// SPDX-License-Identifier: GPL-2.0

  /*
   * kobject.c - library routines for handling generic kernel objects
   *
   * Copyright (c) 2002-2003 Patrick Mochel <mochel@osdl.org>

   * Copyright (c) 2006-2007 Greg Kroah-Hartman <greg@kroah.com>
   * Copyright (c) 2006-2007 Novell Inc.

   *

   * Please see the file Documentation/core-api/kobject.rst for critical information

   * about using the kobject interface.
   */
  
  #include <linux/kobject.h>
  #include <linux/string.h>

  #include <linux/export.h>

  #include <linux/stat.h>

  #include <linux/slab.h>

  #include <linux/random.h>

  /**

   * kobject_namespace() - Return @kobj's namespace tag.

   * @kobj: kobject in question
   *
   * Returns namespace tag of @kobj if its parent has namespace ops enabled
   * and thus @kobj should have a namespace tag associated with it.  Returns
   * %NULL otherwise.
   */
  const void *kobject_namespace(struct kobject *kobj)
  {
  	const struct kobj_ns_type_operations *ns_ops = kobj_ns_ops(kobj);
  
  	if (!ns_ops || ns_ops->type == KOBJ_NS_TYPE_NONE)
  		return NULL;

  	return kobj->ktype->namespace(kobj);

  }

  /**

   * kobject_get_ownership() - Get sysfs ownership data for @kobj.

   * @kobj: kobject in question
   * @uid: kernel user ID for sysfs objects
   * @gid: kernel group ID for sysfs objects
   *
   * Returns initial uid/gid pair that should be used when creating sysfs
   * representation of given kobject. Normally used to adjust ownership of
   * objects in a container.
   */
  void kobject_get_ownership(struct kobject *kobj, kuid_t *uid, kgid_t *gid)
  {
  	*uid = GLOBAL_ROOT_UID;
  	*gid = GLOBAL_ROOT_GID;
  
  	if (kobj->ktype->get_ownership)
  		kobj->ktype->get_ownership(kobj, uid, gid);
  }

  /*
   * 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)

  {

  	const struct kobj_type *ktype = get_ktype(kobj);

  	const struct kobj_ns_type_operations *ops;

  	int error;
  
  	error = sysfs_create_dir_ns(kobj, kobject_namespace(kobj));

  	if (error)
  		return error;
  
  	error = populate_dir(kobj);
  	if (error) {
  		sysfs_remove_dir(kobj);
  		return error;

  	}

  	if (ktype) {
  		error = sysfs_create_groups(kobj, ktype->default_groups);
  		if (error) {
  			sysfs_remove_dir(kobj);
  			return error;
  		}
  	}

  	/*
  	 * @kobj->sd may be deleted by an ancestor going away.  Hold an
  	 * extra reference so that it stays until @kobj is gone.
  	 */
  	sysfs_get(kobj->sd);

  	/*
  	 * If @kobj has ns_ops, its children need to be filtered based on
  	 * their namespace tags.  Enable namespace support on @kobj->sd.
  	 */
  	ops = kobj_child_ns_ops(kobj);
  	if (ops) {
  		BUG_ON(ops->type <= KOBJ_NS_TYPE_NONE);
  		BUG_ON(ops->type >= KOBJ_NS_TYPES);
  		BUG_ON(!kobj_ns_type_registered(ops->type));

  		sysfs_enable_ns(kobj->sd);

  	}
  
  	return 0;

  }

  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;

  		memcpy(path + length, kobject_name(parent), cur);

  		*(path + --length) = '/';
  	}

  	pr_debug("kobject: '%s' (%p): %s: path = '%s'
  ", kobject_name(kobj),

  		 kobj, __func__, path);

  }
  
  /**

   * kobject_get_path() - Allocate memory and fill in the path for @kobj.

