kobject.c

Lib files of linux kernel

/*
 * kobject.c - library routines for handling generic kernel objects
 *
 * Copyright (c) 2002-2003 Patrick Mochel <[e-mail]>
 * Copyright (c) 2006-2007 Greg Kroah-Hartman <[e-mail]>
 * Copyright (c) 2006-2007 Novell Inc.
 *
 * 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++) {
			error = sysfs_create_file(kobj, attr);
			if (error)
				break;
		}
	}
	return error;
}

static int create_dir(struct kobject *kobj)
{
	int error = 0;
	if (kobject_name(kobj)) {
		error = sysfs_create_dir(kobj);
		if (!error) {
			error = populate_dir(kobj);
			if (error)
				sysfs_remove_dir(kobj);
		}
	}
	return error;
}

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("kobject: '%s' (%p): %s: path = '%s'\n", kobject_name(kobj),
		 kobj, __func__, path);
}

/**
 * kobject_get_path - generate and return the path associated with a given kobj and kset pair.
 *
 * @kobj:	kobject in question, with which to build the path
 * @gfp_mask:	the allocation type used to allocate the path
 *
 * The result must be freed by the caller with kfree().
 */
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 = kzalloc(len, gfp_mask);
	if (!path)
		return NULL;
	fill_kobj_path(kobj, path, len);

	return path;
}
EXPORT_SYMBOL_GPL(kobject_get_path);

/* add the kobject to its kset's list */
static void kobj_kset_join(struct kobject *kobj)
{
	if (!kobj->kset)
		return;

	kset_get(kobj->kset);
	spin_lock(&kobj->kset->list_lock);
	list_add_tail(&kobj->entry, &kobj->kset->list);
	spin_unlock(&kobj->kset->list_lock);
}

/* remove the kobject from its kset's list */
static void kobj_kset_leave(struct kobject *kobj)
{
	if (!kobj->kset)
		return;

	spin_lock(&kobj->kset->list_lock);
	list_del_init(&kobj->entry);
	spin_unlock(&kobj->kset->list_lock);
	kset_put(kobj->kset);
}

static void kobject_init_internal(struct kobject *kobj)
{
	if (!kobj)
		return;
	kref_init(&kobj->kref);
	INIT_LIST_HEAD(&kobj->entry);
	kobj->state_in_sysfs = 0;
	kobj->state_add_uevent_sent = 0;
	kobj->state_remove_uevent_sent = 0;
	kobj->state_initialized = 1;
}


static int kobject_add_internal(struct kobject *kobj)
{
	int error = 0;
	struct kobject *parent;

	if (!kobj)
		return -ENOENT;

	if (!kobj->name || !kobj->name[0]) {
		WARN(1, "kobject: (%p): attempted to be registered with empty "
			 "name!\n", kobj);
		return -EINVAL;
	}

	parent = kobject_get(kobj->parent);

	/* join kset if set, use it as parent if we do not already have one */
	if (kobj->kset) {
		if (!parent)
			parent = kobject_get(&kobj->kset->kobj);
		kobj_kset_join(kobj);
		kobj->parent = parent;
	}

	pr_debug("kobject: '%s' (%p): %s: parent: '%s', set: '%s'\n",
		 kobject_name(kobj), kobj, __func__,
		 parent ? kobject_name(parent) : "<NULL>",
		 kobj->kset ? kobject_name(&kobj->kset->kobj) : "<NULL>");

	error = create_dir(kobj);
	if (error) {
		kobj_kset_leave(kobj);
		kobject_put(parent);
		kobj->parent = NULL;

		/* be noisy on error issues */
		if (error == -EEXIST)
			printk(KERN_ERR "%s failed for %s with "
			       "-EEXIST, don't try to register things with "
			       "the same name in the same directory.\n",
			       __func__, kobject_name(kobj));
		else
			printk(KERN_ERR "%s failed for %s (%d)\n",
			       __func__, kobject_name(kobj), error);
		dump_stack();
	} else
		kobj->state_in_sysfs = 1;

	return error;
}

/**
 * kobject_set_name_vargs - Set the name of an kobject
 * @kobj: struct kobject to set the name of
 * @fmt: format string used to build the name
 * @vargs: vargs to format the string.
 */
static int kobject_set_name_vargs(struct kobject *kobj, const char *fmt,
				  va_list vargs)
{
	const char *old_name = kobj->name;
	char *s;

	kobj->name = kvasprintf(GFP_KERNEL, fmt, vargs);
	if (!kobj->name)
		return -ENOMEM;

	/* ewww... some of these buggers have '/' in the name ... */
	while ((s = strchr(kobj->name, '/')))
		s[0] = '!';

	kfree(old_name);
	return 0;
}

/**
 * kobject_set_name - Set the name of a kobject
 * @kobj: struct kobject to set the name of
 * @fmt: format string used to build the name
 *
 * This sets the name of the kobject.  If you have already added the
 * kobject to the system, you must call kobject_rename() in order to
 * change the name of the kobject.
 */
int kobject_set_name(struct kobject *kobj, const char *fmt, ...)
{
	va_list vargs;
	int retval;

	va_start(vargs, fmt);
	retval = kobject_set_name_vargs(kobj, fmt, vargs);
	va_end(vargs);

	return retval;
}
EXPORT_SYMBOL(kobject_set_name);

