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From:   Daniel Lezcano <daniel.lezcano@linaro.org>
To:     daniel.lezcano@linaro.org, rafael@kernel.org
Cc:     rui.zhang@intel.com, linux-pm@vger.kernel.org,
        linux-kernel@vger.kernel.org, Amit Kucheria <amitk@kernel.org>,
        Lukasz Luba <lukasz.luba@arm.com>
Subject: [PATCH 4/5] thermal/core: Move the thermal zone lock out of the governors
Date:   Fri,  5 Aug 2022 17:38:33 +0200
Message-Id: <20220805153834.2510142-4-daniel.lezcano@linaro.org>
In-Reply-To: <20220805153834.2510142-1-daniel.lezcano@linaro.org>
References: <20220805153834.2510142-1-daniel.lezcano@linaro.org>
MIME-Version: 1.0
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All the governors throttling ops are taking/releasing the lock at the
beginning and the end of the function.

We can move the mutex to the throttling call site instead.

Signed-off-by: Daniel Lezcano <daniel.lezcano@linaro.org>
---
 drivers/thermal/gov_bang_bang.c       |  4 +---
 drivers/thermal/gov_fair_share.c      |  4 +---
 drivers/thermal/gov_power_allocator.c | 16 ++++++----------
 drivers/thermal/gov_step_wise.c       |  4 +---
 drivers/thermal/thermal_core.c        |  2 ++
 5 files changed, 11 insertions(+), 19 deletions(-)

diff --git a/drivers/thermal/gov_bang_bang.c b/drivers/thermal/gov_bang_bang.c
index f0bff2e0475b..a08bbe33be96 100644
--- a/drivers/thermal/gov_bang_bang.c
+++ b/drivers/thermal/gov_bang_bang.c
@@ -96,15 +96,13 @@ static int bang_bang_control(struct thermal_zone_device *tz, int trip)
 {
 	struct thermal_instance *instance;
 
-	mutex_lock(&tz->lock);
+	lockdep_assert_held(&tz->lock);
 
 	thermal_zone_trip_update(tz, trip);
 
 	list_for_each_entry(instance, &tz->thermal_instances, tz_node)
 		thermal_cdev_update(instance->cdev);
 
-	mutex_unlock(&tz->lock);
-
 	return 0;
 }
 
diff --git a/drivers/thermal/gov_fair_share.c b/drivers/thermal/gov_fair_share.c
index 5d5ddd648cd2..a4ee4661e9cc 100644
--- a/drivers/thermal/gov_fair_share.c
+++ b/drivers/thermal/gov_fair_share.c
@@ -82,7 +82,7 @@ static int fair_share_throttle(struct thermal_zone_device *tz, int trip)
 	int total_instance = 0;
 	int cur_trip_level = get_trip_level(tz);
 
-	mutex_lock(&tz->lock);
+	lockdep_assert_held(&tz->lock);
 
 	list_for_each_entry(instance, &tz->thermal_instances, tz_node) {
 		if (instance->trip != trip)
@@ -112,8 +112,6 @@ static int fair_share_throttle(struct thermal_zone_device *tz, int trip)
 		mutex_unlock(&cdev->lock);
 	}
 
-	mutex_unlock(&tz->lock);
-
 	return 0;
 }
 
diff --git a/drivers/thermal/gov_power_allocator.c b/drivers/thermal/gov_power_allocator.c
index d3aca236e274..2d1aeaba38a8 100644
--- a/drivers/thermal/gov_power_allocator.c
+++ b/drivers/thermal/gov_power_allocator.c
@@ -697,19 +697,19 @@ static void power_allocator_unbind(struct thermal_zone_device *tz)
 
 static int power_allocator_throttle(struct thermal_zone_device *tz, int trip)
 {
-	int ret = 0;
+	int ret;
 	int switch_on_temp, control_temp;
 	struct power_allocator_params *params = tz->governor_data;
 	bool update;
 
-	mutex_lock(&tz->lock);
+	lockdep_assert_held(&tz->lock);
 
 	/*
 	 * We get called for every trip point but we only need to do
 	 * our calculations once
 	 */
 	if (trip != params->trip_max_desired_temperature)
-		goto out;
+		return 0;
 
 	ret = tz->ops->get_trip_temp(tz, params->trip_switch_on,
 				     &switch_on_temp);
@@ -718,7 +718,7 @@ static int power_allocator_throttle(struct thermal_zone_device *tz, int trip)
 		tz->passive = 0;
 		reset_pid_controller(params);
 		allow_maximum_power(tz, update);
-		goto out;
+		return 0;
 	}
 
 	tz->passive = 1;
@@ -729,14 +729,10 @@ static int power_allocator_throttle(struct thermal_zone_device *tz, int trip)
 		dev_warn(&tz->device,
 			 "Failed to get the maximum desired temperature: %d\n",
 			 ret);
-		goto out;
+		return ret;
 	}
 
-	ret = allocate_power(tz, control_temp);
-
-	mutex_unlock(&tz->lock);
-out:
-	return ret;
+	return allocate_power(tz, control_temp);
 }
 
 static struct thermal_governor thermal_gov_power_allocator = {
diff --git a/drivers/thermal/gov_step_wise.c b/drivers/thermal/gov_step_wise.c
index 597a0ebec7a4..cdd3354bc27f 100644
--- a/drivers/thermal/gov_step_wise.c
+++ b/drivers/thermal/gov_step_wise.c
@@ -160,15 +160,13 @@ static int step_wise_throttle(struct thermal_zone_device *tz, int trip)
 {
 	struct thermal_instance *instance;
 
-	mutex_lock(&tz->lock);
+	lockdep_assert_held(&tz->lock);
 
 	thermal_zone_trip_update(tz, trip);
 
 	list_for_each_entry(instance, &tz->thermal_instances, tz_node)
 		thermal_cdev_update(instance->cdev);
 
-	mutex_unlock(&tz->lock);
-
 	return 0;
 }
 
diff --git a/drivers/thermal/thermal_core.c b/drivers/thermal/thermal_core.c
index d7029fd1c112..9d554f97e081 100644
--- a/drivers/thermal/thermal_core.c
+++ b/drivers/thermal/thermal_core.c
@@ -311,8 +311,10 @@ static void monitor_thermal_zone(struct thermal_zone_device *tz)
 
 static void handle_non_critical_trips(struct thermal_zone_device *tz, int trip)
 {
+	mutex_lock(&tz->lock);
 	tz->governor ? tz->governor->throttle(tz, trip) :
 		       def_governor->throttle(tz, trip);
+	mutex_unlock(&tz->lock);
 }
 
 void thermal_zone_device_critical(struct thermal_zone_device *tz)
-- 
2.25.1