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    Subject[PATCH 3.2 050/153] hrtimer: Ensure POSIX compliance (relative CLOCK_REALTIME hrtimers)
    3.2.102-rc1 review patch.  If anyone has any objections, please let me know.

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

    From: Anna-Maria Gleixner <anna-maria@linutronix.de>

    commit 48d0c9becc7f3c66874c100c126459a9da0fdced upstream.

    The POSIX specification defines that relative CLOCK_REALTIME timers are not
    affected by clock modifications. Those timers have to use CLOCK_MONOTONIC
    to ensure POSIX compliance.

    The introduction of the additional HRTIMER_MODE_PINNED mode broke this
    requirement for pinned timers.

    There is no user space visible impact because user space timers are not
    using pinned mode, but for consistency reasons this needs to be fixed.

    Check whether the mode has the HRTIMER_MODE_REL bit set instead of
    comparing with HRTIMER_MODE_ABS.

    Signed-off-by: Anna-Maria Gleixner <anna-maria@linutronix.de>
    Cc: Christoph Hellwig <hch@lst.de>
    Cc: John Stultz <john.stultz@linaro.org>
    Cc: Linus Torvalds <torvalds@linux-foundation.org>
    Cc: Peter Zijlstra <peterz@infradead.org>
    Cc: Thomas Gleixner <tglx@linutronix.de>
    Cc: keescook@chromium.org
    Fixes: 597d0275736d ("timers: Framework for identifying pinned timers")
    Link: http://lkml.kernel.org/r/20171221104205.7269-7-anna-maria@linutronix.de
    Signed-off-by: Ingo Molnar <mingo@kernel.org>
    [bwh: Backported to 3.2: adjust filename]
    Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
    ---
    kernel/hrtimer.c | 7 ++++++-
    1 file changed, 6 insertions(+), 1 deletion(-)

    --- a/kernel/hrtimer.c
    +++ b/kernel/hrtimer.c
    @@ -1200,7 +1200,12 @@ static void __hrtimer_init(struct hrtime

    cpu_base = &__raw_get_cpu_var(hrtimer_bases);

    - if (clock_id == CLOCK_REALTIME && mode != HRTIMER_MODE_ABS)
    + /*
    + * POSIX magic: Relative CLOCK_REALTIME timers are not affected by
    + * clock modifications, so they needs to become CLOCK_MONOTONIC to
    + * ensure POSIX compliance.
    + */
    + if (clock_id == CLOCK_REALTIME && mode & HRTIMER_MODE_REL)
    clock_id = CLOCK_MONOTONIC;

    base = hrtimer_clockid_to_base(clock_id);
    \
     
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