From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1757305Ab3FSRiy (ORCPT ); Wed, 19 Jun 2013 13:38:54 -0400 Received: from mail-pb0-f41.google.com ([209.85.160.41]:56227 "EHLO mail-pb0-f41.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1757279Ab3FSRiu (ORCPT ); Wed, 19 Jun 2013 13:38:50 -0400 Message-ID: <51C1ECA7.3030001@linaro.org> Date: Wed, 19 Jun 2013 10:38:47 -0700 From: John Stultz User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:17.0) Gecko/20130510 Thunderbird/17.0.6 MIME-Version: 1.0 To: Konrad Rzeszutek Wilk CC: David Vrabel , xen-devel@lists.xen.org, linux-kernel@vger.kernel.org, Thomas Gleixner Subject: Re: [PATCH 2/4] time: add a notifier chain for when the system time is stepped References: <1371655523-15609-1-git-send-email-david.vrabel@citrix.com> <1371655523-15609-3-git-send-email-david.vrabel@citrix.com> <51C1E1B6.8090203@linaro.org> <20130619171321.GE13046@phenom.dumpdata.com> In-Reply-To: <20130619171321.GE13046@phenom.dumpdata.com> Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 06/19/2013 10:13 AM, Konrad Rzeszutek Wilk wrote: > On Wed, Jun 19, 2013 at 09:52:06AM -0700, John Stultz wrote: >> On 06/19/2013 08:25 AM, David Vrabel wrote: >>> From: David Vrabel >>> >>> The high resolution timer code gets notified of step changes to the >>> system time with clock_was_set() or clock_was_set_delayed() calls. If >>> other parts of the kernel require similar notification there is no >>> clear place to hook into. >>> >>> Add a clock_was_set atomic notifier chain >>> (clock_was_set_notifier_list) and call this in place of >>> clock_was_set(). If the timekeeping locks are held, the calls are >>> deferred to a new tasklet. >>> >>> The hrtimer code adds a notifier block to this chain and uses it to >>> call (the now internal) clock_was_set(). Since the timekeeping code >>> does not call the chain from the timer irq clock_was_set_delayed() and >>> associated code can be removed. >> So on my initial quick review, this *looks* pretty reasonable. I get >> a little worried about interface abuse (ie: random drivers trying to >> hook into clock_was_set_notifier_list), but we can move that into >> timekeeper_internal.h or something similar to limit that. >> >> The other issue here is we've been burned pretty badly in the past >> with changes to clock_was_set(), as its key to keeping timers in >> line with timekeeping. So this will need a fair amount of testing >> and run time before this gets merged, so 3.12 is what we'd be >> targeting at the earliest (its getting a bit late for taking changes >> for 3.11 anyway). > I think we have four weeks left? Or you think Linus is going to release > at the end of the month? Well, I have to queue it, and then get Thomas to pull it from me, and that can take some time. And after -rc6 there's just not a lot of time for things to get testing in -next before being pushed to Linus. Its just a bit rushed for me. >> If you want to try to push patch 1/4 in for 3.11 via the Xen tree, > Done. >> I'll see about queuing the other three for hopefully 3.12. > OK, let me run them through the testing gauntleet to have the > warm fuzzy feeling. Thanks. I'll be running it through my test cases as well. -john