356c05d58a
This patch (as1554) fixes a lockdep false-positive report. The problem arises because lockdep is unable to deal with the tree-structured locks created by the device core and sysfs. This particular problem involves a sysfs attribute method that unregisters itself, not from the device it was called for, but from a descendant device. Lockdep doesn't understand the distinction and reports a possible deadlock, even though the operation is safe. This is the sort of thing that would normally be handled by using a nested lock annotation; unfortunately it's not feasible to do that here. There's no sensible way to tell sysfs when attribute removal occurs in the context of a parent attribute method. As a workaround, the patch adds a new flag to struct attribute telling sysfs not to inform lockdep when it acquires a readlock on a sysfs_dirent instance for the attribute. The readlock is still acquired, but lockdep doesn't know about it and hence does not complain about impossible deadlock scenarios. Also added are macros for static initialization of attribute structures with the ignore_lockdep flag set. The three offending attributes in the USB subsystem are converted to use the new macros. Signed-off-by: Alan Stern <stern@rowland.harvard.edu> Acked-by: Tejun Heo <tj@kernel.org> CC: Eric W. Biederman <ebiederm@xmission.com> CC: Peter Zijlstra <peterz@infradead.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
359 lines
9.2 KiB
C
359 lines
9.2 KiB
C
/*
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* sysfs.h - definitions for the device driver filesystem
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*
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* Copyright (c) 2001,2002 Patrick Mochel
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* Copyright (c) 2004 Silicon Graphics, Inc.
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* Copyright (c) 2007 SUSE Linux Products GmbH
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* Copyright (c) 2007 Tejun Heo <teheo@suse.de>
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*
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* Please see Documentation/filesystems/sysfs.txt for more information.
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*/
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#ifndef _SYSFS_H_
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#define _SYSFS_H_
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#include <linux/compiler.h>
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#include <linux/errno.h>
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#include <linux/list.h>
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#include <linux/lockdep.h>
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#include <linux/kobject_ns.h>
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#include <linux/atomic.h>
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struct kobject;
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struct module;
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enum kobj_ns_type;
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struct attribute {
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const char *name;
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umode_t mode;
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#ifdef CONFIG_DEBUG_LOCK_ALLOC
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bool ignore_lockdep:1;
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struct lock_class_key *key;
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struct lock_class_key skey;
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#endif
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};
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/**
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* sysfs_attr_init - initialize a dynamically allocated sysfs attribute
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* @attr: struct attribute to initialize
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*
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* Initialize a dynamically allocated struct attribute so we can
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* make lockdep happy. This is a new requirement for attributes
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* and initially this is only needed when lockdep is enabled.
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* Lockdep gives a nice error when your attribute is added to
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* sysfs if you don't have this.
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*/
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#ifdef CONFIG_DEBUG_LOCK_ALLOC
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#define sysfs_attr_init(attr) \
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do { \
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static struct lock_class_key __key; \
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\
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(attr)->key = &__key; \
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} while(0)
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#else
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#define sysfs_attr_init(attr) do {} while(0)
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#endif
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struct attribute_group {
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const char *name;
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umode_t (*is_visible)(struct kobject *,
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struct attribute *, int);
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struct attribute **attrs;
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};
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/**
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* Use these macros to make defining attributes easier. See include/linux/device.h
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* for examples..
