fs/sysfs/file.c - kernel/msm-4.9 - Gitiles

 /*
  * fs/sysfs/file.c - sysfs regular (text) file implementation
  *
  * Copyright (c) 2001-3 Patrick Mochel
  * Copyright (c) 2007 SUSE Linux Products GmbH
  * Copyright (c) 2007 Tejun Heo <teheo@suse.de>
  *
  * This file is released under the GPLv2.
  *
  * Please see Documentation/filesystems/sysfs.txt for more information.
  */

 #include <linux/module.h>
 #include <linux/kobject.h>
 #include <linux/kallsyms.h>
 #include <linux/slab.h>
 #include <linux/list.h>
 #include <linux/mutex.h>
 #include <linux/seq_file.h>

 #include "sysfs.h"
 #include "../kernfs/kernfs-internal.h"

 /*
  * Determine ktype->sysfs_ops for the given kernfs_node.  This function
  * must be called while holding an active reference.
  */
 static const struct sysfs_ops *sysfs_file_ops(struct kernfs_node *kn)
 {
 	struct kobject *kobj = kn->parent->priv;

 	if (kn->flags & KERNFS_LOCKDEP)
 		lockdep_assert_held(kn);
 	return kobj->ktype ? kobj->ktype->sysfs_ops : NULL;
 }

 /*
  * Reads on sysfs are handled through seq_file, which takes care of hairy
  * details like buffering and seeking.  The following function pipes
  * sysfs_ops->show() result through seq_file.
  */
 static int sysfs_kf_seq_show(struct seq_file *sf, void *v)
 {
 	struct kernfs_open_file *of = sf->private;
 	struct kobject *kobj = of->kn->parent->priv;
 	const struct sysfs_ops *ops = sysfs_file_ops(of->kn);
 	ssize_t count;
 	char *buf;

 	/* acquire buffer and ensure that it's >= PAGE_SIZE and clear */
 	count = seq_get_buf(sf, &buf);
 	if (count < PAGE_SIZE) {
 		seq_commit(sf, -1);
 		return 0;
 	}
 	memset(buf, 0, PAGE_SIZE);

 	/*
 	 * Invoke show().  Control may reach here via seq file lseek even
 	 * if @ops->show() isn't implemented.
 	 */
 	if (ops->show) {
 		count = ops->show(kobj, of->kn->priv, buf);
 		if (count < 0)
 			return count;
 	}

 	/*
 	 * The code works fine with PAGE_SIZE return but it's likely to
 	 * indicate truncated result or overflow in normal use cases.
 	 */
 	if (count >= (ssize_t)PAGE_SIZE) {
 		print_symbol("fill_read_buffer: %s returned bad count\n",
 			(unsigned long)ops->show);
 		/* Try to struggle along */
 		count = PAGE_SIZE - 1;
 	}
 	seq_commit(sf, count);
 	return 0;
 }

 static ssize_t sysfs_kf_bin_read(struct kernfs_open_file *of, char *buf,
 				 size_t count, loff_t pos)
 {
 	struct bin_attribute *battr = of->kn->priv;
 	struct kobject *kobj = of->kn->parent->priv;
 	loff_t size = file_inode(of->file)->i_size;

 	if (!count)
 		return 0;

 	if (size) {
 		if (pos > size)
 			return 0;
 		if (pos + count > size)
 			count = size - pos;
 	}

 	if (!battr->read)
 		return -EIO;

 	return battr->read(of->file, kobj, battr, buf, pos, count);
 }

 /* kernfs write callback for regular sysfs files */
 static ssize_t sysfs_kf_write(struct kernfs_open_file *of, char *buf,
 			      size_t count, loff_t pos)
 {
 	const struct sysfs_ops *ops = sysfs_file_ops(of->kn);
 	struct kobject *kobj = of->kn->parent->priv;

 	if (!count)
 		return 0;

 	return ops->store(kobj, of->kn->priv, buf, count);
 }

 /* kernfs write callback for bin sysfs files */
 static ssize_t sysfs_kf_bin_write(struct kernfs_open_file *of, char *buf,
 				  size_t count, loff_t pos)
 {
 	struct bin_attribute *battr = of->kn->priv;
 	struct kobject *kobj = of->kn->parent->priv;
 	loff_t size = file_inode(of->file)->i_size;

