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[PATCH] configfs: Convenience macros for attribute definition.

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Sysfs has the _ATTR() and _ATTR_RO() macros to make defining extended
form attributes easier.  configfs should have something similiar.

- _CONFIGFS_ATTR() and _CONFIGFS_ATTR_RO() are the counterparts to the
  sysfs macros.
- CONFIGFS_ATTR_STRUCT() creates the extended form attribute structure.
- CONFIGFS_ATTR_OPS() defines the show_attribute()/store_attribute()
  operations that call the show()/store() operations of the extended
  form configfs_attributes.

Signed-off-by: Joel Becker <joel.becker@oracle.com>
Signed-off-by: Mark Fasheh <mfasheh@suse.com>
This commit is contained in:
Joel Becker 2008-06-18 19:29:05 -07:00 committed by Mark Fasheh
parent 70526b6744
commit ecb3d28c7e
4 changed files with 536 additions and 14 deletions
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17
Documentation/filesystems/configfs/configfs.txt
View file

@ -311,9 +311,20 @@ the subsystem must be ready for it.
[An Example]
The best example of these basic concepts is the simple_children
subsystem/group and the simple_child item in configfs_example.c It
shows a trivial object displaying and storing an attribute, and a simple
group creating and destroying these children.
subsystem/group and the simple_child item in configfs_example_explicit.c
and configfs_example_macros.c. It shows a trivial object displaying and
storing an attribute, and a simple group creating and destroying these
children.
The only difference between configfs_example_explicit.c and
configfs_example_macros.c is how the attributes of the childless item
are defined. The childless item has extended attributes, each with
their own show()/store() operation. This follows a convention commonly
used in sysfs. configfs_example_explicit.c creates these attributes
by explicitly defining the structures involved. Conversely
configfs_example_macros.c uses some convenience macros from configfs.h
to define the attributes. These macros are similar to their sysfs
counterparts.
[Hierarchy Navigation and the Subsystem Mutex]

18
Documentation/filesystems/configfs/configfs_example.c → Documentation/filesystems/configfs/configfs_example_explicit.c
View file

@ -1,8 +1,10 @@
/*
* vim: noexpandtab ts=8 sts=0 sw=8:
*
* configfs_example.c - This file is a demonstration module containing
* a number of configfs subsystems.
* 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
@ -281,7 +283,6 @@ static struct config_item *simple_children_make_item(struct config_group *group,
if (!simple_child)
return ERR_PTR(-ENOMEM);
config_item_init_type_name(&simple_child->item, name,
&simple_child_type);
@ -302,8 +303,8 @@ static struct configfs_attribute *simple_children_attrs[] = {
};
static ssize_t simple_children_attr_show(struct config_item *item,
struct configfs_attribute *attr,
char *page)
struct configfs_attribute *attr,
char *page)
{
return sprintf(page,
"[02-simple-children]\n"
@ -318,7 +319,7 @@ static void simple_children_release(struct config_item *item)
}
static struct configfs_item_operations simple_children_item_ops = {
.release = simple_children_release,
.release = simple_children_release,
.show_attribute = simple_children_attr_show,
};
@ -368,7 +369,6 @@ static struct config_group *group_children_make_group(struct config_group *group
if (!simple_children)
return ERR_PTR(-ENOMEM);
config_group_init_type_name(&simple_children->group, name,
&simple_children_type);
@ -387,8 +387,8 @@ static struct configfs_attribute *group_children_attrs[] = {
};
static ssize_t group_children_attr_show(struct config_item *item,
struct configfs_attribute *attr,
char *page)
struct configfs_attribute *attr,
char *page)
{
return sprintf(page,
"[03-group-children]\n"

