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    Subject[tip:timers/core] perf/core: Mark hrtimers to expire in hard interrupt context
    Commit-ID:  c23a8bd3ac02df2ca5e77396df1dee247db3d49f
    Gitweb: https://git.kernel.org/tip/c23a8bd3ac02df2ca5e77396df1dee247db3d49f
    Author: Thomas Gleixner <tglx@linutronix.de>
    AuthorDate: Fri, 26 Jul 2019 20:30:53 +0200
    Committer: Thomas Gleixner <tglx@linutronix.de>
    CommitDate: Tue, 30 Jul 2019 23:57:54 +0200

    perf/core: Mark hrtimers to expire in hard interrupt context

    To guarantee that the multiplexing mechanism and the hrtimer driven events
    work on PREEMPT_RT enabled kernels it's required that the related hrtimers
    expire in hard interrupt context. Mark them so PREEMPT_RT kernels wont
    defer them to soft interrupt context.

    No functional change.

    [ tglx: Split out of larger combo patch. Added changelog ]

    Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
    Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
    Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
    Link: https://lkml.kernel.org/r/20190726185753.169509224@linutronix.de

    ---
    kernel/events/core.c | 8 ++++----
    1 file changed, 4 insertions(+), 4 deletions(-)

    diff --git a/kernel/events/core.c b/kernel/events/core.c
    index 026a14541a38..9d623e257a51 100644
    --- a/kernel/events/core.c
    +++ b/kernel/events/core.c
    @@ -1103,7 +1103,7 @@ static void __perf_mux_hrtimer_init(struct perf_cpu_context *cpuctx, int cpu)
    cpuctx->hrtimer_interval = ns_to_ktime(NSEC_PER_MSEC * interval);

    raw_spin_lock_init(&cpuctx->hrtimer_lock);
    - hrtimer_init(timer, CLOCK_MONOTONIC, HRTIMER_MODE_ABS_PINNED);
    + hrtimer_init(timer, CLOCK_MONOTONIC, HRTIMER_MODE_ABS_PINNED_HARD);
    timer->function = perf_mux_hrtimer_handler;
    }

    @@ -1121,7 +1121,7 @@ static int perf_mux_hrtimer_restart(struct perf_cpu_context *cpuctx)
    if (!cpuctx->hrtimer_active) {
    cpuctx->hrtimer_active = 1;
    hrtimer_forward_now(timer, cpuctx->hrtimer_interval);
    - hrtimer_start_expires(timer, HRTIMER_MODE_ABS_PINNED);
    + hrtimer_start_expires(timer, HRTIMER_MODE_ABS_PINNED_HARD);
    }
    raw_spin_unlock_irqrestore(&cpuctx->hrtimer_lock, flags);

    @@ -9491,7 +9491,7 @@ static void perf_swevent_start_hrtimer(struct perf_event *event)
    period = max_t(u64, 10000, hwc->sample_period);
    }
    hrtimer_start(&hwc->hrtimer, ns_to_ktime(period),
    - HRTIMER_MODE_REL_PINNED);
    + HRTIMER_MODE_REL_PINNED_HARD);
    }

    static void perf_swevent_cancel_hrtimer(struct perf_event *event)
    @@ -9513,7 +9513,7 @@ static void perf_swevent_init_hrtimer(struct perf_event *event)
    if (!is_sampling_event(event))
    return;

    - hrtimer_init(&hwc->hrtimer, CLOCK_MONOTONIC, HRTIMER_MODE_REL);
    + hrtimer_init(&hwc->hrtimer, CLOCK_MONOTONIC, HRTIMER_MODE_REL_HARD);
    hwc->hrtimer.function = perf_swevent_hrtimer;

    /*
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