On Wed, Nov 16, 2016 at 10:27 AM, Cong Wang <xiyou.wangc...@gmail.com> wrote:
> Andrei reports we still allocate netns ID from idr after we destroy
> it in cleanup_net().
>
> cleanup_net():
> ...
> idr_destroy(&net->netns_ids);
> ...
> list_for_each_entry_reverse(ops, &pernet_list, list)
> ops_exit_list(ops, &net_exit_list);
> -> rollback_registered_many()
> -> rtmsg_ifinfo_build_skb()
> -> rtnl_fill_ifinfo()
> -> peernet2id_alloc()
>
> After that point we should not even access net->netns_ids, we
> should check the death of the current netns as early as we can in
> peernet2id_alloc().
>
> For net-next we can consider to avoid sending rtmsg totally,
> it is a good optimization for netns teardown path.
It works for me and looks good. Thanks.
Acked-by: Andrei Vagin <ava...@openvz.org>
>
> Fixes: 0c7aecd4bde4 ("netns: add rtnl cmd to add and get peer netns ids")
> Reported-by: Andrei Vagin <ava...@gmail.com>
> Cc: Nicolas Dichtel <nicolas.dich...@6wind.com>
> Signed-off-by: Cong Wang <xiyou.wangc...@gmail.com>
> ---
> net/core/net_namespace.c | 2 ++
> 1 file changed, 2 insertions(+)
>
> diff --git a/net/core/net_namespace.c b/net/core/net_namespace.c
> index f61c0e0..7001da9 100644
> --- a/net/core/net_namespace.c
> +++ b/net/core/net_namespace.c
> @@ -219,6 +219,8 @@ int peernet2id_alloc(struct net *net, struct net *peer)
> bool alloc;
> int id;
>
> + if (atomic_read(&net->count) == 0)
> + return NETNSA_NSID_NOT_ASSIGNED;
> spin_lock_irqsave(&net->nsid_lock, flags);
> alloc = atomic_read(&peer->count) == 0 ? false : true;
> id = __peernet2id_alloc(net, peer, &alloc);
> --
> 2.1.0
>