448
Documentation/filesystems/configfs/configfs_example_macros.c Normal file
View file

@ -0,0 +1,448 @@
/*
* vim: noexpandtab ts=8 sts=0 sw=8:
*
* configfs_example_macros.c - This file is a demonstration module
* containing a number of configfs subsystems. It uses the helper
* macros defined by 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;
};
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;
}
CONFIGFS_ATTR_STRUCT(childless);
#define CHILDLESS_ATTR(_name, _mode, _show, _store) \
struct childless_attribute childless_attr_##_name = __CONFIGFS_ATTR(_name, _mode, _show, _store)
#define CHILDLESS_ATTR_RO(_name, _show) \
struct childless_attribute childless_attr_##_name = __CONFIGFS_ATTR_RO(_name, _show);
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");
}
CHILDLESS_ATTR_RO(showme, childless_showme_read);
CHILDLESS_ATTR(storeme, S_IRUGO | S_IWUSR, childless_storeme_read,
childless_storeme_write);
CHILDLESS_ATTR_RO(description, childless_description_read);
static struct configfs_attribute *childless_attrs[] = {
&childless_attr_showme.attr,
&childless_attr_storeme.attr,
&childless_attr_description.attr,
NULL,
};
CONFIGFS_ATTR_OPS(childless);
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");

67
include/linux/configfs.h
View file

@ -130,8 +130,25 @@ struct configfs_attribute {
/*
* Users often need to create attribute structures for their configurable
* attributes, containing a configfs_attribute member and function pointers
* for the show() and store() operations on that attribute. They can use
* this macro (similar to sysfs' __ATTR) to make defining attributes easier.
* for the show() and store() operations on that attribute. If they don't
* need anything else on the extended attribute structure, they can use
* this macro to define it The argument _item is the name of the
* config_item structure.
*/
#define CONFIGFS_ATTR_STRUCT(_item) \
struct _item##_attribute { \
struct configfs_attribute attr; \
ssize_t (*show)(struct _item *, char *); \
ssize_t (*store)(struct _item *, const char *, size_t); \
}
/*
* With the extended attribute structure, users can use this macro
* (similar to sysfs' __ATTR) to make defining attributes easier.
* An example:
* #define MYITEM_ATTR(_name, _mode, _show, _store) \
* struct myitem_attribute childless_attr_##_name = \
* __CONFIGFS_ATTR(_name, _mode, _show, _store)
*/
#define __CONFIGFS_ATTR(_name, _mode, _show, _store) \
{ \
@ -143,6 +160,52 @@ struct configfs_attribute {
.show = _show, \
.store = _store, \
}
/* Here is a readonly version, only requiring a show() operation */
#define __CONFIGFS_ATTR_RO(_name, _show) \
{ \
.attr = { \
.ca_name = __stringify(_name), \
.ca_mode = 0444, \
.ca_owner = THIS_MODULE, \
}, \
.show = _show, \
}
/*
* With these extended attributes, the simple show_attribute() and
* store_attribute() operations need to call the show() and store() of the
* attributes. This is a common pattern, so we provide a macro to define
* them. The argument _item is the name of the config_item structure.
* This macro expects the attributes to be named "struct <name>_attribute"
* and the function to_<name>() to exist;
*/
#define CONFIGFS_ATTR_OPS(_item) \
static ssize_t _item##_attr_show(struct config_item *item, \
struct configfs_attribute *attr, \
char *page) \
{ \
struct _item *_item = to_##_item(item); \
struct _item##_attribute *_item##_attr = \
container_of(attr, struct _item##_attribute, attr); \
ssize_t ret = 0; \
\
if (_item##_attr->show) \
ret = _item##_attr->show(_item, page); \
return ret; \
} \
static ssize_t _item##_attr_store(struct config_item *item, \
struct configfs_attribute *attr, \
const char *page, size_t count) \
{ \
struct _item *_item = to_##_item(item); \
struct _item##_attribute *_item##_attr = \
container_of(attr, struct _item##_attribute, attr); \
ssize_t ret = -EINVAL; \
\
if (_item##_attr->store) \
ret = _item##_attr->store(_item, page, count); \
return ret; \
}
/*
* If allow_link() exists, the item can symlink(2) out to other