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    Subject[PATCH v6 18/21] tick/sched: Split out jiffies update helper function
    Date
    From: "Richard Cochran (linutronix GmbH)" <richardcochran@gmail.com>

    The logic to get the time of the last jiffies update will be needed by
    the timer pull model as well.

    Move the code into a global function in anticipation of the new caller.

    No functional change.

    Signed-off-by: Richard Cochran (linutronix GmbH) <richardcochran@gmail.com>
    Signed-off-by: Anna-Maria Behnsen <anna-maria@linutronix.de>
    ---
    kernel/time/tick-internal.h | 1 +
    kernel/time/tick-sched.c | 18 +++++++++++++++---
    2 files changed, 16 insertions(+), 3 deletions(-)

    diff --git a/kernel/time/tick-internal.h b/kernel/time/tick-internal.h
    index c7bba0bb19d9..630ed43cd8d6 100644
    --- a/kernel/time/tick-internal.h
    +++ b/kernel/time/tick-internal.h
    @@ -158,6 +158,7 @@ static inline void tick_nohz_init(void) { }
    #ifdef CONFIG_NO_HZ_COMMON
    extern unsigned long tick_nohz_active;
    extern void timers_update_nohz(void);
    +extern u64 get_jiffies_update(unsigned long *basej);
    # ifdef CONFIG_SMP
    extern struct static_key_false timers_migration_enabled;
    # endif
    diff --git a/kernel/time/tick-sched.c b/kernel/time/tick-sched.c
    index 62836490ba4d..847c459c01f2 100644
    --- a/kernel/time/tick-sched.c
    +++ b/kernel/time/tick-sched.c
    @@ -787,18 +787,30 @@ static inline bool local_timer_softirq_pending(void)
    return local_softirq_pending() & BIT(TIMER_SOFTIRQ);
    }

    -static ktime_t tick_nohz_next_event(struct tick_sched *ts, int cpu)
    +/*
    + * Read jiffies and the time when jiffies were updated last
    + */
    +u64 get_jiffies_update(unsigned long *basej)
    {
    - u64 basemono, next_tick, delta, expires;
    unsigned long basejiff;
    unsigned int seq;
    + u64 basemono;

    - /* Read jiffies and the time when jiffies were updated last */
    do {
    seq = read_seqcount_begin(&jiffies_seq);
    basemono = last_jiffies_update;
    basejiff = jiffies;
    } while (read_seqcount_retry(&jiffies_seq, seq));
    + *basej = basejiff;
    + return basemono;
    +}
    +
    +static ktime_t tick_nohz_next_event(struct tick_sched *ts, int cpu)
    +{
    + u64 basemono, next_tick, delta, expires;
    + unsigned long basejiff;
    +
    + basemono = get_jiffies_update(&basejiff);
    ts->last_jiffies = basejiff;
    ts->timer_expires_base = basemono;

    --
    2.30.2
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