[linux.git] / drivers / base / attribute_container.c

// SPDX-License-Identifier: GPL-2.0
/*
 * attribute_container.c - implementation of a simple container for classes
 *
 * Copyright (c) 2005 - James Bottomley <[email protected]>
 *
 * The basic idea here is to enable a device to be attached to an
 * aritrary numer of classes without having to allocate storage for them.
 * Instead, the contained classes select the devices they need to attach
 * to via a matching function.
 */

#include <linux/attribute_container.h>
#include <linux/device.h>
#include <linux/kernel.h>
#include <linux/slab.h>
#include <linux/list.h>
#include <linux/module.h>
#include <linux/mutex.h>

#include "base.h"

/* This is a private structure used to tie the classdev and the
 * container .. it should never be visible outside this file */
struct internal_container {
	struct klist_node node;
	struct attribute_container *cont;
	struct device classdev;
};

static void internal_container_klist_get(struct klist_node *n)
{
	struct internal_container *ic =
		container_of(n, struct internal_container, node);
	get_device(&ic->classdev);
}

static void internal_container_klist_put(struct klist_node *n)
{
	struct internal_container *ic =
		container_of(n, struct internal_container, node);
	put_device(&ic->classdev);
}


/**
 * attribute_container_classdev_to_container - given a classdev, return the container
 *
 * @classdev: the class device created by attribute_container_add_device.
 *
 * Returns the container associated with this classdev.
 */
struct attribute_container *
attribute_container_classdev_to_container(struct device *classdev)
{
	struct internal_container *ic =
		container_of(classdev, struct internal_container, classdev);
	return ic->cont;
}
EXPORT_SYMBOL_GPL(attribute_container_classdev_to_container);

static LIST_HEAD(attribute_container_list);

static DEFINE_MUTEX(attribute_container_mutex);

/**
 * attribute_container_register - register an attribute container
 *
 * @cont: The container to register.  This must be allocated by the
 *        callee and should also be zeroed by it.
 */
int
attribute_container_register(struct attribute_container *cont)
{
	INIT_LIST_HEAD(&cont->node);
	klist_init(&cont->containers, internal_container_klist_get,
		   internal_container_klist_put);

	mutex_lock(&attribute_container_mutex);
	list_add_tail(&cont->node, &attribute_container_list);
	mutex_unlock(&attribute_container_mutex);

	return 0;
}
EXPORT_SYMBOL_GPL(attribute_container_register);

/**
 * attribute_container_unregister - remove a container registration
 *
 * @cont: previously registered container to remove
 */
int
attribute_container_unregister(struct attribute_container *cont)
{
	int retval = -EBUSY;

	mutex_lock(&attribute_container_mutex);
	spin_lock(&cont->containers.k_lock);
	if (!list_empty(&cont->containers.k_list))
		goto out;
	retval = 0;
	list_del(&cont->node);
 out:
	spin_unlock(&cont->containers.k_lock);
	mutex_unlock(&attribute_container_mutex);
	return retval;

}
EXPORT_SYMBOL_GPL(attribute_container_unregister);

/* private function used as class release */
static void attribute_container_release(struct device *classdev)
{
	struct internal_container *ic
		= container_of(classdev, struct internal_container, classdev);
	struct device *dev = classdev->parent;

	kfree(ic);
	put_device(dev);
}

/**
 * attribute_container_add_device - see if any container is interested in dev
 *
 * @dev: device to add attributes to
 * @fn:	 function to trigger addition of class device.
 *
 * This function allocates storage for the class device(s) to be
 * attached to dev (one for each matching attribute_container).  If no
 * fn is provided, the code will simply register the class device via
 * device_add.  If a function is provided, it is expected to add
 * the class device at the appropriate time.  One of the things that
 * might be necessary is to allocate and initialise the classdev and
 * then add it a later time.  To do this, call this routine for
 * allocation and initialisation and then use
 * attribute_container_device_trigger() to call device_add() on
 * it.  Note: after this, the class device contains a reference to dev
 * which is not relinquished until the release of the classdev.
 */
void
attribute_container_add_device(struct device *dev,
			       int (*fn)(struct attribute_container *,
					 struct device *,
					 struct device *))
{
	struct attribute_container *cont;

	mutex_lock(&attribute_container_mutex);
	list_for_each_entry(cont, &attribute_container_list, node) {
		struct internal_container *ic;

		if (attribute_container_no_classdevs(cont))
			continue;

		if (!cont->match(cont, dev))
			continue;

