[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]
+++ /dev/null
-/*
- * vim: noexpandtab ts=8 sts=0 sw=8:
- *
- * configfs_example.c - This file is a demonstration module containing
- * a number of configfs subsystems.
- *
- * 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");
--- /dev/null
+/*
+ * 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");
--- /dev/null
+/*
+ * 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");
/*
* 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) \
{ \
.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
projects / GitHub / LineageOS / android_kernel_motorola_exynos9610.git / commitdiff