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1// SPDX-License-Identifier: GPL-2.0-or-later2/*3 * item.c - library routines for handling generic config items4 *5 * Based on kobject:6 * kobject is Copyright (c) 2002-2003 Patrick Mochel7 *8 * configfs Copyright (C) 2005 Oracle. All rights reserved.9 *10 * Please see the file Documentation/filesystems/configfs.rst for11 * 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 22static 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 */28static void config_item_release(struct kref *kref);29 30/**31 * config_item_init - initialize item.32 * @item: item in question.33 */34static 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 item42 * @item: item.43 * @fmt: The vsnprintf()'s format string.44 *45 * If strlen(name) >= CONFIGFS_ITEM_NAME_LEN, then use a46 * dynamically allocated string that @item->ci_name points to.47 * Otherwise, use the static @item->ci_namebuf array.48 */49int 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 array58 */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}80EXPORT_SYMBOL(config_item_set_name);81 82void 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}90EXPORT_SYMBOL(config_item_init_type_name);91 92void 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}99EXPORT_SYMBOL(config_group_init_type_name);100 101struct config_item *config_item_get(struct config_item *item)102{103 if (item)104 kref_get(&item->ci_kref);105 return item;106}107EXPORT_SYMBOL(config_item_get);108 109struct 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}115EXPORT_SYMBOL(config_item_get_unless_zero);116 117static 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 135static 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 */146void config_item_put(struct config_item *item)147{148 if (item)149 kref_put(&item->ci_kref, config_item_release);150}151EXPORT_SYMBOL(config_item_put);152 153/**154 * config_group_init - initialize a group for use155 * @group: config_group156 */157void 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}163EXPORT_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 */174struct 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}190EXPORT_SYMBOL(config_group_find_item);191