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    Subject[tip:timers/core] time: Move clock_was_set_seq update before updating shadow-timekeeper
    Commit-ID:  d151832650ed98961a5650e73e85c349ad7839cb
    Gitweb: http://git.kernel.org/tip/d151832650ed98961a5650e73e85c349ad7839cb
    Author: John Stultz <john.stultz@linaro.org>
    AuthorDate: Thu, 11 Jun 2015 15:54:53 -0700
    Committer: Thomas Gleixner <tglx@linutronix.de>
    CommitDate: Fri, 12 Jun 2015 10:56:20 +0200

    time: Move clock_was_set_seq update before updating shadow-timekeeper

    It was reported that 868a3e915f7f5eba (hrtimer: Make offset
    update smarter) was causing timer problems after suspend/resume.

    The problem with that change is the modification to
    clock_was_set_seq in timekeeping_update is done prior to
    mirroring the time state to the shadow-timekeeper. Thus the
    next time we do update_wall_time() the updated sequence is
    overwritten by whats in the shadow copy.

    This patch moves the shadow-timekeeper mirroring to the end
    of the function, after all updates have been made, so all data
    is kept in sync.

    (This patch also affects the update_fast_timekeeper calls which
    were also problematically done prior to the mirroring).

    Reported-and-tested-by: Jeremiah Mahler <jmmahler@gmail.com>
    Signed-off-by: John Stultz <john.stultz@linaro.org>
    Cc: Preeti U Murthy <preeti@linux.vnet.ibm.com>
    Cc: Peter Zijlstra <peterz@infradead.org>
    Cc: Viresh Kumar <viresh.kumar@linaro.org>
    Cc: Marcelo Tosatti <mtosatti@redhat.com>
    Cc: Frederic Weisbecker <fweisbec@gmail.com>
    Link: http://lkml.kernel.org/r/1434063297-28657-2-git-send-email-john.stultz@linaro.org
    Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
    ---
    kernel/time/timekeeping.c | 12 ++++++++----
    1 file changed, 8 insertions(+), 4 deletions(-)

    diff --git a/kernel/time/timekeeping.c b/kernel/time/timekeeping.c
    index 90ed5db..849b932 100644
    --- a/kernel/time/timekeeping.c
    +++ b/kernel/time/timekeeping.c
    @@ -585,15 +585,19 @@ static void timekeeping_update(struct timekeeper *tk, unsigned int action)
    update_vsyscall(tk);
    update_pvclock_gtod(tk, action & TK_CLOCK_WAS_SET);

    - if (action & TK_MIRROR)
    - memcpy(&shadow_timekeeper, &tk_core.timekeeper,
    - sizeof(tk_core.timekeeper));
    -
    update_fast_timekeeper(&tk->tkr_mono, &tk_fast_mono);
    update_fast_timekeeper(&tk->tkr_raw, &tk_fast_raw);

    if (action & TK_CLOCK_WAS_SET)
    tk->clock_was_set_seq++;
    + /*
    + * The mirroring of the data to the shadow-timekeeper needs
    + * to happen last here to ensure we don't over-write the
    + * timekeeper structure on the next update with stale data
    + */
    + if (action & TK_MIRROR)
    + memcpy(&shadow_timekeeper, &tk_core.timekeeper,
    + sizeof(tk_core.timekeeper));
    }

    /**

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