fs/configfs/item.c

   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);