[linux-2.6-block.git] / Documentation / filesystems / configfs / configfs_example_explicit.c

/*
 * vim: noexpandtab ts=8 sts=0 sw=8:
 *
 * configfs_example_explicit.c - This file is a demonstration module
 *      containing a number of configfs subsystems.  It explicitly defines
 *      each structure without using the helper macros defined in
 *      configfs.h.
 *
 * This program is free software; you can redistribute it and/or
 * modify it under the terms of the GNU General Public
 * License as published by the Free Software Foundation; either
 * version 2 of the License, or (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
 * General Public License for more details.
 *
 * You should have received a copy of the GNU General Public
 * License along with this program; if not, write to the
 * Free Software Foundation, Inc., 59 Temple Place - Suite 330,
 * Boston, MA 021110-1307, USA.
 *
 * Based on sysfs:
 * 	sysfs is Copyright (C) 2001, 2002, 2003 Patrick Mochel
 *
 * configfs Copyright (C) 2005 Oracle.  All rights reserved.
 */

#include <linux/init.h>
#include <linux/module.h>
#include <linux/slab.h>

#include <linux/configfs.h>


/*
 * 01-childless
 *
 * This first example is a childless subsystem.  It cannot create
 * any config_items.  It just has attributes.
 *
 * Note that we are enclosing the configfs_subsystem inside a container.
 * This is not necessary if a subsystem has no attributes directly
 * on the subsystem.  See the next example, 02-simple-children, for
 * such a subsystem.
 */

struct childless {
	struct configfs_subsystem subsys;
	int showme;
	int storeme;
};

struct childless_attribute {
	struct configfs_attribute attr;
	ssize_t (*show)(struct childless *, char *);
	ssize_t (*store)(struct childless *, const char *, size_t);
};

static inline struct childless *to_childless(struct config_item *item)
{
	return item ? container_of(to_configfs_subsystem(to_config_group(item)), struct childless, subsys) : NULL;
}

static ssize_t childless_showme_read(struct childless *childless,
				     char *page)
{
	ssize_t pos;

	pos = sprintf(page, "%d\n", childless->showme);
	childless->showme++;

	return pos;
}

static ssize_t childless_storeme_read(struct childless *childless,
				      char *page)
{
	return sprintf(page, "%d\n", childless->storeme);
}

static ssize_t childless_storeme_write(struct childless *childless,
				       const char *page,
				       size_t count)
{
	unsigned long tmp;
	char *p = (char *) page;

	tmp = simple_strtoul(p, &p, 10);
	if (!p || (*p && (*p != '\n')))
		return -EINVAL;

	if (tmp > INT_MAX)
		return -ERANGE;

	childless->storeme = tmp;

	return count;
}

static ssize_t childless_description_read(struct childless *childless,
					  char *page)
{
	return sprintf(page,
"[01-childless]\n"
"\n"
"The childless subsystem is the simplest possible subsystem in\n"
"configfs.  It does not support the creation of child config_items.\n"
"It only has a few attributes.  In fact, it isn't much different\n"
"than a directory in /proc.\n");
}

static struct childless_attribute childless_attr_showme = {
	.attr	= { .ca_owner = THIS_MODULE, .ca_name = "showme", .ca_mode = S_IRUGO },
	.show	= childless_showme_read,
};
static struct childless_attribute childless_attr_storeme = {
	.attr	= { .ca_owner = THIS_MODULE, .ca_name = "storeme", .ca_mode = S_IRUGO | S_IWUSR },
	.show	= childless_storeme_read,
	.store	= childless_storeme_write,
};
static struct childless_attribute childless_attr_description = {
	.attr = { .ca_owner = THIS_MODULE, .ca_name = "description", .ca_mode = S_IRUGO },
	.show = childless_description_read,
};

static struct configfs_attribute *childless_attrs[] = {
	&childless_attr_showme.attr,
	&childless_attr_storeme.attr,
	&childless_attr_description.attr,
	NULL,
};

static ssize_t childless_attr_show(struct config_item *item,
				   struct configfs_attribute *attr,
				   char *page)
{
	struct childless *childless = to_childless(item);
	struct childless_attribute *childless_attr =
		container_of(attr, struct childless_attribute, attr);
	ssize_t ret = 0;

