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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
 /*
  * class.c - basic device class management
  *
  * Copyright (c) 2002-3 Patrick Mochel
  * Copyright (c) 2002-3 Open Source Development Labs
  * Copyright (c) 2003-2004 Greg Kroah-Hartman
  * Copyright (c) 2003-2004 IBM Corp.
  */
 
 #include <linux/device/class.h>
 #include <linux/device.h>
 #include <linux/module.h>
 #include <linux/init.h>
 #include <linux/string.h>
 #include <linux/kdev_t.h>
 #include <linux/err.h>
 #include <linux/slab.h>
 #include <linux/blkdev.h>
 #include <linux/mutex.h>
 #include "base.h"
 
 #define to_class_attr(_attr) container_of(_attr, struct class_attribute, attr)
 
 static ssize_t class_attr_show(struct kobject *kobj, struct attribute *attr,
                    char *buf)
 {
     struct class_attribute *class_attr = to_class_attr(attr);
     struct subsys_private *cp = to_subsys_private(kobj);
     ssize_t ret = -EIO;
 
     if (class_attr->show)
         ret = class_attr->show(cp->class, class_attr, buf);
     return ret;
 }
 
 static ssize_t class_attr_store(struct kobject *kobj, struct attribute *attr,
                 const char *buf, size_t count)
 {
     struct class_attribute *class_attr = to_class_attr(attr);
     struct subsys_private *cp = to_subsys_private(kobj);
     ssize_t ret = -EIO;
 
     if (class_attr->store)
         ret = class_attr->store(cp->class, class_attr, buf, count);
     return ret;
 }
 
 static void class_release(struct kobject *kobj)
 {
     struct subsys_private *cp = to_subsys_private(kobj);
     struct class *class = cp->class;
 
     pr_debug("class '%s': release.\n", class->name);
 
     if (class->class_release)
         class->class_release(class);
     else
         pr_debug("class '%s' does not have a release() function, "
              "be careful\n", class->name);
 
     kfree(cp);
 }
 
 static const struct kobj_ns_type_operations *class_child_ns_type(struct kobject *kobj)
 {
     struct subsys_private *cp = to_subsys_private(kobj);
     struct class *class = cp->class;
 
     return class->ns_type;
 }
 
 static const struct sysfs_ops class_sysfs_ops = {
     .show      = class_attr_show,
     .store     = class_attr_store,
 };
 
 static struct kobj_type class_ktype = {
     .sysfs_ops  = &class_sysfs_ops,
     .release    = class_release,
     .child_ns_type  = class_child_ns_type,
 };
 
 /* Hotplug events for classes go to the class subsys */
 static struct kset *class_kset;
 
 
 int class_create_file_ns(struct class *cls, const struct class_attribute *attr,
              const void *ns)
 {
     int error;
 
     if (cls)
         error = sysfs_create_file_ns(&cls->p->subsys.kobj,
                          &attr->attr, ns);
     else
         error = -EINVAL;
     return error;
 }
 
 void class_remove_file_ns(struct class *cls, const struct class_attribute *attr,
               const void *ns)
 {
     if (cls)
         sysfs_remove_file_ns(&cls->p->subsys.kobj, &attr->attr, ns);
 }
 
 static struct class *class_get(struct class *cls)
 {
     if (cls)
         kset_get(&cls->p->subsys);
     return cls;
 }
 
 static void class_put(struct class *cls)
 {
     if (cls)
         kset_put(&cls->p->subsys);
 }
 
 static struct device *klist_class_to_dev(struct klist_node *n)
 {
     struct device_private *p = to_device_private_class(n);
     return p->device;
 }
 
 static void klist_class_dev_get(struct klist_node *n)
 {
     struct device *dev = klist_class_to_dev(n);
 
     get_device(dev);
 }
 
 static void klist_class_dev_put(struct klist_node *n)
 {
     struct device *dev = klist_class_to_dev(n);
 
     put_device(dev);
 }
 
 static int class_add_groups(struct class *cls,
                 const struct attribute_group **groups)
 {
     return sysfs_create_groups(&cls->p->subsys.kobj, groups);
 }
 
 static void class_remove_groups(struct class *cls,
                 const struct attribute_group **groups)
 {
     return sysfs_remove_groups(&cls->p->subsys.kobj, groups);
 }
 
 int __class_register(struct class *cls, struct lock_class_key *key)
 {
     struct subsys_private *cp;
     int error;
 
     pr_debug("device class '%s': registering\n", cls->name);
 
     cp = kzalloc(sizeof(*cp), GFP_KERNEL);
     if (!cp)
         return -ENOMEM;
     klist_init(&cp->klist_devices, klist_class_dev_get, klist_class_dev_put);
     INIT_LIST_HEAD(&cp->interfaces);
     kset_init(&cp->glue_dirs);
     __mutex_init(&cp->mutex, "subsys mutex", key);
     error = kobject_set_name(&cp->subsys.kobj, "%s", cls->name);
     if (error) {
         kfree(cp);
         return error;
     }
 
