drivers/vfio/mdev/mdev_core.c - linux/kernel/git/gregkh/usb - Git at Google

 // SPDX-License-Identifier: GPL-2.0-only
 /*
  * Mediated device Core Driver
  *
  * Copyright (c) 2016, NVIDIA CORPORATION. All rights reserved.
  *     Author: Neo Jia <cjia@nvidia.com>
  *             Kirti Wankhede <kwankhede@nvidia.com>
  */

 #include <linux/module.h>
 #include <linux/slab.h>
 #include <linux/sysfs.h>
 #include <linux/mdev.h>

 #include "mdev_private.h"

 #define DRIVER_VERSION		"0.1"
 #define DRIVER_AUTHOR		"NVIDIA Corporation"
 #define DRIVER_DESC		"Mediated device Core Driver"

 static struct class_compat *mdev_bus_compat_class;

 static LIST_HEAD(mdev_list);
 static DEFINE_MUTEX(mdev_list_lock);

 /* Caller must hold parent unreg_sem read or write lock */
 static void mdev_device_remove_common(struct mdev_device *mdev)
 {
 	struct mdev_parent *parent = mdev->type->parent;

 	mdev_remove_sysfs_files(mdev);
 	device_del(&mdev->dev);
 	lockdep_assert_held(&parent->unreg_sem);
 	/* Balances with device_initialize() */
 	put_device(&mdev->dev);
 }

 static int mdev_device_remove_cb(struct device *dev, void *data)
 {
 	if (dev->bus == &mdev_bus_type)
 		mdev_device_remove_common(to_mdev_device(dev));
 	return 0;
 }

 /*
  * mdev_register_parent: Register a device as parent for mdevs
  * @parent: parent structure registered
  * @dev: device structure representing parent device.
  * @mdev_driver: Device driver to bind to the newly created mdev
  * @types: Array of supported mdev types
  * @nr_types: Number of entries in @types
  *
  * Registers the @parent stucture as a parent for mdev types and thus mdev
  * devices.  The caller needs to hold a reference on @dev that must not be
  * released until after the call to mdev_unregister_parent().
  *
  * Returns a negative value on error, otherwise 0.
  */
 int mdev_register_parent(struct mdev_parent *parent, struct device *dev,
 		struct mdev_driver *mdev_driver, struct mdev_type **types,
 		unsigned int nr_types)
 {
 	char *env_string = "MDEV_STATE=registered";
 	char *envp[] = { env_string, NULL };
 	int ret;

 	memset(parent, 0, sizeof(*parent));
 	init_rwsem(&parent->unreg_sem);
 	parent->dev = dev;
 	parent->mdev_driver = mdev_driver;
 	parent->types = types;
 	parent->nr_types = nr_types;
 	atomic_set(&parent->available_instances, mdev_driver->max_instances);

 	ret = parent_create_sysfs_files(parent);
 	if (ret)
 		return ret;

 	ret = class_compat_create_link(mdev_bus_compat_class, dev, NULL);
 	if (ret)
 		dev_warn(dev, "Failed to create compatibility class link\n");

 	dev_info(dev, "MDEV: Registered\n");
 	kobject_uevent_env(&dev->kobj, KOBJ_CHANGE, envp);
 	return 0;
 }
 EXPORT_SYMBOL(mdev_register_parent);

 /*
  * mdev_unregister_parent : Unregister a parent device
  * @parent: parent structure to unregister
  */
 void mdev_unregister_parent(struct mdev_parent *parent)
 {
 	char *env_string = "MDEV_STATE=unregistered";
 	char *envp[] = { env_string, NULL };

 	dev_info(parent->dev, "MDEV: Unregistering\n");

 	down_write(&parent->unreg_sem);
 	class_compat_remove_link(mdev_bus_compat_class, parent->dev, NULL);
 	device_for_each_child(parent->dev, NULL, mdev_device_remove_cb);
 	parent_remove_sysfs_files(parent);
 	up_write(&parent->unreg_sem);

 	kobject_uevent_env(&parent->dev->kobj, KOBJ_CHANGE, envp);
 }
 EXPORT_SYMBOL(mdev_unregister_parent);

 static void mdev_device_release(struct device *dev)
 {
 	struct mdev_device *mdev = to_mdev_device(dev);
 	struct mdev_parent *parent = mdev->type->parent;

 	mutex_lock(&mdev_list_lock);
 	list_del(&mdev->next);
 	if (!parent->mdev_driver->get_available)
 		atomic_inc(&parent->available_instances);
 	mutex_unlock(&mdev_list_lock);

 	/* Pairs with the get in mdev_device_create() */
 	kobject_put(&mdev->type->kobj);

 	dev_dbg(&mdev->dev, "MDEV: destroying\n");
 	kfree(mdev);
 }

 int mdev_device_create(struct mdev_type *type, const guid_t *uuid)
 {
 	int ret;
 	struct mdev_device *mdev, *tmp;
 	struct mdev_parent *parent = type->parent;
 	struct mdev_driver *drv = parent->mdev_driver;

 	mutex_lock(&mdev_list_lock);