	if (childless_attr->show)
		ret = childless_attr->show(childless, page);
	return ret;
}

static ssize_t childless_attr_store(struct config_item *item,
				    struct configfs_attribute *attr,
				    const char *page, size_t count)
{
	struct childless *childless = to_childless(item);
	struct childless_attribute *childless_attr =
		container_of(attr, struct childless_attribute, attr);
	ssize_t ret = -EINVAL;

	if (childless_attr->store)
		ret = childless_attr->store(childless, page, count);
	return ret;
}

static struct configfs_item_operations childless_item_ops = {
	.show_attribute		= childless_attr_show,
	.store_attribute	= childless_attr_store,
};

static struct config_item_type childless_type = {
	.ct_item_ops	= &childless_item_ops,
	.ct_attrs	= childless_attrs,
	.ct_owner	= THIS_MODULE,
};

static struct childless childless_subsys = {
	.subsys = {
		.su_group = {
			.cg_item = {
				.ci_namebuf = "01-childless",
				.ci_type = &childless_type,
			},
		},
	},
};


/* ----------------------------------------------------------------- */

/*
 * 02-simple-children
 *
 * This example merely has a simple one-attribute child.  Note that
 * there is no extra attribute structure, as the child's attribute is
 * known from the get-go.  Also, there is no container for the
 * subsystem, as it has no attributes of its own.
 */

struct simple_child {
	struct config_item item;
	int storeme;
};

static inline struct simple_child *to_simple_child(struct config_item *item)
{
	return item ? container_of(item, struct simple_child, item) : NULL;
}

static struct configfs_attribute simple_child_attr_storeme = {
	.ca_owner = THIS_MODULE,
	.ca_name = "storeme",
	.ca_mode = S_IRUGO | S_IWUSR,
};

static struct configfs_attribute *simple_child_attrs[] = {
	&simple_child_attr_storeme,
	NULL,
};

static ssize_t simple_child_attr_show(struct config_item *item,
				      struct configfs_attribute *attr,
				      char *page)
{
	ssize_t count;
	struct simple_child *simple_child = to_simple_child(item);

	count = sprintf(page, "%d\n", simple_child->storeme);

	return count;
}

static ssize_t simple_child_attr_store(struct config_item *item,
				       struct configfs_attribute *attr,
				       const char *page, size_t count)
{
	struct simple_child *simple_child = to_simple_child(item);
	unsigned long tmp;
	char *p = (char *) page;

	tmp = simple_strtoul(p, &p, 10);
	if (!p || (*p && (*p != '\n')))
		return -EINVAL;

	if (tmp > INT_MAX)
		return -ERANGE;

	simple_child->storeme = tmp;

	return count;
}

static void simple_child_release(struct config_item *item)
{
	kfree(to_simple_child(item));
}

static struct configfs_item_operations simple_child_item_ops = {
	.release		= simple_child_release,
	.show_attribute		= simple_child_attr_show,
	.store_attribute	= simple_child_attr_store,
};

static struct config_item_type simple_child_type = {
	.ct_item_ops	= &simple_child_item_ops,
	.ct_attrs	= simple_child_attrs,
	.ct_owner	= THIS_MODULE,
};


struct simple_children {
	struct config_group group;
};

static inline struct simple_children *to_simple_children(struct config_item *item)
{
	return item ? container_of(to_config_group(item), struct simple_children, group) : NULL;
}

static struct config_item *simple_children_make_item(struct config_group *group, const char *name)
{
	struct simple_child *simple_child;

	simple_child = kzalloc(sizeof(struct simple_child), GFP_KERNEL);
	if (!simple_child)
		return ERR_PTR(-ENOMEM);

	config_item_init_type_name(&simple_child->item, name,
				   &simple_child_type);

	simple_child->storeme = 0;

	return &simple_child->item;
}

static struct configfs_attribute simple_children_attr_description = {
	.ca_owner = THIS_MODULE,
	.ca_name = "description",
	.ca_mode = S_IRUGO,
};

static struct configfs_attribute *simple_children_attrs[] = {
	&simple_children_attr_description,
	NULL,
};

static ssize_t simple_children_attr_show(struct config_item *item,
					 struct configfs_attribute *attr,
					 char *page)
{
	return sprintf(page,
"[02-simple-children]\n"
"\n"
"This subsystem allows the creation of child config_items.  These\n"
"items have only one attribute that is readable and writeable.\n");
}

static void simple_children_release(struct config_item *item)
{
	kfree(to_simple_children(item));
}

static struct configfs_item_operations simple_children_item_ops = {
	.release	= simple_children_release,
	.show_attribute	= simple_children_attr_show,
};

