/*
* kobject.c - library routines for handling generic kernel objects
*
* Copyright (c) 2002-2003 Patrick Mochel <mochel@osdl.org>
*
* This file is released under the GPLv2.
*
*
* Please see the file Documentation/kobject.txt for critical information
* about using the kobject interface.
*/
#include <linux/kobject.h>
#include <linux/string.h>
#include <linux/module.h>
#include <linux/stat.h>
#include <linux/slab.h>
/**
* populate_dir - populate directory with attributes.
* @kobj: object we're working on.
*
* Most subsystems have a set of default attributes that
* are associated with an object that registers with them.
* This is a helper called during object registration that
* loops through the default attributes of the subsystem
* and creates attributes files for them in sysfs.
*
*/
static int populate_dir(struct kobject * kobj)
{
struct kobj_type * t = get_ktype(kobj);
struct attribute * attr;
int error = 0;
int i;
if (t && t->default_attrs) {
for (i = 0; (attr = t->default_attrs[i]) != NULL; i++) {
if ((error = sysfs_create_file(kobj,attr)))
break;
}
}
return error;
}
static int create_dir(struct kobject * kobj)
{
int error = 0;
if (kobject_name(kobj)) {
error = sysfs_create_dir(kobj);
if (!error) {
if ((error = populate_dir(kobj)))
sysfs_remove_dir(kobj);
}
}
return error;
}
static inline struct kobject * to_kobj(struct list_head * entry)
{
return container_of(entry,struct kobject,entry);
}
static int get_kobj_path_length(struct kobject *kobj)
{
int length = 1;
struct kobject * parent = kobj;
/* walk up the ancestors until we hit the one pointing to the
* root.
* Add 1 to strlen for leading '/' of each level.
*/
do {
if (kobject_name(parent) == NULL)
return 0;
length += strlen(kobject_name(parent)) + 1;
parent = parent->parent;
} while (parent);
return length;
}
static void fill_kobj_path(struct kobject *kobj, char *path, int length)
{
struct kobject * parent;
--length;
for (parent = kobj; parent; parent = parent->parent) {
int cur = strlen(kobject_name(parent));
/* back up enough to print this name with '/' */
length -= cur;
strncpy (path + length, kobject_name(parent), cur);
*(path + --length) = '/';
}
pr_debug("%s: path = '%s'\n",__FUNCTION__,path);
}
/**
* kobject_get_path - generate and return the path associated with a given kobj
* and kset pair. The result must be freed by the caller with kfree().
*
* @kobj: kobject in question, with which to build the path
* @gfp_mask: the allocation type used to allocate the path
*/
char *kobject_get_path(struct kobject *kobj, gfp_t gfp_mask)
{
char *path;
int len;
len = get_kobj_path_length(kobj);
if (len == 0)
return NULL;
path = kmalloc(len, gfp_mask);
if (!path)
return NULL;
memset(path, 0x00, len);
fill_kobj_path(kobj, path, len);
return path;
}
/**
* kobject_init - initialize object.
* @kobj: object in question.
*/
void kobject_init(struct kobject * kobj)
{
kref_init(&kobj->kref);
INIT_LIST_HEAD(&kobj->entry);
init_waitqueue_head(&kobj->poll);
kobj->kset = kset_get(kobj->kset);
}
/**
* unlink - remove kobject from kset list.
* @kobj: kobject.
*
* Remove the kobject from the kset list and decrement
* its parent's refcount.
* This is separated out, so we can use it in both
* kobject_del() and kobject_add() on error.
*/
static void unlink(struct kobject * kobj)
{
if (kobj->kset) {
spin_lock(&kobj->kset->list_lock);
list_del_init(&kobj->entry);
spin_unlock(&kobj->kset->list_lock);
}
kobject_put(kobj);
}
/**
* kobject_add - add an object to the hierarchy.
* @kobj: object.
*/
int kobject_add(struct kobject * kobj)
{
int error = 0;
struct kobject * parent;
if (!(kobj = kobject_get(kobj)))
return -ENOENT;
if (!kobj->k_name)
kobj->k_name = kobj->name;
if (!kobj->k_name) {
pr_debug("kobject attempted to be registered with no name!\n");
WARN_ON(1);
return -EINVAL;
}
parent = kobject_get(kobj->parent);
pr_debug("kobject %s: registering. parent: %s, set: %s\n",
kobject_name(kobj), parent ? kobject_name(parent) : "<NULL>",
kobj->kset ? kobj->kset->kobj.name : "<NULL>" );
if (kobj->kset) {
spin_lock(&kobj->kset->list_lock);
if (!parent)
parent = kobject_get(&kobj->kset->kobj);
list_add_tail(&kobj->entry,&kobj->kset->list);
spin_unlock(&kobj->kset->list_lock);
}
kobj->parent = parent;
error = create_dir(kobj);
if (error) {
/* unlink does the kobject_put() for us */
unlink(kobj);
if (parent)
kobject_put(parent);
/* be noisy on error issues */
if (error == -EEXIST)
printk("kobject_add failed for %s with -EEXIST, "
"don't try to register things with the "
"same name in the same directory.\n",
kobject_name(kobj));
else
printk("kobject_add failed for %s (%d)\n",
kobject_name(kobj), error);
dump_stack();
}
return error;
}
/**
* kobject_register - initialize and add an object.