 	if (size) {
 		if (size <= pos)
 			return 0;
 		count = min_t(ssize_t, count, size - pos);
 	}
 	if (!count)
 		return 0;

 	if (!battr->write)
 		return -EIO;

 	return battr->write(of->file, kobj, battr, buf, pos, count);
 }

 static int sysfs_kf_bin_mmap(struct kernfs_open_file *of,
 			     struct vm_area_struct *vma)
 {
 	struct bin_attribute *battr = of->kn->priv;
 	struct kobject *kobj = of->kn->parent->priv;

 	return battr->mmap(of->file, kobj, battr, vma);
 }

 void sysfs_notify(struct kobject *kobj, const char *dir, const char *attr)
 {
 	struct kernfs_node *kn = kobj->sd, *tmp;

 	if (kn && dir)
 		kn = kernfs_find_and_get(kn, dir);
 	else
 		kernfs_get(kn);

 	if (kn && attr) {
 		tmp = kernfs_find_and_get(kn, attr);
 		kernfs_put(kn);
 		kn = tmp;
 	}

 	if (kn) {
 		kernfs_notify(kn);
 		kernfs_put(kn);
 	}
 }
 EXPORT_SYMBOL_GPL(sysfs_notify);

 static const struct kernfs_ops sysfs_file_kfops_empty = {
 };

 static const struct kernfs_ops sysfs_file_kfops_ro = {
 	.seq_show	= sysfs_kf_seq_show,
 };

 static const struct kernfs_ops sysfs_file_kfops_wo = {
 	.write		= sysfs_kf_write,
 };

 static const struct kernfs_ops sysfs_file_kfops_rw = {
 	.seq_show	= sysfs_kf_seq_show,
 	.write		= sysfs_kf_write,
 };

 static const struct kernfs_ops sysfs_bin_kfops_ro = {
 	.read		= sysfs_kf_bin_read,
 };

 static const struct kernfs_ops sysfs_bin_kfops_wo = {
 	.write		= sysfs_kf_bin_write,
 };

 static const struct kernfs_ops sysfs_bin_kfops_rw = {
 	.read		= sysfs_kf_bin_read,
 	.write		= sysfs_kf_bin_write,
 };

 static const struct kernfs_ops sysfs_bin_kfops_mmap = {
 	.read		= sysfs_kf_bin_read,
 	.write		= sysfs_kf_bin_write,
 	.mmap		= sysfs_kf_bin_mmap,
 };

 int sysfs_add_file_mode_ns(struct kernfs_node *parent,
 			   const struct attribute *attr, bool is_bin,
 			   umode_t mode, const void *ns)
 {
 	struct lock_class_key *key = NULL;
 	const struct kernfs_ops *ops;
 	struct kernfs_node *kn;
 	loff_t size;

 	if (!is_bin) {
 		struct kobject *kobj = parent->priv;
 		const struct sysfs_ops *sysfs_ops = kobj->ktype->sysfs_ops;

 		/* every kobject with an attribute needs a ktype assigned */
 		if (WARN(!sysfs_ops, KERN_ERR
 			 "missing sysfs attribute operations for kobject: %s\n",
 			 kobject_name(kobj)))
 			return -EINVAL;

 		if (sysfs_ops->show && sysfs_ops->store)
 			ops = &sysfs_file_kfops_rw;
 		else if (sysfs_ops->show)
 			ops = &sysfs_file_kfops_ro;
 		else if (sysfs_ops->store)
 			ops = &sysfs_file_kfops_wo;
 		else
 			ops = &sysfs_file_kfops_empty;

 		size = PAGE_SIZE;
 	} else {
 		struct bin_attribute *battr = (void *)attr;

 		if (battr->mmap)
 			ops = &sysfs_bin_kfops_mmap;
 		else if (battr->read && battr->write)
 			ops = &sysfs_bin_kfops_rw;
 		else if (battr->read)
 			ops = &sysfs_bin_kfops_ro;
 		else if (battr->write)
 			ops = &sysfs_bin_kfops_wo;
 		else
 			ops = &sysfs_file_kfops_empty;

