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 void config_item_init(struct config_item *item) 51 { 52 kref_init(&item->ci_kref); 53 INIT_LIST_HEAD(&item->ci_entry); 54 } 55 EXPORT_SYMBOL(config_item_init); 56 57 /** 58 * config_item_set_name - Set the name of an item 59 * @item: item. 60 * @fmt: The vsnprintf()'s format string. 61 * 62 * If strlen(name) >= CONFIGFS_ITEM_NAME_LEN, then use a 63 * dynamically allocated string that @item->ci_name points to. 64 * Otherwise, use the static @item->ci_namebuf array. 65 */ 66 int config_item_set_name(struct config_item *item, const char *fmt, ...) 67 { 68 int error = 0; 69 int limit = CONFIGFS_ITEM_NAME_LEN; 70 int need; 71 va_list args; 72 char *name; 73 74 /* 75 * First, try the static array 76 */ 77 va_start(args, fmt); 78 need = vsnprintf(item->ci_namebuf, limit, fmt, args); 79 va_end(args); 80 if (need < limit) 81 name = item->ci_namebuf; 82 else { 83 /* 84 * Need more space? Allocate it and try again 85 */ 86 limit = need + 1; 87 name = kmalloc(limit, GFP_KERNEL); 88 if (!name) { 89 error = -ENOMEM; 90 goto Done; 91 } 92 va_start(args, fmt); 93 need = vsnprintf(name, limit, fmt, args); 94 va_end(args); 95 96 /* Still? Give up. */ 97 if (need >= limit) { 98 kfree(name); 99 error = -EFAULT; 100 goto Done; 101 } 102 } 103 104 /* Free the old name, if necessary. */ 105 if (item->ci_name && item->ci_name != item->ci_namebuf) 106 kfree(item->ci_name); 107 108 /* Now, set the new name */ 109 item->ci_name = name; 110 Done: 111 return error; 112 } 113 EXPORT_SYMBOL(config_item_set_name); 114 115 void config_item_init_type_name(struct config_item *item, 116 const char *name, 117 struct config_item_type *type) 118 { 119 config_item_set_name(item, name); 120 item->ci_type = type; 121 config_item_init(item); 122 } 123 EXPORT_SYMBOL(config_item_init_type_name); 124 125 void config_group_init_type_name(struct config_group *group, const char *name, 126 struct config_item_type *type) 127 { 128 config_item_set_name(&group->cg_item, name); 129 group->cg_item.ci_type = type; 130 config_group_init(group); 131 } 132 EXPORT_SYMBOL(config_group_init_type_name); 133 134 struct config_item *config_item_get(struct config_item *item) 135 { 136 if (item) 137 kref_get(&item->ci_kref); 138 return item; 139 } 140 EXPORT_SYMBOL(config_item_get); 141 142 static void config_item_cleanup(struct config_item *item) 143 { 144 struct config_item_type *t = item->ci_type; 145 struct config_group *s = item->ci_group; 146 struct config_item *parent = item->ci_parent; 147 148 pr_debug("config_item %s: cleaning up\n", config_item_name(item)); 149 if (item->ci_name != item->ci_namebuf) 150 kfree(item->ci_name); 151 item->ci_name = NULL; 152 if (t && t->ct_item_ops && t->ct_item_ops->release) 153 t->ct_item_ops->release(item); 154 if (s) 155 config_group_put(s); 156 if (parent) 157 config_item_put(parent); 158 } 159 160 static void config_item_release(struct kref *kref) 161 { 162 config_item_cleanup(container_of(kref, struct config_item, ci_kref)); 163 } 164 165 /** 166 * config_item_put - decrement refcount for item. 167 * @item: item. 168 * 169 * Decrement the refcount, and if 0, call config_item_cleanup(). 170 */ 171 void config_item_put(struct config_item *item) 172 { 173 if (item) 174 kref_put(&item->ci_kref, config_item_release); 175 } 176 EXPORT_SYMBOL(config_item_put); 177 178 /** 179 * config_group_init - initialize a group for use 180 * @group: config_group 181 */ 182 void config_group_init(struct config_group *group) 183 { 184 config_item_init(&group->cg_item); 185 INIT_LIST_HEAD(&group->cg_children); 186 } 187 EXPORT_SYMBOL(config_group_init); 188 189 /** 190 * config_group_find_item - search for item in group. 191 * @group: group we're looking in. 192 * @name: item's name. 193 * 194 * Iterate over @group->cg_list, looking for a matching config_item. 195 * If matching item is found take a reference and return the item. 196 * Caller must have locked group via @group->cg_subsys->su_mtx. 197 */ 198 struct config_item *config_group_find_item(struct config_group *group, 199 const char *name) 200 { 201 struct list_head *entry; 202 struct config_item *ret = NULL; 203 204 list_for_each(entry, &group->cg_children) { 205 struct config_item *item = to_item(entry); 206 if (config_item_name(item) && 207 !strcmp(config_item_name(item), name)) { 208 ret = config_item_get(item); 209 break; 210 } 211 } 212 return ret; 213 } 214 EXPORT_SYMBOL(config_group_find_item); 215