timekeeping: Ignore the bogus sleep time if pm_trace is enabled
Power management suspend/resume tracing (ab)uses the RTC to store suspend/resume information persistently. As a consequence the RTC value is clobbered when timekeeping is resumed and tries to inject the sleep time. Commit a4f8f666 ("timekeeping: Cap array access in timekeeping_debug") plugged a out of bounds array access in the timekeeping debug code which was caused by the clobbered RTC value, but we still use the clobbered RTC value for sleep time injection into kernel timekeeping, which will result in random adjustments depending on the stored "hash" value. To prevent this keep track of the RTC clobbering and ignore the invalid RTC timestamp at resume. If the system resumed successfully clear the flag, which marks the RTC as unusable, warn the user about the RTC clobber and recommend to adjust the RTC with 'ntpdate' or 'rdate'. [jstultz: Fixed up pr_warn formating, and implemented suggestions from Ingo] [ tglx: Rewrote changelog ] Originally-from: Thomas Gleixner <tglx@linutronix.de> Signed-off-by: NChen Yu <yu.c.chen@intel.com> Signed-off-by: NJohn Stultz <john.stultz@linaro.org> Acked-by: NPavel Machek <pavel@ucw.cz> Acked-by: NThomas Gleixner <tglx@linutronix.de> Cc: Prarit Bhargava <prarit@redhat.com> Cc: "Rafael J. Wysocki" <rjw@rjwysocki.net> Cc: Richard Cochran <richardcochran@gmail.com> Cc: Xunlei Pang <xlpang@redhat.com> Cc: Len Brown <lenb@kernel.org> Link: http://lkml.kernel.org/r/1480372524-15181-3-git-send-email-john.stultz@linaro.orgSigned-off-by: NThomas Gleixner <tglx@linutronix.de>
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