 		size = battr->size;
 	}

 #ifdef CONFIG_DEBUG_LOCK_ALLOC
 	if (!attr->ignore_lockdep)
 		key = attr->key ?: (struct lock_class_key *)&attr->skey;
 #endif
 	kn = __kernfs_create_file(parent, attr->name, mode, size, ops,
 				  (void *)attr, ns, true, key);
 	if (IS_ERR(kn)) {
 		if (PTR_ERR(kn) == -EEXIST)
 			sysfs_warn_dup(parent, attr->name);
 		return PTR_ERR(kn);
 	}
 	return 0;
 }

 int sysfs_add_file(struct kernfs_node *parent, const struct attribute *attr,
 		   bool is_bin)
 {
 	return sysfs_add_file_mode_ns(parent, attr, is_bin, attr->mode, NULL);
 }

 /**
  * sysfs_create_file_ns - create an attribute file for an object with custom ns
  * @kobj: object we're creating for
  * @attr: attribute descriptor
  * @ns: namespace the new file should belong to
  */
 int sysfs_create_file_ns(struct kobject *kobj, const struct attribute *attr,
 			 const void *ns)
 {
 	BUG_ON(!kobj || !kobj->sd || !attr);

 	return sysfs_add_file_mode_ns(kobj->sd, attr, false, attr->mode, ns);

 }
 EXPORT_SYMBOL_GPL(sysfs_create_file_ns);

 int sysfs_create_files(struct kobject *kobj, const struct attribute **ptr)
 {
 	int err = 0;
 	int i;

 	for (i = 0; ptr[i] && !err; i++)
 		err = sysfs_create_file(kobj, ptr[i]);
 	if (err)
 		while (--i >= 0)
 			sysfs_remove_file(kobj, ptr[i]);
 	return err;
 }
 EXPORT_SYMBOL_GPL(sysfs_create_files);

 /**
  * sysfs_add_file_to_group - add an attribute file to a pre-existing group.
  * @kobj: object we're acting for.
  * @attr: attribute descriptor.
  * @group: group name.
  */
 int sysfs_add_file_to_group(struct kobject *kobj,
 		const struct attribute *attr, const char *group)
 {
 	struct kernfs_node *parent;
 	int error;

 	if (group) {
 		parent = kernfs_find_and_get(kobj->sd, group);
 	} else {
 		parent = kobj->sd;
 		kernfs_get(parent);
 	}

 	if (!parent)
 		return -ENOENT;

 	error = sysfs_add_file(parent, attr, false);
 	kernfs_put(parent);

 	return error;
 }
 EXPORT_SYMBOL_GPL(sysfs_add_file_to_group);

 /**
  * sysfs_chmod_file - update the modified mode value on an object attribute.
  * @kobj: object we're acting for.
  * @attr: attribute descriptor.
  * @mode: file permissions.
  *
  */
 int sysfs_chmod_file(struct kobject *kobj, const struct attribute *attr,
 		     umode_t mode)
 {
 	struct kernfs_node *kn;
 	struct iattr newattrs;
 	int rc;

 	kn = kernfs_find_and_get(kobj->sd, attr->name);
 	if (!kn)
 		return -ENOENT;

 	newattrs.ia_mode = (mode & S_IALLUGO) | (kn->mode & ~S_IALLUGO);
 	newattrs.ia_valid = ATTR_MODE;

 	rc = kernfs_setattr(kn, &newattrs);

 	kernfs_put(kn);
 	return rc;
 }
 EXPORT_SYMBOL_GPL(sysfs_chmod_file);

 /**
  * sysfs_remove_file_ns - remove an object attribute with a custom ns tag
  * @kobj: object we're acting for
  * @attr: attribute descriptor
  * @ns: namespace tag of the file to remove
  *
  * Hash the attribute name and namespace tag and kill the victim.
  */
 void sysfs_remove_file_ns(struct kobject *kobj, const struct attribute *attr,
 			  const void *ns)
 {
 	struct kernfs_node *parent = kobj->sd;

 	kernfs_remove_by_name_ns(parent, attr->name, ns);
 }
 EXPORT_SYMBOL_GPL(sysfs_remove_file_ns);

