LXR linux/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/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 */
  50static 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 */
  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}
 112EXPORT_SYMBOL(config_item_set_name);
 113
 114void config_item_init_type_name(struct config_item *item,
 115                                const char *name,
 116                                const 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}
 122EXPORT_SYMBOL(config_item_init_type_name);
 123
 124void config_group_init_type_name(struct config_group *group, const char *name,
 125                         const 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}
 131EXPORT_SYMBOL(config_group_init_type_name);
 132
 133struct config_item *config_item_get(struct config_item *item)
 134{
 135        if (item)
 136                kref_get(&item->ci_kref);
 137        return item;
 138}
 139EXPORT_SYMBOL(config_item_get);
 140
 141struct 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}
 147EXPORT_SYMBOL(config_item_get_unless_zero);
 148
 149static void config_item_cleanup(struct config_item *item)
 150{
 151        const 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
 167static 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 */
 178void config_item_put(struct config_item *item)
 179{
 180        if (item)
 181                kref_put(&item->ci_kref, config_item_release);
 182}
 183EXPORT_SYMBOL(config_item_put);
 184
 185/**
 186 *      config_group_init - initialize a group for use
 187 *      @group: config_group
 188 */
 189void 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}
 195EXPORT_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 */
 206struct 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}
 222EXPORT_SYMBOL(config_group_find_item);
 223