   * @kobj:	kobject in question, with which to build the path
   * @gfp_mask:	the allocation type used to allocate the path

   *

   * Return: The newly allocated memory, caller must free 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!
  ",
  		     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'
  ",

  		 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)

  			pr_err("%s failed for %s with -EEXIST, don't try to register things with the same name in the same directory.
  ",
  			       __func__, kobject_name(kobj));

  		else

  			pr_err("%s failed for %s (error: %d parent: %s)
  ",
  			       __func__, kobject_name(kobj), error,
  			       parent ? kobject_name(parent) : "'none'");

  	} else
  		kobj->state_in_sysfs = 1;

  
  	return error;
  }

  /**

   * kobject_set_name_vargs() - Set the name of a kobject.

   * @kobj: struct kobject to set the name of
   * @fmt: format string used to build the name
   * @vargs: vargs to format the string.
   */

  int kobject_set_name_vargs(struct kobject *kobj, const char *fmt,

  				  va_list vargs)
  {

  	const char *s;

  	if (kobj->name && !fmt)
  		return 0;

  	s = kvasprintf_const(GFP_KERNEL, fmt, vargs);

  	if (!s)

  		return -ENOMEM;

  	/*
  	 * ewww... some of these buggers have '/' in the name ... If
  	 * that's the case, we need to make sure we have an actual
  	 * allocated copy to modify, since kvasprintf_const may have
  	 * returned something from .rodata.
  	 */
  	if (strchr(s, '/')) {
  		char *t;
  
  		t = kstrdup(s, GFP_KERNEL);
  		kfree_const(s);
  		if (!t)
  			return -ENOMEM;
  		strreplace(t, '/', '!');
  		s = t;
  	}
  	kfree_const(kobj->name);

  	kobj->name = s;

  	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!
  ";
  		goto error;
  	}

  	if (kobj->state_initialized) {

  		/* do not error out as sometimes we can recover */

  		pr_err("kobject (%p): tried to init an initialized object, something is seriously wrong.
  ",
  		       kobj);

  		dump_stack();
  	}

  	kobject_init_internal(kobj);

  	kobj->ktype = ktype;
  	return;
  
  error:

  	pr_err("kobject (%p): %s
  ", kobj, err_str);

  	dump_stack();
  }

  EXPORT_SYMBOL(kobject_init);

  static __printf(3, 0) 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) {

  		pr_err("kobject: can not set name properly!
  ");

  		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 associated 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.
   *

   * 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.

   *
   * Return: 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.
   *

   *         If this function returns success, kobject_put() must also be called
   *         in order to properly clean up the memory associated with the object.
   *
   *         In short, once this function is called, kobject_put() MUST be called
   *         when the use of the object is finished in order to properly free
   *         everything.

   */

  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) {

  		pr_err("kobject '%s' (%p): tried to add an uninitialized object, something is seriously wrong.
  ",

  		       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().
   *
   * If this function returns an error, kobject_put() must be called to
   * properly clean up the memory associated with the object.  This is 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

   *
   * It is the responsibility of the caller to provide mutual
   * exclusion between two different calls of kobject_rename
   * on the same kobject and to ensure that new_name is valid and
   * won't conflict with other kobjects.

   */

  int kobject_rename(struct kobject *kobj, const char *new_name)

  {
  	int error = 0;

  	const char *devpath = NULL;

  	const char *dup_name = NULL, *name;

  	char *devpath_string = NULL;
  	char *envp[2];

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

  	if (!kobj->parent) {
  		kobject_put(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) {
  		error = -ENOMEM;
  		goto out;
  	}
  	sprintf(devpath_string, "DEVPATH_OLD=%s", devpath);
  	envp[0] = devpath_string;
  	envp[1] = NULL;

  	name = dup_name = kstrdup_const(new_name, GFP_KERNEL);

  	if (!name) {
  		error = -ENOMEM;
  		goto out;
  	}

  	error = sysfs_rename_dir_ns(kobj, new_name, kobject_namespace(kobj));

  	if (error)
  		goto out;
  
  	/* Install the new kobject name */
  	dup_name = kobj->name;
  	kobj->name = name;

  
  	/* This function is mostly/only used for network interface.
  	 * Some hotplug package track interfaces by their name and
  	 * therefore want to know when the name is changed by the user. */

  	kobject_uevent_env(kobj, KOBJ_MOVE, envp);

  
  out:

  	kfree_const(dup_name);

  	kfree(devpath_string);
  	kfree(devpath);

  	kobject_put(kobj);
  
  	return error;
  }

  EXPORT_SYMBOL_GPL(kobject_rename);

  
  /**

   * kobject_move() - Move object to another parent.

