[PATCH] cpuidle: Always stop scheduler tick on adaptive-tick CPUs

[Rafael J. Wysocki]

From: Rafael J. Wysocki <rafael.j.wysocki@xxxxxxxxx>

Running the scheduler tick on idle adaptive-tick CPUs is not useful
and it may also be not expected by users (as reported by Thomas), so
add a check to cpuidle_idle_call() to always stop the tick on them
regardless of the idle duration predicted by the governor.

Fixes: 554c8aa8ecad ("sched: idle: Select idle state before stopping the tick")
Reported-by: Thomas Lindroth <thomas.lindroth@xxxxxxxxx>
Tested-by: Thomas Lindroth <thomas.lindroth@xxxxxxxxx>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@xxxxxxxxx>
---
 kernel/sched/idle.c |    3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

Index: linux-pm/kernel/sched/idle.c
===================================================================
--- linux-pm.orig/kernel/sched/idle.c
+++ linux-pm/kernel/sched/idle.c
@@ -191,7 +191,8 @@ static void cpuidle_idle_call(void)
 		 */
 		next_state = cpuidle_select(drv, dev, &stop_tick);
 
-		if (stop_tick || tick_nohz_tick_stopped())
+		if (stop_tick || tick_nohz_tick_stopped() ||
+		    !housekeeping_cpu(dev->cpu, HK_FLAG_TICK))
 			tick_nohz_idle_stop_tick();
 		else
 			tick_nohz_idle_retain_tick();