1 /* -*- mode: c; c-basic-offset: 8; -*- 2 * vim: noexpandtab sw=8 ts=8 sts=0: 3 * 4 * item.c - library routines for handling generic config items 5 * 6 * This program is free software; you can redistribute it and/or 7 * modify it under the terms of the GNU General Public 8 * License as published by the Free Software Foundation; either 9 * version 2 of the License, or (at your option) any later version. 10 * 11 * This program is distributed in the hope that it will be useful, 12 * but WITHOUT ANY WARRANTY; without even the implied warranty of 13 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU 14 * General Public License for more details. 15 * 16 * You should have received a copy of the GNU General Public 17 * License along with this program; if not, write to the 18 * Free Software Foundation, Inc., 59 Temple Place - Suite 330, 19 * Boston, MA 021110-1307, USA. 20 * 21 * Based on kobject: 22 * kobject is Copyright (c) 2002-2003 Patrick Mochel 23 * 24 * configfs Copyright (C) 2005 Oracle. All rights reserved. 25 * 26 * Please see the file Documentation/filesystems/configfs/configfs.txt for 27 * critical information about using the config_item interface. 28 */ 29 30 #include <linux/string.h> 31 #include <linux/module.h> 32 #include <linux/stat.h> 33 #include <linux/slab.h> 34 35 #include <linux/configfs.h> 36 37 38 static inline struct config_item *to_item(struct list_head *entry) 39 { 40 return container_of(entry, struct config_item, ci_entry); 41 } 42 43 /* Evil kernel */ 44 static void config_item_release(struct kref *kref); 45 46 /** 47 * config_item_init - initialize item. 48 * @item: item in question. 49 */ 50 static void config_item_init(struct config_item *item) 51 { 52 kref_init(&item->ci_kref); 53 INIT_LIST_HEAD(&item->ci_entry); 54 } 55 56 /** 57 * config_item_set_name - Set the name of an item 58 * @item: item. 59 * @fmt: The vsnprintf()'s format string. 60 * 61 * If strlen(name) >= CONFIGFS_ITEM_NAME_LEN, then use a 62 * dynamically allocated string that @item->ci_name points to. 63 * Otherwise, use the static @item->ci_namebuf array. 64 */ 65 int config_item_set_name(struct config_item *item, const char *fmt, ...) 66 { 67 int limit = CONFIGFS_ITEM_NAME_LEN; 68 int need; 69 va_list args; 70 char *name; 71 72 /* 73 * First, try the static array 74 */ 75 va_start(args, fmt); 76 need = vsnprintf(item->ci_namebuf, limit, fmt, args); 77 va_end(args); 78 if (need < limit) 79 name = item->ci_namebuf; 80 else { 81 va_start(args, fmt); 82 name = kvasprintf(GFP_KERNEL, fmt, args); 83 va_end(args); 84 if (!name) 85 return -EFAULT; 86 } 87 88 /* Free the old name, if necessary. */ 89 if (item->ci_name && item->ci_name != item->ci_namebuf) 90 kfree(item->ci_name); 91 92 /* Now, set the new name */ 93 item->ci_name = name; 94 return 0; 95 } 96 EXPORT_SYMBOL(config_item_set_name); 97 98 void config_item_init_type_name(struct config_item *item, 99 const char *name, 100 const struct config_item_type *type) 101 { 102 config_item_set_name(item, "%s", name); 103 item->ci_type = type; 104 config_item_init(item); 105 } 106 EXPORT_SYMBOL(config_item_init_type_name); 107 108 void config_group_init_type_name(struct config_group *group, const char *name, 109 const struct config_item_type *type) 110 { 111 config_item_set_name(&group->cg_item, "%s", name); 112 group->cg_item.ci_type = type; 113 config_group_init(group); 114 } 115 EXPORT_SYMBOL(config_group_init_type_name); 116 117 struct config_item *config_item_get(struct config_item *item) 118 { 119 if (item) 120 kref_get(&item->ci_kref); 121 return item; 122 } 123 EXPORT_SYMBOL(config_item_get); 124 125 struct config_item *config_item_get_unless_zero(struct config_item *item) 126 { 127 if (item && kref_get_unless_zero(&item->ci_kref)) 128 return item; 129 return NULL; 130 } 131 EXPORT_SYMBOL(config_item_get_unless_zero); 132 133 static void config_item_cleanup(struct config_item *item) 134 { 135 const struct config_item_type *t = item->ci_type; 136 struct config_group *s = item->ci_group; 137 struct config_item *parent = item->ci_parent; 138 139 pr_debug("config_item %s: cleaning up\n", config_item_name(item)); 140 if (item->ci_name != item->ci_namebuf) 141 kfree(item->ci_name); 142 item->ci_name = NULL; 143 if (t && t->ct_item_ops && t->ct_item_ops->release) 144 t->ct_item_ops->release(item); 145 if (s) 146 config_group_put(s); 147 if (parent) 148 config_item_put(parent); 149 } 150 151 static void config_item_release(struct kref *kref) 152 { 153 config_item_cleanup(container_of(kref, struct config_item, ci_kref)); 154 } 155 156 /** 157 * config_item_put - decrement refcount for item. 158 * @item: item. 159 * 160 * Decrement the refcount, and if 0, call config_item_cleanup(). 161 */ 162 void config_item_put(struct config_item *item) 163 { 164 if (item) 165 kref_put(&item->ci_kref, config_item_release); 166 } 167 EXPORT_SYMBOL(config_item_put); 168 169 /** 170 * config_group_init - initialize a group for use 171 * @group: config_group 172 */ 173 void config_group_init(struct config_group *group) 174 { 175 config_item_init(&group->cg_item); 176 INIT_LIST_HEAD(&group->cg_children); 177 INIT_LIST_HEAD(&group->default_groups); 178 } 179 EXPORT_SYMBOL(config_group_init); 180 181 /** 182 * config_group_find_item - search for item in group. 183 * @group: group we're looking in. 184 * @name: item's name. 185 * 186 * Iterate over @group->cg_list, looking for a matching config_item. 187 * If matching item is found take a reference and return the item. 188 * Caller must have locked group via @group->cg_subsys->su_mtx. 189 */ 190 struct config_item *config_group_find_item(struct config_group *group, 191 const char *name) 192 { 193 struct list_head *entry; 194 struct config_item *ret = NULL; 195 196 list_for_each(entry, &group->cg_children) { 197 struct config_item *item = to_item(entry); 198 if (config_item_name(item) && 199 !strcmp(config_item_name(item), name)) { 200 ret = config_item_get(item); 201 break; 202 } 203 } 204 return ret; 205 } 206 EXPORT_SYMBOL(config_group_find_item); 207