Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S934683Ab0HEWjW (ORCPT ); Thu, 5 Aug 2010 18:39:22 -0400 Received: from cantor.suse.de ([195.135.220.2]:59597 "EHLO mx1.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S934550Ab0HEWjK (ORCPT ); Thu, 5 Aug 2010 18:39:10 -0400 Date: Thu, 5 Aug 2010 15:38:54 -0700 From: Greg KH To: Kay Sievers Cc: john stultz , Alexander Shishkin , lkml@vger.kernel.org, "Kirill A. Shutemov" , Thomas Gleixner , Martin Schwidefsky , Andrew Morton , Jon Hunter , Ingo Molnar , Peter Zijlstra , "Paul E. McKenney" , David Howells , Avi Kivity , "H. Peter Anvin" , John Kacur , linux-kernel@vger.kernel.org Subject: Re: [PATCH] [RFC] notify userspace about time changes Message-ID: <20100805223854.GA19511@suse.de> References: <1280926108-24668-1-git-send-email-virtuoso@slind.org> <1280937526.28884.21.camel@work-vm> <1281042665.3405.15.camel@localhost.localdomain> <20100805213851.GA13868@suse.de> MIME-Version: 1.0 Content-Type: text/plain; charset=iso-8859-1 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: User-Agent: Mutt/1.5.20 (2009-06-14) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2340 Lines: 49 On Fri, Aug 06, 2010 at 12:22:27AM +0200, Kay Sievers wrote: > On Thu, Aug 5, 2010 at 23:38, Greg KH wrote: > > On Thu, Aug 05, 2010 at 02:11:05PM -0700, john stultz wrote: > >> On Thu, 2010-08-05 at 15:33 +0300, Alexander Shishkin wrote: > >> > On 4 August 2010 18:58, john stultz wrote: > >> > > Is there a actual use case that you need this for? ?I don't really have > >> > > an issue with the code I just really want to make sure the feature would > >> > > be useful enough to justify the API and code maintenance going forward. > >> > > >> > Yes. What we have here is an application which takes care of different means > >> > of time synchronization (trusted time servers, different GSM operators, etc) > >> > and also different kinds of time-based events/notifications (like "dentist > >> > appointment next thursday"). When it encounters a time change that is > >> > made by some other application, it basically wants to disable automatic > >> > time adjustment and trigger the events/notifications which are due at this > >> > (new) time. > >> > >> Ok. Something specific is always more helpful then theoretical uses. > >> > >> I think the filtering is still a bit controversial, so you might want to > >> respin it without that. But otherwise I'm ok with it as long as no one > >> else objects to any of the minor details of the interface > >> > >> GregKH: Does /sys/kernel/time_notify seem ok by you? > > > > Um, it depends, what is that file going to do? ?I don't see a > > Documentation/ABI/ entry here that describes it fully :) > > I think that's really awkward interface, to pass file descriptor > numbers around and write them to magic sysfs files. Ick, really? That's not ok for sysfs. > I would very much prefer a file that contains the current time, and > wakes up possible users with a POLL_ERR on changes caused by some > other process. That works very well for things like /proc/mounts, is > easy to get, and does not need a full page of weird instructions to > get stuff done. :) That sounds more reasonable. thanks, greg k-h -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/