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From: Dave Jones <davej@codemonkey.org.uk>
To: John Stultz <john.stultz@linaro.org>
Cc: linux-kernel@vger.kernel.org, Prarit Bhargava <prarit@redhat.com>,
	Daniel Bristot de Oliveira <bristot@redhat.com>,
	Richard Cochran <richardcochran@gmail.com>,
	Jan Kara <jack@suse.cz>, Jiri Bohac <jbohac@suse.cz>,
	Thomas Gleixner <tglx@linutronix.de>,
	Ingo Molnar <mingo@redhat.com>,
	Shuah Khan <shuahkh@osg.samsung.com>
Subject: Re: [PATCH 0/5 v2] Fixes for leapsecond expiring early ABS_TIME CLOCK_REALTIME timers
Date: Fri, 12 Jun 2015 10:52:12 -0400	[thread overview]
Message-ID: <20150612145211.GA22489@codemonkey.org.uk> (raw)
In-Reply-To: <1434063297-28657-1-git-send-email-john.stultz@linaro.org>

On Thu, Jun 11, 2015 at 03:54:52PM -0700, John Stultz wrote:
 > So this is a second round at trying to address the issue, trying
 > to integrate feedback from Ingo and Thomas, trying to simplify
 > what I can. I've also split out the changes so each can be
 > more easily reviewed. Its still not tiny, but its simpler.
 > 
 > This series is against tip/timers/core, and the first patch isn't
 > strictly related but is a fix that is needed in tip/timers/core.
 > 
 > As Prarit reported here:
 > https://lkml.org/lkml/2015/5/27/458
 > 
 > Since the leapsecond is applied at timer tick time, and not
 > the actual second edge, ABS_TIME CLOCK_REALTIME timers set for
 > right after the leapsecond could fire a second early, since
 > some timers may be expired before we trigger the timekeeping
 > timer, which then applies the leapsecond.
 > 
 > Thus this patch series tries to address this issue, including
 > extending the leap-a-day test to catch this problem, as well
 > as other relevant fixups I found while working on the code.
 > 
 > This series has only had limited testing, so I wanted to send
 > it out for initial review and comment. Folks can grab this tree
 > via git for testing here:
 > https://git.linaro.org/people/john.stultz/linux.git dev/early-leap-timer

Any idea how far back this reaches ? Ie, which longterm stable releases
might be affected by this ?

(It really creeps me out that we're still changing this code so close
 to the next leap second event).

	Dave


  parent reply	other threads:[~2015-06-12 14:52 UTC|newest]

Thread overview: 23+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2015-06-11 22:54 John Stultz
2015-06-11 22:54 ` [PATCH 1/5] time: Move clock_was_set_seq update to before we update the shadow-timekeeper John Stultz
2015-06-12  9:31   ` [tip:timers/core] time: Move clock_was_set_seq update before updating shadow-timekeeper tip-bot for John Stultz
2015-06-11 22:54 ` [PATCH 2/5] ntp: Introduce and use SECS_PER_DAY macro instead of 86400 John Stultz
2015-06-12  9:31   ` [tip:timers/core] " tip-bot for John Stultz
2015-06-11 22:54 ` [PATCH 3/5] time: Do leapsecond adjustment to avoid early timer expirations John Stultz
2015-06-12  9:32   ` [tip:timers/core] time: Prevent early expiry of hrtimers[ CLOCK_REALTIME] at the leap second edge tip-bot for John Stultz
2015-06-11 22:54 ` [PATCH 4/5] ntp: Do leapsecond adjustment in adjtimex read path John Stultz
2015-06-12  7:37   ` Richard Cochran
2015-06-12  9:32   ` [tip:timers/core] " tip-bot for John Stultz
2015-06-11 22:54 ` [PATCH 5/5] selftests: timers: Add leap-second timer edge testing to leap-a-day.c John Stultz
2015-06-12  9:32   ` [tip:timers/core] " tip-bot for John Stultz
2015-06-12 14:52 ` Dave Jones [this message]
2015-06-12 14:55   ` [PATCH 0/5 v2] Fixes for leapsecond expiring early ABS_TIME CLOCK_REALTIME timers Prarit Bhargava
2015-06-12 14:59     ` Dave Jones
2015-06-12 15:02       ` Prarit Bhargava
2015-06-12 17:58   ` John Stultz
2015-06-12 18:06     ` John Stultz
2015-06-12 18:11       ` Thomas Gleixner
2015-06-13  7:17         ` Ingo Molnar
2015-06-15 13:10 ` Prarit Bhargava
2015-06-15 13:46   ` Prarit Bhargava
2015-06-15 18:55     ` John Stultz

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