LXR linux/fs/sysfs/dir.c

   1// SPDX-License-Identifier: GPL-2.0
   2/*
   3 * fs/sysfs/dir.c - sysfs core and dir operation implementation
   4 *
   5 * Copyright (c) 2001-3 Patrick Mochel
   6 * Copyright (c) 2007 SUSE Linux Products GmbH
   7 * Copyright (c) 2007 Tejun Heo <teheo@suse.de>
   8 *
   9 * Please see Documentation/filesystems/sysfs.txt for more information.
  10 */
  11
  12#define pr_fmt(fmt)     "sysfs: " fmt
  13
  14#include <linux/fs.h>
  15#include <linux/kobject.h>
  16#include <linux/slab.h>
  17#include "sysfs.h"
  18
  19DEFINE_SPINLOCK(sysfs_symlink_target_lock);
  20
  21void sysfs_warn_dup(struct kernfs_node *parent, const char *name)
  22{
  23        char *buf;
  24
  25        buf = kzalloc(PATH_MAX, GFP_KERNEL);
  26        if (buf)
  27                kernfs_path(parent, buf, PATH_MAX);
  28
  29        pr_warn("cannot create duplicate filename '%s/%s'\n", buf, name);
  30        dump_stack();
  31
  32        kfree(buf);
  33}
  34
  35/**
  36 * sysfs_create_dir_ns - create a directory for an object with a namespace tag
  37 * @kobj: object we're creating directory for
  38 * @ns: the namespace tag to use
  39 */
  40int sysfs_create_dir_ns(struct kobject *kobj, const void *ns)
  41{
  42        struct kernfs_node *parent, *kn;
  43
  44        BUG_ON(!kobj);
  45
  46        if (kobj->parent)
  47                parent = kobj->parent->sd;
  48        else
  49                parent = sysfs_root_kn;
  50
  51        if (!parent)
  52                return -ENOENT;
  53
  54        kn = kernfs_create_dir_ns(parent, kobject_name(kobj),
  55                                  S_IRWXU | S_IRUGO | S_IXUGO, kobj, ns);
  56        if (IS_ERR(kn)) {
  57                if (PTR_ERR(kn) == -EEXIST)
  58                        sysfs_warn_dup(parent, kobject_name(kobj));
  59                return PTR_ERR(kn);
  60        }
  61
  62        kobj->sd = kn;
  63        return 0;
  64}
  65
  66/**
  67 *      sysfs_remove_dir - remove an object's directory.
  68 *      @kobj:  object.
  69 *
  70 *      The only thing special about this is that we remove any files in
  71 *      the directory before we remove the directory, and we've inlined
  72 *      what used to be sysfs_rmdir() below, instead of calling separately.
  73 */
  74void sysfs_remove_dir(struct kobject *kobj)
  75{
  76        struct kernfs_node *kn = kobj->sd;
  77
  78        /*
  79         * In general, kboject owner is responsible for ensuring removal
  80         * doesn't race with other operations and sysfs doesn't provide any
  81         * protection; however, when @kobj is used as a symlink target, the
  82         * symlinking entity usually doesn't own @kobj and thus has no
  83         * control over removal.  @kobj->sd may be removed anytime
  84         * and symlink code may end up dereferencing an already freed node.
  85         *
  86         * sysfs_symlink_target_lock synchronizes @kobj->sd
  87         * disassociation against symlink operations so that symlink code
  88         * can safely dereference @kobj->sd.
  89         */
  90        spin_lock(&sysfs_symlink_target_lock);
  91        kobj->sd = NULL;
  92        spin_unlock(&sysfs_symlink_target_lock);
  93
  94        if (kn) {
  95                WARN_ON_ONCE(kernfs_type(kn) != KERNFS_DIR);
  96                kernfs_remove(kn);
  97        }
  98}
  99
 100int sysfs_rename_dir_ns(struct kobject *kobj, const char *new_name,
 101                        const void *new_ns)
 102{
 103        struct kernfs_node *parent;
 104        int ret;
 105
 106        parent = kernfs_get_parent(kobj->sd);
 107        ret = kernfs_rename_ns(kobj->sd, parent, new_name, new_ns);
 108        kernfs_put(parent);
 109        return ret;
 110}
 111
 112int sysfs_move_dir_ns(struct kobject *kobj, struct kobject *new_parent_kobj,
 113                      const void *new_ns)
 114{
 115        struct kernfs_node *kn = kobj->sd;
 116        struct kernfs_node *new_parent;
 117
 118        new_parent = new_parent_kobj && new_parent_kobj->sd ?
 119                new_parent_kobj->sd : sysfs_root_kn;
 120
 121        return kernfs_rename_ns(kn, new_parent, kn->name, new_ns);
 122}
 123
 124/**
 125 * sysfs_create_mount_point - create an always empty directory
 126 * @parent_kobj:  kobject that will contain this always empty directory
 127 * @name: The name of the always empty directory to add
 128 */
 129int sysfs_create_mount_point(struct kobject *parent_kobj, const char *name)
 130{
 131        struct kernfs_node *kn, *parent = parent_kobj->sd;
 132
 133        kn = kernfs_create_empty_dir(parent, name);
 134        if (IS_ERR(kn)) {
 135                if (PTR_ERR(kn) == -EEXIST)
 136                        sysfs_warn_dup(parent, name);
 137                return PTR_ERR(kn);
 138        }
 139
 140        return 0;
 141}
 142EXPORT_SYMBOL_GPL(sysfs_create_mount_point);
 143
 144/**
 145 *      sysfs_remove_mount_point - remove an always empty directory.
 146 *      @parent_kobj: kobject that will contain this always empty directory
 147 *      @name: The name of the always empty directory to remove
 148 *
 149 */
 150void sysfs_remove_mount_point(struct kobject *parent_kobj, const char *name)
 151{
 152        struct kernfs_node *parent = parent_kobj->sd;
 153
 154        kernfs_remove_by_name_ns(parent, name, NULL);
 155}
 156EXPORT_SYMBOL_GPL(sysfs_remove_mount_point);
 157