		ic = kzalloc(sizeof(*ic), GFP_KERNEL);
		if (!ic) {
			dev_err(dev, "failed to allocate class container\n");
			continue;
		}

		ic->cont = cont;
		device_initialize(&ic->classdev);
		ic->classdev.parent = get_device(dev);
		ic->classdev.class = cont->class;
		cont->class->dev_release = attribute_container_release;
		dev_set_name(&ic->classdev, "%s", dev_name(dev));
		if (fn)
			fn(cont, dev, &ic->classdev);
		else
			attribute_container_add_class_device(&ic->classdev);
		klist_add_tail(&ic->node, &cont->containers);
	}
	mutex_unlock(&attribute_container_mutex);
}

/* FIXME: can't break out of this unless klist_iter_exit is also
 * called before doing the break
 */
#define klist_for_each_entry(pos, head, member, iter) \
	for (klist_iter_init(head, iter); (pos = ({ \
		struct klist_node *n = klist_next(iter); \
		n ? container_of(n, typeof(*pos), member) : \
			({ klist_iter_exit(iter) ; NULL; }); \
	})) != NULL;)


/**
 * attribute_container_remove_device - make device eligible for removal.
 *
 * @dev:  The generic device
 * @fn:	  A function to call to remove the device
 *
 * This routine triggers device removal.  If fn is NULL, then it is
 * simply done via device_unregister (note that if something
 * still has a reference to the classdev, then the memory occupied
 * will not be freed until the classdev is released).  If you want a
 * two phase release: remove from visibility and then delete the
 * device, then you should use this routine with a fn that calls
 * device_del() and then use attribute_container_device_trigger()
 * to do the final put on the classdev.
 */
void
attribute_container_remove_device(struct device *dev,
				  void (*fn)(struct attribute_container *,
					     struct device *,
					     struct device *))
{
	struct attribute_container *cont;

	mutex_lock(&attribute_container_mutex);
	list_for_each_entry(cont, &attribute_container_list, node) {
		struct internal_container *ic;
		struct klist_iter iter;

		if (attribute_container_no_classdevs(cont))
			continue;

		if (!cont->match(cont, dev))
			continue;

		klist_for_each_entry(ic, &cont->containers, node, &iter) {
			if (dev != ic->classdev.parent)
				continue;
			klist_del(&ic->node);
			if (fn)
				fn(cont, dev, &ic->classdev);
			else {
				attribute_container_remove_attrs(&ic->classdev);
				device_unregister(&ic->classdev);
			}
		}
	}
	mutex_unlock(&attribute_container_mutex);
}

static int
do_attribute_container_device_trigger_safe(struct device *dev,
					   struct attribute_container *cont,
					   int (*fn)(struct attribute_container *,
						     struct device *, struct device *),
					   int (*undo)(struct attribute_container *,
						       struct device *, struct device *))
{
	int ret;
	struct internal_container *ic, *failed;
	struct klist_iter iter;

	if (attribute_container_no_classdevs(cont))
		return fn(cont, dev, NULL);

	klist_for_each_entry(ic, &cont->containers, node, &iter) {
		if (dev == ic->classdev.parent) {
			ret = fn(cont, dev, &ic->classdev);
			if (ret) {
				failed = ic;
				klist_iter_exit(&iter);
				goto fail;
			}
		}
	}
	return 0;

fail:
	if (!undo)
		return ret;

	/* Attempt to undo the work partially done. */
	klist_for_each_entry(ic, &cont->containers, node, &iter) {
		if (ic == failed) {
			klist_iter_exit(&iter);
			break;
		}
		if (dev == ic->classdev.parent)
			undo(cont, dev, &ic->classdev);
	}
	return ret;
}

/**
 * attribute_container_device_trigger_safe - execute a trigger for each
 * matching classdev or fail all of them.
 *
 * @dev:  The generic device to run the trigger for
 * @fn	  the function to execute for each classdev.
 * @undo  A function to undo the work previously done in case of error
 *
 * This function is a safe version of
 * attribute_container_device_trigger. It stops on the first error and
 * undo the partial work that has been done, on previous classdev.  It
 * is guaranteed that either they all succeeded, or none of them
 * succeeded.
 */
int
attribute_container_device_trigger_safe(struct device *dev,
					int (*fn)(struct attribute_container *,
						  struct device *,
						  struct device *),
					int (*undo)(struct attribute_container *,
						    struct device *,
						    struct device *))
{
	struct attribute_container *cont, *failed = NULL;
	int ret = 0;

	mutex_lock(&attribute_container_mutex);

	list_for_each_entry(cont, &attribute_container_list, node) {

		if (!cont->match(cont, dev))
			continue;

		ret = do_attribute_container_device_trigger_safe(dev, cont,
								 fn, undo);
		if (ret) {
			failed = cont;
			break;
		}
	}

	if (ret && !WARN_ON(!undo)) {
		list_for_each_entry(cont, &attribute_container_list, node) {

			if (failed == cont)
				break;

			if (!cont->match(cont, dev))
				continue;

			do_attribute_container_device_trigger_safe(dev, cont,
								   undo, NULL);
		}
	}

	mutex_unlock(&attribute_container_mutex);
	return ret;

