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    Subject[ 020/180] 2.6.32.y: time: Avoid making adjustments if we havent accumulated anything
    2.6.32-longterm review patch.  If anyone has any objections, please let me know.

    ------------------

    From: John Stultz <john.stultz@linaro.org>

    This is a -stable backport of bf2ac312195155511a0f79325515cbb61929898a

    If update_wall_time() is called and the current offset isn't large
    enough to accumulate, avoid re-calling timekeeping_adjust which may
    change the clock freq and can cause 1ns inconsistencies with
    CLOCK_REALTIME_COARSE/CLOCK_MONOTONIC_COARSE.

    Signed-off-by: John Stultz <john.stultz@linaro.org>
    Cc: Prarit Bhargava <prarit@redhat.com>
    Cc: Ingo Molnar <mingo@kernel.org>
    Cc: stable@vger.kernel.org
    Link: http://lkml.kernel.org/r/1345595449-34965-5-git-send-email-john.stultz@linaro.org
    Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
    Cc: Linux Kernel <linux-kernel@vger.kernel.org>
    Signed-off-by: John Stultz <john.stultz@linaro.org>
    Signed-off-by: Willy Tarreau <w@1wt.eu>
    ---
    kernel/time/timekeeping.c | 4 ++++
    1 files changed, 4 insertions(+), 0 deletions(-)

    diff --git a/kernel/time/timekeeping.c b/kernel/time/timekeeping.c
    index 85d51c4..b451c93 100644
    --- a/kernel/time/timekeeping.c
    +++ b/kernel/time/timekeeping.c
    @@ -807,6 +807,10 @@ void update_wall_time(void)
    #else
    offset = timekeeper.cycle_interval;
    #endif
    + /* Check if there's really nothing to do */
    + if (offset < timekeeper.cycle_interval)
    + return;
    +
    timekeeper.xtime_nsec = (s64)xtime.tv_nsec << timekeeper.shift;

    /* normally this loop will run just once, however in the
    --
    1.7.2.1.45.g54fbc




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