From 99e98d3fb1008ef7416e16a1fd355cb73a253502 Mon Sep 17 00:00:00 2001
From: "Rafael J. Wysocki" <rafael.j.wysocki@intel.com>
Date: Mon, 4 Nov 2019 12:16:17 +0100
Subject: [PATCH] cpuidle: Consolidate disabled state checks
Git-commit: 99e98d3fb1008ef7416e16a1fd355cb73a253502
Patch-mainline: v5.5-rc1
References: bsc#1175543

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>
Signed-off-by: Lin Ma <lma@suse.com>
---
 drivers/cpuidle/cpuidle-powernv.c  |  7 ++--
 drivers/cpuidle/cpuidle.c          | 24 +++++++-------
 drivers/cpuidle/governors/ladder.c |  4 +--
 drivers/cpuidle/governors/menu.c   |  8 ++---
 drivers/cpuidle/governors/teo.c    |  5 ++-
 drivers/cpuidle/sysfs.c            | 51 ++++++++++++++++++------------
 include/linux/cpuidle.h            |  3 ++
 7 files changed, 54 insertions(+), 48 deletions(-)

diff --git a/drivers/cpuidle/cpuidle-powernv.c b/drivers/cpuidle/cpuidle-powernv.c
index 84b1ebe212b3..1b299e801f74 100644
--- a/drivers/cpuidle/cpuidle-powernv.c
+++ b/drivers/cpuidle/cpuidle-powernv.c
@@ -56,13 +56,10 @@ static u64 get_snooze_timeout(struct cpu
 		return default_snooze_timeout;
 
 	for (i = index + 1; 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;
 
-		return s->target_residency * tb_ticks_per_usec;
+		return drv->states[i].target_residency * tb_ticks_per_usec;
 	}
 
 	return default_snooze_timeout;
diff --git a/drivers/cpuidle/cpuidle.c b/drivers/cpuidle/cpuidle.c
index b903016e653b..069efad29ea6 100644
--- a/drivers/cpuidle/cpuidle.c
+++ b/drivers/cpuidle/cpuidle.c
@@ -84,12 +84,12 @@ static int find_deepest_state(struct cpu
 
 	for (i = 1; 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 || s->exit_latency <= latency_req
-		    || s->exit_latency > max_latency
-		    || (s->flags & forbidden_flags)
-		    || (s2idle && !s->enter_s2idle))
+		if (dev->states_usage[i].disable ||
+		    s->exit_latency <= latency_req ||
+		    s->exit_latency > max_latency ||
+		    (s->flags & forbidden_flags) ||
+		    (s2idle && !s->enter_s2idle))
 			continue;
 
 		latency_req = s->exit_latency;
@@ -265,8 +265,7 @@ int cpuidle_enter_state(struct cpuidle_d
 
 		if (diff < drv->states[entered_state].target_residency) {
 			for (i = entered_state - 1; i >= 0; i--) {
-				if (drv->states[i].disabled ||
-				    dev->states_usage[i].disable)
+				if (dev->states_usage[i].disable)
 					continue;
 
 				/* Shallower states are enabled, so update. */
@@ -275,8 +274,7 @@ int cpuidle_enter_state(struct cpuidle_d
 			}
 		} else if (diff > delay) {
 			for (i = entered_state + 1; i < drv->state_count; i++) {
-				if (drv->states[i].disabled ||
-				    dev->states_usage[i].disable)
+				if (dev->states_usage[i].disable)
 					continue;
 
 				/*
@@ -380,7 +378,7 @@ u64 cpuidle_poll_time(struct cpuidle_dri
 
 	limit_ns = TICK_NSEC;
 	for (i = 1; i < drv->state_count; i++) {
-		if (drv->states[i].disabled || dev->states_usage[i].disable)
+		if (dev->states_usage[i].disable)
 			continue;
 
 		limit_ns = (u64)drv->states[i].target_residency * NSEC_PER_USEC;
@@ -567,12 +565,16 @@ static void __cpuidle_device_init(struct
  */
 static int __cpuidle_register_device(struct cpuidle_device *dev)
 {
-	int ret;
 	struct cpuidle_driver *drv = cpuidle_get_cpu_driver(dev);
+	int i, ret;
 
 	if (!try_module_get(drv->owner))
 		return -EINVAL;
 