/*
 * Note that, since no extra work is required on ->drop_item(),
 * no ->drop_item() is provided.
 */
static struct configfs_group_operations simple_children_group_ops = {
	.make_item	= simple_children_make_item,
};

static struct config_item_type simple_children_type = {
	.ct_item_ops	= &simple_children_item_ops,
	.ct_group_ops	= &simple_children_group_ops,
	.ct_attrs	= simple_children_attrs,
	.ct_owner	= THIS_MODULE,
};

static struct configfs_subsystem simple_children_subsys = {
	.su_group = {
		.cg_item = {
			.ci_namebuf = "02-simple-children",
			.ci_type = &simple_children_type,
		},
	},
};


/* ----------------------------------------------------------------- */

/*
 * 03-group-children
 *
 * This example reuses the simple_children group from above.  However,
 * the simple_children group is not the subsystem itself, it is a
 * child of the subsystem.  Creation of a group in the subsystem creates
 * a new simple_children group.  That group can then have simple_child
 * children of its own.
 */

static struct config_group *group_children_make_group(struct config_group *group, const char *name)
{
	struct simple_children *simple_children;

	simple_children = kzalloc(sizeof(struct simple_children),
				  GFP_KERNEL);
	if (!simple_children)
		return ERR_PTR(-ENOMEM);

	config_group_init_type_name(&simple_children->group, name,
				    &simple_children_type);

	return &simple_children->group;
}

static struct configfs_attribute group_children_attr_description = {
	.ca_owner = THIS_MODULE,
	.ca_name = "description",
	.ca_mode = S_IRUGO,
};

static struct configfs_attribute *group_children_attrs[] = {
	&group_children_attr_description,
	NULL,
};

static ssize_t group_children_attr_show(struct config_item *item,
					struct configfs_attribute *attr,
					char *page)
{
	return sprintf(page,
"[03-group-children]\n"
"\n"
"This subsystem allows the creation of child config_groups.  These\n"
"groups are like the subsystem simple-children.\n");
}

static struct configfs_item_operations group_children_item_ops = {
	.show_attribute	= group_children_attr_show,
};

/*
 * Note that, since no extra work is required on ->drop_item(),
 * no ->drop_item() is provided.
 */
static struct configfs_group_operations group_children_group_ops = {
	.make_group	= group_children_make_group,
};

static struct config_item_type group_children_type = {
	.ct_item_ops	= &group_children_item_ops,
	.ct_group_ops	= &group_children_group_ops,
	.ct_attrs	= group_children_attrs,
	.ct_owner	= THIS_MODULE,
};

static struct configfs_subsystem group_children_subsys = {
	.su_group = {
		.cg_item = {
			.ci_namebuf = "03-group-children",
			.ci_type = &group_children_type,
		},
	},
};

/* ----------------------------------------------------------------- */

/*
 * We're now done with our subsystem definitions.
 * For convenience in this module, here's a list of them all.  It
 * allows the init function to easily register them.  Most modules
 * will only have one subsystem, and will only call register_subsystem
 * on it directly.
 */
static struct configfs_subsystem *example_subsys[] = {
	&childless_subsys.subsys,
	&simple_children_subsys,
	&group_children_subsys,
	NULL,
};

static int __init configfs_example_init(void)
{
	int ret;
	int i;
	struct configfs_subsystem *subsys;

	for (i = 0; example_subsys[i]; i++) {
		subsys = example_subsys[i];

		config_group_init(&subsys->su_group);
		mutex_init(&subsys->su_mutex);
		ret = configfs_register_subsystem(subsys);
		if (ret) {
			printk(KERN_ERR "Error %d while registering subsystem %s\n",
			       ret,
			       subsys->su_group.cg_item.ci_namebuf);
			goto out_unregister;
		}
	}

