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    SubjectRe: [PATCH -mm 0/3] proc: task->signal can't be NULL
    On 03/23, Eric W. Biederman wrote:
    >
    > We need a value that can be computed in constant time, and is not correct
    > except when the number of threads is actively changing.

    Sure. I was thinking of something like

    int get_nr_threads(struct task_struct *tsk)
    {
    int nr = atomic_read(&task->signal->live);
    int reasonable_min = 1;

    rcu_read_lock();
    if (!thread_group_leader(tsk) && pid_alive(tsk) &&
    tsk->group_leader->exit_state)
    reasonable_min = 2;
    rcu_read_unlock();

    return max(nr, reasonable_min);
    }

    but as I said this doesn't look nice at all.

    > > OK. Let's keep this counter as "int nr_thread".
    > >
    > > Besides, when I tried to re-implement get_nr_threads() using signal->live
    > > I got the really ugly result ;)
    >
    > Sounds good.

    OK, please see the "final" patch I am going to send...

    Oleg.



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