[patch V2 07/10] tick/sched: Split out jiffies update helper function

Thomas Gleixner
2017-04-18T16:44:41Z

[-- Attachment #1: tick-sched_Split-out-jiffies-update-helper.patch --]
[-- Type: text/plain, Size: 2050 bytes --]

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 funtion in anticipation of the new caller.

No functional change.

Signed-off-by: Richard Cochran <rcochran@linutronix.de>
Signed-off-by: Anna-Maria Gleixner <anna-maria@linutronix.de>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>

---
kernel/time/tick-internal.h | 1 +
kernel/time/tick-sched.c | 27 ++++++++++++++++++++-------
2 files changed, 21 insertions(+), 7 deletions(-)

--- a/kernel/time/tick-internal.h
+++ b/kernel/time/tick-internal.h
@@ -151,6 +151,7 @@ static inline void tick_nohz_init(void)

#ifdef CONFIG_NO_HZ_COMMON
extern unsigned long tick_nohz_active;
+extern u64 get_jiffies_update(unsigned long *basej);
#else
#define tick_nohz_active (0)
#endif
--- a/kernel/time/tick-sched.c
+++ b/kernel/time/tick-sched.c
@@ -112,6 +112,24 @@ static ktime_t tick_init_jiffy_update(vo
return period;
}

+#ifdef CONFIG_NO_HZ_COMMON
+/*
+ * Read jiffies and the time when jiffies were updated last
+ */
+u64 get_jiffies_update(unsigned long *basej)
+{
+ unsigned long seq, basejiff;
+ u64 basemono;
+
+ do {
+ seq = read_seqbegin(&jiffies_lock);
+ basemono = last_jiffies_update;
+ basejiff = jiffies;
+ } while (read_seqretry(&jiffies_lock, seq));
+ *basej = basejiff;
+ return basemono;
+}
+#endif

static void tick_sched_do_timer(ktime_t now)
{
@@ -667,15 +685,10 @@ static ktime_t tick_nohz_stop_sched_tick
{
struct clock_event_device *dev = __this_cpu_read(tick_cpu_device.evtdev);
u64 basemono, next_tick, next_local, next_global, next_rcu, delta, expires;
- unsigned long seq, basejiff;
+ unsigned long basejiff;
ktime_t tick;

- /* Read jiffies and the time when jiffies were updated last */
- do {
- seq = read_seqbegin(&jiffies_lock);
- basemono = last_jiffies_update;
- basejiff = jiffies;
- } while (read_seqretry(&jiffies_lock, seq));
+ basemono = get_jiffies_update(&basejiff);
ts->last_jiffies = basejiff;

if (rcu_needs_cpu(basemono, &next_rcu) ||