Re: [PATCH] time: Remove CONFIG_TIMER_STATS

[Thomas Gleixner]

On Tue, 7 Feb 2017, John Stultz wrote:
> On Tue, Feb 7, 2017 at 3:40 PM, Kees Cook <keescook@xxxxxxxxxxxx> wrote:
> > Currently CONFIG_TIMER_STATS exposes process information across namespaces:
> >
> > kernel/time/timer_list.c print_timer():
> >
> >         SEQ_printf(m, ", %s/%d", tmp, timer->start_pid);
> >
> > /proc/timer_list:
> >
> >  #11: <0000000000000000>, hrtimer_wakeup, S:01, do_nanosleep, cron/2570
> >
> > Given that the tracer can give the same information, this patch entirely
> > removes CONFIG_TIMER_STATS.
> >
> > Suggested-by: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
> > Signed-off-by: Kees Cook <keescook@xxxxxxxxxxxx>
> 
> I don't have an issue with this, but I worry this would break some
> tooling out there. Should it be marked as deprecated first?
> 
> Or maybe just pulling the band-aid off is the best way?

I think we should just kill it.

No tools can really rely on the behaviour of that file because it depends
on CONFIG_TIMER_STATS and the information available there is just a random
snapshot of queued timers at a given point of time, which is in no way
usefull.

Thanks,

	tglx