On Mon, Oct 14, 2019 at 11:43:01AM +0200, Christian Kellner wrote:
> On Sat, 2019-10-12 at 12:21 +0200, Christian Brauner wrote:
> > I think this might be more what we want.
> Yep, indeed.
>
> > I tried to think of cases where the first entry of Pid is not
> > identical
> > to the first entry of NSpid but I came up with none. Maybe you do,
> > Jann?
> Yeah, I don't think that can be the case. By looking at the source of
> 'pid_nr_ns(pid, ns)' a non-zero return means that a) 'pid' valid, ie.
> non-null and b) 'ns' is in the pid namespace hierarchy of 'pid' (at
> pid->level, i.e. "pid->numbers[ns->level].ns == ns").
>
> > Christian, this is just a quick stab I took. Feel free to pick this
> > up as a template.
> Thanks! I slightly re-worked it, with the reasoning above in mind, to
> get rid of one of the branches:
Thanks!
>
> +#ifdef CONFIG_PID_NS
> + seq_put_decimal_ull(m, "\nNSpid:\t", nr);
> + if (nr) {
> + int i;
> +
> + /* If nr is non-zero it means that 'pid' is valid and that
> + * ns, i.e. the pid namespace associated with the procfs
> + * instance, is in the pid namespace hierarchy of pid.
> + * Start at one level below and print all descending pids.
> + */
> + for (i = ns->level + 1; i <= pid->level; i++) {
> + ns = pid->numbers[i].ns;
I'm not a fan of overriding the "ns" pointer. It's not a huge deal but
it's rather subtle.
> + seq_put_decimal_ull(m, "\t", pid_nr_ns(pid, ns));
> + }
> + }
> +#endif
>
> But I now just realized that with the very same reasoning, if nr is
> non-zero, we don't need to redo all the checks and can just do:
>
> for (i = ns->level + 1; i <= pid->level; i++)
> seq_put_decimal_ull(m, "\t", pid->numbers[i].nr);
>
> If this sounds good to you I resend the patches with the change above.
You could probably do:
#ifdef CONFIG_PID_NS
seq_put_decimal_ull(m, "\nNSpid:\t", nr);
for (i = ns->level + 1; i <= pid->level && nr; i++)
seq_put_decimal_ull(m, "\t", pid->numbers[i].nr);
#endif
Christian
