Re: [PATCH 4/9] pid: Generalize task_active_pid_ns

[Oleg Nesterov <oleg-6lXkIZvqkOAvJsYlp49lxw@public.gmane.org>]

On 12/13, Eric W. Biederman wrote:
>
> Oleg Nesterov <oleg-6lXkIZvqkOAvJsYlp49lxw@public.gmane.org> writes:
> 
> > On 12/12, Eric W. Biederman wrote:
> >>
> >> Currently task_active_pid_ns is not safe to call after a
> >> task becomes a zombie and exit_task_namespaces is called,
> >> as nsproxy becomes NULL.  By reading the pid namespace from
> >> the pid of the task we can trivially solve this problem
> >
> > Confused. If the task becomes a zombie, we can't assume it has a valid
> > ->pids[].pid. The parent can release us as soon as exit_notify() drops
> > tasklist.
> 
> 
> What this allows me to do (as seen later in the patchset) is to send
> to call pid_nr_ns and deliver a signal to a task group without caring
> if the element of the task group I am talking to is a zombie or not.

Yes I see, thanks Eric. I was confused by changelog, and I missed the
subsequent changes which need task_active_pid_ns() of the reciever.

Oleg.