From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755064Ab2HERAt (ORCPT ); Sun, 5 Aug 2012 13:00:49 -0400 Received: from terminus.zytor.com ([198.137.202.10]:57067 "EHLO terminus.zytor.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755044Ab2HERAs (ORCPT ); Sun, 5 Aug 2012 13:00:48 -0400 Date: Sun, 5 Aug 2012 10:00:35 -0700 From: tip-bot for Ingo Molnar Message-ID: Cc: linux-kernel@vger.kernel.org, hpa@zytor.com, mingo@kernel.org, tglx@linutronix.de Reply-To: mingo@kernel.org, hpa@zytor.com, linux-kernel@vger.kernel.org, tglx@linutronix.de In-Reply-To: <20120804192114.GA28347@gmail.com> References: <20120804192114.GA28347@gmail.com> To: linux-tip-commits@vger.kernel.org Subject: [tip:timers/urgent] time: Fix adjustment cleanup bug in timekeeping_adjust() Git-Commit-ID: 1d17d17484d40f2d5b35c79518597a2b25296996 X-Mailer: tip-git-log-daemon Robot-ID: Robot-Unsubscribe: Contact to get blacklisted from these emails MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Content-Type: text/plain; charset=UTF-8 Content-Disposition: inline X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.2.6 (terminus.zytor.com [127.0.0.1]); Sun, 05 Aug 2012 10:00:42 -0700 (PDT) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Commit-ID: 1d17d17484d40f2d5b35c79518597a2b25296996 Gitweb: http://git.kernel.org/tip/1d17d17484d40f2d5b35c79518597a2b25296996 Author: Ingo Molnar AuthorDate: Sat, 4 Aug 2012 21:21:14 +0200 Committer: Ingo Molnar CommitDate: Sun, 5 Aug 2012 12:37:14 +0200 time: Fix adjustment cleanup bug in timekeeping_adjust() Tetsuo Handa reported that sporadically the system clock starts counting up too quickly which is enough to confuse the hangcheck timer to print a bogus stall warning. Commit 2a8c0883 "time: Move xtime_nsec adjustment underflow handling timekeeping_adjust" overlooked this exit path: } else return; which should really be a proper exit sequence, fixing the bug as a side effect. Also make the flow more readable by properly balancing curly braces. Reported-by: Tetsuo Handa wrote: Tested-by: Tetsuo Handa wrote: Signed-off-by: Ingo Molnar Cc: john.stultz@linaro.org Cc: a.p.zijlstra@chello.nl Cc: richardcochran@gmail.com Cc: prarit@redhat.com Link: http://lkml.kernel.org/r/20120804192114.GA28347@gmail.com Signed-off-by: Ingo Molnar --- kernel/time/timekeeping.c | 31 +++++++++++++++++-------------- 1 files changed, 17 insertions(+), 14 deletions(-) diff --git a/kernel/time/timekeeping.c b/kernel/time/timekeeping.c index 2988bc8..e16af19 100644 --- a/kernel/time/timekeeping.c +++ b/kernel/time/timekeeping.c @@ -923,20 +923,22 @@ static void timekeeping_adjust(struct timekeeper *tk, s64 offset) if (likely(error <= interval)) adj = 1; else - adj = timekeeping_bigadjust(tk, error, &interval, - &offset); - } else if (error < -interval) { - /* See comment above, this is just switched for the negative */ - error >>= 2; - if (likely(error >= -interval)) { - adj = -1; - interval = -interval; - offset = -offset; - } else - adj = timekeeping_bigadjust(tk, error, &interval, - &offset); - } else - return; + adj = timekeeping_bigadjust(tk, error, &interval, &offset); + } else { + if (error < -interval) { + /* See comment above, this is just switched for the negative */ + error >>= 2; + if (likely(error >= -interval)) { + adj = -1; + interval = -interval; + offset = -offset; + } else { + adj = timekeeping_bigadjust(tk, error, &interval, &offset); + } + } else { + goto out_adjust; + } + } if (unlikely(tk->clock->maxadj && (tk->mult + adj > tk->clock->mult + tk->clock->maxadj))) { @@ -999,6 +1001,7 @@ static void timekeeping_adjust(struct timekeeper *tk, s64 offset) tk->xtime_nsec -= offset; tk->ntp_error -= (interval - offset) << tk->ntp_error_shift; +out_adjust: /* * It may be possible that when we entered this function, xtime_nsec * was very small. Further, if we're slightly speeding the clocksource