From: Christian Brauner <[email protected]>
Date: Fri, 12 Sep 2025 13:52:44 +0200
> Support the generic ns lookup infrastructure to support file handles for
> namespaces.
>
> The network namespace has a separate list with different lifetime rules
> which we can just leave in tact. We have a similar concept for mount
> namespaces as well where it is on two differenet lists for different
> purposes.
>
> Signed-off-by: Christian Brauner <[email protected]>
> ---
> include/net/net_namespace.h | 1 +
> net/core/net_namespace.c | 8 ++++++--
> 2 files changed, 7 insertions(+), 2 deletions(-)
>
> diff --git a/include/net/net_namespace.h b/include/net/net_namespace.h
> index 025a7574b275..42075748dff1 100644
> --- a/include/net/net_namespace.h
> +++ b/include/net/net_namespace.h
> @@ -11,6 +11,7 @@
> #include <linux/list.h>
> #include <linux/sysctl.h>
> #include <linux/uidgid.h>
> +#include <linux/nstree.h>
>
> #include <net/flow.h>
> #include <net/netns/core.h>
> diff --git a/net/core/net_namespace.c b/net/core/net_namespace.c
> index 5fb7bd8ac45a..169ec22c4758 100644
> --- a/net/core/net_namespace.c
> +++ b/net/core/net_namespace.c
> @@ -20,6 +20,7 @@
> #include <linux/sched/task.h>
> #include <linux/uidgid.h>
> #include <linux/proc_fs.h>
> +#include <linux/nstree.h>
>
> #include <net/aligned_data.h>
nit: This is no longer necessary.
> #include <net/sock.h>
> @@ -445,7 +446,7 @@ static __net_init int setup_net(struct net *net)
> LIST_HEAD(net_exit_list);
> int error = 0;
>
> - net->net_cookie = atomic64_inc_return(&net_aligned_data.net_cookie);
> + net->net_cookie = ns_tree_gen_id(&net->ns);
>
> list_for_each_entry(ops, &pernet_list, list) {
> error = ops_init(ops, net);
> @@ -455,6 +456,7 @@ static __net_init int setup_net(struct net *net)
> down_write(&net_rwsem);
> list_add_tail_rcu(&net->list, &net_namespace_list);
> up_write(&net_rwsem);
> + ns_tree_add_raw(net);
> out:
> return error;
>
> @@ -674,8 +676,10 @@ static void cleanup_net(struct work_struct *work)
>
> /* Don't let anyone else find us. */
> down_write(&net_rwsem);
> - llist_for_each_entry(net, net_kill_list, cleanup_list)
> + llist_for_each_entry(net, net_kill_list, cleanup_list) {
> + ns_tree_remove(net);
Looking at refcount_inc_not_zero() in nsfs_fh_to_dentry(),
I think ns_tree_remove() fits better in __put_net() which
is called just after refcount_dec_and_test(&net->ns.count).
cleanup_net() is single threaded work and somtimes takes long with
too many netns and the netns may stay longer unnecessarily until
next cleanup_net().
> list_del_rcu(&net->list);
> + }
> /* Cache last net. After we unlock rtnl, no one new net
> * added to net_namespace_list can assign nsid pointer
> * to a net from net_kill_list (see peernet2id_alloc()).
>
> --
> 2.47.3
