rtc: Fix some bugs that allowed accumulating time drift in suspend/resume (6a8943d9) · Commits · 戴 / test

The current code checks if abs(delta_delta.tv_sec) is greater or equal to two before it discards the old delta value, but this can trigger at close to -1 seconds since -1.000000001 seconds is stored as tv_sec -2 and tv_nsec 999999999 in a normalized timespec. rtc_resume had an early return check if the rtc value had not changed since rtc_suspend. This effectivly stops time for the duration of the short sleep. Check if sleep_time is positive after all the adjustments have been applied instead since this allows the old_system adjustment in rtc_suspend to have an effect even for short sleep cycles. CC: stable@kernel.org Signed-off-by:

Arve Hjønnevåg <arve@android.com> Signed-off-by:

John Stultz <john.stultz@linaro.org>

drivers/rtc/class.c

+5 −5

Original line number	Diff line number	Diff line
		@@ -66,7 +66,7 @@ static int rtc_suspend(struct device *dev, pm_message_t mesg)
		*/
		delta = timespec_sub(old_system, old_rtc);
		delta_delta = timespec_sub(delta, old_delta);
		if (abs(delta_delta.tv_sec) >= 2) {
		if (delta_delta.tv_sec < -2 \|\| delta_delta.tv_sec >= 2) {
		/*
		* if delta_delta is too large, assume time correction
		* has occured and set old_delta to the current delta.
		@@ -100,8 +100,7 @@ static int rtc_resume(struct device *dev)
		rtc_tm_to_time(&tm, &new_rtc.tv_sec);
		new_rtc.tv_nsec = 0;

		if (new_rtc.tv_sec <= old_rtc.tv_sec) {
		if (new_rtc.tv_sec < old_rtc.tv_sec)
		if (new_rtc.tv_sec < old_rtc.tv_sec) {
		pr_debug("%s: time travel!\n", dev_name(&rtc->dev));
		return 0;
		}
		@@ -119,6 +118,7 @@ static int rtc_resume(struct device *dev)
		sleep_time = timespec_sub(sleep_time,
		timespec_sub(new_system, old_system));

		if (sleep_time.tv_sec >= 0)
		timekeeping_inject_sleeptime(&sleep_time);
		return 0;
		}

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