Commit-ID: f473e5f467f6049370575390b08dc42131315d60
Gitweb: https://git.kernel.org/tip/f473e5f467f6049370575390b08dc42131315d60
Author: Mukesh Ojha <mojha@xxxxxxxxxxxxxx>
AuthorDate: Tue, 17 Jul 2018 12:01:29 +0530
Committer: John Stultz <john.stultz@xxxxxxxxxx>
CommitDate: Thu, 19 Jul 2018 17:08:51 -0700
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@xxxxxxxxxxxxx>
Cc: Ingo Molnar <mingo@xxxxxxxxxx>
Cc: Miroslav Lichvar <mlichvar@xxxxxxxxxx>
Cc: Richard Cochran <richardcochran@xxxxxxxxx>
Cc: Prarit Bhargava <prarit@xxxxxxxxxx>
Cc: Stephen Boyd <sboyd@xxxxxxxxxx>
Originally-by: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
Signed-off-by: Mukesh Ojha <mojha@xxxxxxxxxxxxxx>
Signed-off-by: John Stultz <john.stultz@xxxxxxxxxx>
---
kernel/time/timekeeping.c | 32 +++++++++++++++++++++++++-------
1 file 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);
--
To unsubscribe from this list: send the line "unsubscribe linux-tip-commits" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
|