}

/**
 * attribute_container_device_trigger - execute a trigger for each matching classdev
 *
 * @dev:  The generic device to run the trigger for
 * @fn	  the function to execute for each classdev.
 *
 * This function is for executing a trigger when you need to know both
 * the container and the classdev.  If you only care about the
 * container, then use attribute_container_trigger() instead.
 */
void
attribute_container_device_trigger(struct device *dev,
				   int (*fn)(struct attribute_container *,
					     struct device *,
					     struct device *))
{
	struct attribute_container *cont;

	mutex_lock(&attribute_container_mutex);
	list_for_each_entry(cont, &attribute_container_list, node) {
		struct internal_container *ic;
		struct klist_iter iter;

		if (!cont->match(cont, dev))
			continue;

		if (attribute_container_no_classdevs(cont)) {
			fn(cont, dev, NULL);
			continue;
		}

		klist_for_each_entry(ic, &cont->containers, node, &iter) {
			if (dev == ic->classdev.parent)
				fn(cont, dev, &ic->classdev);
		}
	}
	mutex_unlock(&attribute_container_mutex);
}

/**
 * attribute_container_trigger - trigger a function for each matching container
 *
 * @dev:  The generic device to activate the trigger for
 * @fn:	  the function to trigger
 *
 * This routine triggers a function that only needs to know the
 * matching containers (not the classdev) associated with a device.
 * It is more lightweight than attribute_container_device_trigger, so
 * should be used in preference unless the triggering function
 * actually needs to know the classdev.
 */
void
attribute_container_trigger(struct device *dev,
			    int (*fn)(struct attribute_container *,
				      struct device *))
{
	struct attribute_container *cont;

	mutex_lock(&attribute_container_mutex);
	list_for_each_entry(cont, &attribute_container_list, node) {
		if (cont->match(cont, dev))
			fn(cont, dev);
	}
	mutex_unlock(&attribute_container_mutex);
}

/**
 * attribute_container_add_attrs - add attributes
 *
 * @classdev: The class device
 *
 * This simply creates all the class device sysfs files from the
 * attributes listed in the container
 */
int
attribute_container_add_attrs(struct device *classdev)
{
	struct attribute_container *cont =
		attribute_container_classdev_to_container(classdev);
	struct device_attribute **attrs = cont->attrs;
	int i, error;

	BUG_ON(attrs && cont->grp);

	if (!attrs && !cont->grp)
		return 0;

	if (cont->grp)
		return sysfs_create_group(&classdev->kobj, cont->grp);

	for (i = 0; attrs[i]; i++) {
		sysfs_attr_init(&attrs[i]->attr);
		error = device_create_file(classdev, attrs[i]);
		if (error)
			return error;
	}

	return 0;
}

/**
 * attribute_container_add_class_device - same function as device_add
 *
 * @classdev:	the class device to add
 *
 * This performs essentially the same function as device_add except for
 * attribute containers, namely add the classdev to the system and then
 * create the attribute files
 */
int
attribute_container_add_class_device(struct device *classdev)
{
	int error = device_add(classdev);

	if (error)
		return error;
	return attribute_container_add_attrs(classdev);
}

/**
 * attribute_container_add_class_device_adapter - simple adapter for triggers
 *
 * This function is identical to attribute_container_add_class_device except
 * that it is designed to be called from the triggers
 */
int
attribute_container_add_class_device_adapter(struct attribute_container *cont,
					     struct device *dev,
					     struct device *classdev)
{
	return attribute_container_add_class_device(classdev);
}