     /* set the default /sys/dev directory for devices of this class */
     if (!cls->dev_kobj)
         cls->dev_kobj = sysfs_dev_char_kobj;
 
 #if defined(CONFIG_BLOCK)
     /* let the block class directory show up in the root of sysfs */
     if (!sysfs_deprecated || cls != &block_class)
         cp->subsys.kobj.kset = class_kset;
 #else
     cp->subsys.kobj.kset = class_kset;
 #endif
     cp->subsys.kobj.ktype = &class_ktype;
     cp->class = cls;
     cls->p = cp;
 
     error = kset_register(&cp->subsys);
     if (error) {
         kfree(cp);
         return error;
     }
     error = class_add_groups(class_get(cls), cls->class_groups);
     class_put(cls);
     return error;
 }
 EXPORT_SYMBOL_GPL(__class_register);
 
 void class_unregister(struct class *cls)
 {
     pr_debug("device class '%s': unregistering\n", cls->name);
     class_remove_groups(cls, cls->class_groups);
     kset_unregister(&cls->p->subsys);
 }
 
 static void class_create_release(struct class *cls)
 {
     pr_debug("%s called for %s\n", __func__, cls->name);
     kfree(cls);
 }
 
 /**
  * __class_create - create a struct class structure
  * @owner: pointer to the module that is to "own" this struct class
  * @name: pointer to a string for the name of this class.
  * @key: the lock_class_key for this class; used by mutex lock debugging
  *
  * This is used to create a struct class pointer that can then be used
  * in calls to device_create().
  *
  * Returns &struct class pointer on success, or ERR_PTR() on error.
  *
  * Note, the pointer created here is to be destroyed when finished by
  * making a call to class_destroy().
  */
 struct class *__class_create(struct module *owner, const char *name,
                  struct lock_class_key *key)
 {
     struct class *cls;
     int retval;
 
     cls = kzalloc(sizeof(*cls), GFP_KERNEL);
     if (!cls) {
         retval = -ENOMEM;
         goto error;
     }
 
     cls->name = name;
     cls->owner = owner;
     cls->class_release = class_create_release;
 
     retval = __class_register(cls, key);
     if (retval)
         goto error;
 
     return cls;
 
 error:
     kfree(cls);
     return ERR_PTR(retval);
 }
 EXPORT_SYMBOL_GPL(__class_create);
 
 /**
  * class_destroy - destroys a struct class structure
  * @cls: pointer to the struct class that is to be destroyed
  *
  * Note, the pointer to be destroyed must have been created with a call
  * to class_create().
  */
 void class_destroy(struct class *cls)
 {
     if ((cls == NULL) || (IS_ERR(cls)))
         return;
 
     class_unregister(cls);
 }
 
 /**
  * class_dev_iter_init - initialize class device iterator
  * @iter: class iterator to initialize
  * @class: the class we wanna iterate over
  * @start: the device to start iterating from, if any
  * @type: device_type of the devices to iterate over, NULL for all
  *
  * Initialize class iterator @iter such that it iterates over devices
  * of @class.  If @start is set, the list iteration will start there,
  * otherwise if it is NULL, the iteration starts at the beginning of
  * the list.
  */
 void class_dev_iter_init(struct class_dev_iter *iter, struct class *class,
              struct device *start, const struct device_type *type)
 {
     struct klist_node *start_knode = NULL;
 
     if (start)
         start_knode = &start->p->knode_class;
     klist_iter_init_node(&class->p->klist_devices, &iter->ki, start_knode);
     iter->type = type;
 }
 EXPORT_SYMBOL_GPL(class_dev_iter_init);
 