 /**
  * sysfs_remove_file_self - remove an object attribute from its own method
  * @kobj: object we're acting for
  * @attr: attribute descriptor
  *
  * See kernfs_remove_self() for details.
  */
 bool sysfs_remove_file_self(struct kobject *kobj, const struct attribute *attr)
 {
 	struct kernfs_node *parent = kobj->sd;
 	struct kernfs_node *kn;
 	bool ret;

 	kn = kernfs_find_and_get(parent, attr->name);
 	if (WARN_ON_ONCE(!kn))
 		return false;

 	ret = kernfs_remove_self(kn);

 	kernfs_put(kn);
 	return ret;
 }

 void sysfs_remove_files(struct kobject *kobj, const struct attribute **ptr)
 {
 	int i;
 	for (i = 0; ptr[i]; i++)
 		sysfs_remove_file(kobj, ptr[i]);
 }
 EXPORT_SYMBOL_GPL(sysfs_remove_files);

 /**
  * sysfs_remove_file_from_group - remove an attribute file from a group.
  * @kobj: object we're acting for.
  * @attr: attribute descriptor.
  * @group: group name.
  */
 void sysfs_remove_file_from_group(struct kobject *kobj,
 		const struct attribute *attr, const char *group)
 {
 	struct kernfs_node *parent;

 	if (group) {
 		parent = kernfs_find_and_get(kobj->sd, group);
 	} else {
 		parent = kobj->sd;
 		kernfs_get(parent);
 	}

 	if (parent) {
 		kernfs_remove_by_name(parent, attr->name);
 		kernfs_put(parent);
 	}
 }
 EXPORT_SYMBOL_GPL(sysfs_remove_file_from_group);

 /**
  *	sysfs_create_bin_file - create binary file for object.
  *	@kobj:	object.
  *	@attr:	attribute descriptor.
  */
 int sysfs_create_bin_file(struct kobject *kobj,
 			  const struct bin_attribute *attr)
 {
 	BUG_ON(!kobj || !kobj->sd || !attr);

 	return sysfs_add_file(kobj->sd, &attr->attr, true);
 }
 EXPORT_SYMBOL_GPL(sysfs_create_bin_file);

 /**
  *	sysfs_remove_bin_file - remove binary file for object.
  *	@kobj:	object.
  *	@attr:	attribute descriptor.
  */
 void sysfs_remove_bin_file(struct kobject *kobj,
 			   const struct bin_attribute *attr)
 {
 	kernfs_remove_by_name(kobj->sd, attr->attr.name);
 }
 EXPORT_SYMBOL_GPL(sysfs_remove_bin_file);
	/*
	* fs/sysfs/file.c - sysfs regular (text) file implementation
	*
	* Copyright (c) 2001-3 Patrick Mochel
	* Copyright (c) 2007 SUSE Linux Products GmbH
	* Copyright (c) 2007 Tejun Heo <teheo@suse.de>
	*
	* This file is released under the GPLv2.
	*
	* Please see Documentation/filesystems/sysfs.txt for more information.
	*/

	#include <linux/module.h>
	#include <linux/kobject.h>
	#include <linux/kallsyms.h>
	#include <linux/slab.h>
	#include <linux/list.h>
	#include <linux/mutex.h>
	#include <linux/seq_file.h>

	#include "sysfs.h"
	#include "../kernfs/kernfs-internal.h"

	/*
	* Determine ktype->sysfs_ops for the given kernfs_node. This function
	* must be called while holding an active reference.
	*/
	static const struct sysfs_ops sysfs_file_ops(struct kernfs_node kn)
	{
	struct kobject *kobj = kn->parent->priv;

	if (kn->flags & KERNFS_LOCKDEP)
	lockdep_assert_held(kn);
	return kobj->ktype ? kobj->ktype->sysfs_ops : NULL;
	}

	/*
	* Reads on sysfs are handled through seq_file, which takes care of hairy
	* details like buffering and seeking. The following function pipes
	* sysfs_ops->show() result through seq_file.
	*/
	static int sysfs_kf_seq_show(struct seq_file sf, void v)
	{
	struct kernfs_open_file *of = sf->private;
	struct kobject *kobj = of->kn->parent->priv;
	const struct sysfs_ops *ops = sysfs_file_ops(of->kn);
	ssize_t count;
	char *buf;