/**
 * attribute_container_remove_attrs - remove any attribute files
 *
 * @classdev: The class device to remove the files from
 *
 */
void
attribute_container_remove_attrs(struct device *classdev)
{
	struct attribute_container *cont =
		attribute_container_classdev_to_container(classdev);
	struct device_attribute **attrs = cont->attrs;
	int i;

	if (!attrs && !cont->grp)
		return;

	if (cont->grp) {
		sysfs_remove_group(&classdev->kobj, cont->grp);
		return ;
	}

	for (i = 0; attrs[i]; i++)
		device_remove_file(classdev, attrs[i]);
}

/**
 * attribute_container_class_device_del - equivalent of class_device_del
 *
 * @classdev: the class device
 *
 * This function simply removes all the attribute files and then calls
 * device_del.
 */
void
attribute_container_class_device_del(struct device *classdev)
{
	attribute_container_remove_attrs(classdev);
	device_del(classdev);
}

/**
 * attribute_container_find_class_device - find the corresponding class_device
 *
 * @cont:	the container
 * @dev:	the generic device
 *
 * Looks up the device in the container's list of class devices and returns
 * the corresponding class_device.
 */
struct device *
attribute_container_find_class_device(struct attribute_container *cont,
				      struct device *dev)
{
	struct device *cdev = NULL;
	struct internal_container *ic;
	struct klist_iter iter;

	klist_for_each_entry(ic, &cont->containers, node, &iter) {
		if (ic->classdev.parent == dev) {
			cdev = &ic->classdev;
			/* FIXME: must exit iterator then break */
			klist_iter_exit(&iter);
			break;
		}
	}