* @kobj: object in question.
*/
int kobject_register(struct kobject * kobj)
{
int error = -EINVAL;
if (kobj) {
kobject_init(kobj);
error = kobject_add(kobj);
if (!error)
kobject_uevent(kobj, KOBJ_ADD);
}
return error;
}
/**
* kobject_set_name - Set the name of an object
* @kobj: object.
* @fmt: format string used to build the name
*
* If strlen(name) >= KOBJ_NAME_LEN, then use a dynamically allocated
* string that @kobj->k_name points to. Otherwise, use the static
* @kobj->name array.
*/
int kobject_set_name(struct kobject * kobj, const char * fmt, ...)
{
int error = 0;
int limit = KOBJ_NAME_LEN;
int need;
va_list args;
char * name;
/*
* First, try the static array
*/
va_start(args,fmt);
need = vsnprintf(kobj->name,limit,fmt,args);
va_end(args);
if (need < limit)
name = kobj->name;
else {
/*
* Need more space? Allocate it and try again
*/
limit = need + 1;
name = kmalloc(limit,GFP_KERNEL);
if (!name) {
error = -ENOMEM;
goto Done;
}
va_start(args,fmt);
need = vsnprintf(name,limit,fmt,args);
va_end(args);
/* Still? Give up. */
if (need >= limit) {
kfree(name);
error = -EFAULT;
goto Done;
}
}
/* Free the old name, if necessary. */
if (kobj->k_name && kobj->k_name != kobj->name)
kfree(kobj->k_name);
/* Now, set the new name */
kobj->k_name = name;
Done:
return error;
}
EXPORT_SYMBOL(kobject_set_name);
/**
* kobject_rename - change the name of an object
* @kobj: object in question.
* @new_name: object's new name
*/
int kobject_rename(struct kobject * kobj, const char *new_name)
{
int error = 0;
kobj = kobject_get(kobj);
if (!kobj)
return -EINVAL;
error = sysfs_rename_dir(kobj, new_name);
kobject_put(kobj);
return error;
}
/**
* kobject_del - unlink kobject from hierarchy.
* @kobj: object.
*/
void kobject_del(struct kobject * kobj)
{
sysfs_remove_dir(kobj);
unlink(kobj);
}
/**
* kobject_unregister - remove object from hierarchy and decrement refcount.
* @kobj: object going away.
*/
void kobject_unregister(struct kobject * kobj)
{
pr_debug("kobject %s: unregistering\n",kobject_name(kobj));
kobject_uevent(kobj, KOBJ_REMOVE);
kobject_del(kobj);
kobject_put(kobj);
}
/**
* kobject_get - increment refcount for object.
* @kobj: object.
*/
struct kobject * kobject_get(struct kobject * kobj)
{
if (kobj)
kref_get(&kobj->kref);
return kobj;
}
/**
* kobject_cleanup - free kobject resources.
* @kobj: object.
*/
void kobject_cleanup(struct kobject * kobj)
{
struct kobj_type * t = get_ktype(kobj);
struct kset * s = kobj->kset;
struct kobject * parent = kobj->parent;
pr_debug("kobject %s: cleaning up\n",kobject_name(kobj));
if (kobj->k_name != kobj->name)
kfree(kobj->k_name);
kobj->k_name = NULL;
if (t && t->release)
t->release(kobj);
if (s)
kset_put(s);
if (parent)
kobject_put(parent);
}
static void kobject_release(struct kref *kref)
{
kobject_cleanup(container_of(kref, struct kobject, kref));
}
/**
* kobject_put - decrement refcount for object.
* @kobj: object.
*
* Decrement the refcount, and if 0, call kobject_cleanup().
*/
void kobject_put(struct kobject * kobj)
{
if (kobj)
kref_put(&kobj->kref, kobject_release);
}
static void dir_release(struct kobject *kobj)
{
kfree(kobj);
}
static struct kobj_type dir_ktype = {
.release = dir_release,
.sysfs_ops = NULL,
.default_attrs = NULL,
};
/**
* kobject_add_dir - add sub directory of object.
* @parent: object in which a directory is created.
* @name: directory name.
*
* Add a plain directory object as child of given object.