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*/
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#define __ATTR(_name,_mode,_show,_store) { \
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.attr = {.name = __stringify(_name), .mode = _mode }, \
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.show = _show, \
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.store = _store, \
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}
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#define __ATTR_RO(_name) { \
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.attr = { .name = __stringify(_name), .mode = 0444 }, \
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.show = _name##_show, \
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}
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#define __ATTR_NULL { .attr = { .name = NULL } }
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#ifdef CONFIG_DEBUG_LOCK_ALLOC
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#define __ATTR_IGNORE_LOCKDEP(_name, _mode, _show, _store) { \
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.attr = {.name = __stringify(_name), .mode = _mode, \
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.ignore_lockdep = true }, \
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.show = _show, \
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.store = _store, \
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}
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#else
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#define __ATTR_IGNORE_LOCKDEP __ATTR
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#endif
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#define attr_name(_attr) (_attr).attr.name
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struct file;
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struct vm_area_struct;
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struct bin_attribute {
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struct attribute attr;
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size_t size;
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void *private;
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ssize_t (*read)(struct file *, struct kobject *, struct bin_attribute *,
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char *, loff_t, size_t);
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ssize_t (*write)(struct file *,struct kobject *, struct bin_attribute *,
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char *, loff_t, size_t);
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int (*mmap)(struct file *, struct kobject *, struct bin_attribute *attr,
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struct vm_area_struct *vma);
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};
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/**
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* sysfs_bin_attr_init - initialize a dynamically allocated bin_attribute
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* @attr: struct bin_attribute to initialize
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*
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* Initialize a dynamically allocated struct bin_attribute so we
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* can make lockdep happy. This is a new requirement for
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* attributes and initially this is only needed when lockdep is
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* enabled. Lockdep gives a nice error when your attribute is
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* added to sysfs if you don't have this.
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*/
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#define sysfs_bin_attr_init(bin_attr) sysfs_attr_init(&(bin_attr)->attr)
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struct sysfs_ops {
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ssize_t (*show)(struct kobject *, struct attribute *,char *);
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ssize_t (*store)(struct kobject *,struct attribute *,const char *, size_t);
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const void *(*namespace)(struct kobject *, const struct attribute *);
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};
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struct sysfs_dirent;
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#ifdef CONFIG_SYSFS
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int sysfs_schedule_callback(struct kobject *kobj, void (*func)(void *),
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void *data, struct module *owner);
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int __must_check sysfs_create_dir(struct kobject *kobj);
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void sysfs_remove_dir(struct kobject *kobj);
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int __must_check sysfs_rename_dir(struct kobject *kobj, const char *new_name);
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int __must_check sysfs_move_dir(struct kobject *kobj,
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struct kobject *new_parent_kobj);
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int __must_check sysfs_create_file(struct kobject *kobj,
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const struct attribute *attr);
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int __must_check sysfs_create_files(struct kobject *kobj,
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const struct attribute **attr);
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int __must_check sysfs_chmod_file(struct kobject *kobj,
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const struct attribute *attr, umode_t mode);
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void sysfs_remove_file(struct kobject *kobj, const struct attribute *attr);
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void sysfs_remove_files(struct kobject *kobj, const struct attribute **attr);
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int __must_check sysfs_create_bin_file(struct kobject *kobj,
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const struct bin_attribute *attr);
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void sysfs_remove_bin_file(struct kobject *kobj,
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const struct bin_attribute *attr);
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int __must_check sysfs_create_link(struct kobject *kobj, struct kobject *target,
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const char *name);
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int __must_check sysfs_create_link_nowarn(struct kobject *kobj,
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struct kobject *target,
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const char *name);
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void sysfs_remove_link(struct kobject *kobj, const char *name);
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int sysfs_rename_link(struct kobject *kobj, struct kobject *target,
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const char *old_name, const char *new_name);
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void sysfs_delete_link(struct kobject *dir, struct kobject *targ,
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const char *name);
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int __must_check sysfs_create_group(struct kobject *kobj,
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const struct attribute_group *grp);
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int sysfs_update_group(struct kobject *kobj,
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const struct attribute_group *grp);
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void sysfs_remove_group(struct kobject *kobj,
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const struct attribute_group *grp);
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int sysfs_add_file_to_group(struct kobject *kobj,
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const struct attribute *attr, const char *group);
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void sysfs_remove_file_from_group(struct kobject *kobj,
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const struct attribute *attr, const char *group);
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int sysfs_merge_group(struct kobject *kobj,
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const struct attribute_group *grp);
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void sysfs_unmerge_group(struct kobject *kobj,
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const struct attribute_group *grp);
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void sysfs_notify(struct kobject *kobj, const char *dir, const char *attr);
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void sysfs_notify_dirent(struct sysfs_dirent *sd);
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struct sysfs_dirent *sysfs_get_dirent(struct sysfs_dirent *parent_sd,
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const void *ns,
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const unsigned char *name);
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struct sysfs_dirent *sysfs_get(struct sysfs_dirent *sd);
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void sysfs_put(struct sysfs_dirent *sd);
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int __must_check sysfs_init(void);
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#else /* CONFIG_SYSFS */
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static inline int sysfs_schedule_callback(struct kobject *kobj,
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void (*func)(void *), void *data, struct module *owner)
