Re: [PATCH v3 net-next 06/15] neighbour: Store arp_tbl and nd_tbl in net->neigh_tables[].

On Tue, Aug 11, 2026 at 8:19 AM David Ahern <[email protected]> wrote:
>
> On 8/10/26 8:23 PM, Kuniyuki Iwashima wrote:
> > diff --git a/net/ipv4/arp.c b/net/ipv4/arp.c
> > index d409f606aec0..bad17d5aeafc 100644
> > --- a/net/ipv4/arp.c
> > +++ b/net/ipv4/arp.c
> > @@ -1495,15 +1495,34 @@ static const struct seq_operations arp_seq_ops = {
> >
> >  static int __net_init e(struct net *net)
> >  {
> > +     int err;
> > +
> > +     err = neigh_table_register(net, &arp_tbl, NEIGH_ARP_TABLE);
> > +     if (err)
> > +             goto err;
> > +
> > +#ifdef CONFIG_PROC_FS
> >       if (!proc_create_net("arp", 0444, net->proc_net, &arp_seq_ops,
> > -                     sizeof(struct neigh_seq_state)))
>
> proc_create_net already handles CONFIG_PROC_FS. It is not clear to me
> why you need to add the check here and below.

Actually it does not handle the case well because the =n case returns
NULL and setup_net() fails to initialise init_net and dies.

Most callers have the same issue (e.g. NFS can boot w/ =n but triggers
oops immediately) and it can be followed up if needed, but I didn't want
them as the prereq series.


>
> > -             return -ENOMEM;
> > +                          sizeof(struct neigh_seq_state))) {
> > +             err = -ENOMEM;
> > +             goto err_proc_create;
> > +     }
> > +#endif
> > +
> >       return 0;
> > +
> > +#ifdef CONFIG_PROC_FS
> > +err_proc_create:
> > +     neigh_table_unregister(net, NEIGH_ARP_TABLE);
> > +#endif
> > +err:
> > +     return err;
> >  }
> >
> >  static void __net_exit arp_net_exit(struct net *net)
> >  {
> >       remove_proc_entry("arp", net->proc_net);
> > +     neigh_table_unregister(net, NEIGH_ARP_TABLE);
> >  }
> >
> >  static struct pernet_operations arp_net_ops = {
>