linux/fs/configfs/item.c
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   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
  38static 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 */
  44static void config_item_release(struct kref *kref);
  45
  46/**
  47 *      config_item_init - initialize item.
  48 *      @item:  item in question.
  49 */
  50void 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 */
  65int 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
 113EXPORT_SYMBOL(config_item_set_name);
 114
 115void 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}
 123EXPORT_SYMBOL(config_item_init_type_name);
 124
 125void 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}
 132EXPORT_SYMBOL(config_group_init_type_name);
 133
 134struct config_item * config_item_get(struct config_item * item)
 135{
 136        if (item)
 137                kref_get(&item->ci_kref);
 138        return item;
 139}
 140
 141static void config_item_cleanup(struct config_item * item)
 142{
 143        struct config_item_type * t = item->ci_type;
 144        struct config_group * s = item->ci_group;
 145        struct config_item * parent = item->ci_parent;
 146
 147        pr_debug("config_item %s: cleaning up\n",config_item_name(item));
 148        if (item->ci_name != item->ci_namebuf)
 149                kfree(item->ci_name);
 150        item->ci_name = NULL;
 151        if (t && t->ct_item_ops && t->ct_item_ops->release)
 152                t->ct_item_ops->release(item);
 153        if (s)
 154                config_group_put(s);
 155        if (parent)
 156                config_item_put(parent);
 157}
 158
 159static void config_item_release(struct kref *kref)
 160{
 161        config_item_cleanup(container_of(kref, struct config_item, ci_kref));
 162}
 163
 164/**
 165 *      config_item_put - decrement refcount for item.
 166 *      @item:  item.
 167 *
 168 *      Decrement the refcount, and if 0, call config_item_cleanup().
 169 */
 170void config_item_put(struct config_item * item)
 171{
 172        if (item)
 173                kref_put(&item->ci_kref, config_item_release);
 174}
 175
 176/**
 177 *      config_group_init - initialize a group for use
 178 *      @k:     group
 179 */
 180void config_group_init(struct config_group *group)
 181{
 182        config_item_init(&group->cg_item);
 183        INIT_LIST_HEAD(&group->cg_children);
 184}
 185
 186/**
 187 *      config_group_find_item - search for item in group.
 188 *      @group: group we're looking in.
 189 *      @name:  item's name.
 190 *
 191 *      Iterate over @group->cg_list, looking for a matching config_item.
 192 *      If matching item is found take a reference and return the item.
 193 *      Caller must have locked group via @group->cg_subsys->su_mtx.
 194 */
 195struct config_item *config_group_find_item(struct config_group *group,
 196                                           const char *name)
 197{
 198        struct list_head * entry;
 199        struct config_item * ret = NULL;
 200
 201        list_for_each(entry,&group->cg_children) {
 202                struct config_item * item = to_item(entry);
 203                if (config_item_name(item) &&
 204                    !strcmp(config_item_name(item), name)) {
 205                        ret = config_item_get(item);
 206                        break;
 207                }
 208        }
 209        return ret;
 210}
 211
 212EXPORT_SYMBOL(config_item_init);
 213EXPORT_SYMBOL(config_group_init);
 214EXPORT_SYMBOL(config_item_get);
 215EXPORT_SYMBOL(config_item_put);
 216EXPORT_SYMBOL(config_group_find_item);
 217
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