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{
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return -ENOSYS;
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}
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static inline int sysfs_create_dir(struct kobject *kobj)
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{
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return 0;
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}
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static inline void sysfs_remove_dir(struct kobject *kobj)
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{
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}
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static inline int sysfs_rename_dir(struct kobject *kobj, const char *new_name)
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{
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return 0;
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}
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static inline int sysfs_move_dir(struct kobject *kobj,
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struct kobject *new_parent_kobj)
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{
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return 0;
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}
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static inline int sysfs_create_file(struct kobject *kobj,
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const struct attribute *attr)
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{
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return 0;
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}
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static inline int sysfs_create_files(struct kobject *kobj,
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const struct attribute **attr)
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{
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return 0;
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}
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static inline int sysfs_chmod_file(struct kobject *kobj,
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const struct attribute *attr, umode_t mode)
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{
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return 0;
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}
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static inline void sysfs_remove_file(struct kobject *kobj,
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const struct attribute *attr)
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{
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}
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static inline void sysfs_remove_files(struct kobject *kobj,
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const struct attribute **attr)
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{
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}
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static inline int sysfs_create_bin_file(struct kobject *kobj,
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const struct bin_attribute *attr)
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{
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return 0;
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}
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static inline void sysfs_remove_bin_file(struct kobject *kobj,
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const struct bin_attribute *attr)
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{
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}
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static inline int sysfs_create_link(struct kobject *kobj,
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struct kobject *target, const char *name)
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{
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return 0;
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}
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static inline int sysfs_create_link_nowarn(struct kobject *kobj,
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struct kobject *target,
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const char *name)
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{
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return 0;
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}
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static inline void sysfs_remove_link(struct kobject *kobj, const char *name)
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{
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}
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static inline int sysfs_rename_link(struct kobject *k, struct kobject *t,
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const char *old_name, const char *new_name)
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{
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return 0;
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}
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static inline void sysfs_delete_link(struct kobject *k, struct kobject *t,
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const char *name)
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{
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}
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static inline int sysfs_create_group(struct kobject *kobj,
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const struct attribute_group *grp)
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{
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return 0;
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}
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static inline int sysfs_update_group(struct kobject *kobj,
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const struct attribute_group *grp)
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{
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return 0;
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}
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static inline void sysfs_remove_group(struct kobject *kobj,
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const struct attribute_group *grp)
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{
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}
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static inline int sysfs_add_file_to_group(struct kobject *kobj,
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const struct attribute *attr, const char *group)
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{
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return 0;
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}
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static inline void sysfs_remove_file_from_group(struct kobject *kobj,
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const struct attribute *attr, const char *group)
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{
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}
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static inline int sysfs_merge_group(struct kobject *kobj,
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const struct attribute_group *grp)
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{
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return 0;
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}
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static inline void sysfs_unmerge_group(struct kobject *kobj,
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const struct attribute_group *grp)
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{
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}
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static inline void sysfs_notify(struct kobject *kobj, const char *dir,
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const char *attr)
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{
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}
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static inline void sysfs_notify_dirent(struct sysfs_dirent *sd)
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{
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}
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static inline
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struct sysfs_dirent *sysfs_get_dirent(struct sysfs_dirent *parent_sd,
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const void *ns,
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const unsigned char *name)
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{
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return NULL;
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}
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static inline struct sysfs_dirent *sysfs_get(struct sysfs_dirent *sd)
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{
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return NULL;
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}
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static inline void sysfs_put(struct sysfs_dirent *sd)
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{
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}
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static inline int __must_check sysfs_init(void)
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{
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return 0;
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}
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#endif /* CONFIG_SYSFS */
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#endif /* _SYSFS_H_ */
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