	return 0;

out_unregister:
	for (; i >= 0; i--) {
		configfs_unregister_subsystem(example_subsys[i]);
	}

	return ret;
}

static void __exit configfs_example_exit(void)
{
	int i;

	for (i = 0; example_subsys[i]; i++) {
		configfs_unregister_subsystem(example_subsys[i]);
	}
}

module_init(configfs_example_init);
module_exit(configfs_example_exit);
MODULE_LICENSE("GPL");
Commit	Line	Data
7063fbf2 JB	1	/*
	2	* vim: noexpandtab ts=8 sts=0 sw=8:
	3	*
ecb3d28c JB	4	* configfs_example_explicit.c - This file is a demonstration module
	5	* containing a number of configfs subsystems. It explicitly defines
	6	* each structure without using the helper macros defined in
	7	* configfs.h.
7063fbf2 JB	8	*
	9	* This program is free software; you can redistribute it and/or
	10	* modify it under the terms of the GNU General Public
	11	* License as published by the Free Software Foundation; either
	12	* version 2 of the License, or (at your option) any later version.
	13	*
	14	* This program is distributed in the hope that it will be useful,
	15	* but WITHOUT ANY WARRANTY; without even the implied warranty of
	16	* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
	17	* General Public License for more details.
	18	*
	19	* You should have received a copy of the GNU General Public
	20	* License along with this program; if not, write to the
	21	* Free Software Foundation, Inc., 59 Temple Place - Suite 330,
	22	* Boston, MA 021110-1307, USA.
	23	*
	24	* Based on sysfs:
	25	* sysfs is Copyright (C) 2001, 2002, 2003 Patrick Mochel
	26	*
	27	* configfs Copyright (C) 2005 Oracle. All rights reserved.
	28	*/
	29
	30	#include <linux/init.h>
	31	#include <linux/module.h>
	32	#include <linux/slab.h>
	33
	34	#include <linux/configfs.h>
	35
	36
	37
	38	/*
	39	* 01-childless
	40	*
	41	* This first example is a childless subsystem. It cannot create
	42	* any config_items. It just has attributes.
	43	*
	44	* Note that we are enclosing the configfs_subsystem inside a container.
	45	* This is not necessary if a subsystem has no attributes directly
	46	* on the subsystem. See the next example, 02-simple-children, for
	47	* such a subsystem.
	48	*/
	49
	50	struct childless {
	51	struct configfs_subsystem subsys;
	52	int showme;
	53	int storeme;
	54	};
	55
	56	struct childless_attribute {
	57	struct configfs_attribute attr;
	58	ssize_t (show)(struct childless , char *);
	59	ssize_t (store)(struct childless , const char *, size_t);
	60	};
	61
	62	static inline struct childless to_childless(struct config_item item)
	63	{
	64	return item ? container_of(to_configfs_subsystem(to_config_group(item)), struct childless, subsys) : NULL;
	65	}
	66
	67	static ssize_t childless_showme_read(struct childless *childless,
	68	char *page)
	69	{
	70	ssize_t pos;
	71
72	pos = sprintf(page, "%d\n", childless->showme);
73	childless->showme++;
74
75	return pos;
76	}
77
78	static ssize_t childless_storeme_read(struct childless *childless,
79	char *page)
80	{
81	return sprintf(page, "%d\n", childless->storeme);
82	}
83
84	static ssize_t childless_storeme_write(struct childless *childless,
85	const char *page,
86	size_t count)
87	{
88	unsigned long tmp;
89	char p = (char ) page;
90
91	tmp = simple_strtoul(p, &p, 10);
92	if (!p \|\| (p && (p != '\n')))
93	return -EINVAL;
94
95	if (tmp > INT_MAX)
96	return -ERANGE;
97
98	childless->storeme = tmp;
99
100	return count;
101	}
102
103	static ssize_t childless_description_read(struct childless *childless,
104	char *page)
105	{
106	return sprintf(page,
107	"[01-childless]\n"
108	"\n"
109	"The childless subsystem is the simplest possible subsystem in\n"
110	"configfs. It does not support the creation of child config_items.\n"
111	"It only has a few attributes. In fact, it isn't much different\n"
