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    Subject[patch 01/39] hrtimer: Update active_bases before calling hrtimer_force_reprogram()
    From: Viresh Kumar <viresh.kumar@linaro.org>

    'active_bases' indicates which clock-base have active timer. The
    intention of this bit field was to avoid evaluating inactive bases. It
    was introduced with the introduction of the BOOTTIME and TAI clock
    bases, but it was never brought into full use.

    We want to use it now, but in __remove_hrtimer() the update happens
    after the calling hrtimer_force_reprogram() which has to evaluate all
    clock bases for the next expiring timer. So in case the last timer of
    a clock base got removed we still see the active bit and therefor
    evaluate the clock base for no value. There are further optimizations
    possible when active_bases is updated in the right place.

    Move the update before the call to hrtimer_force_reprogram()

    [ tglx: Massaged changelog ]

    Reviewed-by: Preeti U Murthy <preeti@linux.vnet.ibm.com>
    Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org>
    Cc: linaro-kernel@lists.linaro.org
    Cc: Peter Zijlstra <peterz@infradead.org>
    Link: http://lkml.kernel.org/r/c7c8ebcd9ed88bb09d76059c745a1fafb48314e7.1428039899.git.viresh.kumar@linaro.org
    Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
    ---
    kernel/time/hrtimer.c | 5 +++--
    1 file changed, 3 insertions(+), 2 deletions(-)

    Index: tip/kernel/time/hrtimer.c
    ===================================================================
    --- tip.orig/kernel/time/hrtimer.c
    +++ tip/kernel/time/hrtimer.c
    @@ -879,6 +879,9 @@ static void __remove_hrtimer(struct hrti

    next_timer = timerqueue_getnext(&base->active);
    timerqueue_del(&base->active, &timer->node);
    + if (!timerqueue_getnext(&base->active))
    + base->cpu_base->active_bases &= ~(1 << base->index);
    +
    if (&timer->node == next_timer) {
    #ifdef CONFIG_HIGH_RES_TIMERS
    /* Reprogram the clock event device. if enabled */
    @@ -892,8 +895,6 @@ static void __remove_hrtimer(struct hrti
    }
    #endif
    }
    - if (!timerqueue_getnext(&base->active))
    - base->cpu_base->active_bases &= ~(1 << base->index);
    out:
    timer->state = newstate;
    }



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