linux-kernel - [PATCH RESEND] time: Fix sleeptime injection for non-stop clocksource & persistent clock

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Message-Id: <1527587351-26634-1-git-send-email-mojha@codeaurora.org>
Date:   Tue, 29 May 2018 15:19:11 +0530
From:   Mukesh Ojha <mojha@...eaurora.org>
To:     john.stultz@...aro.org, tglx@...utronix.de,
        linux-kernel@...r.kernel.org
Cc:     neeraju@...eaurora.org, gkohli@...eaurora.org,
        cpandya@...eaurora.org, Mukesh Ojha <mojha@...eaurora.org>
Subject: [PATCH RESEND] time: Fix sleeptime injection for non-stop clocksource & persistent clock

Currently, for both non-stop clocksource and persistent clock
there is a corner case, when a driver failed to go suspend mode
rtc_resume() injects the sleeptime as timekeeping_rtc_skipresume()
returned 'false' due to which we can see mismatch in time between
system clock and other timers.

Success case:
                                         {sleeptime_injected=true}
rtc_suspend() => timekeeping_suspend() => timekeeping_resume() => 
  rtc_resume()

Failure case:
             {failure in sleep path} {sleeptime_injected=false}
rtc_suspend()          =>            rtc_resume()

Signed-off-by: Mukesh Ojha <mojha@...eaurora.org>
---

Changes from Resend:
 * updated commit text.

 kernel/time/timekeeping.c | 14 +++++++++-----
 1 file changed, 9 insertions(+), 5 deletions(-)

diff --git a/kernel/time/timekeeping.c b/kernel/time/timekeeping.c
index 427e33d..c022d82 100644
--- a/kernel/time/timekeeping.c
+++ b/kernel/time/timekeeping.c
@@ -1511,9 +1511,6 @@ 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 for if there is a persistent clock on this platform */
 static bool persistent_clock_exists;
 
@@ -1611,7 +1608,14 @@ static void __timekeeping_inject_sleeptime(struct timekeeper *tk,
  */
 bool timekeeping_rtc_skipresume(void)
 {
-	return sleeptime_injected;
+	struct timekeeper *tk = &tk_core.timekeeper;
+	bool skip_rtc_resume = false;
+
+	skip_rtc_resume = ((tk->tkr_mono.clock->flags &
+			CLOCK_SOURCE_SUSPEND_NONSTOP) ||
+			(persistent_clock_exists)) ? true : false;
+
+	return skip_rtc_resume;
 }
 
 /**
@@ -1671,8 +1675,8 @@ void timekeeping_resume(void)
 	unsigned long flags;
 	struct timespec64 ts_new, ts_delta;
 	cycle_t cycle_now, cycle_delta;
+	bool sleeptime_injected = false;
 
-	sleeptime_injected = false;
 	read_persistent_clock64(&ts_new);
 
 	clockevents_resume();
-- 
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Inc. is a member of the Code Aurora Forum, a Linux Foundation Collaborative Project