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 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
 113 EXPORT_SYMBOL(config_item_set_name);
 114
 115 void 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 }
 123 EXPORT_SYMBOL(config_item_init_type_name);
 124
 125 void 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 }
 132 EXPORT_SYMBOL(config_group_init_type_name);
 133
 134 struct config_item * config_item_get(struct config_item * item)
 135 {
 136         if (item)
 137                 kref_get(&item->ci_kref);
 138         return item;
 139 }
 140
 141 static 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
 159 static 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  */
 170 void 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  */
 180 void 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  */
 195 struct 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
 212 EXPORT_SYMBOL(config_item_init);
 213 EXPORT_SYMBOL(config_group_init);
 214 EXPORT_SYMBOL(config_item_get);
 215 EXPORT_SYMBOL(config_item_put);
 216 EXPORT_SYMBOL(config_group_find_item);