Re: [RFC][PATCH 0/3] fork: Add the ability to create tasks withgiven pids

[Oleg Nesterov]

On 11/27, Konstantin Khlebnikov wrote:
>
> We can add flag to sys_wait4(), and stash pid in wait_task_zombie(), right before release_task()
> code will looks something like this:
>
> -       if (p != NULL)
> +       if (p != NULL) {
> +               if ((wo->wo_flags & WCATCHPID) && !current->pid_stash) {
> +                       struct pid *pid = task_pid(p);
> +
> +                       pid->flags |= PID_STASHED;
> +                       current->pid_stash = get_pid(pid);
> +               }
>                 release_task(p);
> +       }
>
> And next fork() creates child with the same pid.
> So, struct pid will work like boomerang =)

Like PR_RESERVE_PID, this can only help if the tracee (or whatever)
is single-threaded and it is the natural child.

Personally I do not think such a limited interface makes sense.

Oleg.

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