[Devel] Re: [PATCH 2/13] Small preparations for namespaces

[Serge E. Hallyn]

Quoting Pavel Emelianov (xemul at openvz.org):
> This includes #ifdefs in get/put_pid_ns and rewriting
> the child_reaper() function to the more logical view.
> 
> This doesn't fit logically into any other patch so
> I decided to make it separate.
> 
> Signed-off-by: Pavel Emelianov <xemul at openvz.org>
> 
> ---
> 
> diff --git a/include/linux/pid_namespace.h b/include/linux/pid_namespace.h
> index 169c6c2..7af7191 100644
> --- a/include/linux/pid_namespace.h
> +++ b/include/linux/pid_namespace.h
> @@ -26,7 +26,9 @@ extern struct pid_namespace init_pid_ns;
> 
>  static inline void get_pid_ns(struct pid_namespace *ns)
>  {
> +#ifdef CONFIG_PID_NS
>  	kref_get(&ns->kref);
> +#endif
>  }
> 
>  extern struct pid_namespace *copy_pid_ns(int flags, struct pid_namespace *ns);
> @@ -34,12 +36,15 @@ extern void free_pid_ns(struct kref *kre
> 
>  static inline void put_pid_ns(struct pid_namespace *ns)
>  {
> +#ifdef CONFIG_PID_NS
>  	kref_put(&ns->kref, free_pid_ns);
> +#endif
>  }
> 
>  static inline struct task_struct *child_reaper(struct task_struct *tsk)
>  {
> -	return init_pid_ns.child_reaper;
> +	BUG_ON(tsk != current);
> +	return tsk->nsproxy->pid_ns->child_reaper;
>  }
> 
>  #endif /* _LINUX_PID_NS_H */

This can't be bisect-safe, right?  You can't just use
tsk->nsproxy->pid_ns, as you've pointed out yourself.

-serge