	return cdev;
}
EXPORT_SYMBOL_GPL(attribute_container_find_class_device);
Commit	Line	Data
989d42e8	1	// SPDX-License-Identifier: GPL-2.0
1da177e4 LT	2	/*
	3	* attribute_container.c - implementation of a simple container for classes
	4	*
	5	* Copyright (c) 2005 - James Bottomley <[email protected]>
	6	*
1da177e4 LT	7	* The basic idea here is to enable a device to be attached to an
	8	* aritrary numer of classes without having to allocate storage for them.
	9	* Instead, the contained classes select the devices they need to attach
	10	* to via a matching function.
	11	*/
	12
	13	#include <linux/attribute_container.h>
1da177e4 LT	14	#include <linux/device.h>
	15	#include <linux/kernel.h>
	16	#include <linux/slab.h>
	17	#include <linux/list.h>
	18	#include <linux/module.h>
f8916c11	19	#include <linux/mutex.h>
1da177e4	20
a1bdc7aa BD	21	#include "base.h"
a1bdc7aa BD	22
1da177e4 LT	23	/* This is a private structure used to tie the classdev and the
	24	* container .. it should never be visible outside this file */
	25	struct internal_container {
53c165e0	26	struct klist_node node;
1da177e4	27	struct attribute_container *cont;
ee959b00	28	struct device classdev;
1da177e4 LT	29	};
1da177e4 LT	30
caf39e87 LT	31	static void internal_container_klist_get(struct klist_node *n)
	32	{
	33	struct internal_container *ic =
	34	container_of(n, struct internal_container, node);
ee959b00	35	get_device(&ic->classdev);
caf39e87 LT	36	}
	37
	38	static void internal_container_klist_put(struct klist_node *n)
	39	{
	40	struct internal_container *ic =
	41	container_of(n, struct internal_container, node);
ee959b00	42	put_device(&ic->classdev);
caf39e87 LT	43	}
	44
	45
1da177e4 LT	46	/**
	47	* attribute_container_classdev_to_container - given a classdev, return the container
	48	*
	49	* @classdev: the class device created by attribute_container_add_device.
	50	*
	51	* Returns the container associated with this classdev.
	52	*/
	53	struct attribute_container *
ee959b00	54	attribute_container_classdev_to_container(struct device *classdev)
1da177e4 LT	55	{
	56	struct internal_container *ic =
	57	container_of(classdev, struct internal_container, classdev);
	58	return ic->cont;
	59	}
	60	EXPORT_SYMBOL_GPL(attribute_container_classdev_to_container);
	61
db1118a4	62	static LIST_HEAD(attribute_container_list);
1da177e4	63
61a2f59a	64	static DEFINE_MUTEX(attribute_container_mutex);
1da177e4 LT	65
	66	/**
	67	* attribute_container_register - register an attribute container
	68	*
	69	* @cont: The container to register. This must be allocated by the
	70	* callee and should also be zeroed by it.
	71	*/
	72	int
	73	attribute_container_register(struct attribute_container *cont)
	74	{
	75	INIT_LIST_HEAD(&cont->node);
287f9bd9	76	klist_init(&cont->containers, internal_container_klist_get,
caf39e87	77	internal_container_klist_put);
24a7d36a	78
61a2f59a	79	mutex_lock(&attribute_container_mutex);
1da177e4	80	list_add_tail(&cont->node, &attribute_container_list);
61a2f59a	81	mutex_unlock(&attribute_container_mutex);
1da177e4 LT	82
	83	return 0;
	84	}
	85	EXPORT_SYMBOL_GPL(attribute_container_register);
	86
	87	/**
	88	* attribute_container_unregister - remove a container registration
	89	*
	90	* @cont: previously registered container to remove
	91	*/
	92	int
	93	attribute_container_unregister(struct attribute_container *cont)
	94	{
	95	int retval = -EBUSY;
481026db	96
61a2f59a	97	mutex_lock(&attribute_container_mutex);
53c165e0 JB	98	spin_lock(&cont->containers.k_lock);
53c165e0 JB	99	if (!list_empty(&cont->containers.k_list))
1da177e4 LT	100	goto out;
	101	retval = 0;
	102	list_del(&cont->node);
	103	out:
53c165e0	104	spin_unlock(&cont->containers.k_lock);
61a2f59a	105	mutex_unlock(&attribute_container_mutex);
1da177e4	106	return retval;
24a7d36a	107
1da177e4 LT	108	}
	109	EXPORT_SYMBOL_GPL(attribute_container_unregister);
	110
	111	/* private function used as class release */
ee959b00	112	static void attribute_container_release(struct device *classdev)
1da177e4	113	{
24a7d36a	114	struct internal_container *ic
1da177e4	115	= container_of(classdev, struct internal_container, classdev);
ee959b00	116	struct device *dev = classdev->parent;
1da177e4 LT	117
	118	kfree(ic);
	119	put_device(dev);
	120	}
	121
	122	/**
	123	* attribute_container_add_device - see if any container is interested in dev
	124	*
	125	* @dev: device to add attributes to
	126	* @fn: function to trigger addition of class device.
	127	*
	128	* This function allocates storage for the class device(s) to be
	129	* attached to dev (one for each matching attribute_container). If no