/**
 * kobject_init - initialize a kobject structure
 * @kobj: pointer to the kobject to initialize
 * @ktype: pointer to the ktype for this kobject.
 *
 * This function will properly initialize a kobject such that it can then
 * be passed to the kobject_add() call.
 *
 * After this function is called, the kobject MUST be cleaned up by a call
 * to kobject_put(), not by a call to kfree directly to ensure that all of
 * the memory is cleaned up properly.
 */
void kobject_init(struct kobject *kobj, struct kobj_type *ktype)
{
	char *err_str;

	if (!kobj) {
		err_str = "invalid kobject pointer!";
		goto error;
	}
	if (!ktype) {
		err_str = "must have a ktype to be initialized properly!\n";
		goto error;
	}
	if (kobj->state_initialized) {
		/* do not error out as sometimes we can recover */
		printk(KERN_ERR "kobject (%p): tried to init an initialized "
		       "object, something is seriously wrong.\n", kobj);
		dump_stack();
	}

	kobject_init_internal(kobj);
	kobj->ktype = ktype;
	return;

error:
	printk(KERN_ERR "kobject (%p): %s\n", kobj, err_str);
	dump_stack();
}
EXPORT_SYMBOL(kobject_init);

static int kobject_add_varg(struct kobject *kobj, struct kobject *parent,
			    const char *fmt, va_list vargs)
{
	int retval;

	retval = kobject_set_name_vargs(kobj, fmt, vargs);
	if (retval) {
		printk(KERN_ERR "kobject: can not set name properly!\n");
		return retval;
	}
	kobj->parent = parent;
	return kobject_add_internal(kobj);
}

/**
 * kobject_add - the main kobject add function
 * @kobj: the kobject to add
 * @parent: pointer to the parent of the kobject.
 * @fmt: format to name the kobject with.
 *
 * The kobject name is set and added to the kobject hierarchy in this
 * function.
 *
 * If @parent is set, then the parent of the @kobj will be set to it.
 * If @parent is NULL, then the parent of the @kobj will be set to the
 * kobject associted with the kset assigned to this kobject.  If no kset
 * is assigned to the kobject, then the kobject will be located in the
 * root of the sysfs tree.
 *
 * If this function returns an error, kobject_put() must be called to
 * properly clean up the memory associated with the object.
 * Under no instance should the kobject that is passed to this function
 * be directly freed with a call to kfree(), that can leak memory.
 *
 * Note, no "add" uevent will be created with this call, the caller should set
 * up all of the necessary sysfs files for the object and then call
 * kobject_uevent() with the UEVENT_ADD parameter to ensure that
 * userspace is properly notified of this kobject's creation.
 */
int kobject_add(struct kobject *kobj, struct kobject *parent,
		const char *fmt, ...)
{
	va_list args;
	int retval;

	if (!kobj)
		return -EINVAL;

	if (!kobj->state_initialized) {
		printk(KERN_ERR "kobject '%s' (%p): tried to add an "
		       "uninitialized object, something is seriously wrong.\n",
		       kobject_name(kobj), kobj);
		dump_stack();
		return -EINVAL;
	}
	va_start(args, fmt);
	retval = kobject_add_varg(kobj, parent, fmt, args);
	va_end(args);

	return retval;
}
EXPORT_SYMBOL(kobject_add);

/**
 * kobject_init_and_add - initialize a kobject structure and add it to the kobject hierarchy
 * @kobj: pointer to the kobject to initialize
 * @ktype: pointer to the ktype for this kobject.
 * @parent: pointer to the parent of this kobject.
 * @fmt: the name of the kobject.
 *
 * This function combines the call to kobject_init() and
 * kobject_add().  The same type of error handling after a call to
 * kobject_add() and kobject lifetime rules are the same here.
 */
int kobject_init_and_add(struct kobject *kobj, struct kobj_type *ktype,
			 struct kobject *parent, const char *fmt, ...)
{
	va_list args;
	int retval;

	kobject_init(kobj, ktype);

	va_start(args, fmt);
	retval = kobject_add_varg(kobj, parent, fmt, args);
	va_end(args);

	return retval;
}
EXPORT_SYMBOL_GPL(kobject_init_and_add);

/**
 * 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;
	const char *devpath = NULL;
	char *devpath_string = NULL;
	char *envp[2];

	kobj = kobject_get(kobj);
	if (!kobj)
		return -EINVAL;
	if (!kobj->parent)
		return -EINVAL;

	/* see if this name is already in use */
	if (kobj->kset) {
		struct kobject *temp_kobj;
		temp_kobj = kset_find_obj(kobj->kset, new_name);
		if (temp_kobj) {
			printk(KERN_WARNING "kobject '%s' cannot be renamed "
			       "to '%s' as '%s' is already in existence.\n",
			       kobject_name(kobj), new_name, new_name);
			kobject_put(temp_kobj);
			return -EINVAL;
		}
	}

	devpath = kobject_get_path(kobj, GFP_KERNEL);
	if (!devpath) {
		error = -ENOMEM;
		goto out;
	}
	devpath_string = kmalloc(strlen(devpath) + 15, GFP_KERNEL);
	if (!devpath_string) {