Merge branch 'sched-idle-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip

Pull sched/idle changes from Ingo Molnar:
 "More idle code reorganization, to prepare for more integration.

  (Sent separately because it depended on pending timer work, which is
  now upstream)"

* 'sched-idle-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  sched/idle: Add more comments to the code
  sched/idle: Move idle conditions in cpuidle_idle main function
  sched/idle: Reorganize the idle loop
  cpuidle/idle: Move the cpuidle_idle_call function to idle.c
  idle/cpuidle: Split cpuidle_idle_call main function into smaller functions

1 files changed, 134 insertions, 16 deletions

diff --git a/kernel/sched/idle.c b/kernel/sched/idle.c
index b7976a1..8f4390a 100644
--- a/kernel/sched/idle.c
+++ b/kernel/sched/idle.c
@@ -63,6 +63,136 @@ void __weak arch_cpu_idle(void)
 	local_irq_enable();
 }
 
+/**
+ * cpuidle_idle_call - the main idle function
+ *
+ * NOTE: no locks or semaphores should be used here
+ * return non-zero on failure
+ */
+static int cpuidle_idle_call(void)
+{
+	struct cpuidle_device *dev = __this_cpu_read(cpuidle_devices);
+	struct cpuidle_driver *drv = cpuidle_get_cpu_driver(dev);
+	int next_state, entered_state, ret;
+	bool broadcast;
+
+	/*
+	 * Check if the idle task must be rescheduled. If it is the
+	 * case, exit the function after re-enabling the local irq and
+	 * set again the polling flag
+	 */
+	if (current_clr_polling_and_test()) {
+		local_irq_enable();
+		__current_set_polling();
+		return 0;
+	}
+
+	/*
+	 * During the idle period, stop measuring the disabled irqs
+	 * critical sections latencies
+	 */
+	stop_critical_timings();
+
+	/*
+	 * Tell the RCU framework we are entering an idle section,
+	 * so no more rcu read side critical sections and one more
+	 * step to the grace period
+	 */
+	rcu_idle_enter();
+
+	/*
+	 * Check if the cpuidle framework is ready, otherwise fallback
+	 * to the default arch specific idle method
+	 */
+	ret = cpuidle_enabled(drv, dev);
+
+	if (!ret) {
+		/*
+		 * Ask the governor to choose an idle state it thinks
+		 * it is convenient to go to. There is *always* a
+		 * convenient idle state
+		 */
+		next_state = cpuidle_select(drv, dev);
+
+		/*
+		 * The idle task must be scheduled, it is pointless to
+		 * go to idle, just update no idle residency and get
+		 * out of this function
+		 */
+		if (current_clr_polling_and_test()) {
+			dev->last_residency = 0;
+			entered_state = next_state;
+			local_irq_enable();
+		} else {
+			broadcast = !!(drv->states[next_state].flags &
+				       CPUIDLE_FLAG_TIMER_STOP);
+
+			if (broadcast)
+				/*
+				 * Tell the time framework to switch
+				 * to a broadcast timer because our
+				 * local timer will be shutdown. If a
+				 * local timer is used from another
+				 * cpu as a broadcast timer, this call
+				 * may fail if it is not available
+				 */
+				ret = clockevents_notify(
+					CLOCK_EVT_NOTIFY_BROADCAST_ENTER,
+					&dev->cpu);
+
+			if (!ret) {
+				trace_cpu_idle_rcuidle(next_state, dev->cpu);
+
+				/*
+				 * Enter the idle state previously
+				 * returned by the governor
+				 * decision. This function will block
+				 * until an interrupt occurs and will
+				 * take care of re-enabling the local
+				 * interrupts
+				 */
+				entered_state = cpuidle_enter(drv, dev,
+							      next_state);
+
+				trace_cpu_idle_rcuidle(PWR_EVENT_EXIT,
+						       dev->cpu);
+
+				if (broadcast)
+					clockevents_notify(
+						CLOCK_EVT_NOTIFY_BROADCAST_EXIT,
+						&dev->cpu);
+
+				/*
+				 * Give the governor an opportunity to reflect on the
+				 * outcome
+				 */
+				cpuidle_reflect(dev, entered_state);
+			}
+		}
+	}
+
+	/*
+	 * We can't use the cpuidle framework, let's use the default
+	 * idle routine
+	 */
+	if (ret)
+		arch_cpu_idle();
+
+	__current_set_polling();
+
+	/*
+	 * It is up to the idle functions to enable back the local
+	 * interrupt
+	 */
+	if (WARN_ON_ONCE(irqs_disabled()))
+		local_irq_enable();
+
+	rcu_idle_exit();
+	start_critical_timings();
+
+	return 0;
+}
+
 /*
  * Generic idle loop implementation
  */
@@ -90,23 +220,11 @@ static void cpu_idle_loop(void)
 			 * know that the IPI is going to arrive right
 			 * away
 			 */
-			if (cpu_idle_force_poll || tick_check_broadcast_expired()) {
+			if (cpu_idle_force_poll || tick_check_broadcast_expired())
 				cpu_idle_poll();
-			} else {
-				if (!current_clr_polling_and_test()) {
-					stop_critical_timings();
-					rcu_idle_enter();
-					if (cpuidle_idle_call())
-						arch_cpu_idle();
-					if (WARN_ON_ONCE(irqs_disabled()))
-						local_irq_enable();
-					rcu_idle_exit();
-					start_critical_timings();
-				} else {
-					local_irq_enable();
-				}
-				__current_set_polling();
-			}
+			else
+				cpuidle_idle_call();
+
 			arch_cpu_idle_exit();
 		}