   * @kobj: object in question.
   * @new_parent: object's new parent (can be NULL)

   */

  int kobject_move(struct kobject *kobj, struct kobject *new_parent)
  {
  	int error;
  	struct kobject *old_parent;
  	const char *devpath = NULL;
  	char *devpath_string = NULL;
  	char *envp[2];
  
  	kobj = kobject_get(kobj);
  	if (!kobj)
  		return -EINVAL;
  	new_parent = kobject_get(new_parent);
  	if (!new_parent) {

  		if (kobj->kset)
  			new_parent = kobject_get(&kobj->kset->kobj);

  	}

  	/* old object path */
  	devpath = kobject_get_path(kobj, GFP_KERNEL);
  	if (!devpath) {
  		error = -ENOMEM;
  		goto out;
  	}
  	devpath_string = kmalloc(strlen(devpath) + 15, GFP_KERNEL);
  	if (!devpath_string) {
  		error = -ENOMEM;
  		goto out;
  	}
  	sprintf(devpath_string, "DEVPATH_OLD=%s", devpath);
  	envp[0] = devpath_string;
  	envp[1] = NULL;

  	error = sysfs_move_dir_ns(kobj, new_parent, kobject_namespace(kobj));

  	if (error)
  		goto out;
  	old_parent = kobj->parent;
  	kobj->parent = new_parent;

  	new_parent = NULL;

  	kobject_put(old_parent);
  	kobject_uevent_env(kobj, KOBJ_MOVE, envp);
  out:

  	kobject_put(new_parent);

  	kobject_put(kobj);
  	kfree(devpath_string);
  	kfree(devpath);
  	return error;
  }

  EXPORT_SYMBOL_GPL(kobject_move);

  static void __kobject_del(struct kobject *kobj)

  {

  	struct kernfs_node *sd;

  	const struct kobj_type *ktype;

  	sd = kobj->sd;

  	ktype = get_ktype(kobj);

  
  	if (ktype)
  		sysfs_remove_groups(kobj, ktype->default_groups);

  	/* send "remove" if the caller did not do it but sent "add" */
  	if (kobj->state_add_uevent_sent && !kobj->state_remove_uevent_sent) {
  		pr_debug("kobject: '%s' (%p): auto cleanup 'remove' event
  ",
  			 kobject_name(kobj), kobj);
  		kobject_uevent(kobj, KOBJ_REMOVE);
  	}

  	sysfs_remove_dir(kobj);

  	sysfs_put(sd);

  	kobj->state_in_sysfs = 0;
  	kobj_kset_leave(kobj);

  	kobj->parent = NULL;

  }

  
  /**
   * kobject_del() - Unlink kobject from hierarchy.
   * @kobj: object.
   *
   * This is the function that should be called to delete an object
   * successfully added via kobject_add().
   */
  void kobject_del(struct kobject *kobj)
  {

  	struct kobject *parent;
  
  	if (!kobj)
  		return;

  	parent = kobj->parent;

  	__kobject_del(kobj);
  	kobject_put(parent);
  }

  EXPORT_SYMBOL(kobject_del);

  
  /**

   * kobject_get() - Increment refcount for object.

   * @kobj: object.

