[Devel] Re: [RFC] Containers infrastructure problems

[Paul Menage]

On 3/5/07, Pavel Emelianov <xemul at sw.ru> wrote:
> Hi.
>
> I'm trying to implement RSS accounting via containers and
> I have some difficulties and proposals.
>
> 1. Fork
>
> container_fork() is placed before new task obtains its
> new mm_struct, files_struct, signal_struct etc. Isn't it
> better to move container fork at the place where newly
> created task it fully initialized to give controller
> possibility to work with new mm, signals etc?

Yes, that seems reasonable.

>
> 2. Early container usage
>
> Consider the following code:
>
>   struct my_container *cnt;
>
>   cnt = my_cnt_from_cont(task_container(current, &my_subsys));
>
> the problem is that when it is used before I register my
> rss subsystem in initcall task_container returns me
> dummytop container which is not my_container actually :(

By definition all tasks are in dummytop (the top container in the
dummy hierarchy) since you can't create sub-containers in the dummy
hierarchy.

You're right that before you're registered, the current container
won't have a pointer for your subsystem. But calling
container_register_subsys() from container_rss_init_early(), and
having that called early on from init/main.c should be OK.

Paul