	/* acquire buffer and ensure that it's >= PAGE_SIZE and clear */
	count = seq_get_buf(sf, &buf);
	if (count < PAGE_SIZE) {
	seq_commit(sf, -1);
	return 0;
	}
	memset(buf, 0, PAGE_SIZE);

	/*
	* Invoke show(). Control may reach here via seq file lseek even
	* if @ops->show() isn't implemented.
	*/
	if (ops->show) {
	count = ops->show(kobj, of->kn->priv, buf);
	if (count < 0)
	return count;
	}

	/*
	* The code works fine with PAGE_SIZE return but it's likely to
	* indicate truncated result or overflow in normal use cases.
	*/
	if (count >= (ssize_t)PAGE_SIZE) {
	print_symbol("fill_read_buffer: %s returned bad count\n",
	(unsigned long)ops->show);
	/* Try to struggle along */
	count = PAGE_SIZE - 1;
	}
	seq_commit(sf, count);
	return 0;
	}

	static ssize_t sysfs_kf_bin_read(struct kernfs_open_file of, char buf,
	size_t count, loff_t pos)
	{
	struct bin_attribute *battr = of->kn->priv;
	struct kobject *kobj = of->kn->parent->priv;
	loff_t size = file_inode(of->file)->i_size;

	if (!count)
	return 0;

	if (size) {
	if (pos > size)
	return 0;
	if (pos + count > size)
	count = size - pos;
	}

	if (!battr->read)
	return -EIO;

	return battr->read(of->file, kobj, battr, buf, pos, count);
	}

	/* kernfs write callback for regular sysfs files */
	static ssize_t sysfs_kf_write(struct kernfs_open_file of, char buf,
	size_t count, loff_t pos)
	{
	const struct sysfs_ops *ops = sysfs_file_ops(of->kn);
	struct kobject *kobj = of->kn->parent->priv;

	if (!count)
	return 0;

	return ops->store(kobj, of->kn->priv, buf, count);
	}

	/* kernfs write callback for bin sysfs files */
	static ssize_t sysfs_kf_bin_write(struct kernfs_open_file of, char buf,
	size_t count, loff_t pos)
	{
	struct bin_attribute *battr = of->kn->priv;
	struct kobject *kobj = of->kn->parent->priv;
	loff_t size = file_inode(of->file)->i_size;

	if (size) {
	if (size <= pos)
	return 0;
	count = min_t(ssize_t, count, size - pos);
	}
	if (!count)
	return 0;

	if (!battr->write)
	return -EIO;

	return battr->write(of->file, kobj, battr, buf, pos, count);
	}

	static int sysfs_kf_bin_mmap(struct kernfs_open_file *of,
	struct vm_area_struct *vma)
	{
	struct bin_attribute *battr = of->kn->priv;
	struct kobject *kobj = of->kn->parent->priv;

	return battr->mmap(of->file, kobj, battr, vma);
	}

	void sysfs_notify(struct kobject kobj, const char dir, const char *attr)
	{
	struct kernfs_node kn = kobj->sd, tmp;

	if (kn && dir)
	kn = kernfs_find_and_get(kn, dir);
	else
	kernfs_get(kn);

	if (kn && attr) {
	tmp = kernfs_find_and_get(kn, attr);
	kernfs_put(kn);
	kn = tmp;
	}

	if (kn) {
	kernfs_notify(kn);
	kernfs_put(kn);
	}
	}
	EXPORT_SYMBOL_GPL(sysfs_notify);

	static const struct kernfs_ops sysfs_file_kfops_empty = {
	};

	static const struct kernfs_ops sysfs_file_kfops_ro = {
	.seq_show = sysfs_kf_seq_show,
	};

	static const struct kernfs_ops sysfs_file_kfops_wo = {
	.write = sysfs_kf_write,
	};

	static const struct kernfs_ops sysfs_file_kfops_rw = {
	.seq_show = sysfs_kf_seq_show,
	.write = sysfs_kf_write,
	};

	static const struct kernfs_ops sysfs_bin_kfops_ro = {
	.read = sysfs_kf_bin_read,
	};

	static const struct kernfs_ops sysfs_bin_kfops_wo = {
	.write = sysfs_kf_bin_write,
	};