 	/* Check for duplicate */
 	list_for_each_entry(tmp, &mdev_list, next) {
 		if (guid_equal(&tmp->uuid, uuid)) {
 			mutex_unlock(&mdev_list_lock);
 			return -EEXIST;
 		}
 	}

 	if (!drv->get_available) {
 		/*
 		 * Note: that non-atomic read and dec is fine here because
 		 * all modifications are under mdev_list_lock.
 		 */
 		if (!atomic_read(&parent->available_instances)) {
 			mutex_unlock(&mdev_list_lock);
 			return -EUSERS;
 		}
 		atomic_dec(&parent->available_instances);
 	}

 	mdev = kzalloc(sizeof(*mdev), GFP_KERNEL);
 	if (!mdev) {
 		mutex_unlock(&mdev_list_lock);
 		return -ENOMEM;
 	}

 	device_initialize(&mdev->dev);
 	mdev->dev.parent  = parent->dev;
 	mdev->dev.bus = &mdev_bus_type;
 	mdev->dev.release = mdev_device_release;
 	mdev->dev.groups = mdev_device_groups;
 	mdev->type = type;
 	/* Pairs with the put in mdev_device_release() */
 	kobject_get(&type->kobj);

 	guid_copy(&mdev->uuid, uuid);
 	list_add(&mdev->next, &mdev_list);
 	mutex_unlock(&mdev_list_lock);

 	ret = dev_set_name(&mdev->dev, "%pUl", uuid);
 	if (ret)
 		goto out_put_device;

 	/* Check if parent unregistration has started */
 	if (!down_read_trylock(&parent->unreg_sem)) {
 		ret = -ENODEV;
 		goto out_put_device;
 	}

 	ret = device_add(&mdev->dev);
 	if (ret)
 		goto out_unlock;

 	ret = device_driver_attach(&drv->driver, &mdev->dev);
 	if (ret)
 		goto out_del;

 	ret = mdev_create_sysfs_files(mdev);
 	if (ret)
 		goto out_del;

 	mdev->active = true;
 	dev_dbg(&mdev->dev, "MDEV: created\n");
 	up_read(&parent->unreg_sem);

 	return 0;

 out_del:
 	device_del(&mdev->dev);
 out_unlock:
 	up_read(&parent->unreg_sem);
 out_put_device:
 	put_device(&mdev->dev);
 	return ret;
 }

 int mdev_device_remove(struct mdev_device *mdev)
 {
 	struct mdev_device *tmp;
 	struct mdev_parent *parent = mdev->type->parent;

 	mutex_lock(&mdev_list_lock);
 	list_for_each_entry(tmp, &mdev_list, next) {
 		if (tmp == mdev)
 			break;
 	}

 	if (tmp != mdev) {
 		mutex_unlock(&mdev_list_lock);
 		return -ENODEV;
 	}

 	if (!mdev->active) {
 		mutex_unlock(&mdev_list_lock);
 		return -EAGAIN;
 	}

 	mdev->active = false;
 	mutex_unlock(&mdev_list_lock);

 	/* Check if parent unregistration has started */
 	if (!down_read_trylock(&parent->unreg_sem))
 		return -ENODEV;

 	mdev_device_remove_common(mdev);
 	up_read(&parent->unreg_sem);
 	return 0;
 }

 static int __init mdev_init(void)
 {
 	int ret;

 	ret = bus_register(&mdev_bus_type);
 	if (ret)
 		return ret;

 	mdev_bus_compat_class = class_compat_register("mdev_bus");
 	if (!mdev_bus_compat_class) {
 		bus_unregister(&mdev_bus_type);
 		return -ENOMEM;
 	}

 	return 0;
 }

 static void __exit mdev_exit(void)
 {
 	class_compat_unregister(mdev_bus_compat_class);
 	bus_unregister(&mdev_bus_type);
 }

 subsys_initcall(mdev_init)
 module_exit(mdev_exit)

 MODULE_VERSION(DRIVER_VERSION);
 MODULE_LICENSE("GPL v2");
 MODULE_AUTHOR(DRIVER_AUTHOR);
 MODULE_DESCRIPTION(DRIVER_DESC);
	// SPDX-License-Identifier: GPL-2.0-only
	/*
	* Mediated device Core Driver
	*
	* Copyright (c) 2016, NVIDIA CORPORATION. All rights reserved.
	* Author: Neo Jia <cjia@nvidia.com>
	* Kirti Wankhede <kwankhede@nvidia.com>
	*/

	#include <linux/module.h>
	#include <linux/slab.h>
	#include <linux/sysfs.h>
	#include <linux/mdev.h>

	#include "mdev_private.h"

