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    Subject[PATCH 3.2 64/92] hrtimer: Set expiry time before switch_hrtimer_base()
    3.2.60-rc1 review patch.  If anyone has any objections, please let me know.

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

    From: Viresh Kumar <viresh.kumar@linaro.org>

    commit 84ea7fe37908254c3bd90910921f6e1045c1747a upstream.

    switch_hrtimer_base() calls hrtimer_check_target() which ensures that
    we do not migrate a timer to a remote cpu if the timer expires before
    the current programmed expiry time on that remote cpu.

    But __hrtimer_start_range_ns() calls switch_hrtimer_base() before the
    new expiry time is set. So the sanity check in hrtimer_check_target()
    is operating on stale or even uninitialized data.

    Update expiry time before calling switch_hrtimer_base().

    [ tglx: Rewrote changelog once again ]

    Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org>
    Cc: linaro-kernel@lists.linaro.org
    Cc: linaro-networking@linaro.org
    Cc: fweisbec@gmail.com
    Cc: arvind.chauhan@arm.com
    Link: http://lkml.kernel.org/r/81999e148745fc51bbcd0615823fbab9b2e87e23.1399882253.git.viresh.kumar@linaro.org
    Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
    Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
    ---
    kernel/hrtimer.c | 8 ++++----
    1 file changed, 4 insertions(+), 4 deletions(-)

    --- a/kernel/hrtimer.c
    +++ b/kernel/hrtimer.c
    @@ -980,11 +980,8 @@ int __hrtimer_start_range_ns(struct hrti
    /* Remove an active timer from the queue: */
    ret = remove_hrtimer(timer, base);

    - /* Switch the timer base, if necessary: */
    - new_base = switch_hrtimer_base(timer, base, mode & HRTIMER_MODE_PINNED);
    -
    if (mode & HRTIMER_MODE_REL) {
    - tim = ktime_add_safe(tim, new_base->get_time());
    + tim = ktime_add_safe(tim, base->get_time());
    /*
    * CONFIG_TIME_LOW_RES is a temporary way for architectures
    * to signal that they simply return xtime in
    @@ -999,6 +996,9 @@ int __hrtimer_start_range_ns(struct hrti

    hrtimer_set_expires_range_ns(timer, tim, delta_ns);

    + /* Switch the timer base, if necessary: */
    + new_base = switch_hrtimer_base(timer, base, mode & HRTIMER_MODE_PINNED);
    +
    timer_stats_hrtimer_set_start_info(timer);

    leftmost = enqueue_hrtimer(timer, new_base);


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