Linux kernel mirror (for testing)
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linux
1/*
2 * fs/sysfs/dir.c - sysfs core and dir operation implementation
3 *
4 * Copyright (c) 2001-3 Patrick Mochel
5 * Copyright (c) 2007 SUSE Linux Products GmbH
6 * Copyright (c) 2007 Tejun Heo <teheo@suse.de>
7 *
8 * This file is released under the GPLv2.
9 *
10 * Please see Documentation/filesystems/sysfs.txt for more information.
11 */
12
13#undef DEBUG
14
15#include <linux/fs.h>
16#include <linux/kobject.h>
17#include <linux/slab.h>
18#include "sysfs.h"
19
20DEFINE_SPINLOCK(sysfs_symlink_target_lock);
21
22/**
23 * sysfs_pathname - return full path to sysfs dirent
24 * @kn: kernfs_node whose path we want
25 * @path: caller allocated buffer of size PATH_MAX
26 *
27 * Gives the name "/" to the sysfs_root entry; any path returned
28 * is relative to wherever sysfs is mounted.
29 */
30static char *sysfs_pathname(struct kernfs_node *kn, char *path)
31{
32 if (kn->parent) {
33 sysfs_pathname(kn->parent, path);
34 strlcat(path, "/", PATH_MAX);
35 }
36 strlcat(path, kn->name, PATH_MAX);
37 return path;
38}
39
40void sysfs_warn_dup(struct kernfs_node *parent, const char *name)
41{
42 char *path;
43
44 path = kzalloc(PATH_MAX, GFP_KERNEL);
45 if (path) {
46 sysfs_pathname(parent, path);
47 strlcat(path, "/", PATH_MAX);
48 strlcat(path, name, PATH_MAX);
49 }
50
51 WARN(1, KERN_WARNING "sysfs: cannot create duplicate filename '%s'\n",
52 path ? path : name);
53
54 kfree(path);
55}
56
57/**
58 * sysfs_create_dir_ns - create a directory for an object with a namespace tag
59 * @kobj: object we're creating directory for
60 * @ns: the namespace tag to use
61 */
62int sysfs_create_dir_ns(struct kobject *kobj, const void *ns)
63{
64 struct kernfs_node *parent, *kn;
65
66 BUG_ON(!kobj);
67
68 if (kobj->parent)
69 parent = kobj->parent->sd;
70 else
71 parent = sysfs_root_kn;
72
73 if (!parent)
74 return -ENOENT;
75
76 kn = kernfs_create_dir_ns(parent, kobject_name(kobj),
77 S_IRWXU | S_IRUGO | S_IXUGO, kobj, ns);
78 if (IS_ERR(kn)) {
79 if (PTR_ERR(kn) == -EEXIST)
80 sysfs_warn_dup(parent, kobject_name(kobj));
81 return PTR_ERR(kn);
82 }
83
84 kobj->sd = kn;
85 return 0;
86}
87
88/**
89 * sysfs_remove_dir - remove an object's directory.
90 * @kobj: object.
91 *
92 * The only thing special about this is that we remove any files in
93 * the directory before we remove the directory, and we've inlined
94 * what used to be sysfs_rmdir() below, instead of calling separately.
95 */
96void sysfs_remove_dir(struct kobject *kobj)
97{
98 struct kernfs_node *kn = kobj->sd;
99
100 /*
101 * In general, kboject owner is responsible for ensuring removal
102 * doesn't race with other operations and sysfs doesn't provide any
103 * protection; however, when @kobj is used as a symlink target, the
104 * symlinking entity usually doesn't own @kobj and thus has no
105 * control over removal. @kobj->sd may be removed anytime
106 * and symlink code may end up dereferencing an already freed node.
107 *
108 * sysfs_symlink_target_lock synchronizes @kobj->sd
109 * disassociation against symlink operations so that symlink code
110 * can safely dereference @kobj->sd.
111 */
112 spin_lock(&sysfs_symlink_target_lock);
113 kobj->sd = NULL;
114 spin_unlock(&sysfs_symlink_target_lock);
115
116 if (kn) {
117 WARN_ON_ONCE(kernfs_type(kn) != KERNFS_DIR);
118 kernfs_remove(kn);
119 }
120}
121
122int sysfs_rename_dir_ns(struct kobject *kobj, const char *new_name,
123 const void *new_ns)
124{
125 struct kernfs_node *parent = kobj->sd->parent;
126
127 return kernfs_rename_ns(kobj->sd, parent, new_name, new_ns);
128}
129
130int sysfs_move_dir_ns(struct kobject *kobj, struct kobject *new_parent_kobj,
131 const void *new_ns)
132{
133 struct kernfs_node *kn = kobj->sd;
134 struct kernfs_node *new_parent;
135
136 BUG_ON(!kn->parent);
137 new_parent = new_parent_kobj && new_parent_kobj->sd ?
138 new_parent_kobj->sd : sysfs_root_kn;
139
140 return kernfs_rename_ns(kn, new_parent, kn->name, new_ns);
141}