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.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 56 /** 57 * config_item_set_name - Set the name of an item 58 * @item: item. 59 * @name: name. 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 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 } 113 114 EXPORT_SYMBOL(config_item_set_name); 115 116 void config_item_init_type_name(struct config_item *item, 117 const char *name, 118 struct config_item_type *type) 119 { 120 config_item_set_name(item, name); 121 item->ci_type = type; 122 config_item_init(item); 123 } 124 EXPORT_SYMBOL(config_item_init_type_name); 125 126 void config_group_init_type_name(struct config_group *group, const char *name, 127 struct config_item_type *type) 128 { 129 config_item_set_name(&group->cg_item, name); 130 group->cg_item.ci_type = type; 131 config_group_init(group); 132 } 133 EXPORT_SYMBOL(config_group_init_type_name); 134 135 struct config_item * config_item_get(struct config_item * item) 136 { 137 if (item) 138 kref_get(&item->ci_kref); 139 return item; 140 } 141 142 /** 143 * config_item_cleanup - free config_item resources. 144 * @item: item. 145 */ 146 147 void config_item_cleanup(struct config_item * item) 148 { 149 struct config_item_type * t = item->ci_type; 150 struct config_group * s = item->ci_group; 151 struct config_item * parent = item->ci_parent; 152 153 pr_debug("config_item %s: cleaning up\n",config_item_name(item)); 154 if (item->ci_name != item->ci_namebuf) 155 kfree(item->ci_name); 156 item->ci_name = NULL; 157 if (t && t->ct_item_ops && t->ct_item_ops->release) 158 t->ct_item_ops->release(item); 159 if (s) 160 config_group_put(s); 161 if (parent) 162 config_item_put(parent); 163 } 164 165 static void config_item_release(struct kref *kref) 166 { 167 config_item_cleanup(container_of(kref, struct config_item, ci_kref)); 168 } 169 170 /** 171 * config_item_put - decrement refcount for item. 172 * @item: item. 173 * 174 * Decrement the refcount, and if 0, call config_item_cleanup(). 175 */ 176 void config_item_put(struct config_item * item) 177 { 178 if (item) 179 kref_put(&item->ci_kref, config_item_release); 180 } 181 182 183 /** 184 * config_group_init - initialize a group for use 185 * @k: group 186 */ 187 188 void config_group_init(struct config_group *group) 189 { 190 config_item_init(&group->cg_item); 191 INIT_LIST_HEAD(&group->cg_children); 192 } 193 194 195 /** 196 * config_group_find_obj - search for item in group. 197 * @group: group we're looking in. 198 * @name: item's name. 199 * 200 * Lock group via @group->cg_subsys, and iterate over @group->cg_list, 201 * looking for a matching config_item. If matching item is found 202 * take a reference and return the item. 203 */ 204 205 struct config_item * config_group_find_obj(struct config_group * group, const char * name) 206 { 207 struct list_head * entry; 208 struct config_item * ret = NULL; 209 210 /* XXX LOCKING! */ 211 list_for_each(entry,&group->cg_children) { 212 struct config_item * item = to_item(entry); 213 if (config_item_name(item) && 214 !strcmp(config_item_name(item), name)) { 215 ret = config_item_get(item); 216 break; 217 } 218 } 219 return ret; 220 } 221 222 223 EXPORT_SYMBOL(config_item_init); 224 EXPORT_SYMBOL(config_group_init); 225 EXPORT_SYMBOL(config_item_get); 226 EXPORT_SYMBOL(config_item_put); 227 EXPORT_SYMBOL(config_group_find_obj); 228