[PATCH 0/3] hwmon: Handle const struct attributes

[PATCH 0/3] hwmon: Handle const struct attributes

[Thomas Weißschuh]

Statically allocated instance of 'struct attribute' and its derivates
like 'struct device_attribute' are never modified.
To avoid accidental or malicious modifications (to hijack control flow)
they should be marked as 'const' and moved into read-only memory.
Historically the sysfs APIs did not allow this, but today it is possible.

Change the attributes in the hwmon core and also lay the groundwork for
the drivers to be changed.

The drivers themselves will also need to
be adapted. Please tell me in which form you want this to happen.
One big patch or per-driver patches; in a big series or separate?
Cc all driver maintainers or just hwmon core ones?

Signed-off-by: Thomas Weißschuh <linux@weissschuh.net>
---
Thomas Weißschuh (3):
      hwmon: (core) Constify device attributes
      hwmon: (core) Use const APIs for the dynamically allocated sysfs attributes
      hwmon: (sysfs) Allow drivers to register const attributes

 drivers/hwmon/hwmon.c       | 70 ++++++++++++++++++++++-----------------------
 include/linux/hwmon-sysfs.h | 14 ++++-----
 2 files changed, 42 insertions(+), 42 deletions(-)
---
base-commit: ef9d75d6705d89d019d950262a11d55b19f5d9e3
change-id: 20260526-sysfs-const-attr-hwmon-f3b5692d2923

Best regards,
--  
Thomas Weißschuh <linux@weissschuh.net>

[PATCH 1/3] hwmon: (core) Constify device attributes

[Thomas Weißschuh]

Mark the attribute structures as const, as they are never modified.

Signed-off-by: Thomas Weißschuh <linux@weissschuh.net>
---
 drivers/hwmon/hwmon.c | 16 ++++++++--------
 1 file changed, 8 insertions(+), 8 deletions(-)

diff --git a/drivers/hwmon/hwmon.c b/drivers/hwmon/hwmon.c
index 55a9a3ddd4aa..84108a16ef60 100644
--- a/drivers/hwmon/hwmon.c
+++ b/drivers/hwmon/hwmon.c
@@ -71,27 +71,27 @@ struct hwmon_thermal_data {
 };
 
 static ssize_t
-name_show(struct device *dev, struct device_attribute *attr, char *buf)
+name_show(struct device *dev, const struct device_attribute *attr, char *buf)
 {
 	return sysfs_emit(buf, "%s\n", to_hwmon_device(dev)->name);
 }
-static DEVICE_ATTR_RO(name);
+static const DEVICE_ATTR_RO(name);
 
 static ssize_t
-label_show(struct device *dev, struct device_attribute *attr, char *buf)
+label_show(struct device *dev, const struct device_attribute *attr, char *buf)
 {
 	return sysfs_emit(buf, "%s\n", to_hwmon_device(dev)->label);
 }
-static DEVICE_ATTR_RO(label);
+static const DEVICE_ATTR_RO(label);
 
-static struct attribute *hwmon_dev_attrs[] = {
+static const struct attribute *const hwmon_dev_attrs[] = {
 	&dev_attr_name.attr,
 	&dev_attr_label.attr,
 	NULL
 };
 
 static umode_t hwmon_dev_attr_is_visible(struct kobject *kobj,
-					 struct attribute *attr, int n)
+					 const struct attribute *attr, int n)
 {
 	struct device *dev = kobj_to_dev(kobj);
 	struct hwmon_device *hdev = to_hwmon_device(dev);
@@ -106,8 +106,8 @@ static umode_t hwmon_dev_attr_is_visible(struct kobject *kobj,
 }
 
 static const struct attribute_group hwmon_dev_attr_group = {
-	.attrs		= hwmon_dev_attrs,
-	.is_visible	= hwmon_dev_attr_is_visible,
+	.attrs_const		= hwmon_dev_attrs,
+	.is_visible_const	= hwmon_dev_attr_is_visible,
 };
 
 static const struct attribute_group *hwmon_dev_attr_groups[] = {

-- 
2.55.0

[PATCH 2/3] hwmon: (core) Use const APIs for the dynamically allocated sysfs attributes

[Thomas Weißschuh]

The non-const sysfs attribute APIs are going to go away at some point.

Switch to the const variants to prepare for that.

