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	Version: linux-6.0.1 spark-3.0.0 hadoop-3.2.0-src hadoop-3.3.0-src spark-2.4.7 linux-4.15.13 hadoop-2.7.4-src Revert   Change

 // SPDX-License-Identifier: GPL-2.0-or-later
 /*
  * 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
  *
  * 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/kernel.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 container_of(to_configfs_subsystem(to_config_group(item)),
                 struct childless, subsys);
 }
 
 static ssize_t childless_showme_show(struct config_item *item, char *page)
 {
     struct childless *childless = to_childless(item);
     ssize_t pos;
 
     pos = sprintf(page, "%d\n", childless->showme);
     childless->showme++;
 
     return pos;
 }
 
 static ssize_t childless_storeme_show(struct config_item *item, char *page)
 {
     return sprintf(page, "%d\n", to_childless(item)->storeme);
 }
 
 static ssize_t childless_storeme_store(struct config_item *item,
         const char *page, size_t count)
 {
     struct childless *childless = to_childless(item);
     int ret;
 
     ret = kstrtoint(page, 10, &childless->storeme);
     if (ret)
         return ret;
 
     return count;
 }
 
 static ssize_t childless_description_show(struct config_item *item, 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");
 }
 
 CONFIGFS_ATTR_RO(childless_, showme);
 CONFIGFS_ATTR(childless_, storeme);
 CONFIGFS_ATTR_RO(childless_, description);
 
 static struct configfs_attribute *childless_attrs[] = {
     &childless_attr_showme,
     &childless_attr_storeme,
     &childless_attr_description,
     NULL,
 };
 
 static const struct config_item_type childless_type = {
     .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 container_of(item, struct simple_child, item);
 }
 
 static ssize_t simple_child_storeme_show(struct config_item *item, char *page)
 {
     return sprintf(page, "%d\n", to_simple_child(item)->storeme);
 }
 
 static ssize_t simple_child_storeme_store(struct config_item *item,
         const char *page, size_t count)
 {
     struct simple_child *simple_child = to_simple_child(item);
     int ret;
 
     ret = kstrtoint(page, 10, &simple_child->storeme);
     if (ret)
         return ret;
 
     return count;
 }
 
 CONFIGFS_ATTR(simple_child_, storeme);
 
 static struct configfs_attribute *simple_child_attrs[] = {
     &simple_child_attr_storeme,
     NULL,
 };
 
 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,
 };
 
 static const 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 container_of(to_config_group(item),
                 struct simple_children, group);
 }
 
 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);
 
     return &simple_child->item;
 }
 
 static ssize_t simple_children_description_show(struct config_item *item,
         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");
 }
 
 CONFIGFS_ATTR_RO(simple_children_, description);
 
 static struct configfs_attribute *simple_children_attrs[] = {
     &simple_children_attr_description,
     NULL,
 };
 
 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,
 };
 
 /*
  * 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 const 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 ssize_t group_children_description_show(struct config_item *item,
         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");
 }
 
 CONFIGFS_ATTR_RO(group_children_, description);
 
 static struct configfs_attribute *group_children_attrs[] = {
     &group_children_attr_description,
     NULL,
 };
 
 /*
  * 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 const struct config_item_type group_children_type = {
     .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)
 {
     struct configfs_subsystem *subsys;
     int ret, i;
 
     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) {
             pr_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--; 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");

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