[PATCH v2 09/11] thermal: core: Add and use cooling device guard

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

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

Add and use a special guard for cooling devices.

This allows quite a few error code paths to be simplified among
other things and brings in code size reduction for a good measure.

No intentional functional impact.

Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
---

This is a new iteration of

https://lore.kernel.org/linux-pm/1890654.atdPhlSkOF@rjwysocki.net/

v1 -> v2: Rearrange cur_state_store()

---
 drivers/thermal/gov_power_allocator.c |   21 +++++++--------
 drivers/thermal/gov_step_wise.c       |    6 ++--
 drivers/thermal/thermal_core.c        |   17 +++---------
 drivers/thermal/thermal_debugfs.c     |   25 +++++++++++-------
 drivers/thermal/thermal_helpers.c     |   19 +++-----------
 drivers/thermal/thermal_sysfs.c       |   45 ++++++++++++----------------------
 include/linux/thermal.h               |    3 ++
 7 files changed, 57 insertions(+), 79 deletions(-)

Index: linux-pm/drivers/thermal/thermal_core.c
===================================================================
--- linux-pm.orig/drivers/thermal/thermal_core.c
+++ linux-pm/drivers/thermal/thermal_core.c
@@ -756,12 +756,10 @@ static int thermal_instance_add(struct t
 
 	list_add_tail(&new_instance->trip_node, &td->thermal_instances);
 
-	mutex_lock(&cdev->lock);
+	guard(cooling_dev)(cdev);
 
 	list_add_tail(&new_instance->cdev_node, &cdev->thermal_instances);
 
-	mutex_unlock(&cdev->lock);
-
 	return 0;
 }
 
@@ -870,11 +868,9 @@ static void thermal_instance_delete(stru
 {
 	list_del(&instance->trip_node);
 
-	mutex_lock(&instance->cdev->lock);
+	guard(cooling_dev)(instance->cdev);
 
 	list_del(&instance->cdev_node);
-
-	mutex_unlock(&instance->cdev->lock);
 }
 
 /**
@@ -1237,10 +1233,10 @@ void thermal_cooling_device_update(struc
 	 * Update under the cdev lock to prevent the state from being set beyond
 	 * the new limit concurrently.
 	 */
-	mutex_lock(&cdev->lock);
+	guard(cooling_dev)(cdev);
 
 	if (cdev->ops->get_max_state(cdev, &cdev->max_state))
-		goto unlock;
+		return;
 
 	thermal_cooling_device_stats_reinit(cdev);
 
@@ -1267,12 +1263,9 @@ void thermal_cooling_device_update(struc
 	}
 
 	if (cdev->ops->get_cur_state(cdev, &state) || state > cdev->max_state)
-		goto unlock;
+		return;
 
 	thermal_cooling_device_stats_update(cdev, state);
-
-unlock:
-	mutex_unlock(&cdev->lock);
 }
 EXPORT_SYMBOL_GPL(thermal_cooling_device_update);
 
Index: linux-pm/include/linux/thermal.h
===================================================================
--- linux-pm.orig/include/linux/thermal.h
+++ linux-pm/include/linux/thermal.h
@@ -137,6 +137,9 @@ struct thermal_cooling_device {
 #endif
 };
 
+DEFINE_GUARD(cooling_dev, struct thermal_cooling_device *, mutex_lock(&_T->lock),
+	     mutex_unlock(&_T->lock))
+
 /* Structure to define Thermal Zone parameters */
 struct thermal_zone_params {
 	const char *governor_name;
Index: linux-pm/drivers/thermal/thermal_sysfs.c
===================================================================
--- linux-pm.orig/drivers/thermal/thermal_sysfs.c
+++ linux-pm/drivers/thermal/thermal_sysfs.c
@@ -544,14 +544,15 @@ cur_state_store(struct device *dev, stru
 	if (state > cdev->max_state)
 		return -EINVAL;
 
-	mutex_lock(&cdev->lock);
+	guard(cooling_dev)(cdev);
 
 	result = cdev->ops->set_cur_state(cdev, state);
-	if (!result)
-		thermal_cooling_device_stats_update(cdev, state);
+	if (result)
+		return result;
 
