From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751093AbdBHSJm (ORCPT ); Wed, 8 Feb 2017 13:09:42 -0500 Received: from mail-wr0-f178.google.com ([209.85.128.178]:35463 "EHLO mail-wr0-f178.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751055AbdBHSJk (ORCPT ); Wed, 8 Feb 2017 13:09:40 -0500 MIME-Version: 1.0 In-Reply-To: References: <20170207234031.GA27933@beast> From: John Stultz Date: Wed, 8 Feb 2017 10:09:39 -0800 Message-ID: Subject: Re: [PATCH] time: Remove CONFIG_TIMER_STATS To: Thomas Gleixner Cc: Kees Cook , Xing Gao , Jessica Frazelle , "Eric W. Biederman" , Jonathan Corbet , Tejun Heo , Lai Jiangshan , Petr Mladek , Andrew Morton , Oleg Nesterov , Nicolas Iooss , Nicolas Pitre , Richard Cochran , "Paul E. McKenney" , Michal Marek , Josh Poimboeuf , Dmitry Vyukov , Olof Johansson , Shuah Khan , linux-doc@vger.kernel.org, lkml , kernel-hardening@lists.openwall.com Content-Type: text/plain; charset=UTF-8 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, Feb 8, 2017 at 2:24 AM, Thomas Gleixner wrote: > On Tue, 7 Feb 2017, John Stultz wrote: >> On Tue, Feb 7, 2017 at 3:40 PM, Kees Cook 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 >> > Signed-off-by: Kees Cook >> >> 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 From mboxrd@z Thu Jan 1 00:00:00 1970 MIME-Version: 1.0 In-Reply-To: References: <20170207234031.GA27933@beast> From: John Stultz Date: Wed, 8 Feb 2017 10:09:39 -0800 Message-ID: Content-Type: text/plain; charset=UTF-8 Subject: [kernel-hardening] Re: [PATCH] time: Remove CONFIG_TIMER_STATS To: Thomas Gleixner Cc: Kees Cook , Xing Gao , Jessica Frazelle , "Eric W. Biederman" , Jonathan Corbet , Tejun Heo , Lai Jiangshan , Petr Mladek , Andrew Morton , Oleg Nesterov , Nicolas Iooss , Nicolas Pitre , Richard Cochran , "Paul E. McKenney" , Michal Marek , Josh Poimboeuf , Dmitry Vyukov , Olof Johansson , Shuah Khan , linux-doc@vger.kernel.org, lkml , kernel-hardening@lists.openwall.com List-ID: On Wed, Feb 8, 2017 at 2:24 AM, Thomas Gleixner wrote: > On Tue, 7 Feb 2017, John Stultz wrote: >> On Tue, Feb 7, 2017 at 3:40 PM, Kees Cook 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 >> > Signed-off-by: Kees Cook >> >> 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