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    Subject[PATCH 5.4 085/151] tick/common: Touch watchdog in tick_unfreeze() on all CPUs
    Date
    From: Chunyan Zhang <zhang.lyra@gmail.com>

    commit 5167c506d62dd9ffab73eba23c79b0a8845c9fe1 upstream.

    Suspend to IDLE invokes tick_unfreeze() on resume. tick_unfreeze() on the
    first resuming CPU resumes timekeeping, which also has the side effect of
    resetting the softlockup watchdog on this CPU.

    But on the secondary CPUs the watchdog is not reset in the resume /
    unfreeze() path, which can result in false softlockup warnings on those
    CPUs depending on the time spent in suspend.

    Prevent this by clearing the softlock watchdog in the unfreeze path also
    on the secondary resuming CPUs.

    [ tglx: Massaged changelog ]

    Signed-off-by: Chunyan Zhang <chunyan.zhang@unisoc.com>
    Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
    Link: https://lore.kernel.org/r/20200110083902.27276-1-chunyan.zhang@unisoc.com
    Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

    ---
    kernel/time/tick-common.c | 2 ++
    1 file changed, 2 insertions(+)

    --- a/kernel/time/tick-common.c
    +++ b/kernel/time/tick-common.c
    @@ -11,6 +11,7 @@
    #include <linux/err.h>
    #include <linux/hrtimer.h>
    #include <linux/interrupt.h>
    +#include <linux/nmi.h>
    #include <linux/percpu.h>
    #include <linux/profile.h>
    #include <linux/sched.h>
    @@ -558,6 +559,7 @@ void tick_unfreeze(void)
    trace_suspend_resume(TPS("timekeeping_freeze"),
    smp_processor_id(), false);
    } else {
    + touch_softlockup_watchdog();
    tick_resume_local();
    }


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