cpuidle: Consolidate disabled state checks

There are two reasons why CPU idle states may be disabled: either
because the driver has disabled them or because they have been
disabled by user space via sysfs.

In the former case, the state's "disabled" flag is set once during
the initialization of the driver and it is never cleared later (it
is read-only effectively).  In the latter case, the "disable" field
of the given state's cpuidle_state_usage struct is set and it may be
changed via sysfs.  Thus checking whether or not an idle state has
been disabled involves reading these two flags every time.

In order to avoid the additional check of the state's "disabled" flag
(which is effectively read-only anyway), use the value of it at the
init time to set a (new) flag in the "disable" field of that state's
cpuidle_state_usage structure and use the sysfs interface to
manipulate another (new) flag in it.  This way the state is disabled
whenever the "disable" field of its cpuidle_state_usage structure is
nonzero, whatever the reason, and it is the only place to look into
to check whether or not the state has been disabled.

Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Acked-by: Daniel Lezcano <daniel.lezcano@linaro.org>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>

3 files changed, 6 insertions, 11 deletions

diff --git a/drivers/cpuidle/governors/ladder.c b/drivers/cpuidle/governors/ladder.c
index 428eeb832fe7..b0126b8c32fe 100644
--- a/drivers/cpuidle/governors/ladder.c
+++ b/drivers/cpuidle/governors/ladder.c
@@ -84,7 +84,6 @@ static int ladder_select_state(struct cpuidle_driver *drv,
 
 	/* consider promotion */
 	if (last_idx < drv->state_count - 1 &&
-	    !drv->states[last_idx + 1].disabled &&
 	    !dev->states_usage[last_idx + 1].disable &&
 	    last_residency > last_state->threshold.promotion_time &&
 	    drv->states[last_idx + 1].exit_latency <= latency_req) {
@@ -98,8 +97,7 @@ static int ladder_select_state(struct cpuidle_driver *drv,
 
 	/* consider demotion */
 	if (last_idx > first_idx &&
-	    (drv->states[last_idx].disabled ||
-	    dev->states_usage[last_idx].disable ||
+	    (dev->states_usage[last_idx].disable ||
 	    drv->states[last_idx].exit_latency > latency_req)) {
 		int i;
 
diff --git a/drivers/cpuidle/governors/menu.c b/drivers/cpuidle/governors/menu.c
index e5a5d0c8d66b..38b2b72102a8 100644
--- a/drivers/cpuidle/governors/menu.c
+++ b/drivers/cpuidle/governors/menu.c
@@ -298,7 +298,7 @@ static int menu_select(struct cpuidle_driver *drv, struct cpuidle_device *dev,
 	if (unlikely(drv->state_count <= 1 || latency_req == 0) ||
 	    ((data->next_timer_us < drv->states[1].target_residency ||
 	      latency_req < drv->states[1].exit_latency) &&
-	     !drv->states[0].disabled && !dev->states_usage[0].disable)) {
+	     !dev->states_usage[0].disable)) {
 		/*
 		 * In this case state[0] will be used no matter what, so return
 		 * it right away and keep the tick running if state[0] is a
@@ -349,9 +349,8 @@ static int menu_select(struct cpuidle_driver *drv, struct cpuidle_device *dev,
 	idx = -1;
 	for (i = 0; i < drv->state_count; i++) {
 		struct cpuidle_state *s = &drv->states[i];
-		struct cpuidle_state_usage *su = &dev->states_usage[i];
 
-		if (s->disabled || su->disable)
+		if (dev->states_usage[i].disable)
 			continue;
 
 		if (idx == -1)
@@ -422,8 +421,7 @@ static int menu_select(struct cpuidle_driver *drv, struct cpuidle_device *dev,
 			 * tick, so try to correct that.
 			 */
 			for (i = idx - 1; i >= 0; i--) {
-				if (drv->states[i].disabled ||
-				    dev->states_usage[i].disable)
+				if (dev->states_usage[i].disable)
 					continue;
 
 				idx = i;
diff --git a/drivers/cpuidle/governors/teo.c b/drivers/cpuidle/governors/teo.c
index b9b9156618e6..702d560eb347 100644
--- a/drivers/cpuidle/governors/teo.c
+++ b/drivers/cpuidle/governors/teo.c
@@ -212,7 +212,7 @@ static int teo_find_shallower_state(struct cpuidle_driver *drv,
 	int i;
 
 	for (i = state_idx - 1; i >= 0; i--) {
-		if (drv->states[i].disabled || dev->states_usage[i].disable)
+		if (dev->states_usage[i].disable)
 			continue;
 
 		state_idx = i;
@@ -256,9 +256,8 @@ static int teo_select(struct cpuidle_driver *drv, struct cpuidle_device *dev,
 
 	for (i = 0; i < drv->state_count; i++) {
 		struct cpuidle_state *s = &drv->states[i];
-		struct cpuidle_state_usage *su = &dev->states_usage[i];
 
-		if (s->disabled || su->disable) {
+		if (dev->states_usage[i].disable) {
 			/*
 			 * Ignore disabled states with target residencies beyond
 			 * the anticipated idle duration.