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    Subject[PATCH 4.16 51/52] clocksource: Consistent de-rate when marking unstable
    Date
    4.16-stable review patch.  If anyone has any objections, please let me know.

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

    From: Peter Zijlstra <peterz@infradead.org>

    commit cd2af07d823e5287cd6c91d54337348c2a873462 upstream.

    When a registered clocksource gets marked unstable the watchdog_kthread
    will de-rate and re-select the clocksource. Ensure it also de-rates
    when getting called on an unregistered clocksource.

    Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
    Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
    Reviewed-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
    Cc: len.brown@intel.com
    Cc: rjw@rjwysocki.net
    Cc: diego.viola@gmail.com
    Cc: rui.zhang@intel.com
    Cc: stable@vger.kernel.org
    Link: https://lkml.kernel.org/r/20180430100344.594904898@infradead.org
    Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

    ---
    kernel/time/clocksource.c | 9 ++++++++-
    1 file changed, 8 insertions(+), 1 deletion(-)

    --- a/kernel/time/clocksource.c
    +++ b/kernel/time/clocksource.c
    @@ -152,12 +152,19 @@ static void __clocksource_unstable(struc
    cs->flags &= ~(CLOCK_SOURCE_VALID_FOR_HRES | CLOCK_SOURCE_WATCHDOG);
    cs->flags |= CLOCK_SOURCE_UNSTABLE;

    - if (list_empty(&cs->list))
    + /*
    + * If the clocksource is registered clocksource_watchdog_kthread() will
    + * re-rate and re-select.
    + */
    + if (list_empty(&cs->list)) {
    + cs->rating = 0;
    return;
    + }

    if (cs->mark_unstable)
    cs->mark_unstable(cs);

    + /* kick clocksource_watchdog_kthread() */
    if (finished_booting)
    schedule_work(&watchdog_work);
    }

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