[PATCH RFC 4/6] power: supply: core: add locking around extension access

[Thomas Weißschuh]

Signed-off-by: Thomas Weißschuh <linux@xxxxxxxxxxxxxx>
---
 drivers/power/supply/power_supply.h       |  6 ++-
 drivers/power/supply/power_supply_core.c  | 65 +++++++++++++++++++++++++------
 drivers/power/supply/power_supply_sysfs.c | 22 ++++++-----
 include/linux/power_supply.h              |  2 +
 4 files changed, 73 insertions(+), 22 deletions(-)

diff --git a/drivers/power/supply/power_supply.h b/drivers/power/supply/power_supply.h
index 7f9e139064cc..b469a9719045 100644
--- a/drivers/power/supply/power_supply.h
+++ b/drivers/power/supply/power_supply.h
@@ -13,10 +13,14 @@ struct device;
 struct device_type;
 struct power_supply;
 
-bool power_supply_has_property(const struct power_supply *psy,
+bool power_supply_has_property(struct power_supply *psy,
 			       enum power_supply_property psp);
+bool power_supply_has_property_nolock(struct power_supply *psy,
+				      enum power_supply_property psp);
 bool power_supply_ext_has_property(const struct power_supply_ext *psy_ext,
 				   enum power_supply_property psp);
+int power_supply_property_is_writeable_nolock(struct power_supply *psy,
+					      enum power_supply_property psp);
 
 #ifdef CONFIG_SYSFS
 
diff --git a/drivers/power/supply/power_supply_core.c b/drivers/power/supply/power_supply_core.c
index b32bbca9a848..ded9748be550 100644
--- a/drivers/power/supply/power_supply_core.c
+++ b/drivers/power/supply/power_supply_core.c
@@ -1218,14 +1218,26 @@ bool power_supply_ext_has_property(const struct power_supply_ext *psy_ext,
 	return found;
 }
 
-bool power_supply_has_property(const struct power_supply *psy,
-			       enum power_supply_property psp)
+bool power_supply_has_property_nolock(struct power_supply *psy,
+				      enum power_supply_property psp)
 {
+	lockdep_assert_held(&psy->ext_lock);
+
 	if (power_supply_ext_has_property(psy->ext, psp))
 		return true;
 	return psy_desc_has_property(psy->desc, psp);
 }
 
+bool power_supply_has_property(struct power_supply *psy,
+			       enum power_supply_property psp)
+{
+	scoped_guard(rwsem_read, &psy->ext_lock) {
+		if (power_supply_ext_has_property(psy->ext, psp))
+			return true;
+	}
+	return psy_desc_has_property(psy->desc, psp);
+}
+
 int power_supply_get_property(struct power_supply *psy,
 			    enum power_supply_property psp,
 			    union power_supply_propval *val)
@@ -1236,9 +1248,12 @@ int power_supply_get_property(struct power_supply *psy,
 		return -ENODEV;
 	}
 
-	if (power_supply_ext_has_property(psy->ext, psp))
-		return psy->ext->get_property(psy, psp, val);
-	else if (psy_desc_has_property(psy->desc, psp))
+	scoped_guard(rwsem_read, &psy->ext_lock) {
+		if (power_supply_ext_has_property(psy->ext, psp))
+			return psy->ext->get_property(psy, psp, val);
+	}
+
+	if (psy_desc_has_property(psy->desc, psp))
 		return psy->desc->get_property(psy, psp, val);
 	else if (power_supply_battery_info_has_prop(psy->battery_info, psp))
 		return power_supply_battery_info_get_prop(psy->battery_info, psp, val);
@@ -1254,11 +1269,13 @@ int power_supply_set_property(struct power_supply *psy,
 	if (atomic_read(&psy->use_cnt) <= 0)
 		return -ENODEV;
 
-	if (power_supply_ext_has_property(psy->ext, psp)) {
-		if (psy->ext->set_property)
-			return psy->ext->set_property(psy, psp, val);
-		else
-			return -ENODEV;
+	scoped_guard(rwsem_read, &psy->ext_lock) {
+		if (power_supply_ext_has_property(psy->ext, psp)) {
+			if (psy->ext->set_property)
+				return psy->ext->set_property(psy, psp, val);
+			else
+				return -ENODEV;
+		}
 	}
 
 	if (!psy->desc->set_property)
@@ -1274,6 +1291,28 @@ int power_supply_property_is_writeable(struct power_supply *psy,
 	if (atomic_read(&psy->use_cnt) <= 0)
 		return -ENODEV;
 