   */

  struct kobject *kobject_get(struct kobject *kobj)

  {

  	if (kobj) {
  		if (!kobj->state_initialized)

  			WARN(1, KERN_WARNING
  				"kobject: '%s' (%p): is not initialized, yet kobject_get() is being called.
  ",
  			     kobject_name(kobj), kobj);

  		kref_get(&kobj->kref);

  	}

  	return kobj;
  }

  EXPORT_SYMBOL(kobject_get);

  struct kobject * __must_check kobject_get_unless_zero(struct kobject *kobj)

  {

  	if (!kobj)
  		return NULL;

  	if (!kref_get_unless_zero(&kobj->kref))
  		kobj = NULL;
  	return kobj;
  }

  EXPORT_SYMBOL(kobject_get_unless_zero);

  /*
   * kobject_cleanup - free kobject resources.
   * @kobj: object to cleanup

   */

  static void kobject_cleanup(struct kobject *kobj)

  {

  	struct kobject *parent = kobj->parent;

  	struct kobj_type *t = get_ktype(kobj);

  	const char *name = kobj->name;

  	pr_debug("kobject: '%s' (%p): %s, parent %p
  ",
  		 kobject_name(kobj), kobj, __func__, kobj->parent);

  
  	if (t && !t->release)

  		pr_debug("kobject: '%s' (%p): does not have a release() function, it is broken and must be fixed. See Documentation/core-api/kobject.rst.
  ",

  			 kobject_name(kobj), kobj);

  	/* remove from sysfs if the caller did not do it */
  	if (kobj->state_in_sysfs) {
  		pr_debug("kobject: '%s' (%p): auto cleanup kobject_del
  ",
  			 kobject_name(kobj), kobj);

  		__kobject_del(kobj);
  	} else {
  		/* avoid dropping the parent reference unnecessarily */
  		parent = NULL;

  	}

  	if (t && t->release) {

  		pr_debug("kobject: '%s' (%p): calling ktype release
  ",
  			 kobject_name(kobj), kobj);

  		t->release(kobj);

  	}
  
  	/* free name if we allocated it */

  	if (name) {

  		pr_debug("kobject: '%s': free name
  ", name);

  		kfree_const(name);

  	}

  
  	kobject_put(parent);

  }

  #ifdef CONFIG_DEBUG_KOBJECT_RELEASE
  static void kobject_delayed_cleanup(struct work_struct *work)
  {
  	kobject_cleanup(container_of(to_delayed_work(work),
  				     struct kobject, release));
  }
  #endif

  static void kobject_release(struct kref *kref)
  {

  	struct kobject *kobj = container_of(kref, struct kobject, kref);
  #ifdef CONFIG_DEBUG_KOBJECT_RELEASE

  	unsigned long delay = HZ + HZ * (get_random_int() & 0x3);
  	pr_info("kobject: '%s' (%p): %s, parent %p (delayed %ld)
  ",
  		 kobject_name(kobj), kobj, __func__, kobj->parent, delay);

  	INIT_DELAYED_WORK(&kobj->release, kobject_delayed_cleanup);

  
  	schedule_delayed_work(&kobj->release, delay);

  #else
  	kobject_cleanup(kobj);
  #endif

  }
  
  /**

   * 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) {

  		if (!kobj->state_initialized)

  			WARN(1, KERN_WARNING
  				"kobject: '%s' (%p): is not initialized, yet kobject_put() is being called.
  ",
  			     kobject_name(kobj), kobj);

  		kref_put(&kobj->kref, kobject_release);

  	}

  }

  EXPORT_SYMBOL(kobject_put);

  static void dynamic_kobj_release(struct kobject *kobj)

  {

  	pr_debug("kobject: (%p): %s
  ", kobj, __func__);

  	kfree(kobj);
  }

  static struct kobj_type dynamic_kobj_ktype = {

  	.release	= dynamic_kobj_release,
  	.sysfs_ops	= &kobj_sysfs_ops,

  };

  /**

   * kobject_create() - Create a struct kobject dynamically.

   *
   * This function creates a kobject structure dynamically and sets it up
   * to be a "dynamic" kobject with a default release function set up.
   *
   * If the kobject was not able to be created, NULL will be returned.