 /**
  * class_dev_iter_next - iterate to the next device
  * @iter: class iterator to proceed
  *
  * Proceed @iter to the next device and return it.  Returns NULL if
  * iteration is complete.
  *
  * The returned device is referenced and won't be released till
  * iterator is proceed to the next device or exited.  The caller is
  * free to do whatever it wants to do with the device including
  * calling back into class code.
  */
 struct device *class_dev_iter_next(struct class_dev_iter *iter)
 {
     struct klist_node *knode;
     struct device *dev;
 
     while (1) {
         knode = klist_next(&iter->ki);
         if (!knode)
             return NULL;
         dev = klist_class_to_dev(knode);
         if (!iter->type || iter->type == dev->type)
             return dev;
     }
 }
 EXPORT_SYMBOL_GPL(class_dev_iter_next);
 
 /**
  * class_dev_iter_exit - finish iteration
  * @iter: class iterator to finish
  *
  * Finish an iteration.  Always call this function after iteration is
  * complete whether the iteration ran till the end or not.
  */
 void class_dev_iter_exit(struct class_dev_iter *iter)
 {
     klist_iter_exit(&iter->ki);
 }
 EXPORT_SYMBOL_GPL(class_dev_iter_exit);
 
 /**
  * class_for_each_device - device iterator
  * @class: the class we're iterating
  * @start: the device to start with in the list, if any.
  * @data: data for the callback
  * @fn: function to be called for each device
  *
  * Iterate over @class's list of devices, and call @fn for each,
  * passing it @data.  If @start is set, the list iteration will start
  * there, otherwise if it is NULL, the iteration starts at the
  * beginning of the list.
  *
  * We check the return of @fn each time. If it returns anything
  * other than 0, we break out and return that value.
  *
  * @fn is allowed to do anything including calling back into class
  * code.  There's no locking restriction.
  */
 int class_for_each_device(struct class *class, struct device *start,
               void *data, int (*fn)(struct device *, void *))
 {
     struct class_dev_iter iter;
     struct device *dev;
     int error = 0;
 
     if (!class)
         return -EINVAL;
     if (!class->p) {
         WARN(1, "%s called for class '%s' before it was initialized",
              __func__, class->name);
         return -EINVAL;
     }
 
     class_dev_iter_init(&iter, class, start, NULL);
     while ((dev = class_dev_iter_next(&iter))) {
         error = fn(dev, data);
         if (error)
             break;
     }
     class_dev_iter_exit(&iter);
 
     return error;
 }
 EXPORT_SYMBOL_GPL(class_for_each_device);
 
 /**
  * class_find_device - device iterator for locating a particular device
  * @class: the class we're iterating
  * @start: Device to begin with
  * @data: data for the match function
  * @match: function to check device
  *
  * This is similar to the class_for_each_dev() function above, but it
  * returns a reference to a device that is 'found' for later use, as
  * determined by the @match callback.
  *
  * The callback should return 0 if the device doesn't match and non-zero
  * if it does.  If the callback returns non-zero, this function will
  * return to the caller and not iterate over any more devices.
  *
  * Note, you will need to drop the reference with put_device() after use.
  *
  * @match is allowed to do anything including calling back into class
  * code.  There's no locking restriction.
  */
 struct device *class_find_device(struct class *class, struct device *start,
                  const void *data,
                  int (*match)(struct device *, const void *))
 {
     struct class_dev_iter iter;
     struct device *dev;
 
     if (!class)
         return NULL;
     if (!class->p) {
         WARN(1, "%s called for class '%s' before it was initialized",
              __func__, class->name);
         return NULL;
     }
 
     class_dev_iter_init(&iter, class, start, NULL);
     while ((dev = class_dev_iter_next(&iter))) {
         if (match(dev, data)) {
             get_device(dev);
             break;
         }
     }
     class_dev_iter_exit(&iter);
 
     return dev;
 }
 EXPORT_SYMBOL_GPL(class_find_device);
 
 int class_interface_register(struct class_interface *class_intf)
 {
     struct class *parent;
     struct class_dev_iter iter;
     struct device *dev;
 
     if (!class_intf || !class_intf->class)
         return -ENODEV;
 
     parent = class_get(class_intf->class);
     if (!parent)
         return -EINVAL;
 
     mutex_lock(&parent->p->mutex);
     list_add_tail(&class_intf->node, &parent->p->interfaces);
     if (class_intf->add_dev) {
         class_dev_iter_init(&iter, parent, NULL, NULL);
         while ((dev = class_dev_iter_next(&iter)))
             class_intf->add_dev(dev, class_intf);
         class_dev_iter_exit(&iter);
     }
     mutex_unlock(&parent->p->mutex);
 