+	for (i = 0; i < drv->state_count; i++)
+		if (drv->states[i].disabled)
+			dev->states_usage[i].disable |= CPUIDLE_STATE_DISABLED_BY_DRIVER;
+
 	per_cpu(cpuidle_devices, dev->cpu) = dev;
 	list_add(&dev->device_list, &cpuidle_detected_devices);
 
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 cp
 
 	/* 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 cp
 
 	/* 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_dr
 	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_dr
 	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_dr
 			 * 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 e55eec2574e7..cccbecd403de 100644
--- a/drivers/cpuidle/governors/teo.c
+++ b/drivers/cpuidle/governors/teo.c
@@ -220,7 +220,7 @@ static int teo_find_shallower_state(stru
 	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;
@@ -264,9 +264,8 @@ static int teo_select(struct cpuidle_dri
 
 	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.
diff --git a/drivers/cpuidle/sysfs.c b/drivers/cpuidle/sysfs.c
index f8747322b3c7..b9d2bae2edb0 100644
--- a/drivers/cpuidle/sysfs.c
+++ b/drivers/cpuidle/sysfs.c
@@ -255,25 +255,6 @@ static ssize_t show_state_##_name(struct
 	return sprintf(buf, "%u\n", state->_name);\
 }
 
-#define define_store_state_ull_function(_name) \
-static ssize_t store_state_##_name(struct cpuidle_state *state, \
-				   struct cpuidle_state_usage *state_usage, \
-				   const char *buf, size_t size)	\
-{ \
-	unsigned long long value; \
-	int err; \
-	if (!capable(CAP_SYS_ADMIN)) \
-		return -EPERM; \
-	err = kstrtoull(buf, 0, &value); \
-	if (err) \
-		return err; \
-	if (value) \
-		state_usage->_name = 1; \
-	else \
-		state_usage->_name = 0; \
-	return size; \
-}
-
 #define define_show_state_ull_function(_name) \
 static ssize_t show_state_##_name(struct cpuidle_state *state, \
 				  struct cpuidle_state_usage *state_usage, \
@@ -299,11 +280,39 @@ define_show_state_ull_function(usage)
 define_show_state_ull_function(time)
 define_show_state_str_function(name)
 define_show_state_str_function(desc)
-define_show_state_ull_function(disable)
-define_store_state_ull_function(disable)
 define_show_state_ull_function(above)
 define_show_state_ull_function(below)
 
+static ssize_t show_state_disable(struct cpuidle_state *state,
+				  struct cpuidle_state_usage *state_usage,
+				  char *buf)
+{
+	return sprintf(buf, "%llu\n",
+		       state_usage->disable & CPUIDLE_STATE_DISABLED_BY_USER);
+}
+
+static ssize_t store_state_disable(struct cpuidle_state *state,
+				   struct cpuidle_state_usage *state_usage,
+				   const char *buf, size_t size)
+{
+	unsigned int value;
+	int err;
+
+	if (!capable(CAP_SYS_ADMIN))
+		return -EPERM;
+
+	err = kstrtouint(buf, 0, &value);
+	if (err)
+		return err;
+
+	if (value)
+		state_usage->disable |= CPUIDLE_STATE_DISABLED_BY_USER;
+	else
+		state_usage->disable &= ~CPUIDLE_STATE_DISABLED_BY_USER;
+
+	return size;
+}
+
 define_one_state_ro(name, show_state_name);
 define_one_state_ro(desc, show_state_desc);
 define_one_state_ro(latency, show_state_exit_latency);
diff --git a/include/linux/cpuidle.h b/include/linux/cpuidle.h
index 2dc4c6b19c25..194ecf4a4ef0 100644
--- a/include/linux/cpuidle.h
+++ b/include/linux/cpuidle.h
@@ -29,6 +29,9 @@ struct cpuidle_driver;
  * CPUIDLE DEVICE INTERFACE *
  ****************************/
 
+#define CPUIDLE_STATE_DISABLED_BY_USER		BIT(0)
+#define CPUIDLE_STATE_DISABLED_BY_DRIVER	BIT(1)
+
 struct cpuidle_state_usage {
 	unsigned long long	disable;
 	unsigned long long	usage;
-- 
2.26.2