Signed-off-by: Thomas Weißschuh <linux@weissschuh.net>
---
 drivers/hwmon/hwmon.c | 54 +++++++++++++++++++++++++--------------------------
 1 file changed, 27 insertions(+), 27 deletions(-)

diff --git a/drivers/hwmon/hwmon.c b/drivers/hwmon/hwmon.c
index 84108a16ef60..90ceb815f43e 100644
--- a/drivers/hwmon/hwmon.c
+++ b/drivers/hwmon/hwmon.c
@@ -57,8 +57,8 @@ struct hwmon_device_attribute {
 };
 
 #define to_hwmon_attr(d) \
-	container_of(d, struct hwmon_device_attribute, dev_attr)
-#define to_dev_attr(a) container_of(a, struct device_attribute, attr)
+	container_of_const(d, struct hwmon_device_attribute, dev_attr)
+#define to_dev_attr(a) container_of_const(a, struct device_attribute, attr)
 
 /*
  * Thermal zone information
@@ -115,13 +115,13 @@ static const struct attribute_group *hwmon_dev_attr_groups[] = {
 	NULL
 };
 
-static void hwmon_free_attrs(struct attribute **attrs)
+static void hwmon_free_attrs(const struct attribute *const *attrs)
 {
 	int i;
 
 	for (i = 0; attrs[i]; i++) {
-		struct device_attribute *dattr = to_dev_attr(attrs[i]);
-		struct hwmon_device_attribute *hattr = to_hwmon_attr(dattr);
+		const struct device_attribute *dattr = to_dev_attr(attrs[i]);
+		const struct hwmon_device_attribute *hattr = to_hwmon_attr(dattr);
 
 		kfree(hattr);
 	}
@@ -132,8 +132,8 @@ static void hwmon_dev_release(struct device *dev)
 {
 	struct hwmon_device *hwdev = to_hwmon_device(dev);
 
-	if (hwdev->group.attrs)
-		hwmon_free_attrs(hwdev->group.attrs);
+	if (hwdev->group.attrs_const)
+		hwmon_free_attrs(hwdev->group.attrs_const);
 	kfree(hwdev->groups);
 	kfree(hwdev->label);
 	kfree(hwdev);
@@ -425,9 +425,9 @@ static int hwmon_pec_register(struct device *hdev)
 /* sysfs attribute management */
 
 static ssize_t hwmon_attr_show(struct device *dev,
-			       struct device_attribute *devattr, char *buf)
+			       const struct device_attribute *devattr, char *buf)
 {
-	struct hwmon_device_attribute *hattr = to_hwmon_attr(devattr);
+	const struct hwmon_device_attribute *hattr = to_hwmon_attr(devattr);
 	struct hwmon_device *hwdev = to_hwmon_device(dev);
 	s64 val64;
 	long val;
@@ -450,10 +450,10 @@ static ssize_t hwmon_attr_show(struct device *dev,
 }
 
 static ssize_t hwmon_attr_show_string(struct device *dev,
-				      struct device_attribute *devattr,
+				      const struct device_attribute *devattr,
 				      char *buf)
 {
-	struct hwmon_device_attribute *hattr = to_hwmon_attr(devattr);
+	const struct hwmon_device_attribute *hattr = to_hwmon_attr(devattr);
 	struct hwmon_device *hwdev = to_hwmon_device(dev);
 	enum hwmon_sensor_types type = hattr->type;
 	const char *s;
@@ -473,10 +473,10 @@ static ssize_t hwmon_attr_show_string(struct device *dev,
 }
 
 static ssize_t hwmon_attr_store(struct device *dev,
-				struct device_attribute *devattr,
+				const struct device_attribute *devattr,
 				const char *buf, size_t count)
 {
-	struct hwmon_device_attribute *hattr = to_hwmon_attr(devattr);
+	const struct hwmon_device_attribute *hattr = to_hwmon_attr(devattr);
 	struct hwmon_device *hwdev = to_hwmon_device(dev);
 	long val;
 	int ret;
@@ -510,12 +510,12 @@ static bool is_string_attr(enum hwmon_sensor_types type, u32 attr)
 	       (type == hwmon_fan && attr == hwmon_fan_label);
 }
 
-static struct attribute *hwmon_genattr(const void *drvdata,
-				       enum hwmon_sensor_types type,
-				       u32 attr,
-				       int index,
-				       const char *template,
-				       const struct hwmon_ops *ops)
+static const struct attribute *hwmon_genattr(const void *drvdata,
+					     enum hwmon_sensor_types type,
+					     u32 attr,
+					     int index,
+					     const char *template,
+					     const struct hwmon_ops *ops)
 {
 	struct hwmon_device_attribute *hattr;
 	struct device_attribute *dattr;
@@ -552,8 +552,8 @@ static struct attribute *hwmon_genattr(const void *drvdata,
 	hattr->ops = ops;
 
