linux-kernel - Re: [Regression][Revert request] Excessive delay or hang during resume from system suspend due to a hrtimer commit

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Message-ID: <alpine.LFD.2.02.1207161035500.32033@ionos>
Date:	Mon, 16 Jul 2012 11:47:31 +0200 (CEST)
From:	Thomas Gleixner <tglx@...utronix.de>
To:	"Rafael J. Wysocki" <rjw@...k.pl>
cc:	Linus Torvalds <torvalds@...ux-foundation.org>,
	Linux PM list <linux-pm@...r.kernel.org>,
	LKML <linux-kernel@...r.kernel.org>,
	John Stultz <johnstul@...ibm.com>,
	Ingo Molnar <mingo@...nel.org>,
	Peter Zijlstra <a.p.zijlstra@...llo.nl>,
	Prarit Bhargava <prarit@...hat.com>, stable@...r.kernel.org,
	Andreas Schwab <schwab@...ux-m68k.org>
Subject: Re: [Regression][Revert request] Excessive delay or hang during
 resume from system suspend due to a hrtimer commit

On Sun, 15 Jul 2012, Rafael J. Wysocki wrote:
> To everyone involved: the fact that this change, which was likely to introduce
> regressions from the look of it alone, has been pushed to Linus (an to -stable
> at the same time!) so late in the cycle, is seriuosly disappointing.

Well, we spent an massive amount of time in testing, reviewing and
discussion and it definitely did not break suspend/resume here.

This was not pushed without a lot of thoughts and in fact what you are
seing is another long standing bug in the timekeeping resume code,
which was just papered over by the incorrect handling of the clock was
set cases in the other parts of the system.

Does the following patch fix the problem for you ?

@John: Should that clear ntp as well or is it enough to set ntp_error
       to 0 ?

/me really goes on vacation now.

Thanks,

	tglx

---------
diff --git a/kernel/time/timekeeping.c b/kernel/time/timekeeping.c
index 269b1fe..3447cfa 100644
--- a/kernel/time/timekeeping.c
+++ b/kernel/time/timekeeping.c
@@ -717,6 +717,7 @@ static void timekeeping_resume(void)
 	timekeeper.clock->cycle_last = timekeeper.clock->read(timekeeper.clock);
 	timekeeper.ntp_error = 0;
 	timekeeping_suspended = 0;
+	timekeeping_update(false);
 	write_sequnlock_irqrestore(&timekeeper.lock, flags);
 
 	touch_softlockup_watchdog();

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