Re: [PATCH] time: Remove CONFIG_TIMER_STATS

[John Stultz]

On Wed, Feb 8, 2017 at 2:24 AM, Thomas Gleixner <tglx@xxxxxxxxxxxxx> wrote:
> 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.

Fair enough.

Acked-by: John Stultz <john.stultz@xxxxxxxxxx>