Messages in this thread Patch in this message | | | From | Mukesh Ojha <> | Subject | [PATCH v3] time: Fix incorrect sleeptime injection when suspend fails | Date | Fri, 6 Jul 2018 18:47:27 +0530 |
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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.
Fix this by handling `sleeptime_injected` flag properly.
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)
Originally-by: Thomas Gleixner <tglx@linutronix.de> Signed-off-by: Mukesh Ojha <mojha@codeaurora.org> --- Changes in v3: * Updated commit subject and description. * Updated the patch as per the fix given by Thomas Gleixner.
Changes in v2: * Updated the commit text. * Removed extra variable and used the earlier static variable 'sleeptime_injected'.
kernel/time/timekeeping.c | 21 ++++++++++++++++++--- 1 file changed, 18 insertions(+), 3 deletions(-)
diff --git a/kernel/time/timekeeping.c b/kernel/time/timekeeping.c index 4786df9..32ae9ae 100644 --- a/kernel/time/timekeeping.c +++ b/kernel/time/timekeeping.c @@ -1510,8 +1510,20 @@ 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 true and is only cleared when a suspend reaches + * timekeeping_suspend(), timekeeping_resume() sets it 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 false and is used by the RTC resume code to decide whether sleep + * time must be injected and if so the flag gets set then. + * + * If a suspend fails before reaching timekeeping_resume() then the flag + * stays true and prevents erroneous sleeptime injection. + */ +static bool sleeptime_injected = true; /* Flag for if there is a persistent clock on this platform */ static bool persistent_clock_exists; @@ -1646,6 +1658,8 @@ void timekeeping_inject_sleeptime64(struct timespec64 *delta) raw_spin_lock_irqsave(&timekeeper_lock, flags); write_seqcount_begin(&tk_core.seq); + sleeptime_injected = true; + timekeeping_forward_now(tk); __timekeeping_inject_sleeptime(tk, delta); @@ -1671,7 +1685,6 @@ void timekeeping_resume(void) struct timespec64 ts_new, ts_delta; u64 cycle_now; - sleeptime_injected = false; read_persistent_clock64(&ts_new); clockevents_resume(); @@ -1743,6 +1756,8 @@ int timekeeping_suspend(void) if (timekeeping_suspend_time.tv_sec || timekeeping_suspend_time.tv_nsec) persistent_clock_exists = true; + sleeptime_injected = false; + raw_spin_lock_irqsave(&timekeeper_lock, flags); write_seqcount_begin(&tk_core.seq); timekeeping_forward_now(tk); -- Qualcomm India Private Limited, on behalf of Qualcomm Innovation Center, Inc. is a member of the Code Aurora Forum, a Linux Foundation Collaborative Project
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