sched/idle: Move idle conditions in cpuidle_idle main function

This patch moves the condition before entering idle into the cpuidle main
function located in idle.c. That simplify the idle mainloop functions and
increase the readibility of the conditions to enter truly idle.

This patch is code reorganization and does not change the behavior of the
function.

Signed-off-by: Daniel Lezcano <daniel.lezcano@linaro.org>
Signed-off-by: Peter Zijlstra <peterz@infradead.org>
Cc: tglx@linutronix.de
Cc: rjw@rjwysocki.net
Cc: nicolas.pitre@linaro.org
Cc: preeti@linux.vnet.ibm.com
Link: http://lkml.kernel.org/r/1393832934-11625-4-git-send-email-daniel.lezcano@linaro.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>

kernel/sched/idle.c

@@ -76,44 +76,59 @@ static int cpuidle_idle_call(void)
 	int next_state, entered_state, ret;
 	bool broadcast;
 
+	if (current_clr_polling_and_test()) {
+		local_irq_enable();
+		__current_set_polling();
+		return 0;
+	}
+
 	stop_critical_timings();
 	rcu_idle_enter();
 
 	ret = cpuidle_enabled(drv, dev);
-	if (ret < 0) {
-		arch_cpu_idle();
-		goto out;
-	}
 
-	/* ask the governor for the next state */
-	next_state = cpuidle_select(drv, dev);
+	if (!ret) {
+		/* ask the governor for the next state */
+		next_state = cpuidle_select(drv, dev);
 
-	if (need_resched()) {
-		dev->last_residency = 0;
-		/* give the governor an opportunity to reflect on the outcome */
-		cpuidle_reflect(dev, next_state);
-		local_irq_enable();
-		goto out;
-	}
+		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)
+				ret = clockevents_notify(
+					CLOCK_EVT_NOTIFY_BROADCAST_ENTER,
+					&dev->cpu);
 
-	broadcast = !!(drv->states[next_state].flags & CPUIDLE_FLAG_TIMER_STOP);
+			if (!ret) {
+				trace_cpu_idle_rcuidle(next_state, dev->cpu);
 
-	if (broadcast &&
-	    clockevents_notify(CLOCK_EVT_NOTIFY_BROADCAST_ENTER, &dev->cpu))
-		return -EBUSY;
+				entered_state = cpuidle_enter(drv, dev,
+							      next_state);
 
-	trace_cpu_idle_rcuidle(next_state, dev->cpu);
+				trace_cpu_idle_rcuidle(PWR_EVENT_EXIT,
+						       dev->cpu);
 
-	entered_state = cpuidle_enter(drv, dev, next_state);
+				if (broadcast)
+					clockevents_notify(
+						CLOCK_EVT_NOTIFY_BROADCAST_EXIT,
+						&dev->cpu);
 
-	trace_cpu_idle_rcuidle(PWR_EVENT_EXIT, dev->cpu);
+				/* give the governor an opportunity to reflect on the outcome */
+				cpuidle_reflect(dev, entered_state);
+			}
+		}
+	}
+
+	if (ret)
+		arch_cpu_idle();
 
-	if (broadcast)
-		clockevents_notify(CLOCK_EVT_NOTIFY_BROADCAST_EXIT, &dev->cpu);
+	__current_set_polling();
 
-	/* give the governor an opportunity to reflect on the outcome */
-	cpuidle_reflect(dev, entered_state);
-out:
 	if (WARN_ON_ONCE(irqs_disabled()))
 		local_irq_enable();
 
@@ -150,16 +165,11 @@ 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()) {
-					cpuidle_idle_call();
-				} else {
-					local_irq_enable();
-				}
-				__current_set_polling();
-			}
+			else
+				cpuidle_idle_call();
+
 			arch_cpu_idle_exit();
 		}