• Chen Yu's avatar
    timekeeping: Ignore the bogus sleep time if pm_trace is enabled · ba58d102
    Chen Yu authored
    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: default avatarChen Yu <yu.c.chen@intel.com>
    Signed-off-by: default avatarJohn Stultz <john.stultz@linaro.org>
    Acked-by: Pavel Machek's avatarPavel Machek <pavel@ucw.cz>
    Acked-by: default avatarThomas 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: default avatarThomas Gleixner <tglx@linutronix.de>
    ba58d102
mc146818rtc.h 4.46 KB