   * The kobject structure returned from here must be cleaned up with a

   * call to kobject_put() and not kfree(), as kobject_init() has

   * already been called on this structure.

   */

  struct kobject *kobject_create(void)

  {
  	struct kobject *kobj;
  
  	kobj = kzalloc(sizeof(*kobj), GFP_KERNEL);
  	if (!kobj)
  		return NULL;

  	kobject_init(kobj, &dynamic_kobj_ktype);

  	return kobj;
  }
  
  /**

   * kobject_create_and_add() - Create a struct kobject dynamically and
   *                            register it with sysfs.

   * @name: the name for the kobject

   * @parent: the parent kobject of this kobject, if any.
   *

   * This function creates a kobject structure dynamically and registers it

   * with sysfs.  When you are finished with this structure, call

   * kobject_put() and the structure will be dynamically freed when

   * it is no longer being used.
   *
   * If the kobject was not able to be created, NULL will be returned.
   */
  struct kobject *kobject_create_and_add(const char *name, struct kobject *parent)
  {
  	struct kobject *kobj;
  	int retval;
  
  	kobj = kobject_create();
  	if (!kobj)
  		return NULL;

  	retval = kobject_add(kobj, parent, "%s", name);

  	if (retval) {

  		pr_warn("%s: kobject_add error: %d
  ", __func__, retval);

  		kobject_put(kobj);
  		kobj = NULL;
  	}
  	return kobj;
  }
  EXPORT_SYMBOL_GPL(kobject_create_and_add);

  /**

   * kset_init() - Initialize a kset for use.

   * @k: kset

   */

  void kset_init(struct kset *k)

  {

  	kobject_init_internal(&k->kobj);

  	INIT_LIST_HEAD(&k->list);
  	spin_lock_init(&k->list_lock);
  }

  /* default kobject attribute operations */
  static ssize_t kobj_attr_show(struct kobject *kobj, struct attribute *attr,
  			      char *buf)
  {
  	struct kobj_attribute *kattr;
  	ssize_t ret = -EIO;
  
  	kattr = container_of(attr, struct kobj_attribute, attr);
  	if (kattr->show)
  		ret = kattr->show(kobj, kattr, buf);
  	return ret;
  }
  
  static ssize_t kobj_attr_store(struct kobject *kobj, struct attribute *attr,
  			       const char *buf, size_t count)
  {
  	struct kobj_attribute *kattr;
  	ssize_t ret = -EIO;
  
  	kattr = container_of(attr, struct kobj_attribute, attr);
  	if (kattr->store)
  		ret = kattr->store(kobj, kattr, buf, count);
  	return ret;
  }

  const struct sysfs_ops kobj_sysfs_ops = {

  	.show	= kobj_attr_show,
  	.store	= kobj_attr_store,
  };

  EXPORT_SYMBOL_GPL(kobj_sysfs_ops);

  
  /**

   * kset_register() - Initialize and add a kset.

   * @k: kset.

   */

  int kset_register(struct kset *k)

  {

  	int err;

  	if (!k)
  		return -EINVAL;

  	kset_init(k);

  	err = kobject_add_internal(&k->kobj);

  	if (err)
  		return err;
  	kobject_uevent(&k->kobj, KOBJ_ADD);
  	return 0;

  }

  EXPORT_SYMBOL(kset_register);

  /**

   * kset_unregister() - Remove a kset.

   * @k: kset.