+	scoped_guard(rwsem_read, &psy->ext_lock) {
+		if (power_supply_ext_has_property(psy->ext, psp)) {
+			if (psy->ext->property_is_writeable)
+				return psy->ext->property_is_writeable(psy, psp);
+			else
+				return -ENODEV;
+		}
+	}
+
+	if (!psy->desc->property_is_writeable)
+		return -ENODEV;
+
+	return psy->desc->property_is_writeable(psy, psp);
+}
+EXPORT_SYMBOL_GPL(power_supply_property_is_writeable);
+
+int power_supply_property_is_writeable_nolock(struct power_supply *psy,
+					      enum power_supply_property psp)
+{
+	if (atomic_read(&psy->use_cnt) <= 0)
+		return -ENODEV;
+
 	if (power_supply_ext_has_property(psy->ext, psp)) {
 		if (psy->ext->property_is_writeable)
 			return psy->ext->property_is_writeable(psy, psp);
@@ -1286,7 +1325,6 @@ int power_supply_property_is_writeable(struct power_supply *psy,
 
 	return psy->desc->property_is_writeable(psy, psp);
 }
-EXPORT_SYMBOL_GPL(power_supply_property_is_writeable);
 
 void power_supply_external_power_changed(struct power_supply *psy)
 {
@@ -1315,6 +1353,8 @@ static int power_supply_update_groups(struct power_supply *psy)
 
 int power_supply_register_extension(struct power_supply *psy, const struct power_supply_ext *ext)
 {
+	guard(rwsem_write)(&psy->ext_lock);
+
 	if (psy->ext)
 		return -EEXIST;
 
@@ -1325,6 +1365,8 @@ EXPORT_SYMBOL_GPL(power_supply_register_extension);
 
 void power_supply_unregister_extension(struct power_supply *psy, const struct power_supply_ext *ext)
 {
+	guard(rwsem_write)(&psy->ext_lock);
+
 	if (psy->ext != ext)
 		dev_warn(&psy->dev, "Trying to unregister invalid extension");
 
@@ -1492,6 +1534,7 @@ __power_supply_register(struct device *parent,
 	}
 
 	spin_lock_init(&psy->changed_lock);
+	init_rwsem(&psy->ext_lock);
 	rc = device_add(dev);
 	if (rc)
 		goto device_add_failed;
diff --git a/drivers/power/supply/power_supply_sysfs.c b/drivers/power/supply/power_supply_sysfs.c
index 3487f161e9bf..d47804cbb500 100644
--- a/drivers/power/supply/power_supply_sysfs.c
+++ b/drivers/power/supply/power_supply_sysfs.c
@@ -378,8 +378,8 @@ static umode_t power_supply_attr_is_visible(struct kobject *kobj,
 	if (attrno == POWER_SUPPLY_PROP_TYPE)
 		return mode;
 
-	if (power_supply_has_property(psy, attrno)) {
-		if (power_supply_property_is_writeable(psy, attrno) > 0)
+	if (power_supply_has_property_nolock(psy, attrno)) {
+		if (power_supply_property_is_writeable_nolock(psy, attrno) > 0)
 			mode |= S_IWUSR;
 		return mode;
 	}
@@ -458,7 +458,7 @@ static int add_prop_uevent(const struct device *dev, struct kobj_uevent_env *env
 
 int power_supply_uevent(const struct device *dev, struct kobj_uevent_env *env)
 {
-	const struct power_supply *psy = dev_get_drvdata(dev);
+	struct power_supply *psy = dev_get_drvdata(dev);
 	const enum power_supply_property *battery_props =
 		power_supply_battery_info_properties;
 	unsigned long psy_drv_properties[POWER_SUPPLY_ATTR_CNT /
@@ -490,13 +490,15 @@ int power_supply_uevent(const struct device *dev, struct kobj_uevent_env *env)
 	if (ret)
 		goto out;
 
-	if (psy->ext) {
-		for (j = 0; j < psy->ext->num_properties; j++) {
-			set_bit(psy->ext->properties[j], psy_drv_properties);
-			ret = add_prop_uevent(dev, env, psy->ext->properties[j],
-					      prop_buf);
-			if (ret)
-				goto out;
+	scoped_guard(rwsem_read, &psy->ext_lock) {
+		if (psy->ext) {
+			for (j = 0; j < psy->ext->num_properties; j++) {
+				set_bit(psy->ext->properties[j], psy_drv_properties);
+				ret = add_prop_uevent(dev, env, psy->ext->properties[j],
+						      prop_buf);
+				if (ret)
+					goto out;
+			}
 		}
 	}
 
diff --git a/include/linux/power_supply.h b/include/linux/power_supply.h
index 0c1e23081d2a..6bba7e6ab161 100644
--- a/include/linux/power_supply.h
+++ b/include/linux/power_supply.h
@@ -15,6 +15,7 @@
 #include <linux/device.h>
 #include <linux/workqueue.h>
 #include <linux/leds.h>
+#include <linux/rwsem.h>
 #include <linux/spinlock.h>
 #include <linux/notifier.h>
 
@@ -306,6 +307,7 @@ struct power_supply {
 	size_t num_supplies;
 	struct device_node *of_node;
 
+	struct rw_semaphore ext_lock;
 	const struct power_supply_ext *ext;
 
 	/* Driver private data */

-- 
2.45.2