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TOMOYO Linux Cross Reference
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.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);
217 

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