112	"than a directory in /proc.\n");
113	}
114
115	static struct childless_attribute childless_attr_showme = {
116	.attr = { .ca_owner = THIS_MODULE, .ca_name = "showme", .ca_mode = S_IRUGO },
117	.show = childless_showme_read,
118	};
119	static struct childless_attribute childless_attr_storeme = {
120	.attr = { .ca_owner = THIS_MODULE, .ca_name = "storeme", .ca_mode = S_IRUGO \| S_IWUSR },
121	.show = childless_storeme_read,
122	.store = childless_storeme_write,
123	};
124	static struct childless_attribute childless_attr_description = {
125	.attr = { .ca_owner = THIS_MODULE, .ca_name = "description", .ca_mode = S_IRUGO },
126	.show = childless_description_read,
127	};
128
129	static struct configfs_attribute *childless_attrs[] = {
130	&childless_attr_showme.attr,
131	&childless_attr_storeme.attr,
132	&childless_attr_description.attr,
133	NULL,
134	};
135
136	static ssize_t childless_attr_show(struct config_item *item,
137	struct configfs_attribute *attr,
138	char *page)
139	{
140	struct childless *childless = to_childless(item);
141	struct childless_attribute *childless_attr =
142	container_of(attr, struct childless_attribute, attr);
143	ssize_t ret = 0;
144
145	if (childless_attr->show)
146	ret = childless_attr->show(childless, page);
147	return ret;
148	}
149
150	static ssize_t childless_attr_store(struct config_item *item,
151	struct configfs_attribute *attr,
152	const char *page, size_t count)
153	{
154	struct childless *childless = to_childless(item);
155	struct childless_attribute *childless_attr =
156	container_of(attr, struct childless_attribute, attr);
157	ssize_t ret = -EINVAL;
158
159	if (childless_attr->store)
160	ret = childless_attr->store(childless, page, count);
161	return ret;
162	}
163
164	static struct configfs_item_operations childless_item_ops = {
165	.show_attribute = childless_attr_show,
166	.store_attribute = childless_attr_store,
167	};
168
169	static struct config_item_type childless_type = {
170	.ct_item_ops = &childless_item_ops,
171	.ct_attrs = childless_attrs,
172	.ct_owner = THIS_MODULE,
173	};
174
175	static struct childless childless_subsys = {
176	.subsys = {
177	.su_group = {
178	.cg_item = {
179	.ci_namebuf = "01-childless",
180	.ci_type = &childless_type,
181	},
182	},
183	},
184	};
185
186
187	/* ----------------------------------------------------------------- */
188
189	/*
190	* 02-simple-children
191	*
192	* This example merely has a simple one-attribute child. Note that
193	* there is no extra attribute structure, as the child's attribute is
194	* known from the get-go. Also, there is no container for the
195	* subsystem, as it has no attributes of its own.
196	*/
197
198	struct simple_child {
199	struct config_item item;
200	int storeme;
201	};
202
203	static inline struct simple_child to_simple_child(struct config_item item)
204	{
205	return item ? container_of(item, struct simple_child, item) : NULL;
206	}
207
208	static struct configfs_attribute simple_child_attr_storeme = {
209	.ca_owner = THIS_MODULE,
210	.ca_name = "storeme",
211	.ca_mode = S_IRUGO \| S_IWUSR,
212	};
213
214	static struct configfs_attribute *simple_child_attrs[] = {
215	&simple_child_attr_storeme,
216	NULL,
217	};
218
219	static ssize_t simple_child_attr_show(struct config_item *item,
220	struct configfs_attribute *attr,
221	char *page)
222	{
223	ssize_t count;
224	struct simple_child *simple_child = to_simple_child(item);
225
226	count = sprintf(page, "%d\n", simple_child->storeme);
227
228	return count;
229	}
230
231	static ssize_t simple_child_attr_store(struct config_item *item,
232	struct configfs_attribute *attr,
233	const char *page, size_t count)
234	{
235	struct simple_child *simple_child = to_simple_child(item);