 	dattr = &hattr->dev_attr;
-	dattr->show = is_string ? hwmon_attr_show_string : hwmon_attr_show;
-	dattr->store = hwmon_attr_store;
+	dattr->show_const = is_string ? hwmon_attr_show_string : hwmon_attr_show;
+	dattr->store_const = hwmon_attr_store;
 
 	a = &dattr->attr;
 	sysfs_attr_init(a);
@@ -831,7 +831,7 @@ static int hwmon_num_channel_attrs(const struct hwmon_channel_info *info)
 }
 
 static int hwmon_genattrs(const void *drvdata,
-			  struct attribute **attrs,
+			  const struct attribute **attrs,
 			  const struct hwmon_ops *ops,
 			  const struct hwmon_channel_info *info)
 {
@@ -850,7 +850,7 @@ static int hwmon_genattrs(const void *drvdata,
 		u32 attr;
 
 		while (attr_mask) {
-			struct attribute *a;
+			const struct attribute *a;
 
 			attr = __ffs(attr_mask);
 			attr_mask &= ~BIT(attr);
@@ -869,11 +869,11 @@ static int hwmon_genattrs(const void *drvdata,
 	return aindex;
 }
 
-static struct attribute **
+static const struct attribute **
 __hwmon_create_attrs(const void *drvdata, const struct hwmon_chip_info *chip)
 {
 	int ret, i, aindex = 0, nattrs = 0;
-	struct attribute **attrs;
+	const struct attribute **attrs;
 
 	for (i = 0; chip->info[i]; i++)
 		nattrs += hwmon_num_channel_attrs(chip->info[i]);
@@ -928,7 +928,7 @@ __hwmon_device_register(struct device *dev, const char *name, void *drvdata,
 	hdev = &hwdev->dev;
 
 	if (chip) {
-		struct attribute **attrs;
+		const struct attribute **attrs;
 		int ngroups = 2; /* terminating NULL plus &hwdev->groups */
 
 		if (groups)
@@ -947,7 +947,7 @@ __hwmon_device_register(struct device *dev, const char *name, void *drvdata,
 			goto free_hwmon;
 		}
 
-		hwdev->group.attrs = attrs;
+		hwdev->group.attrs_const = attrs;
 		ngroups = 0;
 		hwdev->groups[ngroups++] = &hwdev->group;
 

-- 
2.55.0

[PATCH 3/3] hwmon: (sysfs) Allow drivers to register const attributes

[Thomas Weißschuh]

Switch to the __DRIVER_ATTR() macro which can handle callbacks taking
both const and non-const attribute structure arguments.
Allow the step-wise migration of the drivers.

Also use container_of_const() over container_of() to avoid casting away
the constness accidentally.

Signed-off-by: Thomas Weißschuh <linux@weissschuh.net>
---
 include/linux/hwmon-sysfs.h | 14 +++++++-------
 1 file changed, 7 insertions(+), 7 deletions(-)

diff --git a/include/linux/hwmon-sysfs.h b/include/linux/hwmon-sysfs.h
index d896713359cd..ee5b33185b2d 100644
--- a/include/linux/hwmon-sysfs.h
+++ b/include/linux/hwmon-sysfs.h
@@ -15,10 +15,10 @@ struct sensor_device_attribute{
 	int index;
 };
 #define to_sensor_dev_attr(_dev_attr) \
-	container_of(_dev_attr, struct sensor_device_attribute, dev_attr)
+	container_of_const(_dev_attr, struct sensor_device_attribute, dev_attr)
 
-#define SENSOR_ATTR(_name, _mode, _show, _store, _index)	\
-	{ .dev_attr = __ATTR(_name, _mode, _show, _store),	\
+#define SENSOR_ATTR(_name, _mode, _show, _store, _index)		\
+	{ .dev_attr = __DEVICE_ATTR(_name, _mode, _show, _store),	\
 	  .index = _index }
 
 #define SENSOR_ATTR_RO(_name, _func, _index)			\
@@ -49,11 +49,11 @@ struct sensor_device_attribute_2 {
 	u8 nr;
 };
 #define to_sensor_dev_attr_2(_dev_attr) \
-	container_of(_dev_attr, struct sensor_device_attribute_2, dev_attr)
+	container_of_const(_dev_attr, struct sensor_device_attribute_2, dev_attr)
 
-#define SENSOR_ATTR_2(_name, _mode, _show, _store, _nr, _index)	\
-	{ .dev_attr = __ATTR(_name, _mode, _show, _store),	\
-	  .index = _index,					\
+#define SENSOR_ATTR_2(_name, _mode, _show, _store, _nr, _index)		\
+	{ .dev_attr = __DEVICE_ATTR(_name, _mode, _show, _store),	\
+	  .index = _index,						\
 	  .nr = _nr }
 
 #define SENSOR_ATTR_2_RO(_name, _func, _nr, _index)		\

-- 
2.55.0

Re: [PATCH 2/3] hwmon: (core) Use const APIs for the dynamically allocated sysfs attributes

[sashiko-bot]

> The non-const sysfs attribute APIs are going to go away at some point.
> 
> Switch to the const variants to prepare for that.
> 
> Signed-off-by: Thomas Weißschuh <linux@weissschuh.net>

Sashiko has reviewed this patch and found no issues. It looks great!

