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Commit f473e5f4 authored by Mukesh Ojha's avatar Mukesh Ojha Committed by John Stultz
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time: Fix extra sleeptime injection when suspend fails 



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.

Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Miroslav Lichvar <mlichvar@redhat.com>
Cc: Richard Cochran <richardcochran@gmail.com>
Cc: Prarit Bhargava <prarit@redhat.com>
Cc: Stephen Boyd <sboyd@kernel.org>
Originally-by: default avatarThomas Gleixner <tglx@linutronix.de>
Signed-off-by: default avatarMukesh Ojha <mojha@codeaurora.org>
Signed-off-by: default avatarJohn Stultz <john.stultz@linaro.org>
parent 985e6950

kernel/time/timekeeping.c

+25 −7
Original line number Diff line number Diff line
@@ -1519,8 +1519,20 @@ void __weak read_boot_clock64(struct timespec64 *ts) 
	ts->tv_nsec = 0;

}



/* Flag for if timekeeping_resume() has injected sleeptime */

static bool sleeptime_injected;

/*

 * Flag reflecting whether timekeeping_resume() has injected sleeptime.

 *

 * The flag starts of false and is only set when a suspend reaches

 * timekeeping_suspend(), timekeeping_resume() sets it to false when the

 * timekeeper clocksource is not stopping across suspend and has been

 * used to update sleep time. If the timekeeper clocksource has stopped

 * then the flag stays true and is used by the RTC resume code to decide

 * whether sleeptime must be injected and if so the flag gets false then.

 *

 * If a suspend fails before reaching timekeeping_resume() then the flag

 * stays false and prevents erroneous sleeptime injection.

 */

static bool suspend_timing_needed;



/* Flag for if there is a persistent clock on this platform */

static bool persistent_clock_exists;
@@ -1619,7 +1631,7 @@ static void __timekeeping_inject_sleeptime(struct timekeeper *tk, 
 */

bool timekeeping_rtc_skipresume(void)

{

	return sleeptime_injected;

	return !suspend_timing_needed;

}



/**
@@ -1655,6 +1667,8 @@ void timekeeping_inject_sleeptime64(const struct timespec64 *delta) 
	raw_spin_lock_irqsave(&timekeeper_lock, flags);

	write_seqcount_begin(&tk_core.seq);



	suspend_timing_needed = false;



	timekeeping_forward_now(tk);



	__timekeeping_inject_sleeptime(tk, delta);
@@ -1679,8 +1693,8 @@ void timekeeping_resume(void) 
	unsigned long flags;

	struct timespec64 ts_new, ts_delta;

	u64 cycle_now;

	bool inject_sleeptime = false;



	sleeptime_injected = false;

	read_persistent_clock64(&ts_new);



	clockevents_resume();
@@ -1710,14 +1724,16 @@ void timekeeping_resume(void) 
					      tk->tkr_mono.mask);

		nsec = mul_u64_u32_shr(cyc_delta, clock->mult, clock->shift);

		ts_delta = ns_to_timespec64(nsec);

		sleeptime_injected = true;

		inject_sleeptime = true;

	} else if (timespec64_compare(&ts_new, &timekeeping_suspend_time) > 0) {

		ts_delta = timespec64_sub(ts_new, timekeeping_suspend_time);

		sleeptime_injected = true;

		inject_sleeptime = true;

	}



	if (sleeptime_injected)

	if (inject_sleeptime) {

		suspend_timing_needed = false;

		__timekeeping_inject_sleeptime(tk, &ts_delta);

	}



	/* Re-base the last cycle value */

	tk->tkr_mono.cycle_last = cycle_now;
@@ -1752,6 +1768,8 @@ int timekeeping_suspend(void) 
	if (timekeeping_suspend_time.tv_sec || timekeeping_suspend_time.tv_nsec)

		persistent_clock_exists = true;



	suspend_timing_needed = true;



	raw_spin_lock_irqsave(&timekeeper_lock, flags);

	write_seqcount_begin(&tk_core.seq);

	timekeeping_forward_now(tk);