linux-kernel - Re: [PATCH][RFC v4] timekeeping: ignore the bogus sleep time if pm

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Date:	Thu, 18 Aug 2016 12:36:51 +0200
From:	Oliver Neukum <oneukum@...e.com>
To:	Chen Yu <yu.c.chen@...el.com>
Cc:	linux-pm@...r.kernel.org, Ingo Molnar <mingo@...hat.com>,
	"H . Peter Anvin" <hpa@...or.com>, x86@...nel.org,
	"Rafael J . Wysocki" <rjw@...ysocki.net>,
	John Stultz <john.stultz@...aro.org>,
	Thomas Gleixner <tglx@...utronix.de>,
	Xunlei Pang <xlpang@...hat.com>,
	Zhang Rui <rui.zhang@...el.com>, linux-kernel@...r.kernel.org
Subject: Re: [PATCH][RFC v4] timekeeping: ignore the bogus sleep time if
 pm_trace is enabled

On Thu, 2016-08-18 at 18:43 +0800, Chen Yu wrote:
> Previously we encountered some memory overflow issues due to
> the bogus sleep time brought by inconsistent rtc, which is
> triggered when pm_trace is enabled, please refer to:
> https://patchwork.kernel.org/patch/9286365/
> It's improper in the first place to call __timekeeping_inject_sleeptime()
> in case that pm_trace is enabled simply because that "hash" time value
> will wreckage the timekeeping subsystem.

Hi,

do you know since when this bug exists?

>  /**
> @@ -1662,6 +1668,12 @@ void timekeeping_resume(void)
>  	} else if (timespec64_compare(&ts_new, &timekeeping_suspend_time) > 0) {
>  		ts_delta = timespec64_sub(ts_new, timekeeping_suspend_time);
>  		sleeptime_injected = true;
> +		/*
> +		 * If rtc is used as persist clock thus it
> +		 * would be bogus when pm_trace is enabled.
> +		 */
> +		if (!persistent_clock_is_usable())
> +			sleeptime_injected = false;
>  	}
>  
>  	if (sleeptime_injected)

How about

sleeptime_injected = persistent_clock_is_usable();

	Regards
		Oliver