	static const struct kernfs_ops sysfs_bin_kfops_rw = {
	.read = sysfs_kf_bin_read,
	.write = sysfs_kf_bin_write,
	};

	static const struct kernfs_ops sysfs_bin_kfops_mmap = {
	.read = sysfs_kf_bin_read,
	.write = sysfs_kf_bin_write,
	.mmap = sysfs_kf_bin_mmap,
	};

	int sysfs_add_file_mode_ns(struct kernfs_node *parent,
	const struct attribute *attr, bool is_bin,
	umode_t mode, const void *ns)
	{
	struct lock_class_key *key = NULL;
	const struct kernfs_ops *ops;
	struct kernfs_node *kn;
	loff_t size;

	if (!is_bin) {
	struct kobject *kobj = parent->priv;
	const struct sysfs_ops *sysfs_ops = kobj->ktype->sysfs_ops;

	/* every kobject with an attribute needs a ktype assigned */
	if (WARN(!sysfs_ops, KERN_ERR
	"missing sysfs attribute operations for kobject: %s\n",
	kobject_name(kobj)))
	return -EINVAL;

	if (sysfs_ops->show && sysfs_ops->store)
	ops = &sysfs_file_kfops_rw;
	else if (sysfs_ops->show)
	ops = &sysfs_file_kfops_ro;
	else if (sysfs_ops->store)
	ops = &sysfs_file_kfops_wo;
	else
	ops = &sysfs_file_kfops_empty;

	size = PAGE_SIZE;
	} else {
	struct bin_attribute battr = (void )attr;

	if (battr->mmap)
	ops = &sysfs_bin_kfops_mmap;
	else if (battr->read && battr->write)
	ops = &sysfs_bin_kfops_rw;
	else if (battr->read)
	ops = &sysfs_bin_kfops_ro;
	else if (battr->write)
	ops = &sysfs_bin_kfops_wo;
	else
	ops = &sysfs_file_kfops_empty;

	size = battr->size;
	}

	#ifdef CONFIG_DEBUG_LOCK_ALLOC
	if (!attr->ignore_lockdep)
	key = attr->key ?: (struct lock_class_key *)&attr->skey;
	#endif
	kn = __kernfs_create_file(parent, attr->name, mode, size, ops,
	(void *)attr, ns, true, key);
	if (IS_ERR(kn)) {
	if (PTR_ERR(kn) == -EEXIST)
	sysfs_warn_dup(parent, attr->name);
	return PTR_ERR(kn);
	}
	return 0;
	}

	int sysfs_add_file(struct kernfs_node parent, const struct attribute attr,
	bool is_bin)
	{
	return sysfs_add_file_mode_ns(parent, attr, is_bin, attr->mode, NULL);
	}

	/**
	* sysfs_create_file_ns - create an attribute file for an object with custom ns
	* @kobj: object we're creating for
	* @attr: attribute descriptor
	* @ns: namespace the new file should belong to
	*/
	int sysfs_create_file_ns(struct kobject kobj, const struct attribute attr,
	const void *ns)
	{
	BUG_ON(!kobj \|\| !kobj->sd \|\| !attr);

	return sysfs_add_file_mode_ns(kobj->sd, attr, false, attr->mode, ns);

	}
	EXPORT_SYMBOL_GPL(sysfs_create_file_ns);

	int sysfs_create_files(struct kobject kobj, const struct attribute *ptr)
	{
	int err = 0;
	int i;

	for (i = 0; ptr[i] && !err; i++)
	err = sysfs_create_file(kobj, ptr[i]);
	if (err)
	while (--i >= 0)
	sysfs_remove_file(kobj, ptr[i]);
	return err;
	}
	EXPORT_SYMBOL_GPL(sysfs_create_files);

	/**
	* sysfs_add_file_to_group - add an attribute file to a pre-existing group.
	* @kobj: object we're acting for.
	* @attr: attribute descriptor.
	* @group: group name.
	*/
	int sysfs_add_file_to_group(struct kobject *kobj,
	const struct attribute attr, const char group)
	{
	struct kernfs_node *parent;
	int error;

	if (group) {
	parent = kernfs_find_and_get(kobj->sd, group);
	} else {
	parent = kobj->sd;
	kernfs_get(parent);
	}

	if (!parent)
	return -ENOENT;

	error = sysfs_add_file(parent, attr, false);
	kernfs_put(parent);

	return error;
	}
	EXPORT_SYMBOL_GPL(sysfs_add_file_to_group);

