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Commit 51164251 authored Jan 16, 2016 by Rafael J. Wysocki

sched / idle: Drop default_idle_call() fallback from call_cpuidle()



After commit 9c4b2867 (cpuidle: menu: Fix menu_select() for
CPUIDLE_DRIVER_STATE_START == 0) it is clear that menu_select()
cannot return negative values.  Moreover, ladder_select_state()
will never return a negative value too, so make find_deepest_state()
return non-negative values too and drop the default_idle_call()
fallback from call_cpuidle().

This eliminates one branch from the idle loop and makes the governors
and find_deepest_state() handle the case when all states have been
disabled from sysfs consistently.

Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Acked-by: Ingo Molnar <mingo@kernel.org>
Tested-by: Sudeep Holla <sudeep.holla@arm.com>

parent 10475b34

drivers/cpuidle/cpuidle.c

+3 −3

Original line number	Original line	Diff line number	Diff line
	@@ -79,9 +79,9 @@ static int find_deepest_state(struct cpuidle_driver *drv,
	bool freeze)		bool freeze)
	{		{
	unsigned int latency_req = 0;		unsigned int latency_req = 0;
	int i, ret = -ENXIO;		int i, ret = 0;

	for (i = 0; i < drv->state_count; i++) {		for (i = 1; i < drv->state_count; i++) {
	struct cpuidle_state *s = &drv->states[i];		struct cpuidle_state *s = &drv->states[i];
	struct cpuidle_state_usage *su = &dev->states_usage[i];		struct cpuidle_state_usage *su = &dev->states_usage[i];

	@@ -243,7 +243,7 @@ int cpuidle_enter_state(struct cpuidle_device dev, struct cpuidle_driver drv,
	* @drv: the cpuidle driver		* @drv: the cpuidle driver
	* @dev: the cpuidle device		* @dev: the cpuidle device
	*		*
	* Returns the index of the idle state.		* Returns the index of the idle state. The return value must not be negative.
	*/		*/
	int cpuidle_select(struct cpuidle_driver drv, struct cpuidle_device dev)		int cpuidle_select(struct cpuidle_driver drv, struct cpuidle_device dev)
	{		{

kernel/sched/idle.c

+0 −6

Original line number	Original line	Diff line number	Diff line
	@@ -97,12 +97,6 @@ void default_idle_call(void)
	static int call_cpuidle(struct cpuidle_driver drv, struct cpuidle_device dev,		static int call_cpuidle(struct cpuidle_driver drv, struct cpuidle_device dev,
	int next_state)		int next_state)
	{		{
	/* Fall back to the default arch idle method on errors. */
	if (next_state < 0) {
	default_idle_call();
	return next_state;
	}

	/*		/*
	* The idle task must be scheduled, it is pointless to go to idle, just		* The idle task must be scheduled, it is pointless to go to idle, just
	* update no idle residency and return.		* update no idle residency and return.