	130	* fn is provided, the code will simply register the class device via
ee959b00	131	* device_add. If a function is provided, it is expected to add
1da177e4 LT	132	* the class device at the appropriate time. One of the things that
	133	* might be necessary is to allocate and initialise the classdev and
	134	* then add it a later time. To do this, call this routine for
	135	* allocation and initialisation and then use
ee959b00	136	* attribute_container_device_trigger() to call device_add() on
1da177e4 LT	137	* it. Note: after this, the class device contains a reference to dev
	138	* which is not relinquished until the release of the classdev.
	139	*/
	140	void
	141	attribute_container_add_device(struct device *dev,
	142	int (fn)(struct attribute_container ,
	143	struct device *,
ee959b00	144	struct device *))
1da177e4 LT	145	{
	146	struct attribute_container *cont;
	147
61a2f59a	148	mutex_lock(&attribute_container_mutex);
1da177e4 LT	149	list_for_each_entry(cont, &attribute_container_list, node) {
	150	struct internal_container *ic;
	151
	152	if (attribute_container_no_classdevs(cont))
	153	continue;
	154
	155	if (!cont->match(cont, dev))
	156	continue;
4aed0644 JS	157
4aed0644 JS	158	ic = kzalloc(sizeof(*ic), GFP_KERNEL);
1da177e4	159	if (!ic) {
a369a7eb	160	dev_err(dev, "failed to allocate class container\n");
1da177e4 LT	161	continue;
1da177e4 LT	162	}
4aed0644	163
1da177e4	164	ic->cont = cont;
ee959b00 TJ	165	device_initialize(&ic->classdev);
ee959b00 TJ	166	ic->classdev.parent = get_device(dev);
1da177e4	167	ic->classdev.class = cont->class;
ee959b00	168	cont->class->dev_release = attribute_container_release;
02aa2a37	169	dev_set_name(&ic->classdev, "%s", dev_name(dev));
1da177e4 LT	170	if (fn)
	171	fn(cont, dev, &ic->classdev);
	172	else
	173	attribute_container_add_class_device(&ic->classdev);
53c165e0	174	klist_add_tail(&ic->node, &cont->containers);
1da177e4	175	}
61a2f59a	176	mutex_unlock(&attribute_container_mutex);
1da177e4 LT	177	}
1da177e4 LT	178
53c165e0 JB	179	/* FIXME: can't break out of this unless klist_iter_exit is also
	180	* called before doing the break
	181	*/
	182	#define klist_for_each_entry(pos, head, member, iter) \
	183	for (klist_iter_init(head, iter); (pos = ({ \
	184	struct klist_node *n = klist_next(iter); \
caf39e87 LT	185	n ? container_of(n, typeof(*pos), member) : \
caf39e87 LT	186	({ klist_iter_exit(iter) ; NULL; }); \
287f9bd9	187	})) != NULL;)
24a7d36a	188
53c165e0	189
1da177e4 LT	190	/**
	191	* attribute_container_remove_device - make device eligible for removal.
	192	*
	193	* @dev: The generic device
	194	* @fn: A function to call to remove the device
	195	*
	196	* This routine triggers device removal. If fn is NULL, then it is
ee959b00	197	* simply done via device_unregister (note that if something
1da177e4 LT	198	* still has a reference to the classdev, then the memory occupied
	199	* will not be freed until the classdev is released). If you want a
	200	* two phase release: remove from visibility and then delete the
	201	* device, then you should use this routine with a fn that calls
ee959b00 TJ	202	* device_del() and then use attribute_container_device_trigger()
ee959b00 TJ	203	* to do the final put on the classdev.
1da177e4 LT	204	*/
	205	void
	206	attribute_container_remove_device(struct device *dev,
	207	void (fn)(struct attribute_container ,
	208	struct device *,
ee959b00	209	struct device *))
1da177e4 LT	210	{
	211	struct attribute_container *cont;
	212
61a2f59a	213	mutex_lock(&attribute_container_mutex);
1da177e4	214	list_for_each_entry(cont, &attribute_container_list, node) {
53c165e0 JB	215	struct internal_container *ic;
53c165e0 JB	216	struct klist_iter iter;
1da177e4 LT	217
	218	if (attribute_container_no_classdevs(cont))
	219	continue;
	220
	221	if (!cont->match(cont, dev))
	222	continue;
53c165e0 JB	223
53c165e0 JB	224	klist_for_each_entry(ic, &cont->containers, node, &iter) {
ee959b00	225	if (dev != ic->classdev.parent)
1da177e4	226	continue;
caf39e87	227	klist_del(&ic->node);
1da177e4 LT	228	if (fn)
	229	fn(cont, dev, &ic->classdev);
	230	else {
	231	attribute_container_remove_attrs(&ic->classdev);
ee959b00	232	device_unregister(&ic->classdev);
1da177e4 LT	233	}
	234	}
	235	}
61a2f59a	236	mutex_unlock(&attribute_container_mutex);
1da177e4	237	}
1da177e4	238
7c1ef338 GKB	239	static int
	240	do_attribute_container_device_trigger_safe(struct device *dev,
	241	struct attribute_container *cont,
	242	int (fn)(struct attribute_container ,
	243	struct device , struct device ),
	244	int (undo)(struct attribute_container ,
	245	struct device , struct device ))
	246	{
