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time: Fix extra sleeptime injection when suspend fails

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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 <[email protected]>
Cc: Ingo Molnar <[email protected]>
Cc: Miroslav Lichvar <[email protected]>
Cc: Richard Cochran <[email protected]>
Cc: Prarit Bhargava <[email protected]>
Cc: Stephen Boyd <[email protected]>
Originally-by: Thomas Gleixner <[email protected]>
Signed-off-by: Mukesh Ojha <[email protected]>
Signed-off-by: John Stultz <[email protected]>
This commit is contained in:
Mukesh Ojha 2018-07-17 12:01:29 +05:30 • committed by John Stultz
commit f473e5f467
1 changed files with 25 additions and 7 deletions
Download patch file Download diff file Expand all files Collapse all files

32
kernel/time/timekeeping.c
View file

@ -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);