[PATCH 4/4] sched / idle: Call default_idle_call() from cpuidle_enter_state()

["Rafael J. Wysocki" <rjw@rjwysocki.net>]

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

The check of the cpuidle_enter() return value against -EBUSY
made in call_cpuidle() will not be necessary any more if
cpuidle_enter_state() calls default_idle_call() directly when it
is about to return -EBUSY, so make that happen and eliminate the
check.

Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
---
 drivers/cpuidle/cpuidle.c |    4 +++-
 drivers/cpuidle/cpuidle.h |    2 ++
 kernel/sched/idle.c       |   14 ++++++--------
 3 files changed, 11 insertions(+), 9 deletions(-)

Index: linux-pm/drivers/cpuidle/cpuidle.c
===================================================================
--- linux-pm.orig/drivers/cpuidle/cpuidle.c
+++ linux-pm/drivers/cpuidle/cpuidle.c
@@ -167,8 +167,10 @@ int cpuidle_enter_state(struct cpuidle_d
 	 * local timer will be shut down.  If a local timer is used from another
 	 * CPU as a broadcast timer, this call may fail if it is not available.
 	 */
-	if (broadcast && tick_broadcast_enter())
+	if (broadcast && tick_broadcast_enter()) {
+		default_idle_call();
 		return -EBUSY;
+	}
 
 	trace_cpu_idle_rcuidle(index, dev->cpu);
 	time_start = ktime_get();
Index: linux-pm/drivers/cpuidle/cpuidle.h
===================================================================
--- linux-pm.orig/drivers/cpuidle/cpuidle.h
+++ linux-pm/drivers/cpuidle/cpuidle.h
@@ -18,6 +18,8 @@ extern int cpuidle_enter_state(struct cp
 /* idle loop */
 extern void cpuidle_install_idle_handler(void);
 extern void cpuidle_uninstall_idle_handler(void);
+/* kernel/sched/idle.c */
+extern void default_idle_call(void);
 
 /* governors */
 extern int cpuidle_switch_governor(struct cpuidle_governor *gov);
Index: linux-pm/kernel/sched/idle.c
===================================================================
--- linux-pm.orig/kernel/sched/idle.c
+++ linux-pm/kernel/sched/idle.c
@@ -67,11 +67,12 @@ void __weak arch_cpu_idle(void)
 	local_irq_enable();
 }
 
-static void default_idle_call(void) {
-	/*
-	 * We can't use the cpuidle framework, let's use the default idle
-	 * routine.
-	 */
+/**
+ * default_idle_call - Default CPU idle routine.
+ *
+ * To use when the cpuidle framework cannot be used.
+ */
+void default_idle_call(void) {
 	if (current_clr_polling_and_test())
 		local_irq_enable();
 	else
@@ -112,9 +113,6 @@ static int call_cpuidle(struct cpuidle_d
 	/* The cpu is no longer idle or about to enter idle. */
 	idle_set_state(this_rq(), NULL);
 
-	if (entered_state == -EBUSY)
-		default_idle_call();
-
 	return entered_state;
 }