tick/sched: Split out jiffies update helper function

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>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Frederic Weisbecker <frederic@kernel.org>
Link: https://lore.kernel.org/r/20240221090548.36600-17-anna-maria@linutronix.de

diff --git a/kernel/time/tick-internal.h b/kernel/time/tick-internal.h
index 8b0c28edbd090ec465e8d79e2dd210b1e255863b..ccf39befde853db695574d216eabb4d8fc31dbda 100644 (file)
--- a/kernel/time/tick-internal.h
+++ b/kernel/time/tick-internal.h
@@ -157,6 +157,7 @@ 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;
 extern void fetch_next_timer_interrupt_remote(unsigned long basej, u64 basem,

diff --git a/kernel/time/tick-sched.c b/kernel/time/tick-sched.c
index f6b6133802298769322fab66d22bf4981c60a6ee..417bb7f880ca06f62224dcde6ee5d900a5cf573c 100644 (file)
--- a/kernel/time/tick-sched.c
+++ b/kernel/time/tick-sched.c
@@ -799,6 +799,24 @@ static inline bool local_timer_softirq_pending(void)
        return local_softirq_pending() & BIT(TIMER_SOFTIRQ);
 }
 
+/*
+ * Read jiffies and the time when jiffies were updated last
+ */
+u64 get_jiffies_update(unsigned long *basej)
+{
+       unsigned long basejiff;
+       unsigned int seq;
+       u64 basemono;
+
+       do {
+               seq = read_seqcount_begin(&jiffies_seq);
+               basemono = last_jiffies_update;
+               basejiff = jiffies;
+       } while (read_seqcount_retry(&jiffies_seq, seq));
+       *basej = basejiff;
+       return basemono;
+}
+
 /**
  * tick_nohz_next_event() - return the clock monotonic based next event
  * @ts:                pointer to tick_sched struct
@@ -813,14 +831,8 @@ static ktime_t tick_nohz_next_event(struct tick_sched *ts, int cpu)
 {
        u64 basemono, next_tick, delta, expires;
        unsigned long basejiff;
-       unsigned int seq;
 
-       /* 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));
+       basemono = get_jiffies_update(&basejiff);
        ts->last_jiffies = basejiff;
        ts->timer_expires_base = basemono;