     return 0;
 }
 
 void class_interface_unregister(struct class_interface *class_intf)
 {
     struct class *parent = class_intf->class;
     struct class_dev_iter iter;
     struct device *dev;
 
     if (!parent)
         return;
 
     mutex_lock(&parent->p->mutex);
     list_del_init(&class_intf->node);
     if (class_intf->remove_dev) {
         class_dev_iter_init(&iter, parent, NULL, NULL);
         while ((dev = class_dev_iter_next(&iter)))
             class_intf->remove_dev(dev, class_intf);
         class_dev_iter_exit(&iter);
     }
     mutex_unlock(&parent->p->mutex);
 
     class_put(parent);
 }
 
 ssize_t show_class_attr_string(struct class *class,
                    struct class_attribute *attr, char *buf)
 {
     struct class_attribute_string *cs;
 
     cs = container_of(attr, struct class_attribute_string, attr);
     return sysfs_emit(buf, "%s\n", cs->str);
 }
 
 EXPORT_SYMBOL_GPL(show_class_attr_string);
 
 struct class_compat {
     struct kobject *kobj;
 };
 
 /**
  * class_compat_register - register a compatibility class
  * @name: the name of the class
  *
  * Compatibility class are meant as a temporary user-space compatibility
  * workaround when converting a family of class devices to a bus devices.
  */
 struct class_compat *class_compat_register(const char *name)
 {
     struct class_compat *cls;
 
     cls = kmalloc(sizeof(struct class_compat), GFP_KERNEL);
     if (!cls)
         return NULL;
     cls->kobj = kobject_create_and_add(name, &class_kset->kobj);
     if (!cls->kobj) {
         kfree(cls);
         return NULL;
     }
     return cls;
 }
 EXPORT_SYMBOL_GPL(class_compat_register);
 
 /**
  * class_compat_unregister - unregister a compatibility class
  * @cls: the class to unregister
  */
 void class_compat_unregister(struct class_compat *cls)
 {
     kobject_put(cls->kobj);
     kfree(cls);
 }
 EXPORT_SYMBOL_GPL(class_compat_unregister);
 
 /**
  * class_compat_create_link - create a compatibility class device link to
  *                a bus device
  * @cls: the compatibility class
  * @dev: the target bus device
  * @device_link: an optional device to which a "device" link should be created
  */
 int class_compat_create_link(struct class_compat *cls, struct device *dev,
                  struct device *device_link)
 {
     int error;
 
     error = sysfs_create_link(cls->kobj, &dev->kobj, dev_name(dev));
     if (error)
         return error;
 
     /*
      * Optionally add a "device" link (typically to the parent), as a
      * class device would have one and we want to provide as much
      * backwards compatibility as possible.
      */
     if (device_link) {
         error = sysfs_create_link(&dev->kobj, &device_link->kobj,
                       "device");
         if (error)
             sysfs_remove_link(cls->kobj, dev_name(dev));
     }
 
     return error;
 }
 EXPORT_SYMBOL_GPL(class_compat_create_link);
 
 /**
  * class_compat_remove_link - remove a compatibility class device link to
  *                a bus device
  * @cls: the compatibility class
  * @dev: the target bus device
  * @device_link: an optional device to which a "device" link was previously
  *       created
  */
 void class_compat_remove_link(struct class_compat *cls, struct device *dev,
                   struct device *device_link)
 {
     if (device_link)
         sysfs_remove_link(&dev->kobj, "device");
     sysfs_remove_link(cls->kobj, dev_name(dev));
 }
 EXPORT_SYMBOL_GPL(class_compat_remove_link);
 
 int __init classes_init(void)
 {
     class_kset = kset_create_and_add("class", NULL, NULL);
     if (!class_kset)
         return -ENOMEM;
     return 0;
 }
 
 EXPORT_SYMBOL_GPL(class_create_file_ns);
 EXPORT_SYMBOL_GPL(class_remove_file_ns);
 EXPORT_SYMBOL_GPL(class_unregister);
 EXPORT_SYMBOL_GPL(class_destroy);
 
 EXPORT_SYMBOL_GPL(class_interface_register);
 EXPORT_SYMBOL_GPL(class_interface_unregister);

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