linux-kernel - Re: [PATCH] nsproxy: remove judge of timens_on

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Message-ID: <CANaxB-zC9pCF-Vkda4dbPTdn+m8ObLunNFiOf5aAcECh6MFYQQ@mail.gmail.com>
Date:   Tue, 17 Nov 2020 00:30:26 -0800
From:   Andrey Vagin <avagin@...nvz.org>
To:     Hui Su <sh_def@....com>
Cc:     Christian Brauner <christian.brauner@...ntu.com>,
        "Serge E. Hallyn" <serge@...lyn.com>,
        Thomas Gleixner <tglx@...utronix.de>,
        LKML <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] nsproxy: remove judge of timens_on_fork()'s return val

On Sun, Nov 15, 2020 at 10:36 AM Hui Su <sh_def@....com> wrote:
>
> timens_on_fork() always return 0, and maybe not
> need to judge the return value in copy_namespaces().

Thank you for cleaning this up. I think we can go even further and
change timens_on_fork to return nothing:

-int timens_on_fork(struct nsproxy *nsproxy, struct task_struct *tsk)
+void timens_on_fork(struct nsproxy *nsproxy, struct task_struct *tsk)
 {
        struct ns_common *nsc = &nsproxy->time_ns_for_children->ns;
        struct time_namespace *ns = to_time_ns(nsc);

        /* create_new_namespaces() already incremented the ref counter */
        if (nsproxy->time_ns == nsproxy->time_ns_for_children)
-               return 0;
+               return;

        get_time_ns(ns);
        put_time_ns(nsproxy->time_ns);
        nsproxy->time_ns = ns;

        timens_commit(tsk, ns);
-
-       return 0;
 }


>
> Signed-off-by: Hui Su <sh_def@....com>
> ---
>  kernel/nsproxy.c | 7 +------
>  1 file changed, 1 insertion(+), 6 deletions(-)
>
> diff --git a/kernel/nsproxy.c b/kernel/nsproxy.c
> index 12dd41b39a7f..e2e6c5dc433f 100644
> --- a/kernel/nsproxy.c
> +++ b/kernel/nsproxy.c
> @@ -153,7 +153,6 @@ int copy_namespaces(unsigned long flags, struct task_struct *tsk)
>         struct nsproxy *old_ns = tsk->nsproxy;
>         struct user_namespace *user_ns = task_cred_xxx(tsk, user_ns);
>         struct nsproxy *new_ns;
> -       int ret;
>
>         if (likely(!(flags & (CLONE_NEWNS | CLONE_NEWUTS | CLONE_NEWIPC |
>                               CLONE_NEWPID | CLONE_NEWNET |
> @@ -180,11 +179,7 @@ int copy_namespaces(unsigned long flags, struct task_struct *tsk)
>         if (IS_ERR(new_ns))
>                 return  PTR_ERR(new_ns);
>
> -       ret = timens_on_fork(new_ns, tsk);
> -       if (ret) {
> -               free_nsproxy(new_ns);
> -               return ret;
> -       }
> +       timens_on_fork(new_ns, tsk);
>
>         tsk->nsproxy = new_ns;
>         return 0;
> --
> 2.29.0
>
>