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

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Date:	Mon, 16 Jul 2012 13:16:28 +0200
From:	"Rafael J. Wysocki" <rjw@...k.pl>
To:	Thomas Gleixner <tglx@...utronix.de>
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 Monday, July 16, 2012, Thomas Gleixner wrote:
> 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.

I'm not saying that you didn't consider it thoroughly, but unfortunately you
did overlook this particular issue, didn't you?

> 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 ?

Yes, it does, thanks!

> @John: Should that clear ntp as well or is it enough to set ntp_error
>        to 0 ?
> 
> /me really goes on vacation now.

So who's going to take care of the patch? :-)

Rafael


> ---------
> 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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