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}
55EXPORT_SYMBOL(config_item_init);
56
57/**
58 *	config_item_set_name - Set the name of an item
59 *	@item:	item.
60 *	@fmt:  The vsnprintf()'s format string.
61 *
62 *	If strlen(name) >= CONFIGFS_ITEM_NAME_LEN, then use a
63 *	dynamically allocated string that @item->ci_name points to.
64 *	Otherwise, use the static @item->ci_namebuf array.
65 */
66int 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}
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}
140EXPORT_SYMBOL(config_item_get);
141
142static void config_item_cleanup(struct config_item *item)
143{
144	struct config_item_type *t = item->ci_type;
145	struct config_group *s = item->ci_group;
146	struct config_item *parent = item->ci_parent;
147
148	pr_debug("config_item %s: cleaning up\n", config_item_name(item));
149	if (item->ci_name != item->ci_namebuf)
150		kfree(item->ci_name);
151	item->ci_name = NULL;
152	if (t && t->ct_item_ops && t->ct_item_ops->release)
153		t->ct_item_ops->release(item);
154	if (s)
155		config_group_put(s);
156	if (parent)
157		config_item_put(parent);
158}
159
160static void config_item_release(struct kref *kref)
161{
162	config_item_cleanup(container_of(kref, struct config_item, ci_kref));
163}
164
165/**
166 *	config_item_put - decrement refcount for item.
167 *	@item:	item.
168 *
169 *	Decrement the refcount, and if 0, call config_item_cleanup().
170 */
171void config_item_put(struct config_item *item)
172{
173	if (item)
174		kref_put(&item->ci_kref, config_item_release);
175}
176EXPORT_SYMBOL(config_item_put);
177
178/**
179 *	config_group_init - initialize a group for use
180 *	@group:	config_group
181 */
182void config_group_init(struct config_group *group)
183{
184	config_item_init(&group->cg_item);
185	INIT_LIST_HEAD(&group->cg_children);
186}
187EXPORT_SYMBOL(config_group_init);
188
189/**
190 *	config_group_find_item - search for item in group.
191 *	@group:	group we're looking in.
192 *	@name:	item's name.
193 *
194 *	Iterate over @group->cg_list, looking for a matching config_item.
195 *	If matching item is found take a reference and return the item.
196 *	Caller must have locked group via @group->cg_subsys->su_mtx.
197 */
198struct config_item *config_group_find_item(struct config_group *group,
199					   const char *name)
200{
201	struct list_head *entry;
202	struct config_item *ret = NULL;
203
204	list_for_each(entry, &group->cg_children) {
205		struct config_item *item = to_item(entry);
206		if (config_item_name(item) &&
207		    !strcmp(config_item_name(item), name)) {
208			ret = config_item_get(item);
209			break;
210		}
211	}
212	return ret;
213}
214EXPORT_SYMBOL(config_group_find_item);
215