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authorMukesh Ojha <mojha@codeaurora.org>2018-07-17 12:01:29 +0530
committerJohn Stultz <john.stultz@linaro.org>2018-07-19 17:08:51 -0700
commitf473e5f467f6049370575390b08dc42131315d60 (patch)
tree5872330f85209273d677eb28891048f72215e350 /kernel/time/timekeeping.c
parent985e695074d35768cb04d65f58bca45f7bf1a99d (diff)
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: Thomas Gleixner <tglx@linutronix.de> Signed-off-by: Mukesh Ojha <mojha@codeaurora.org> Signed-off-by: John Stultz <john.stultz@linaro.org>
Diffstat (limited to 'kernel/time/timekeeping.c')
-rw-r--r--kernel/time/timekeeping.c32
1 files changed, 25 insertions, 7 deletions
diff --git a/kernel/time/timekeeping.c b/kernel/time/timekeeping.c
index 7033ac1fee65..19414b16cf9e 100644
--- a/kernel/time/timekeeping.c
+++ b/kernel/time/timekeeping.c
@@ -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);