236	unsigned long tmp;
237	char p = (char ) page;
238
239	tmp = simple_strtoul(p, &p, 10);
240	if (!p \|\| (p && (p != '\n')))
241	return -EINVAL;
242
243	if (tmp > INT_MAX)
244	return -ERANGE;
245
246	simple_child->storeme = tmp;
247
248	return count;
249	}
250
251	static void simple_child_release(struct config_item *item)
252	{
253	kfree(to_simple_child(item));
254	}
255
256	static struct configfs_item_operations simple_child_item_ops = {
257	.release = simple_child_release,
258	.show_attribute = simple_child_attr_show,
259	.store_attribute = simple_child_attr_store,
260	};
261
262	static struct config_item_type simple_child_type = {
263	.ct_item_ops = &simple_child_item_ops,
264	.ct_attrs = simple_child_attrs,
265	.ct_owner = THIS_MODULE,
266	};
267
268
22dd0e88 JB	269	struct simple_children {
	270	struct config_group group;
	271	};
	272
	273	static inline struct simple_children to_simple_children(struct config_item item)
	274	{
	275	return item ? container_of(to_config_group(item), struct simple_children, group) : NULL;
	276	}
	277
f89ab861	278	static struct config_item simple_children_make_item(struct config_group group, const char *name)
7063fbf2 JB	279	{
	280	struct simple_child *simple_child;
	281
dd00cc48	282	simple_child = kzalloc(sizeof(struct simple_child), GFP_KERNEL);
7063fbf2	283	if (!simple_child)
a6795e9e	284	return ERR_PTR(-ENOMEM);
7063fbf2	285
7063fbf2 JB	286	config_item_init_type_name(&simple_child->item, name,
	287	&simple_child_type);
	288
	289	simple_child->storeme = 0;
	290
f89ab861	291	return &simple_child->item;
7063fbf2 JB	292	}
	293
	294	static struct configfs_attribute simple_children_attr_description = {
	295	.ca_owner = THIS_MODULE,
	296	.ca_name = "description",
	297	.ca_mode = S_IRUGO,
	298	};
	299
	300	static struct configfs_attribute *simple_children_attrs[] = {
	301	&simple_children_attr_description,
	302	NULL,
	303	};
	304
	305	static ssize_t simple_children_attr_show(struct config_item *item,
ecb3d28c JB	306	struct configfs_attribute *attr,
ecb3d28c JB	307	char *page)
7063fbf2 JB	308	{
	309	return sprintf(page,
	310	"[02-simple-children]\n"
	311	"\n"
	312	"This subsystem allows the creation of child config_items. These\n"
	313	"items have only one attribute that is readable and writeable.\n");
	314	}
	315
22dd0e88 JB	316	static void simple_children_release(struct config_item *item)
	317	{
	318	kfree(to_simple_children(item));
	319	}
	320
7063fbf2	321	static struct configfs_item_operations simple_children_item_ops = {
ecb3d28c	322	.release = simple_children_release,
7063fbf2 JB	323	.show_attribute = simple_children_attr_show,
	324	};
	325
	326	/*
	327	* Note that, since no extra work is required on ->drop_item(),
	328	* no ->drop_item() is provided.
	329	*/
	330	static struct configfs_group_operations simple_children_group_ops = {
	331	.make_item = simple_children_make_item,
	332	};
	333
	334	static struct config_item_type simple_children_type = {
	335	.ct_item_ops = &simple_children_item_ops,
	336	.ct_group_ops = &simple_children_group_ops,
	337	.ct_attrs = simple_children_attrs,
3d0f89bb	338	.ct_owner = THIS_MODULE,
7063fbf2 JB	339	};
	340
	341	static struct configfs_subsystem simple_children_subsys = {
	342	.su_group = {
	343	.cg_item = {
	344	.ci_namebuf = "02-simple-children",
	345	.ci_type = &simple_children_type,
	346	},
	347	},
	348	};
	349
	350
	351	/* ----------------------------------------------------------------- */
	352
	353	/*
	354	* 03-group-children
	355	*
	356	* This example reuses the simple_children group from above. However,
	357	* the simple_children group is not the subsystem itself, it is a
	358	* child of the subsystem. Creation of a group in the subsystem creates
