From: Jeff Layton <[email protected]> Date: Wed, 30 Apr 2025 19:59:23 -0700 > On Wed, 2025-04-30 at 14:29 -0700, Kuniyuki Iwashima wrote: > > From: Jeff Layton <[email protected]> > > Date: Wed, 30 Apr 2025 08:06:54 -0700 > > > After assigning the inode number to the namespace, use it to create a > > > unique name for each netns refcount tracker with the ns.inum value in > > > it, and register a symlink to the debugfs file for it. > > > > > > init_net is registered before the ref_tracker dir is created, so add a > > > late_initcall() to register its files and symlinks. > > > > > > Signed-off-by: Jeff Layton <[email protected]> > > > --- > > > net/core/net_namespace.c | 28 +++++++++++++++++++++++++++- > > > 1 file changed, 27 insertions(+), 1 deletion(-) > > > > > > diff --git a/net/core/net_namespace.c b/net/core/net_namespace.c > > > index > > > 008de9675ea98fa8c18628b2f1c3aee7f3ebc9c6..6cbc8eabb8e56c847fc34fa8ec9994e8b275b0af > > > 100644 > > > --- a/net/core/net_namespace.c > > > +++ b/net/core/net_namespace.c > > > @@ -763,12 +763,38 @@ struct net *get_net_ns_by_pid(pid_t pid) > > > } > > > EXPORT_SYMBOL_GPL(get_net_ns_by_pid); > > > > > > +#ifdef CONFIG_NET_NS_REFCNT_TRACKER > > > +static void net_ns_net_debugfs(struct net *net) > > > +{ > > > + ref_tracker_dir_symlink(&net->refcnt_tracker, "netns-%u-refcnt", > > > net->ns.inum); > > > + ref_tracker_dir_symlink(&net->notrefcnt_tracker, "netns-%u-notrefcnt", > > > net->ns.inum); > > > > Could you use net->net_cookie ? > > > > net->ns.inum is always 1 when CONFIG_PROC_FS=n. > > My main use-case for this is to be able to match the inode number in > the /proc/<pid>/ns/net symlink with the correct ref_tracker debugfs > file. Is there a way to use the net_cookie to make that association?
It's roundabout, but net_cookie can be retrieved by creating a random socket in the netns and calling setsockopt(SO_NETNS_COOKIE). Ido proposed a handy ip-netns subcommand here, and I guess it will be implemented soon(?) https://lore.kernel.org/netdev/[email protected]/ > > If there isn't, and ns.inum is always 1 with procfs is disabled, we > could just skip adding the symlink when CONFIG_PROC_FS=n.
