| 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(&item->ci_kref); |
| 37 | INIT_LIST_HEAD(&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(item->ci_namebuf, 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(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(&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(&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(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(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(&item->ci_kref, 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(&group->cg_item); |
| 160 | INIT_LIST_HEAD(&group->cg_children); |
| 161 | INIT_LIST_HEAD(&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); |