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PATCH [2/2] Documentation/filesystems/sysfs.txt: fix descriptions of device attributes 

Fix descriptions of device attributes to be consistent with the actual
implementations in include/linux/device.h

Signed-off-by: Mike Murphy <mamurph[at]cs.clemson.edu>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
Mike Murphy 2009-02-22 01:19:23 -05:00 committed by Linus Torvalds
parent 245127dbe9
commit f8a1af6bbc
1 changed files with 28 additions and 22 deletions
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50
Documentation/filesystems/sysfs.txt
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@ -2,8 +2,10 @@
sysfs - _The_ filesystem for exporting kernel objects.
Patrick Mochel <mochel@osdl.org>
Mike Murphy <mamurph@cs.clemson.edu>
10 January 2003
Revised: 22 February 2009
Original: 10 January 2003
What it is:
@ -64,12 +66,13 @@ An attribute definition is simply:
struct attribute {
char * name;
struct module *owner;
mode_t mode;
};
int sysfs_create_file(struct kobject * kobj, struct attribute * attr);
void sysfs_remove_file(struct kobject * kobj, struct attribute * attr);
int sysfs_create_file(struct kobject * kobj, const struct attribute * attr);
void sysfs_remove_file(struct kobject * kobj, const struct attribute * attr);
A bare attribute contains no means to read or write the value of the
@ -80,9 +83,11 @@ a specific object type.
For example, the driver model defines struct device_attribute like:
struct device_attribute {
struct attribute attr;
ssize_t (*show)(struct device * dev, char * buf);
ssize_t (*store)(struct device * dev, const char * buf);
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);
};
int device_create_file(struct device *, struct device_attribute *);
@ -90,12 +95,8 @@ void device_remove_file(struct device *, struct device_attribute *);
It also defines this helper for defining device attributes:
#define DEVICE_ATTR(_name, _mode, _show, _store) \
struct device_attribute dev_attr_##_name = { \
.attr = {.name = __stringify(_name) , .mode = _mode }, \
.show = _show, \
.store = _store, \
};
#define DEVICE_ATTR(_name, _mode, _show, _store) \
struct device_attribute dev_attr_##_name = __ATTR(_name, _mode, _show, _store)
For example, declaring
@ -107,9 +108,9 @@ static struct device_attribute dev_attr_foo = {
.attr = {
.name = "foo",
.mode = S_IWUSR | S_IRUGO,
.show = show_foo,
.store = store_foo,
},
.show = show_foo,
.store = store_foo,
};
@ -161,10 +162,12 @@ To read or write attributes, show() or store() methods must be
specified when declaring the attribute. The method types should be as
simple as those defined for device attributes:
ssize_t (*show)(struct device * dev, char * buf);
ssize_t (*store)(struct device * dev, const char * buf);
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);
IOW, they should take only an object and a buffer as parameters.
IOW, they should take only an object, an attribute, and a buffer as parameters.
sysfs allocates a buffer of size (PAGE_SIZE) and passes it to the
@ -299,14 +302,16 @@ The following interface layers currently exist in sysfs:
Structure:
struct device_attribute {
struct attribute attr;
ssize_t (*show)(struct device * dev, char * buf);
ssize_t (*store)(struct device * dev, const char * buf);
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);
};
Declaring:
DEVICE_ATTR(_name, _str, _mode, _show, _store);
DEVICE_ATTR(_name, _mode, _show, _store);
Creation/Removal:
@ -342,7 +347,8 @@ Structure:
struct driver_attribute {
struct attribute attr;
ssize_t (*show)(struct device_driver *, char * buf);
ssize_t (*store)(struct device_driver *, const char * buf);
ssize_t (*store)(struct device_driver *, const char * buf,
size_t count);
};
Declaring: