[PATCH] tick/nohz: Make the idle_exittime update correctly

[Yunfeng Ye]

The idle_exittime field of tick_sched is used to record the time when
the idle state was left. but currently the idle_exittime is updated in
the function tick_nohz_restart_sched_tick(), which is not always in idle
state when nohz_full is configured.

  tick_irq_exit
    tick_nohz_irq_exit
      tick_nohz_full_update_tick
        tick_nohz_restart_sched_tick
          ts->idle_exittime = now;

So move to tick_nohz_stop_idle() to make the idle_exittime update
correctly.

Signed-off-by: Yunfeng Ye <yeyunf...@huawei.com>
---
 kernel/time/tick-sched.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/kernel/time/tick-sched.c b/kernel/time/tick-sched.c
index 749ec2a583de..be2e5d772d50 100644
--- a/kernel/time/tick-sched.c
+++ b/kernel/time/tick-sched.c
@@ -591,6 +591,7 @@ static void tick_nohz_stop_idle(struct tick_sched *ts, 
ktime_t now)
 {
        update_ts_time_stats(smp_processor_id(), ts, now, NULL);
        ts->idle_active = 0;
+       ts->idle_exittime = now;

        sched_clock_idle_wakeup_event();
 }
@@ -901,7 +902,6 @@ static void tick_nohz_restart_sched_tick(struct tick_sched 
*ts, ktime_t now)
         * Cancel the scheduled timer and restore the tick
         */
        ts->tick_stopped  = 0;
-       ts->idle_exittime = now;

        tick_nohz_restart(ts, now);
 }
-- 
2.18.4