   */

  void kset_unregister(struct kset *k)

  {

  	if (!k)
  		return;

  	kobject_del(&k->kobj);

  	kobject_put(&k->kobj);

  }

  EXPORT_SYMBOL(kset_unregister);

  /**

   * 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 kobject *k;

  	struct kobject *ret = NULL;

  
  	spin_lock(&kset->list_lock);

  	list_for_each_entry(k, &kset->list, entry) {

  		if (kobject_name(k) && !strcmp(kobject_name(k), name)) {

  			ret = kobject_get_unless_zero(k);

  			break;
  		}
  	}

  	spin_unlock(&kset->list_lock);
  	return ret;
  }

  EXPORT_SYMBOL_GPL(kset_find_obj);

  static void kset_release(struct kobject *kobj)
  {
  	struct kset *kset = container_of(kobj, struct kset, kobj);

  	pr_debug("kobject: '%s' (%p): %s
  ",

  		 kobject_name(kobj), kobj, __func__);

  	kfree(kset);
  }

  static void kset_get_ownership(struct kobject *kobj, kuid_t *uid, kgid_t *gid)

  {
  	if (kobj->parent)
  		kobject_get_ownership(kobj->parent, uid, gid);
  }

  static struct kobj_type kset_ktype = {
  	.sysfs_ops	= &kobj_sysfs_ops,

  	.release	= kset_release,
  	.get_ownership	= kset_get_ownership,

  };
  
  /**

   * kset_create() - Create a struct kset dynamically.

   *
   * @name: the name for the kset
   * @uevent_ops: a struct kset_uevent_ops for the kset
   * @parent_kobj: the parent kobject of this kset, if any.
   *
   * This function creates a kset structure dynamically.  This structure can
   * then be registered with the system and show up in sysfs with a call to
   * kset_register().  When you are finished with this structure, if
   * kset_register() has been called, call kset_unregister() and the
   * structure will be dynamically freed when it is no longer being used.
   *
   * If the kset was not able to be created, NULL will be returned.
   */
  static struct kset *kset_create(const char *name,

  				const struct kset_uevent_ops *uevent_ops,

  				struct kobject *parent_kobj)
  {
  	struct kset *kset;

  	int retval;

  
  	kset = kzalloc(sizeof(*kset), GFP_KERNEL);
  	if (!kset)
  		return NULL;

  	retval = kobject_set_name(&kset->kobj, "%s", name);

  	if (retval) {
  		kfree(kset);
  		return NULL;
  	}

  	kset->uevent_ops = uevent_ops;
  	kset->kobj.parent = parent_kobj;
  
  	/*

  	 * The kobject of this kset will have a type of kset_ktype and belong to

  	 * no kset itself.  That way we can properly free it when it is
  	 * finished being used.
  	 */

  	kset->kobj.ktype = &kset_ktype;

  	kset->kobj.kset = NULL;
  
  	return kset;
  }
  
  /**

   * kset_create_and_add() - Create a struct kset dynamically and add it to sysfs.

   *
   * @name: the name for the kset
   * @uevent_ops: a struct kset_uevent_ops for the kset
   * @parent_kobj: the parent kobject of this kset, if any.
   *
   * This function creates a kset structure dynamically and registers it
   * with sysfs.  When you are finished with this structure, call
   * kset_unregister() and the structure will be dynamically freed when it
   * is no longer being used.
   *
   * If the kset was not able to be created, NULL will be returned.
   */
  struct kset *kset_create_and_add(const char *name,

  				 const struct kset_uevent_ops *uevent_ops,

  				 struct kobject *parent_kobj)
  {
  	struct kset *kset;
  	int error;
  
  	kset = kset_create(name, uevent_ops, parent_kobj);
  	if (!kset)
  		return NULL;
  	error = kset_register(kset);
  	if (error) {
  		kfree(kset);
  		return NULL;
  	}
  	return kset;
  }
  EXPORT_SYMBOL_GPL(kset_create_and_add);

  
  static DEFINE_SPINLOCK(kobj_ns_type_lock);
  static const struct kobj_ns_type_operations *kobj_ns_ops_tbl[KOBJ_NS_TYPES];
  
  int kobj_ns_type_register(const struct kobj_ns_type_operations *ops)
  {
  	enum kobj_ns_type type = ops->type;
  	int error;
  
  	spin_lock(&kobj_ns_type_lock);
  
  	error = -EINVAL;
  	if (type >= KOBJ_NS_TYPES)
  		goto out;
  
  	error = -EINVAL;
  	if (type <= KOBJ_NS_TYPE_NONE)
  		goto out;
  
