1 // SPDX-License-Identifier: GPL-2.0-or-later
2 /* -*- mode: c; c-basic-offset: 8; -*-
3 * vim: noexpandtab sw=8 ts=8 sts=0:
4 *
5 * item.c - library routines for handling generic config items
6 *
7 * Based on kobject:
8 * kobject is Copyright (c) 2002-2003 Patrick Mochel
9 *
10 * configfs Copyright (C) 2005 Oracle. All rights reserved.
11 *
12 * Please see the file Documentation/filesystems/configfs/configfs.txt for
13 * critical information about using the config_item interface.
14 */
15
16 #include <linux/string.h>
17 #include <linux/module.h>
18 #include <linux/stat.h>
19 #include <linux/slab.h>
20
21 #include <linux/configfs.h>
22
23
to_item(struct list_head * entry)24 static inline struct config_item *to_item(struct list_head *entry)
25 {
26 return container_of(entry, struct config_item, ci_entry);
27 }
28
29 /* Evil kernel */
30 static void config_item_release(struct kref *kref);
31
32 /**
33 * config_item_init - initialize item.
34 * @item: item in question.
35 */
config_item_init(struct config_item * item)36 static void config_item_init(struct config_item *item)
37 {
38 kref_init(&item->ci_kref);
39 INIT_LIST_HEAD(&item->ci_entry);
40 }
41
42 /**
43 * config_item_set_name - Set the name of an item
44 * @item: item.
45 * @fmt: The vsnprintf()'s format string.
46 *
47 * If strlen(name) >= CONFIGFS_ITEM_NAME_LEN, then use a
48 * dynamically allocated string that @item->ci_name points to.
49 * Otherwise, use the static @item->ci_namebuf array.
50 */
config_item_set_name(struct config_item * item,const char * fmt,...)51 int config_item_set_name(struct config_item *item, const char *fmt, ...)
52 {
53 int limit = CONFIGFS_ITEM_NAME_LEN;
54 int need;
55 va_list args;
56 char *name;
57
58 /*
59 * First, try the static array
60 */
61 va_start(args, fmt);
62 need = vsnprintf(item->ci_namebuf, limit, fmt, args);
63 va_end(args);
64 if (need < limit)
65 name = item->ci_namebuf;
66 else {
67 va_start(args, fmt);
68 name = kvasprintf(GFP_KERNEL, fmt, args);
69 va_end(args);
70 if (!name)
71 return -EFAULT;
72 }
73
74 /* Free the old name, if necessary. */
75 if (item->ci_name && item->ci_name != item->ci_namebuf)
76 kfree(item->ci_name);
77
78 /* Now, set the new name */
79 item->ci_name = name;
80 return 0;
81 }
82 EXPORT_SYMBOL(config_item_set_name);
83
config_item_init_type_name(struct config_item * item,const char * name,const struct config_item_type * type)84 void config_item_init_type_name(struct config_item *item,
85 const char *name,
86 const struct config_item_type *type)
87 {
88 config_item_set_name(item, "%s", name);
89 item->ci_type = type;
90 config_item_init(item);
91 }
92 EXPORT_SYMBOL(config_item_init_type_name);
93
config_group_init_type_name(struct config_group * group,const char * name,const struct config_item_type * type)94 void config_group_init_type_name(struct config_group *group, const char *name,
95 const struct config_item_type *type)
96 {
97 config_item_set_name(&group->cg_item, "%s", name);
98 group->cg_item.ci_type = type;
99 config_group_init(group);
100 }
101 EXPORT_SYMBOL(config_group_init_type_name);
102
config_item_get(struct config_item * item)103 struct config_item *config_item_get(struct config_item *item)
104 {
105 if (item)
106 kref_get(&item->ci_kref);
107 return item;
108 }
109 EXPORT_SYMBOL(config_item_get);
110
config_item_get_unless_zero(struct config_item * item)111 struct config_item *config_item_get_unless_zero(struct config_item *item)
112 {
113 if (item && kref_get_unless_zero(&item->ci_kref))
114 return item;
115 return NULL;
116 }
117 EXPORT_SYMBOL(config_item_get_unless_zero);
118
config_item_cleanup(struct config_item * item)119 static void config_item_cleanup(struct config_item *item)
120 {
121 const struct config_item_type *t = item->ci_type;
122 struct config_group *s = item->ci_group;
123 struct config_item *parent = item->ci_parent;
124
125 pr_debug("config_item %s: cleaning up\n", config_item_name(item));
126 if (item->ci_name != item->ci_namebuf)
127 kfree(item->ci_name);
128 item->ci_name = NULL;
129 if (t && t->ct_item_ops && t->ct_item_ops->release)
130 t->ct_item_ops->release(item);
131 if (s)
132 config_group_put(s);
133 if (parent)
134 config_item_put(parent);
135 }
136
config_item_release(struct kref * kref)137 static void config_item_release(struct kref *kref)
138 {
139 config_item_cleanup(container_of(kref, struct config_item, ci_kref));
140 }
141
142 /**
143 * config_item_put - decrement refcount for item.
144 * @item: item.
145 *
146 * Decrement the refcount, and if 0, call config_item_cleanup().
147 */
config_item_put(struct config_item * item)148 void config_item_put(struct config_item *item)
149 {
150 if (item)
151 kref_put(&item->ci_kref, config_item_release);
152 }
153 EXPORT_SYMBOL(config_item_put);
154
155 /**
156 * config_group_init - initialize a group for use
157 * @group: config_group
158 */
config_group_init(struct config_group * group)159 void config_group_init(struct config_group *group)
160 {
161 config_item_init(&group->cg_item);
162 INIT_LIST_HEAD(&group->cg_children);
163 INIT_LIST_HEAD(&group->default_groups);
164 }
165 EXPORT_SYMBOL(config_group_init);
166
167 /**
168 * config_group_find_item - search for item in group.
169 * @group: group we're looking in.
170 * @name: item's name.
171 *
172 * Iterate over @group->cg_list, looking for a matching config_item.
173 * If matching item is found take a reference and return the item.
174 * Caller must have locked group via @group->cg_subsys->su_mtx.
175 */
config_group_find_item(struct config_group * group,const char * name)176 struct config_item *config_group_find_item(struct config_group *group,
177 const char *name)
178 {
179 struct list_head *entry;
180 struct config_item *ret = NULL;
181
182 list_for_each(entry, &group->cg_children) {
183 struct config_item *item = to_item(entry);
184 if (config_item_name(item) &&
185 !strcmp(config_item_name(item), name)) {
186 ret = config_item_get(item);
187 break;
188 }
189 }
190 return ret;
191 }
192 EXPORT_SYMBOL(config_group_find_item);
193