-	mutex_unlock(&cdev->lock);
-	return result ? result : count;
+	thermal_cooling_device_stats_update(cdev, state);
+
+	return count;
 }
 
 static struct device_attribute
@@ -625,21 +626,18 @@ static ssize_t total_trans_show(struct d
 {
 	struct thermal_cooling_device *cdev = to_cooling_device(dev);
 	struct cooling_dev_stats *stats;
-	int ret = 0;
+	int ret;
 
-	mutex_lock(&cdev->lock);
+	guard(cooling_dev)(cdev);
 
 	stats = cdev->stats;
 	if (!stats)
-		goto unlock;
+		return 0;
 
 	spin_lock(&stats->lock);
 	ret = sprintf(buf, "%u\n", stats->total_trans);
 	spin_unlock(&stats->lock);
 
-unlock:
-	mutex_unlock(&cdev->lock);
-
 	return ret;
 }
 
@@ -652,11 +650,11 @@ time_in_state_ms_show(struct device *dev
 	ssize_t len = 0;
 	int i;
 
-	mutex_lock(&cdev->lock);
+	guard(cooling_dev)(cdev);
 
 	stats = cdev->stats;
 	if (!stats)
-		goto unlock;
+		return 0;
 
 	spin_lock(&stats->lock);
 
@@ -668,9 +666,6 @@ time_in_state_ms_show(struct device *dev
 	}
 	spin_unlock(&stats->lock);
 
-unlock:
-	mutex_unlock(&cdev->lock);
-
 	return len;
 }
 
@@ -682,11 +677,11 @@ reset_store(struct device *dev, struct d
 	struct cooling_dev_stats *stats;
 	int i, states;
 
-	mutex_lock(&cdev->lock);
+	guard(cooling_dev)(cdev);
 
 	stats = cdev->stats;
 	if (!stats)
-		goto unlock;
+		return count;
 
 	states = cdev->max_state + 1;
 
@@ -702,9 +697,6 @@ reset_store(struct device *dev, struct d
 
 	spin_unlock(&stats->lock);
 
-unlock:
-	mutex_unlock(&cdev->lock);
-
 	return count;
 }
 
@@ -716,13 +708,11 @@ static ssize_t trans_table_show(struct d
 	ssize_t len = 0;
 	int i, j;
 
-	mutex_lock(&cdev->lock);
+	guard(cooling_dev)(cdev);
 
 	stats = cdev->stats;
-	if (!stats) {
-		len = -ENODATA;
-		goto unlock;
-	}
+	if (!stats)
+		return -ENODATA;
 
 	len += snprintf(buf + len, PAGE_SIZE - len, " From  :    To\n");
 	len += snprintf(buf + len, PAGE_SIZE - len, "       : ");
@@ -760,9 +750,6 @@ static ssize_t trans_table_show(struct d
 		len = -EFBIG;
 	}
 
-unlock:
-	mutex_unlock(&cdev->lock);
-
 	return len;
 }
 
Index: linux-pm/drivers/thermal/thermal_helpers.c
===================================================================
--- linux-pm.orig/drivers/thermal/thermal_helpers.c
+++ linux-pm/drivers/thermal/thermal_helpers.c
@@ -58,17 +58,10 @@ bool thermal_trip_is_bound_to_cdev(struc
 				   const struct thermal_trip *trip,
 				   struct thermal_cooling_device *cdev)
 {
-	bool ret;
-
 	guard(thermal_zone)(tz);
+	guard(cooling_dev)(cdev);
 
-	mutex_lock(&cdev->lock);
-
-	ret = thermal_instance_present(tz, cdev, trip);
-
-	mutex_unlock(&cdev->lock);
-
-	return ret;
+	return thermal_instance_present(tz, cdev, trip);
 }
 EXPORT_SYMBOL_GPL(thermal_trip_is_bound_to_cdev);
 