-- 
Sashiko AI review · https://sashiko.dev/#/patchset/20260805-sysfs-const-attr-hwmon-v1-0-4c0cb2b290a1@weissschuh.net?part=2

Re: [PATCH 3/3] hwmon: (sysfs) Allow drivers to register const attributes

[sashiko-bot]

Thank you for your contribution! Sashiko AI review found 1 potential issue(s) to consider:
- [Low] The commit message incorrectly states that the patch switches to the `__DRIVER_ATTR()` macro, while the code actually switches to the `__DEVICE_ATTR()` macro.
--

--- Patch [3]: [PATCH 3/3] hwmon: (sysfs) Allow drivers to register const attributes ---
commit 91e4cdd2e4ad9f4eaa7572f21133759d5e925d9e
Author: Thomas Weißschuh <linux@weissschuh.net>

hwmon: (sysfs) Allow drivers to register const attributes

This commit updates the hwmon-sysfs macros to use container_of_const() and
__DEVICE_ATTR(). This change supports callbacks taking both const and
non-const attribute arguments, allowing for a step-wise migration of drivers.

> Switch to the __DRIVER_ATTR() macro which can handle callbacks taking
> both const and non-const attribute structure arguments.

[Severity: Low]
This isn't a bug, but the commit message states the patch switches to the
__DRIVER_ATTR() macro. However, the code actually switches to the
__DEVICE_ATTR() macro:

include/linux/hwmon-sysfs.h:SENSOR_ATTR()
    { .dev_attr = __DEVICE_ATTR(_name, _mode, _show, _store),

Could the commit message be updated to accurately reflect the macro used in
the code?

-- 
Sashiko AI review · https://sashiko.dev/#/patchset/20260805-sysfs-const-attr-hwmon-v1-0-4c0cb2b290a1@weissschuh.net?part=3

Re: [PATCH 1/3] hwmon: (core) Constify device attributes

[sashiko-bot]

> Mark the attribute structures as const, as they are never modified.
> 
> Signed-off-by: Thomas Weißschuh <linux@weissschuh.net>

Sashiko has reviewed this patch and found no issues. It looks great!

-- 
Sashiko AI review · https://sashiko.dev/#/patchset/20260805-sysfs-const-attr-hwmon-v1-0-4c0cb2b290a1@weissschuh.net?part=1

Re: [PATCH 3/3] hwmon: (sysfs) Allow drivers to register const attributes

[Guenter Roeck]

On 8/5/26 13:07, sashiko-bot@kernel.org wrote:
> Thank you for your contribution! Sashiko AI review found 1 potential issue(s) to consider:
> - [Low] The commit message incorrectly states that the patch switches to the `__DRIVER_ATTR()` macro, while the code actually switches to the `__DEVICE_ATTR()` macro.
> --
> 

I see no evidence that __DRIVER_ATTR actually exists anywhere ...

Guenter

> --- Patch [3]: [PATCH 3/3] hwmon: (sysfs) Allow drivers to register const attributes ---
> commit 91e4cdd2e4ad9f4eaa7572f21133759d5e925d9e
> Author: Thomas Weißschuh <linux@weissschuh.net>
> 
> hwmon: (sysfs) Allow drivers to register const attributes
> 
> This commit updates the hwmon-sysfs macros to use container_of_const() and
> __DEVICE_ATTR(). This change supports callbacks taking both const and
> non-const attribute arguments, allowing for a step-wise migration of drivers.
> 
>> Switch to the __DRIVER_ATTR() macro which can handle callbacks taking
>> both const and non-const attribute structure arguments.
> 
> [Severity: Low]
> This isn't a bug, but the commit message states the patch switches to the
> __DRIVER_ATTR() macro. However, the code actually switches to the
> __DEVICE_ATTR() macro:
> 
> include/linux/hwmon-sysfs.h:SENSOR_ATTR()
>      { .dev_attr = __DEVICE_ATTR(_name, _mode, _show, _store),
> 
> Could the commit message be updated to accurately reflect the macro used in
> the code?
>