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