From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754914AbbJHIwP (ORCPT ); Thu, 8 Oct 2015 04:52:15 -0400 Received: from mout.kundenserver.de ([212.227.17.24]:53790 "EHLO mout.kundenserver.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753932AbbJHIwM (ORCPT ); Thu, 8 Oct 2015 04:52:12 -0400 From: Arnd Bergmann To: Miroslav Lichvar Cc: linux-kernel@vger.kernel.org, y2038@lists.linaro.org, John Stultz , Thomas Gleixner , Prarit Bhargava , Richard Cochran Subject: Re: [PATCH] timekeeping: Limit system time to prevent 32-bit time_t overflow Date: Thu, 08 Oct 2015 10:52:05 +0200 Message-ID: <5836683.t4iPTifntz@wuerfel> User-Agent: KMail/4.11.5 (Linux/3.16.0-10-generic; KDE/4.11.5; x86_64; ; ) In-Reply-To: <20151008062344.GO5778@localhost> References: <1444224137-32510-1-git-send-email-mlichvar@redhat.com> <5753784.UXVo9jVTVp@wuerfel> <20151008062344.GO5778@localhost> MIME-Version: 1.0 Content-Transfer-Encoding: 7Bit Content-Type: text/plain; charset="us-ascii" X-Provags-ID: V03:K0:40qcqJeFYgMBbzPzR00J8xPUNWkFoRnJ/AXOPwSSJvRav7SkIhu EhDyLo92csK0ZxinDZnEkbYzMiPe9F86i7x0RUOmHZWeoRckzU4o4j/icypp8kSNZge2MeT 0cf/RwbUsgo5hHUNhPyw7y5wcdaP0273rcDlujQ+2Z2oMJjDhm1/7RlId5N2JSAnOdbn1Ia uLneHN2BlR4Uuurb22RvQ== X-UI-Out-Filterresults: notjunk:1;V01:K0:LB7nAU7qKNU=:qeNyzdtctyaqfSfBCEnoCw ArQzMf+MekzE1TOedEAmCVNVXdK0cli+91PehaFXdqHZpJVdcZwb2elh8zpZE/4qJ88SUJ3TT uHLZgiFB+pebJuagqbx9mYl51S9ycLCG+JugH2cQdNjUlN5V6ekItd+W11jOPmz4mMIgRaEnS ff5ggZg5XxW/+ySOCQBcbrxvp/gZ+dGnbulI94f9a3ScECJBfOouxVbI/YhMDmub5056ZQVWW UMboo9DKYNftE3MRMbUaV82iMJS2UFGXB+qkGo17+5YVUwh0vsWY5jqKG6TcWIiDgeCi7eLWN Gt01nhbcyl2EFgkVFv5U4zqrjqjgIq2BtjUZW4IrCIVmCxbgjg8ztjcKzngrtszQ7X6o5705x 7Kb8uYqagDhexFgCzu57sXfxTnh5GBuSyVUXGYwlGxANI1zKPMmFJyyYWjYxrj8w3gTTNbP6d 46Ea8aRJrA4qYAZ54QuP5QGZA/jhrRlCvCXIstnnATckuJi8ubVJClmwFCJfuAxIjHSgxBiMS VKFKYRupjp6RXvd5RZtrxIpMoY3wDobp1ijMFag1nH0pc+KSjWvYDaXr5T6460O2AyfO4egBz IU2W+s+vgHwUWSbHDdO9scAp0AFeUodN9vKj6Bw05IArPWxgtgDEpccEscYhAMOqZOJJOWY76 k8Tg/QP0UBcX1W7x8RVjhKZ7364YiWve87gJv/RU4lZOofHfJXAOsGAXoQYrcxDMpNkTAWB+d iBb3SmXoT9TUTWHs Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thursday 08 October 2015 08:23:44 Miroslav Lichvar wrote: > On Wed, Oct 07, 2015 at 05:10:34PM +0200, Arnd Bergmann wrote: > > On Wednesday 07 October 2015 16:23:44 Miroslav Lichvar wrote: > > > Without the limit added by this patch make will go nuts just one week > > > later when the 32-bit time_t overflows to Dec 13 1901 and the files > > > will appear as 136 years in the future. How is that better? > > > > Not better or worse at all, that was my point. The time is still > > wrong either way, whether you step back by a week or 136 years. > > The difference is that with the one-week step the kernel and userspace > still agree on the current time and it is always valid from the kernel > point of view, absolute timers can be set, etc. Ok, I can see that as an improvement, but it still seems to give a false sense of safety, and I feel we really should not have any code rely on this behavior. Arnd