*/
struct kobject *kobject_add_dir(struct kobject *parent, const char *name)
{
struct kobject *k;
if (!parent)
return NULL;
k = kzalloc(sizeof(*k), GFP_KERNEL);
if (!k)
return NULL;
k->parent = parent;
k->ktype = &dir_ktype;
kobject_set_name(k, name);
kobject_register(k);
return k;
}
EXPORT_SYMBOL_GPL(kobject_add_dir);
/**
* kset_init - initialize a kset for use
* @k: kset
*/
void kset_init(struct kset * k)
{
kobject_init(&k->kobj);
INIT_LIST_HEAD(&k->list);
spin_lock_init(&k->list_lock);
}
/**
* kset_add - add a kset object to the hierarchy.
* @k: kset.
*
* Simply, this adds the kset's embedded kobject to the
* hierarchy.
* We also try to make sure that the kset's embedded kobject
* has a parent before it is added. We only care if the embedded
* kobject is not part of a kset itself, since kobject_add()
* assigns a parent in that case.
* If that is the case, and the kset has a controlling subsystem,
* then we set the kset's parent to be said subsystem.
*/
int kset_add(struct kset * k)
{
if (!k->kobj.parent && !k->kobj.kset && k->subsys)
k->kobj.parent = &k->subsys->kset.kobj;
return kobject_add(&k->kobj);
}
/**
* kset_register - initialize and add a kset.
* @k: kset.
*/
int kset_register(struct kset * k)
{
kset_init(k);
return kset_add(k);
}
/**
* kset_unregister - remove a kset.
* @k: kset.
*/
void kset_unregister(struct kset * k)
{
kobject_unregister(&k->kobj);
}
/**
* kset_find_obj - search for object in kset.
* @kset: kset we're looking in.
* @name: object's name.
*
* Lock kset via @kset->subsys, and iterate over @kset->list,
* looking for a matching kobject. If matching object is found
* take a reference and return the object.
*/
struct kobject * kset_find_obj(struct kset * kset, const char * name)
{
struct list_head * entry;
struct kobject * ret = NULL;
spin_lock(&kset->list_lock);
list_for_each(entry,&kset->list) {
struct kobject * k = to_kobj(entry);
if (kobject_name(k) && !strcmp(kobject_name(k),name)) {
ret = kobject_get(k);
break;
}
}
spin_unlock(&kset->list_lock);
return ret;
}
void subsystem_init(struct subsystem * s)
{
init_rwsem(&s->rwsem);
kset_init(&s->kset);
}
/**
* subsystem_register - register a subsystem.
* @s: the subsystem we're registering.
*
* Once we register the subsystem, we want to make sure that
* the kset points back to this subsystem for correct usage of
* the rwsem.
*/
int subsystem_register(struct subsystem * s)
{
int error;
subsystem_init(s);
pr_debug("subsystem %s: registering\n",s->kset.kobj.name);
if (!(error = kset_add(&s->kset))) {
if (!s->kset.subsys)
s->kset.subsys = s;
}
return error;
}
void subsystem_unregister(struct subsystem * s)
{
pr_debug("subsystem %s: unregistering\n",s->kset.kobj.name);
kset_unregister(&s->kset);
}
/**
* subsystem_create_file - export sysfs attribute file.
* @s: subsystem.
* @a: subsystem attribute descriptor.
*/
int subsys_create_file(struct subsystem * s, struct subsys_attribute * a)
{
int error = 0;
if (subsys_get(s)) {
error = sysfs_create_file(&s->kset.kobj,&a->attr);
subsys_put(s);
}
return error;
}
/**
* subsystem_remove_file - remove sysfs attribute file.
* @s: subsystem.
* @a: attribute desciptor.
*/
void subsys_remove_file(struct subsystem * s, struct subsys_attribute * a)
{
if (subsys_get(s)) {
sysfs_remove_file(&s->kset.kobj,&a->attr);
subsys_put(s);
}
}
EXPORT_SYMBOL(kobject_init);
EXPORT_SYMBOL(kobject_register);
EXPORT_SYMBOL(kobject_unregister);
EXPORT_SYMBOL(kobject_get);
EXPORT_SYMBOL(kobject_put);
EXPORT_SYMBOL(kobject_add);
EXPORT_SYMBOL(kobject_del);
EXPORT_SYMBOL(kset_register);
EXPORT_SYMBOL(kset_unregister);
EXPORT_SYMBOL(kset_find_obj);
EXPORT_SYMBOL(subsystem_init);
EXPORT_SYMBOL(subsystem_register);
EXPORT_SYMBOL(subsystem_unregister);
EXPORT_SYMBOL(subsys_create_file);
EXPORT_SYMBOL(subsys_remove_file);
