linux-kernel - Re: [PATCH v5] time: Fix extra sleeptime injection when suspend fails

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Date:   Tue, 17 Jul 2018 13:10:04 -0700
From:   John Stultz <john.stultz@...aro.org>
To:     Mukesh Ojha <mojha@...eaurora.org>
Cc:     Thomas Gleixner <tglx@...utronix.de>,
        lkml <linux-kernel@...r.kernel.org>, gkohli@...eaurora.org,
        cpandya@...eaurora.org, neeraju@...eaurora.org
Subject: Re: [PATCH v5] time: Fix extra sleeptime injection when suspend fails

On Mon, Jul 16, 2018 at 11:31 PM, Mukesh Ojha <mojha@...eaurora.org> wrote:
> Currently, there exists a corner case assuming when there is
> only one clocksource e.g RTC, and system failed to go to
> suspend mode. While resume rtc_resume() injects the sleeptime
> as timekeeping_rtc_skipresume() returned 'false' (default value
> of sleeptime_injected) due to which we can see mismatch in
> timestamps.
>
> This issue can also come in a system where more than one
> clocksource are present and very first suspend fails.
>
> Success case:
> ------------
>                                         {sleeptime_injected=false}
> rtc_suspend() => timekeeping_suspend() => timekeeping_resume() =>
>
> (sleeptime injected)
>  rtc_resume()
>
> Failure case:
> ------------
>          {failure in sleep path} {sleeptime_injected=false}
> rtc_suspend()     =>          rtc_resume()
>
> {sleeptime injected again which was not required as the suspend failed}
>
> Fix this by handling the boolean logic properly.
>
> Originally-by: Thomas Gleixner <tglx@...utronix.de>
> Signed-off-by: Mukesh Ojha <mojha@...eaurora.org>
> ---
> Changes in V5:
>  * Took extra variable `inject_sleeptime` to take care of injecting sleeptime
>    inside timekeeping_resume().
>  * Inverted the return logic inside timekeeping_skipresume() instead of doing
>    it in rtc_resume().
>  * Updated commit description.


Thanks again, I'lll get this queued up for testing.

thanks
-john