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 
to_item(struct list_head * entry)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  */
config_item_init(struct config_item * item)50 static 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  */
config_item_set_name(struct config_item * item,const char * fmt,...)65 int config_item_set_name(struct config_item *item, const char *fmt, ...)
66 {
67 	int limit = CONFIGFS_ITEM_NAME_LEN;
68 	int need;
69 	va_list args;
70 	char *name;
71 
72 	/*
73 	 * First, try the static array
74 	 */
75 	va_start(args, fmt);
76 	need = vsnprintf(item->ci_namebuf, limit, fmt, args);
77 	va_end(args);
78 	if (need < limit)
79 		name = item->ci_namebuf;
80 	else {
81 		va_start(args, fmt);
82 		name = kvasprintf(GFP_KERNEL, fmt, args);
83 		va_end(args);
84 		if (!name)
85 			return -EFAULT;
86 	}
87 
88 	/* Free the old name, if necessary. */
89 	if (item->ci_name && item->ci_name != item->ci_namebuf)
90 		kfree(item->ci_name);
91 
92 	/* Now, set the new name */
93 	item->ci_name = name;
94 	return 0;
95 }
96 EXPORT_SYMBOL(config_item_set_name);
97 
config_item_init_type_name(struct config_item * item,const char * name,const struct config_item_type * type)98 void config_item_init_type_name(struct config_item *item,
99 				const char *name,
100 				const struct config_item_type *type)
101 {
102 	config_item_set_name(item, "%s", name);
103 	item->ci_type = type;
104 	config_item_init(item);
105 }
106 EXPORT_SYMBOL(config_item_init_type_name);
107 
config_group_init_type_name(struct config_group * group,const char * name,const struct config_item_type * type)108 void config_group_init_type_name(struct config_group *group, const char *name,
109 			 const struct config_item_type *type)
110 {
111 	config_item_set_name(&group->cg_item, "%s", name);
112 	group->cg_item.ci_type = type;
113 	config_group_init(group);
114 }
115 EXPORT_SYMBOL(config_group_init_type_name);
116 
config_item_get(struct config_item * item)117 struct config_item *config_item_get(struct config_item *item)
118 {
119 	if (item)
120 		kref_get(&item->ci_kref);
121 	return item;
122 }
123 EXPORT_SYMBOL(config_item_get);
124 
config_item_get_unless_zero(struct config_item * item)125 struct config_item *config_item_get_unless_zero(struct config_item *item)
126 {
127 	if (item && kref_get_unless_zero(&item->ci_kref))
128 		return item;
129 	return NULL;
130 }
131 EXPORT_SYMBOL(config_item_get_unless_zero);
132 
config_item_cleanup(struct config_item * item)133 static void config_item_cleanup(struct config_item *item)
134 {
135 	const struct config_item_type *t = item->ci_type;
136 	struct config_group *s = item->ci_group;
137 	struct config_item *parent = item->ci_parent;
138 
139 	pr_debug("config_item %s: cleaning up\n", config_item_name(item));
140 	if (item->ci_name != item->ci_namebuf)
141 		kfree(item->ci_name);
142 	item->ci_name = NULL;
143 	if (t && t->ct_item_ops && t->ct_item_ops->release)
144 		t->ct_item_ops->release(item);
145 	if (s)
146 		config_group_put(s);
147 	if (parent)
148 		config_item_put(parent);
149 }
150 
config_item_release(struct kref * kref)151 static void config_item_release(struct kref *kref)
152 {
153 	config_item_cleanup(container_of(kref, struct config_item, ci_kref));
154 }
155 
156 /**
157  *	config_item_put - decrement refcount for item.
158  *	@item:	item.
159  *
160  *	Decrement the refcount, and if 0, call config_item_cleanup().
161  */
config_item_put(struct config_item * item)162 void config_item_put(struct config_item *item)
163 {
164 	if (item)
165 		kref_put(&item->ci_kref, config_item_release);
166 }
167 EXPORT_SYMBOL(config_item_put);
168 
169 /**
170  *	config_group_init - initialize a group for use
171  *	@group:	config_group
172  */
config_group_init(struct config_group * group)173 void config_group_init(struct config_group *group)
174 {
175 	config_item_init(&group->cg_item);
176 	INIT_LIST_HEAD(&group->cg_children);
177 	INIT_LIST_HEAD(&group->default_groups);
178 }
179 EXPORT_SYMBOL(config_group_init);
180 
181 /**
182  *	config_group_find_item - search for item in group.
183  *	@group:	group we're looking in.
184  *	@name:	item's name.
185  *
186  *	Iterate over @group->cg_list, looking for a matching config_item.
187  *	If matching item is found take a reference and return the item.
188  *	Caller must have locked group via @group->cg_subsys->su_mtx.
189  */
config_group_find_item(struct config_group * group,const char * name)190 struct config_item *config_group_find_item(struct config_group *group,
191 					   const char *name)
192 {
193 	struct list_head *entry;
194 	struct config_item *ret = NULL;
195 
196 	list_for_each(entry, &group->cg_children) {
197 		struct config_item *item = to_item(entry);
198 		if (config_item_name(item) &&
199 		    !strcmp(config_item_name(item), name)) {
200 			ret = config_item_get(item);
201 			break;
202 		}
203 	}
204 	return ret;
205 }
206 EXPORT_SYMBOL(config_group_find_item);
207