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driver core: Allow the constification of device attributes

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Allow device attribute to reside in read-only memory.
Both const and non-const attributes are handled by the utility macros
and attributes can be migrated one-by-one.

Signed-off-by: Thomas Weißschuh <linux@weissschuh.net>
Link: https://patch.msgid.link/20260512-sysfs-const-attr-device_attr-prep-v3-4-cb7c17b34d52@weissschuh.net
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Thomas Weißschuh 2026-05-12 18:39:14 +02:00 committed by Greg Kroah-Hartman
parent 13443fbf62
commit 434506b86a
2 changed files with 65 additions and 16 deletions
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12
drivers/base/core.c
View File

@ -2485,9 +2485,11 @@ static ssize_t dev_attr_show(struct kobject *kobj, struct attribute *attr,
if (dev_attr->show)
ret = dev_attr->show(dev, dev_attr, buf);
else if (dev_attr->show_const)
ret = dev_attr->show_const(dev, dev_attr, buf);
if (ret >= (ssize_t)PAGE_SIZE) {
printk("dev_attr_show: %pS returned bad count\n",
dev_attr->show);
printk("dev_attr_show: %pS/%pS returned bad count\n",
dev_attr->show, dev_attr->show_const);
}
return ret;
}
@ -2501,6 +2503,8 @@ static ssize_t dev_attr_store(struct kobject *kobj, struct attribute *attr,
if (dev_attr->store)
ret = dev_attr->store(dev, dev_attr, buf, count);
else if (dev_attr->store_const)
ret = dev_attr->store_const(dev, dev_attr, buf, count);
return ret;
}
@ -3113,10 +3117,10 @@ int device_create_file(struct device *dev,
int error = 0;
if (dev) {
WARN(((attr->attr.mode & S_IWUGO) && !attr->store),
WARN(((attr->attr.mode & S_IWUGO) && !(attr->store || attr->store_const)),
"Attribute %s: write permission without 'store'\n",
attr->attr.name);
WARN(((attr->attr.mode & S_IRUGO) && !attr->show),
WARN(((attr->attr.mode & S_IRUGO) && !(attr->show || attr->show_const)),
"Attribute %s: read permission without 'show'\n",
attr->attr.name);
error = sysfs_create_file(&dev->kobj, &attr->attr);

69
include/linux/device.h
View File

@ -103,10 +103,18 @@ struct device_type {
*/
struct device_attribute {
struct attribute attr;
ssize_t (*show)(struct device *dev, struct device_attribute *attr,
char *buf);
ssize_t (*store)(struct device *dev, struct device_attribute *attr,
const char *buf, size_t count);
__SYSFS_FUNCTION_ALTERNATIVE(
ssize_t (*show)(struct device *dev, struct device_attribute *attr,
char *buf);
ssize_t (*show_const)(struct device *dev, const struct device_attribute *attr,
char *buf);
);
__SYSFS_FUNCTION_ALTERNATIVE(
ssize_t (*store)(struct device *dev, struct device_attribute *attr,
const char *buf, size_t count);
ssize_t (*store_const)(struct device *dev, const struct device_attribute *attr,
const char *buf, size_t count);
);
};
/**
@ -134,11 +142,50 @@ ssize_t device_store_bool(struct device *dev, struct device_attribute *attr,
ssize_t device_show_string(struct device *dev, struct device_attribute *attr,
char *buf);
typedef ssize_t __device_show_handler_const(struct device *dev, const struct device_attribute *attr,
char *buf);
typedef ssize_t __device_store_handler_const(struct device *dev, const struct device_attribute *attr,
const char *buf, size_t count);
#ifdef CONFIG_CFI
#define __DEVICE_ATTR_SHOW_STORE(_show, _store) \
.show = _Generic(_show, \
__device_show_handler_const * : NULL, \
default : _show \
), \
.show_const = _Generic(_show, \
__device_show_handler_const * : _show, \
default : NULL \
), \
.store = _Generic(_store, \
__device_store_handler_const * : NULL, \
default : _store \
), \
.store_const = _Generic(_store, \
__device_store_handler_const * : _store, \
default : NULL \
),
#else
#define __DEVICE_ATTR_SHOW_STORE(_show, _store) \
.show = _Generic(_show, \
__device_show_handler_const * : (void *)_show, \
default : _show \
), \
.store = _Generic(_store, \
__device_store_handler_const * : (void *)_store, \
default : _store \
), \
#endif
#define __DEVICE_ATTR(_name, _mode, _show, _store) { \
.attr = {.name = __stringify(_name), \
.mode = VERIFY_OCTAL_PERMISSIONS(_mode) }, \
.show = _show, \
.store = _store, \
__DEVICE_ATTR_SHOW_STORE(_show, _store) \
}
#define __DEVICE_ATTR_RO_MODE(_name, _mode) \
@ -160,8 +207,7 @@ ssize_t device_show_string(struct device *dev, struct device_attribute *attr,
#define __DEVICE_ATTR_IGNORE_LOCKDEP(_name, _mode, _show, _store) { \
.attr = {.name = __stringify(_name), .mode = _mode, \
.ignore_lockdep = true }, \
.show = _show, \
.store = _store, \
__DEVICE_ATTR_SHOW_STORE(_show, _store) \
}
#else
#define __DEVICE_ATTR_IGNORE_LOCKDEP __DEVICE_ATTR
@ -220,8 +266,7 @@ ssize_t device_show_string(struct device *dev, struct device_attribute *attr,
#define DEVICE_ATTR_RW_NAMED(_name, _attrname) \
struct device_attribute dev_attr_##_name = { \
.attr = { .name = _attrname, .mode = 0644 }, \
.show = _name##_show, \
.store = _name##_store, \
__DEVICE_ATTR_SHOW_STORE(_name##_show, _name##_store) \
}
/**
@ -254,7 +299,7 @@ ssize_t device_show_string(struct device *dev, struct device_attribute *attr,
#define DEVICE_ATTR_RO_NAMED(_name, _attrname) \
struct device_attribute dev_attr_##_name = { \
.attr = { .name = _attrname, .mode = 0444 }, \
.show = _name##_show, \
__DEVICE_ATTR_SHOW_STORE(_name##_show, NULL) \
}
/**
@ -278,7 +323,7 @@ ssize_t device_show_string(struct device *dev, struct device_attribute *attr,
#define DEVICE_ATTR_WO_NAMED(_name, _attrname) \
struct device_attribute dev_attr_##_name = { \
.attr = { .name = _attrname, .mode = 0200 }, \
.store = _name##_store, \
__DEVICE_ATTR_SHOW_STORE(NULL, _name##_store) \
}
/**