@@ -197,12 +190,12 @@ void __thermal_cdev_update(struct therma
  */
 void thermal_cdev_update(struct thermal_cooling_device *cdev)
 {
-	mutex_lock(&cdev->lock);
+	guard(cooling_dev)(cdev);
+
 	if (!cdev->updated) {
 		__thermal_cdev_update(cdev);
 		cdev->updated = true;
 	}
-	mutex_unlock(&cdev->lock);
 }
 
 /**
@@ -211,11 +204,9 @@ void thermal_cdev_update(struct thermal_
  */
 void thermal_cdev_update_nocheck(struct thermal_cooling_device *cdev)
 {
-	mutex_lock(&cdev->lock);
+	guard(cooling_dev)(cdev);
 
 	__thermal_cdev_update(cdev);
-
-	mutex_unlock(&cdev->lock);
 }
 
 /**
Index: linux-pm/drivers/thermal/thermal_debugfs.c
===================================================================
--- linux-pm.orig/drivers/thermal/thermal_debugfs.c
+++ linux-pm/drivers/thermal/thermal_debugfs.c
@@ -516,6 +516,19 @@ void thermal_debug_cdev_add(struct therm
 	cdev->debugfs = thermal_dbg;
 }
 
+static struct thermal_debugfs *thermal_debug_cdev_clear(struct thermal_cooling_device *cdev)
+{
+	struct thermal_debugfs *thermal_dbg;
+
+	guard(cooling_dev)(cdev);
+
+	thermal_dbg = cdev->debugfs;
+	if (thermal_dbg)
+		cdev->debugfs = NULL;
+
+	return thermal_dbg;
+}
+
 /**
  * thermal_debug_cdev_remove - Remove a cooling device debugfs entry
  *
@@ -527,17 +540,9 @@ void thermal_debug_cdev_remove(struct th
 {
 	struct thermal_debugfs *thermal_dbg;
 
-	mutex_lock(&cdev->lock);
-
-	thermal_dbg = cdev->debugfs;
-	if (!thermal_dbg) {
-		mutex_unlock(&cdev->lock);
+	thermal_dbg = thermal_debug_cdev_clear(cdev);
+	if (!thermal_dbg)
 		return;
-	}
-
-	cdev->debugfs = NULL;
-
-	mutex_unlock(&cdev->lock);
 
 	mutex_lock(&thermal_dbg->lock);
 
Index: linux-pm/drivers/thermal/gov_power_allocator.c
===================================================================
--- linux-pm.orig/drivers/thermal/gov_power_allocator.c
+++ linux-pm/drivers/thermal/gov_power_allocator.c
@@ -549,18 +549,17 @@ static void allow_maximum_power(struct t
 		cdev = instance->cdev;
 
 		instance->target = 0;
-		mutex_lock(&cdev->lock);
-		/*
-		 * Call for updating the cooling devices local stats and avoid
-		 * periods of dozen of seconds when those have not been
-		 * maintained.
-		 */
-		cdev->ops->get_requested_power(cdev, &req_power);
+		scoped_guard(cooling_dev, cdev) {
+			/*
+			 * Call for updating the cooling devices local stats and
+			 * avoid periods of dozen of seconds when those have not
+			 * been maintained.
+			 */
+			cdev->ops->get_requested_power(cdev, &req_power);
 
-		if (params->update_cdevs)
-			__thermal_cdev_update(cdev);
-
-		mutex_unlock(&cdev->lock);
+			if (params->update_cdevs)
+				__thermal_cdev_update(cdev);
+		}
 	}
 }
 
Index: linux-pm/drivers/thermal/gov_step_wise.c
===================================================================
--- linux-pm.orig/drivers/thermal/gov_step_wise.c
+++ linux-pm/drivers/thermal/gov_step_wise.c
@@ -97,9 +97,9 @@ static void thermal_zone_trip_update(str
 
 		instance->initialized = true;
 
-		mutex_lock(&instance->cdev->lock);
-		instance->cdev->updated = false; /* cdev needs update */
-		mutex_unlock(&instance->cdev->lock);
+		scoped_guard(cooling_dev, instance->cdev) {
+			instance->cdev->updated = false; /* cdev needs update */
+		}
 	}
 }