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 error = 0; 68 int limit = CONFIGFS_ITEM_NAME_LEN; 69 int need; 70 va_list args; 71 char *name; 72 73 /* 74 * First, try the static array 75 */ 76 va_start(args, fmt); 77 need = vsnprintf(item->ci_namebuf, limit, fmt, args); 78 va_end(args); 79 if (need < limit) 80 name = item->ci_namebuf; 81 else { 82 /* 83 * Need more space? Allocate it and try again 84 */ 85 limit = need + 1; 86 name = kmalloc(limit, GFP_KERNEL); 87 if (!name) { 88 error = -ENOMEM; 89 goto Done; 90 } 91 va_start(args, fmt); 92 need = vsnprintf(name, limit, fmt, args); 93 va_end(args); 94 95 /* Still? Give up. */ 96 if (need >= limit) { 97 kfree(name); 98 error = -EFAULT; 99 goto Done; 100 } 101 } 102 103 /* Free the old name, if necessary. */ 104 if (item->ci_name && item->ci_name != item->ci_namebuf) 105 kfree(item->ci_name); 106 107 /* Now, set the new name */ 108 item->ci_name = name; 109 Done: 110 return error; 111 } 112 EXPORT_SYMBOL(config_item_set_name); 113 114 void config_item_init_type_name(struct config_item *item, 115 const char *name, 116 struct config_item_type *type) 117 { 118 config_item_set_name(item, "%s", name); 119 item->ci_type = type; 120 config_item_init(item); 121 } 122 EXPORT_SYMBOL(config_item_init_type_name); 123 124 void config_group_init_type_name(struct config_group *group, const char *name, 125 struct config_item_type *type) 126 { 127 config_item_set_name(&group->cg_item, "%s", name); 128 group->cg_item.ci_type = type; 129 config_group_init(group); 130 } 131 EXPORT_SYMBOL(config_group_init_type_name); 132 133 struct config_item *config_item_get(struct config_item *item) 134 { 135 if (item) 136 kref_get(&item->ci_kref); 137 return item; 138 } 139 EXPORT_SYMBOL(config_item_get); 140 141 struct config_item *config_item_get_unless_zero(struct config_item *item) 142 { 143 if (item && kref_get_unless_zero(&item->ci_kref)) 144 return item; 145 return NULL; 146 } 147 EXPORT_SYMBOL(config_item_get_unless_zero); 148 149 static void config_item_cleanup(struct config_item *item) 150 { 151 struct config_item_type *t = item->ci_type; 152 struct config_group *s = item->ci_group; 153 struct config_item *parent = item->ci_parent; 154 155 pr_debug("config_item %s: cleaning up\n", config_item_name(item)); 156 if (item->ci_name != item->ci_namebuf) 157 kfree(item->ci_name); 158 item->ci_name = NULL; 159 if (t && t->ct_item_ops && t->ct_item_ops->release) 160 t->ct_item_ops->release(item); 161 if (s) 162 config_group_put(s); 163 if (parent) 164 config_item_put(parent); 165 } 166 167 static void config_item_release(struct kref *kref) 168 { 169 config_item_cleanup(container_of(kref, struct config_item, ci_kref)); 170 } 171 172 /** 173 * config_item_put - decrement refcount for item. 174 * @item: item. 175 * 176 * Decrement the refcount, and if 0, call config_item_cleanup(). 177 */ 178 void config_item_put(struct config_item *item) 179 { 180 if (item) 181 kref_put(&item->ci_kref, config_item_release); 182 } 183 EXPORT_SYMBOL(config_item_put); 184 185 /** 186 * config_group_init - initialize a group for use 187 * @group: config_group 188 */ 189 void config_group_init(struct config_group *group) 190 { 191 config_item_init(&group->cg_item); 192 INIT_LIST_HEAD(&group->cg_children); 193 INIT_LIST_HEAD(&group->default_groups); 194 } 195 EXPORT_SYMBOL(config_group_init); 196 197 /** 198 * config_group_find_item - search for item in group. 199 * @group: group we're looking in. 200 * @name: item's name. 201 * 202 * Iterate over @group->cg_list, looking for a matching config_item. 203 * If matching item is found take a reference and return the item. 204 * Caller must have locked group via @group->cg_subsys->su_mtx. 205 */ 206 struct config_item *config_group_find_item(struct config_group *group, 207 const char *name) 208 { 209 struct list_head *entry; 210 struct config_item *ret = NULL; 211 212 list_for_each(entry, &group->cg_children) { 213 struct config_item *item = to_item(entry); 214 if (config_item_name(item) && 215 !strcmp(config_item_name(item), name)) { 216 ret = config_item_get(item); 217 break; 218 } 219 } 220 return ret; 221 } 222 EXPORT_SYMBOL(config_group_find_item); 223