	247	int ret;
	248	struct internal_container ic, failed;
	249	struct klist_iter iter;
	250
	251	if (attribute_container_no_classdevs(cont))
	252	return fn(cont, dev, NULL);
	253
	254	klist_for_each_entry(ic, &cont->containers, node, &iter) {
	255	if (dev == ic->classdev.parent) {
	256	ret = fn(cont, dev, &ic->classdev);
	257	if (ret) {
	258	failed = ic;
	259	klist_iter_exit(&iter);
	260	goto fail;
	261	}
	262	}
	263	}
	264	return 0;
	265
	266	fail:
	267	if (!undo)
	268	return ret;
	269
	270	/* Attempt to undo the work partially done. */
	271	klist_for_each_entry(ic, &cont->containers, node, &iter) {
	272	if (ic == failed) {
	273	klist_iter_exit(&iter);
	274	break;
	275	}
	276	if (dev == ic->classdev.parent)
	277	undo(cont, dev, &ic->classdev);
	278	}
	279	return ret;
	280	}
	281
	282	/**
	283	* attribute_container_device_trigger_safe - execute a trigger for each
	284	* matching classdev or fail all of them.
	285	*
	286	* @dev: The generic device to run the trigger for
	287	* @fn the function to execute for each classdev.
	288	* @undo A function to undo the work previously done in case of error
	289	*
	290	* This function is a safe version of
	291	* attribute_container_device_trigger. It stops on the first error and
	292	* undo the partial work that has been done, on previous classdev. It
	293	* is guaranteed that either they all succeeded, or none of them
	294	* succeeded.
	295	*/
	296	int
	297	attribute_container_device_trigger_safe(struct device *dev,
	298	int (fn)(struct attribute_container ,
	299	struct device *,
	300	struct device *),
	301	int (undo)(struct attribute_container ,
	302	struct device *,
303	struct device *))
304	{
305	struct attribute_container cont, failed = NULL;
306	int ret = 0;
307
308	mutex_lock(&attribute_container_mutex);
309
310	list_for_each_entry(cont, &attribute_container_list, node) {
311
312	if (!cont->match(cont, dev))
313	continue;
314
315	ret = do_attribute_container_device_trigger_safe(dev, cont,
316	fn, undo);
317	if (ret) {
318	failed = cont;
319	break;
320	}
321	}
322
323	if (ret && !WARN_ON(!undo)) {
324	list_for_each_entry(cont, &attribute_container_list, node) {
325
326	if (failed == cont)
327	break;
328
329	if (!cont->match(cont, dev))
330	continue;
331
332	do_attribute_container_device_trigger_safe(dev, cont,
333	undo, NULL);
334	}
335	}
336
337	mutex_unlock(&attribute_container_mutex);
338	return ret;
339
340	}
341
1da177e4 LT	342	/**
	343	* attribute_container_device_trigger - execute a trigger for each matching classdev
	344	*
	345	* @dev: The generic device to run the trigger for
	346	* @fn the function to execute for each classdev.
	347	*
03aca7b2	348	* This function is for executing a trigger when you need to know both
1da177e4 LT	349	* the container and the classdev. If you only care about the
	350	* container, then use attribute_container_trigger() instead.
	351	*/
	352	void
24a7d36a	353	attribute_container_device_trigger(struct device *dev,
1da177e4 LT	354	int (fn)(struct attribute_container ,
1da177e4 LT	355	struct device *,
ee959b00	356	struct device *))
1da177e4 LT	357	{
	358	struct attribute_container *cont;
	359
61a2f59a	360	mutex_lock(&attribute_container_mutex);
1da177e4	361	list_for_each_entry(cont, &attribute_container_list, node) {
53c165e0 JB	362	struct internal_container *ic;
53c165e0 JB	363	struct klist_iter iter;
1da177e4 LT	364
	365	if (!cont->match(cont, dev))
	366	continue;
	367
ebd8bb76 JB	368	if (attribute_container_no_classdevs(cont)) {
	369	fn(cont, dev, NULL);
	370	continue;
	371	}
	372
53c165e0	373	klist_for_each_entry(ic, &cont->containers, node, &iter) {
ee959b00	374	if (dev == ic->classdev.parent)
1da177e4 LT	375	fn(cont, dev, &ic->classdev);
	376	}
	377	}
61a2f59a	378	mutex_unlock(&attribute_container_mutex);
1da177e4	379	}
1da177e4 LT	380
	381	/**
	382	* attribute_container_trigger - trigger a function for each matching container
	383	*
	384	* @dev: The generic device to activate the trigger for
	385	* @fn: the function to trigger
	386	*
	387	* This routine triggers a function that only needs to know the
	388	* matching containers (not the classdev) associated with a device.
	389	* It is more lightweight than attribute_container_device_trigger, so
	390	* should be used in preference unless the triggering function
	391	* actually needs to know the classdev.
	392	*/
	393	void
	394	attribute_container_trigger(struct device *dev,
	395	int (fn)(struct attribute_container ,
	396	struct device *))
	397	{
	398	struct attribute_container *cont;
	399
61a2f59a	400	mutex_lock(&attribute_container_mutex);