	/**
	* sysfs_chmod_file - update the modified mode value on an object attribute.
	* @kobj: object we're acting for.
	* @attr: attribute descriptor.
	* @mode: file permissions.
	*
	*/
	int sysfs_chmod_file(struct kobject kobj, const struct attribute attr,
	umode_t mode)
	{
	struct kernfs_node *kn;
	struct iattr newattrs;
	int rc;

	kn = kernfs_find_and_get(kobj->sd, attr->name);
	if (!kn)
	return -ENOENT;

	newattrs.ia_mode = (mode & S_IALLUGO) \| (kn->mode & ~S_IALLUGO);
	newattrs.ia_valid = ATTR_MODE;

	rc = kernfs_setattr(kn, &newattrs);

	kernfs_put(kn);
	return rc;
	}
	EXPORT_SYMBOL_GPL(sysfs_chmod_file);

	/**
	* sysfs_remove_file_ns - remove an object attribute with a custom ns tag
	* @kobj: object we're acting for
	* @attr: attribute descriptor
	* @ns: namespace tag of the file to remove
	*
	* Hash the attribute name and namespace tag and kill the victim.
	*/
	void sysfs_remove_file_ns(struct kobject kobj, const struct attribute attr,
	const void *ns)
	{
	struct kernfs_node *parent = kobj->sd;

	kernfs_remove_by_name_ns(parent, attr->name, ns);
	}
	EXPORT_SYMBOL_GPL(sysfs_remove_file_ns);

	/**
	* sysfs_remove_file_self - remove an object attribute from its own method
	* @kobj: object we're acting for
	* @attr: attribute descriptor
	*
	* See kernfs_remove_self() for details.
	*/
	bool sysfs_remove_file_self(struct kobject kobj, const struct attribute attr)
	{
	struct kernfs_node *parent = kobj->sd;
	struct kernfs_node *kn;
	bool ret;

	kn = kernfs_find_and_get(parent, attr->name);
	if (WARN_ON_ONCE(!kn))
	return false;

	ret = kernfs_remove_self(kn);

	kernfs_put(kn);
	return ret;
	}

	void sysfs_remove_files(struct kobject kobj, const struct attribute *ptr)
	{
	int i;
	for (i = 0; ptr[i]; i++)
	sysfs_remove_file(kobj, ptr[i]);
	}
	EXPORT_SYMBOL_GPL(sysfs_remove_files);

	/**
	* sysfs_remove_file_from_group - remove an attribute file from a group.
	* @kobj: object we're acting for.
	* @attr: attribute descriptor.
	* @group: group name.
	*/
	void sysfs_remove_file_from_group(struct kobject *kobj,
	const struct attribute attr, const char group)
	{
	struct kernfs_node *parent;

	if (group) {
	parent = kernfs_find_and_get(kobj->sd, group);
	} else {
	parent = kobj->sd;
	kernfs_get(parent);
	}

	if (parent) {
	kernfs_remove_by_name(parent, attr->name);
	kernfs_put(parent);
	}
	}
	EXPORT_SYMBOL_GPL(sysfs_remove_file_from_group);

	/**
	* sysfs_create_bin_file - create binary file for object.
	* @kobj: object.
	* @attr: attribute descriptor.
	*/
	int sysfs_create_bin_file(struct kobject *kobj,
	const struct bin_attribute *attr)
	{
	BUG_ON(!kobj \|\| !kobj->sd \|\| !attr);

	return sysfs_add_file(kobj->sd, &attr->attr, true);
	}
	EXPORT_SYMBOL_GPL(sysfs_create_bin_file);

	/**
	* sysfs_remove_bin_file - remove binary file for object.
	* @kobj: object.
	* @attr: attribute descriptor.
	*/
	void sysfs_remove_bin_file(struct kobject *kobj,
	const struct bin_attribute *attr)
	{
	kernfs_remove_by_name(kobj->sd, attr->attr.name);
	}
	EXPORT_SYMBOL_GPL(sysfs_remove_bin_file);