	359	* a new simple_children group. That group can then have simple_child
	360	* children of its own.
	361	*/
	362
f89ab861	363	static struct config_group group_children_make_group(struct config_group group, const char *name)
7063fbf2 JB	364	{
	365	struct simple_children *simple_children;
	366
dd00cc48	367	simple_children = kzalloc(sizeof(struct simple_children),
7063fbf2 JB	368	GFP_KERNEL);
7063fbf2 JB	369	if (!simple_children)
a6795e9e	370	return ERR_PTR(-ENOMEM);
7063fbf2	371
7063fbf2 JB	372	config_group_init_type_name(&simple_children->group, name,
	373	&simple_children_type);
	374
f89ab861	375	return &simple_children->group;
7063fbf2 JB	376	}
	377
	378	static struct configfs_attribute group_children_attr_description = {
	379	.ca_owner = THIS_MODULE,
	380	.ca_name = "description",
	381	.ca_mode = S_IRUGO,
	382	};
	383
	384	static struct configfs_attribute *group_children_attrs[] = {
	385	&group_children_attr_description,
	386	NULL,
	387	};
	388
	389	static ssize_t group_children_attr_show(struct config_item *item,
ecb3d28c JB	390	struct configfs_attribute *attr,
ecb3d28c JB	391	char *page)
7063fbf2 JB	392	{
	393	return sprintf(page,
	394	"[03-group-children]\n"
	395	"\n"
	396	"This subsystem allows the creation of child config_groups. These\n"
	397	"groups are like the subsystem simple-children.\n");
	398	}
	399
	400	static struct configfs_item_operations group_children_item_ops = {
	401	.show_attribute = group_children_attr_show,
	402	};
	403
	404	/*
	405	* Note that, since no extra work is required on ->drop_item(),
	406	* no ->drop_item() is provided.
	407	*/
	408	static struct configfs_group_operations group_children_group_ops = {
	409	.make_group = group_children_make_group,
	410	};
	411
	412	static struct config_item_type group_children_type = {
	413	.ct_item_ops = &group_children_item_ops,
	414	.ct_group_ops = &group_children_group_ops,
	415	.ct_attrs = group_children_attrs,
3d0f89bb	416	.ct_owner = THIS_MODULE,
7063fbf2 JB	417	};
	418
	419	static struct configfs_subsystem group_children_subsys = {
	420	.su_group = {
	421	.cg_item = {
	422	.ci_namebuf = "03-group-children",
	423	.ci_type = &group_children_type,
	424	},
	425	},
	426	};
	427
	428	/* ----------------------------------------------------------------- */
	429
	430	/*
	431	* We're now done with our subsystem definitions.
	432	* For convenience in this module, here's a list of them all. It
	433	* allows the init function to easily register them. Most modules
	434	* will only have one subsystem, and will only call register_subsystem
	435	* on it directly.
	436	*/
	437	static struct configfs_subsystem *example_subsys[] = {
	438	&childless_subsys.subsys,
	439	&simple_children_subsys,
	440	&group_children_subsys,
	441	NULL,
	442	};
	443
	444	static int __init configfs_example_init(void)
	445	{
	446	int ret;
	447	int i;
	448	struct configfs_subsystem *subsys;
	449
	450	for (i = 0; example_subsys[i]; i++) {
	451	subsys = example_subsys[i];
	452
	453	config_group_init(&subsys->su_group);
e6bd07ae	454	mutex_init(&subsys->su_mutex);
7063fbf2 JB	455	ret = configfs_register_subsystem(subsys);
	456	if (ret) {
	457	printk(KERN_ERR "Error %d while registering subsystem %s\n",
	458	ret,
	459	subsys->su_group.cg_item.ci_namebuf);
	460	goto out_unregister;
	461	}
	462	}
	463
	464	return 0;
	465
	466	out_unregister:
	467	for (; i >= 0; i--) {
	468	configfs_unregister_subsystem(example_subsys[i]);
	469	}
	470
	471	return ret;
	472	}
	473
	474	static void __exit configfs_example_exit(void)
	475	{
	476	int i;
	477
	478	for (i = 0; example_subsys[i]; i++) {
	479	configfs_unregister_subsystem(example_subsys[i]);
	480	}
	481	}
	482
	483	module_init(configfs_example_init);
	484	module_exit(configfs_example_exit);
	485	MODULE_LICENSE("GPL");