1da177e4 LT	401	list_for_each_entry(cont, &attribute_container_list, node) {
	402	if (cont->match(cont, dev))
	403	fn(cont, dev);
	404	}
61a2f59a	405	mutex_unlock(&attribute_container_mutex);
1da177e4	406	}
1da177e4 LT	407
	408	/**
	409	* attribute_container_add_attrs - add attributes
	410	*
	411	* @classdev: The class device
	412	*
	413	* This simply creates all the class device sysfs files from the
	414	* attributes listed in the container
	415	*/
	416	int
ee959b00	417	attribute_container_add_attrs(struct device *classdev)
1da177e4 LT	418	{
	419	struct attribute_container *cont =
	420	attribute_container_classdev_to_container(classdev);
ee959b00	421	struct device_attribute **attrs = cont->attrs;
1da177e4 LT	422	int i, error;
1da177e4 LT	423
fd110971 JB	424	BUG_ON(attrs && cont->grp);
	425
	426	if (!attrs && !cont->grp)
1da177e4 LT	427	return 0;
1da177e4 LT	428
fd110971 JB	429	if (cont->grp)
	430	return sysfs_create_group(&classdev->kobj, cont->grp);
	431
1da177e4	432	for (i = 0; attrs[i]; i++) {
ebd09ec9	433	sysfs_attr_init(&attrs[i]->attr);
ee959b00	434	error = device_create_file(classdev, attrs[i]);
1da177e4 LT	435	if (error)
	436	return error;
	437	}
	438
	439	return 0;
	440	}
1da177e4 LT	441
1da177e4 LT	442	/**
ee959b00	443	* attribute_container_add_class_device - same function as device_add
1da177e4 LT	444	*
	445	* @classdev: the class device to add
	446	*
ee959b00	447	* This performs essentially the same function as device_add except for
1da177e4 LT	448	* attribute containers, namely add the classdev to the system and then
	449	* create the attribute files
	450	*/
	451	int
ee959b00	452	attribute_container_add_class_device(struct device *classdev)
1da177e4	453	{
ee959b00	454	int error = device_add(classdev);
481026db	455
1da177e4 LT	456	if (error)
	457	return error;
	458	return attribute_container_add_attrs(classdev);
	459	}
1da177e4 LT	460
	461	/**
	462	* attribute_container_add_class_device_adapter - simple adapter for triggers
	463	*
	464	* This function is identical to attribute_container_add_class_device except
	465	* that it is designed to be called from the triggers
	466	*/
	467	int
	468	attribute_container_add_class_device_adapter(struct attribute_container *cont,
	469	struct device *dev,
ee959b00	470	struct device *classdev)
1da177e4 LT	471	{
	472	return attribute_container_add_class_device(classdev);
	473	}
1da177e4 LT	474
	475	/**
	476	* attribute_container_remove_attrs - remove any attribute files
	477	*
	478	* @classdev: The class device to remove the files from
	479	*
	480	*/
	481	void
ee959b00	482	attribute_container_remove_attrs(struct device *classdev)
1da177e4 LT	483	{
	484	struct attribute_container *cont =
	485	attribute_container_classdev_to_container(classdev);
ee959b00	486	struct device_attribute **attrs = cont->attrs;
1da177e4 LT	487	int i;
1da177e4 LT	488
fd110971	489	if (!attrs && !cont->grp)
1da177e4 LT	490	return;
1da177e4 LT	491
fd110971 JB	492	if (cont->grp) {
	493	sysfs_remove_group(&classdev->kobj, cont->grp);
	494	return ;
	495	}
	496
1da177e4	497	for (i = 0; attrs[i]; i++)
ee959b00	498	device_remove_file(classdev, attrs[i]);
1da177e4	499	}
1da177e4 LT	500
	501	/**
	502	* attribute_container_class_device_del - equivalent of class_device_del
	503	*
	504	* @classdev: the class device
	505	*
	506	* This function simply removes all the attribute files and then calls
ee959b00	507	* device_del.
1da177e4 LT	508	*/
1da177e4 LT	509	void
ee959b00	510	attribute_container_class_device_del(struct device *classdev)
1da177e4 LT	511	{
1da177e4 LT	512	attribute_container_remove_attrs(classdev);
ee959b00	513	device_del(classdev);
1da177e4	514	}
1da177e4	515
d0a7e574 JB	516	/**
	517	* attribute_container_find_class_device - find the corresponding class_device
	518	*
	519	* @cont: the container
	520	* @dev: the generic device
	521	*
	522	* Looks up the device in the container's list of class devices and returns
	523	* the corresponding class_device.
	524	*/
ee959b00	525	struct device *
d0a7e574 JB	526	attribute_container_find_class_device(struct attribute_container *cont,
	527	struct device *dev)
	528	{
ee959b00	529	struct device *cdev = NULL;
d0a7e574	530	struct internal_container *ic;
53c165e0	531	struct klist_iter iter;
d0a7e574	532
53c165e0	533	klist_for_each_entry(ic, &cont->containers, node, &iter) {
ee959b00	534	if (ic->classdev.parent == dev) {
d0a7e574	535	cdev = &ic->classdev;
53c165e0 JB	536	/* FIXME: must exit iterator then break */
53c165e0 JB	537	klist_iter_exit(&iter);
d0a7e574 JB	538	break;
	539	}
	540	}
d0a7e574 JB	541
	542	return cdev;
	543	}
	544	EXPORT_SYMBOL_GPL(attribute_container_find_class_device);