proc_misc_dentry_ops is a general ops for dentry under /proc, except
for "/proc/${pid}/net"，other dentries may also use there own ops too,
so I think change proc_misc_d_delete may be better?
see patch under: https://lkml.org/lkml/2022/3/17/319
Alexey Dobriyan <adobriyan@xxxxxxxxx> 于2022年3月21日周一 00:24写道：
>
> When a process exits, /proc/${pid}, and /proc/${pid}/net dentries are flushed.
> However some leaf dentries like /proc/${pid}/net/arp_cache aren't.
> That's because respective PDEs have proc_misc_d_revalidate() hook which
> returns 1 and leaves dentries/inodes in the LRU.
>
> Force revalidation/lookup on everything under /proc/${pid}/net by inheriting
> proc_net_dentry_ops.
>
> Fixes: c6c75deda813 ("proc: fix lookup in /proc/net subdirectories after setns(2)")
> Reported-by: hui li <juanfengpy@xxxxxxxxx>
> Signed-off-by: Alexey Dobriyan <adobriyan@xxxxxxxxx>
> ---
>
> fs/proc/generic.c | 4 ++++
> fs/proc/proc_net.c | 3 +++
> 2 files changed, 7 insertions(+)
>
> --- a/fs/proc/generic.c
> +++ b/fs/proc/generic.c
> @@ -448,6 +448,10 @@ static struct proc_dir_entry *__proc_create(struct proc_dir_entry **parent,
> proc_set_user(ent, (*parent)->uid, (*parent)->gid);
>
> ent->proc_dops = &proc_misc_dentry_ops;
> + /* Revalidate everything under /proc/${pid}/net */
> + if ((*parent)->proc_dops == &proc_net_dentry_ops) {
> + pde_force_lookup(ent);
> + }
>
> out:
> return ent;
> --- a/fs/proc/proc_net.c
> +++ b/fs/proc/proc_net.c
> @@ -376,6 +376,9 @@ static __net_init int proc_net_ns_init(struct net *net)
>
> proc_set_user(netd, uid, gid);
>
> + /* Seed dentry revalidation for /proc/${pid}/net */
> + pde_force_lookup(netd);
> +
> err = -EEXIST;
> net_statd = proc_net_mkdir(net, "stat", netd);
> if (!net_statd)
