_net_work_func+136
> >           process_scheduled_works+2538
> >   ...
> >   PID: 571
> >           geneve_exit_net+5
> >           ops_undo_list+1064
> >           cleanup_net+1122
> >           process_scheduled_works+2538
> >   ...
> >
> > Signed-off-by: Kuniyuki Iwashima <[email protected]>
> > ---
> >  drivers/net/geneve.c | 12 +++++++-----
> >  1 file changed, 7 insertions(+), 5 deletions(-)
> >
> > diff --git a/drivers/net/geneve.c b/drivers/net/geneve.c
> > index f456a85dca77..a6a8978e3b81 100644
> > --- a/drivers/net/geneve.c
> > +++ b/drivers/net/geneve.c
> > @@ -2502,12 +2502,13 @@ static int geneve_changelink(struct net_device *dev, struct nlattr *tb[],
> >       return err;
> >  }
> >
> > -static void __geneve_dellink(struct net_device *dev, struct list_head *head)
> > +static void __geneve_dellink(struct net *net, struct net_device *dev,
> > +                          struct list_head *head)
> >  {
> >       struct geneve_dev *geneve = netdev_priv(dev);
> >
> > -     list_del(&geneve->next);
> > -     unregister_netdevice_queue(dev, head);
> > +     list_del_init(&geneve->next);
> > +     unregister_netdevice_queue_net(net, dev, head);
> >  }
> >
> >  static void geneve_dellink(struct net_device *dev, struct list_head *head)
> > @@ -2518,7 +2519,8 @@ static void geneve_dellink(struct net_device *dev, struct list_head *head)
> >       gn = net_generic(geneve->net, geneve_net_id);
> >
> >       mutex_lock(&gn->lock);
> > -     __geneve_dellink(dev, head);
> > +     if (!list_empty(&geneve->next))
> > +             __geneve_dellink(dev_net(dev), dev, head);
>
> Sashiko noted that the lockdep chain between dev->lock, utn->loc and
> gn->lock is not trivial, possibly a documentation follow-up would be useful
>
> >       mutex_unlock(&gn->lock);
> >  }
> >
> > @@ -2754,7 +2756,7 @@ static void __net_exit geneve_exit_rtnl_net(struct net *net,
> >       mutex_lock(&gn->lock);
> >
> >       list_for_each_entry_safe(geneve, next, &gn->geneve_list, next)
> > -             __geneve_dellink(geneve->dev, dev_to_kill);
> > +             __geneve_dellink(net, geneve->dev, dev_to_kill);
>
> Here sashiko foresees some problem with CONFIG_DEBUG_NET_SMALL_RTNL
> before full conversion to per netns lock even of ovs. Just more
> follow-up, I guess.

Is it Sashiko-nipa output ?
I can't find the comments from patchwork.
https://patchwork.kernel.org/project/netdevbpf/patch/[email protected]/
https://sashiko.dev/#/patchset/[email protected]

btw, I was hoping this series would land upstream so that
I don't need to care about OVS :)
https://lore.kernel.org/netdev/[email protected]/


>
> /P
>
> >
> >       mutex_unlock(&gn->lock);
> >  }
>