linux-kernel - [PATCH v2] power: supply: core: constify the struct device

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Message-Id: <20240224-device_cleanup-power-v2-1-465ff94b896c@marliere.net>
Date: Sat, 24 Feb 2024 17:15:41 -0300
From: "Ricardo B. Marliere" <ricardo@...liere.net>
To: Sebastian Reichel <sre@...nel.org>
Cc: linux-pm@...r.kernel.org, linux-kernel@...r.kernel.org, 
 Greg Kroah-Hartman <gregkh@...uxfoundation.org>, 
 "Ricardo B. Marliere" <ricardo@...liere.net>
Subject: [PATCH v2] power: supply: core: constify the struct device_type
 usage

Since commit aed65af1cc2f ("drivers: make device_type const"), the driver
core can properly handle constant struct device_type. Move the
power_supply_dev_type variable to be a constant structure as well, placing
it into read-only memory which can not be modified at runtime.

In order to accomplish that, export power_supply_attr_group in
power_supply.h and use it with the macro __ATTRIBUTE_GROUPS when defining
power_supply_dev_type in power_supply_core.c. Therefore the attribute group
is no longer static. Lastly, because power_supply_attr_groups is no longer
dynamically associated to power_supply_dev_type in
power_supply_init_attrs(), make the function receive zero arguments.

Cc: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
Signed-off-by: Ricardo B. Marliere <ricardo@...liere.net>
---
Changes in v2:
- Exported attribute group and made use of __ATTRIBUTE_GROUPS macro.
- Properly put the struct back where it should be (power_supply_core.c).
- Cleaned power_supply_init_attrs()
- Link to v1: https://lore.kernel.org/r/20240220-device_cleanup-power-v1-1-e2b9e0cea072@marliere.net
---
 drivers/power/supply/power_supply.h       |  4 +++-
 drivers/power/supply/power_supply_core.c  |  8 ++++++--
 drivers/power/supply/power_supply_sysfs.c | 11 ++---------
 3 files changed, 11 insertions(+), 12 deletions(-)

diff --git a/drivers/power/supply/power_supply.h b/drivers/power/supply/power_supply.h
index 645eee4d6b6a..232fdd8c1212 100644
--- a/drivers/power/supply/power_supply.h
+++ b/drivers/power/supply/power_supply.h
@@ -13,9 +13,11 @@ struct device;
 struct device_type;
 struct power_supply;
 
+extern const struct attribute_group power_supply_attr_group;
+
 #ifdef CONFIG_SYSFS
 
-extern void power_supply_init_attrs(struct device_type *dev_type);
+extern void power_supply_init_attrs(void);
 extern int power_supply_uevent(const struct device *dev, struct kobj_uevent_env *env);
 
 #else
diff --git a/drivers/power/supply/power_supply_core.c b/drivers/power/supply/power_supply_core.c
index ecef35ac3b7e..37dac7669090 100644
--- a/drivers/power/supply/power_supply_core.c
+++ b/drivers/power/supply/power_supply_core.c
@@ -31,7 +31,11 @@ EXPORT_SYMBOL_GPL(power_supply_class);
 
 static BLOCKING_NOTIFIER_HEAD(power_supply_notifier);
 
-static struct device_type power_supply_dev_type;
+__ATTRIBUTE_GROUPS(power_supply_attr);
+static const struct device_type power_supply_dev_type = {
+	.name = "power_supply",
+	.groups = power_supply_attr_groups,
+};
 
 #define POWER_SUPPLY_DEFERRED_REGISTER_TIME	msecs_to_jiffies(10)
 
@@ -1623,7 +1627,7 @@ static int __init power_supply_class_init(void)
 		return PTR_ERR(power_supply_class);
 
 	power_supply_class->dev_uevent = power_supply_uevent;
-	power_supply_init_attrs(&power_supply_dev_type);
+	power_supply_init_attrs();
 
 	return 0;
 }
diff --git a/drivers/power/supply/power_supply_sysfs.c b/drivers/power/supply/power_supply_sysfs.c
index 977611e16373..edb240450e38 100644
--- a/drivers/power/supply/power_supply_sysfs.c
+++ b/drivers/power/supply/power_supply_sysfs.c
@@ -389,22 +389,15 @@ static umode_t power_supply_attr_is_visible(struct kobject *kobj,
 	return 0;
 }
 
-static const struct attribute_group power_supply_attr_group = {
+const struct attribute_group power_supply_attr_group = {
 	.attrs = __power_supply_attrs,
 	.is_visible = power_supply_attr_is_visible,
 };
 
-static const struct attribute_group *power_supply_attr_groups[] = {
-	&power_supply_attr_group,
-	NULL,
-};
-
-void power_supply_init_attrs(struct device_type *dev_type)
+void power_supply_init_attrs(void)
 {
 	int i;
 
-	dev_type->groups = power_supply_attr_groups;
-
 	for (i = 0; i < ARRAY_SIZE(power_supply_attrs); i++) {
 		struct device_attribute *attr;
 

---
base-commit: a9b254892ce1a447b06c5019cbf0e9caeb48c138
change-id: 20240220-device_cleanup-power-037594022cb1

Best regards,
-- 
Ricardo B. Marliere <ricardo@...liere.net>