  	error = -EBUSY;
  	if (kobj_ns_ops_tbl[type])
  		goto out;
  
  	error = 0;
  	kobj_ns_ops_tbl[type] = ops;
  
  out:
  	spin_unlock(&kobj_ns_type_lock);
  	return error;
  }
  
  int kobj_ns_type_registered(enum kobj_ns_type type)
  {
  	int registered = 0;
  
  	spin_lock(&kobj_ns_type_lock);
  	if ((type > KOBJ_NS_TYPE_NONE) && (type < KOBJ_NS_TYPES))
  		registered = kobj_ns_ops_tbl[type] != NULL;
  	spin_unlock(&kobj_ns_type_lock);
  
  	return registered;
  }
  
  const struct kobj_ns_type_operations *kobj_child_ns_ops(struct kobject *parent)
  {
  	const struct kobj_ns_type_operations *ops = NULL;

  	if (parent && parent->ktype && parent->ktype->child_ns_type)

  		ops = parent->ktype->child_ns_type(parent);
  
  	return ops;
  }
  
  const struct kobj_ns_type_operations *kobj_ns_ops(struct kobject *kobj)
  {
  	return kobj_child_ns_ops(kobj->parent);
  }

  bool kobj_ns_current_may_mount(enum kobj_ns_type type)
  {

  	bool may_mount = true;

  
  	spin_lock(&kobj_ns_type_lock);
  	if ((type > KOBJ_NS_TYPE_NONE) && (type < KOBJ_NS_TYPES) &&
  	    kobj_ns_ops_tbl[type])
  		may_mount = kobj_ns_ops_tbl[type]->current_may_mount();
  	spin_unlock(&kobj_ns_type_lock);
  
  	return may_mount;
  }

  void *kobj_ns_grab_current(enum kobj_ns_type type)

  {

  	void *ns = NULL;

  
  	spin_lock(&kobj_ns_type_lock);
  	if ((type > KOBJ_NS_TYPE_NONE) && (type < KOBJ_NS_TYPES) &&
  	    kobj_ns_ops_tbl[type])

  		ns = kobj_ns_ops_tbl[type]->grab_current_ns();

  	spin_unlock(&kobj_ns_type_lock);
  
  	return ns;
  }

  EXPORT_SYMBOL_GPL(kobj_ns_grab_current);

  
  const void *kobj_ns_netlink(enum kobj_ns_type type, struct sock *sk)
  {
  	const void *ns = NULL;
  
  	spin_lock(&kobj_ns_type_lock);
  	if ((type > KOBJ_NS_TYPE_NONE) && (type < KOBJ_NS_TYPES) &&
  	    kobj_ns_ops_tbl[type])
  		ns = kobj_ns_ops_tbl[type]->netlink_ns(sk);
  	spin_unlock(&kobj_ns_type_lock);
  
  	return ns;
  }
  
  const void *kobj_ns_initial(enum kobj_ns_type type)
  {
  	const void *ns = NULL;
  
  	spin_lock(&kobj_ns_type_lock);
  	if ((type > KOBJ_NS_TYPE_NONE) && (type < KOBJ_NS_TYPES) &&
  	    kobj_ns_ops_tbl[type])
  		ns = kobj_ns_ops_tbl[type]->initial_ns();
  	spin_unlock(&kobj_ns_type_lock);
  
  	return ns;
  }

  void kobj_ns_drop(enum kobj_ns_type type, void *ns)

  {

  	spin_lock(&kobj_ns_type_lock);
  	if ((type > KOBJ_NS_TYPE_NONE) && (type < KOBJ_NS_TYPES) &&
  	    kobj_ns_ops_tbl[type] && kobj_ns_ops_tbl[type]->drop_ns)
  		kobj_ns_ops_tbl[type]->drop_ns(ns);
  	spin_unlock(&kobj_ns_type_lock);

  }

  EXPORT_SYMBOL_GPL(kobj_ns_drop);