	#define DRIVER_VERSION "0.1"
	#define DRIVER_AUTHOR "NVIDIA Corporation"
	#define DRIVER_DESC "Mediated device Core Driver"

	static struct class_compat *mdev_bus_compat_class;

	static LIST_HEAD(mdev_list);
	static DEFINE_MUTEX(mdev_list_lock);

	/* Caller must hold parent unreg_sem read or write lock */
	static void mdev_device_remove_common(struct mdev_device *mdev)
	{
	struct mdev_parent *parent = mdev->type->parent;

	mdev_remove_sysfs_files(mdev);
	device_del(&mdev->dev);
	lockdep_assert_held(&parent->unreg_sem);
	/* Balances with device_initialize() */
	put_device(&mdev->dev);
	}

	static int mdev_device_remove_cb(struct device dev, void data)
	{
	if (dev->bus == &mdev_bus_type)
	mdev_device_remove_common(to_mdev_device(dev));
	return 0;
	}

	/*
	* mdev_register_parent: Register a device as parent for mdevs
	* @parent: parent structure registered
	* @dev: device structure representing parent device.
	* @mdev_driver: Device driver to bind to the newly created mdev
	* @types: Array of supported mdev types
	* @nr_types: Number of entries in @types
	*
	* Registers the @parent stucture as a parent for mdev types and thus mdev
	* devices. The caller needs to hold a reference on @dev that must not be
	* released until after the call to mdev_unregister_parent().
	*
	* Returns a negative value on error, otherwise 0.
	*/
	int mdev_register_parent(struct mdev_parent parent, struct device dev,
	struct mdev_driver mdev_driver, struct mdev_type *types,
	unsigned int nr_types)
	{
	char *env_string = "MDEV_STATE=registered";
	char *envp[] = { env_string, NULL };
	int ret;

	memset(parent, 0, sizeof(*parent));
	init_rwsem(&parent->unreg_sem);
	parent->dev = dev;
	parent->mdev_driver = mdev_driver;
	parent->types = types;
	parent->nr_types = nr_types;
	atomic_set(&parent->available_instances, mdev_driver->max_instances);

	ret = parent_create_sysfs_files(parent);
	if (ret)
	return ret;

	ret = class_compat_create_link(mdev_bus_compat_class, dev, NULL);
	if (ret)
	dev_warn(dev, "Failed to create compatibility class link\n");

	dev_info(dev, "MDEV: Registered\n");
	kobject_uevent_env(&dev->kobj, KOBJ_CHANGE, envp);
	return 0;
	}
	EXPORT_SYMBOL(mdev_register_parent);

	/*
	* mdev_unregister_parent : Unregister a parent device
	* @parent: parent structure to unregister
	*/
	void mdev_unregister_parent(struct mdev_parent *parent)
	{
	char *env_string = "MDEV_STATE=unregistered";
	char *envp[] = { env_string, NULL };

	dev_info(parent->dev, "MDEV: Unregistering\n");

	down_write(&parent->unreg_sem);
	class_compat_remove_link(mdev_bus_compat_class, parent->dev, NULL);
	device_for_each_child(parent->dev, NULL, mdev_device_remove_cb);
	parent_remove_sysfs_files(parent);
	up_write(&parent->unreg_sem);

	kobject_uevent_env(&parent->dev->kobj, KOBJ_CHANGE, envp);
	}
	EXPORT_SYMBOL(mdev_unregister_parent);

	static void mdev_device_release(struct device *dev)
	{
	struct mdev_device *mdev = to_mdev_device(dev);
	struct mdev_parent *parent = mdev->type->parent;

	mutex_lock(&mdev_list_lock);
	list_del(&mdev->next);
	if (!parent->mdev_driver->get_available)
	atomic_inc(&parent->available_instances);
	mutex_unlock(&mdev_list_lock);

	/* Pairs with the get in mdev_device_create() */
	kobject_put(&mdev->type->kobj);

	dev_dbg(&mdev->dev, "MDEV: destroying\n");
	kfree(mdev);
	}

	int mdev_device_create(struct mdev_type type, const guid_t uuid)
	{
	int ret;
	struct mdev_device mdev, tmp;
	struct mdev_parent *parent = type->parent;
	struct mdev_driver *drv = parent->mdev_driver;

	mutex_lock(&mdev_list_lock);

	/* Check for duplicate */
	list_for_each_entry(tmp, &mdev_list, next) {
	if (guid_equal(&tmp->uuid, uuid)) {
	mutex_unlock(&mdev_list_lock);
	return -EEXIST;
	}
	}

	if (!drv->get_available) {
	/*
	* Note: that non-atomic read and dec is fine here because
	* all modifications are under mdev_list_lock.
	*/
	if (!atomic_read(&parent->available_instances)) {
	mutex_unlock(&mdev_list_lock);
	return -EUSERS;
	}
	atomic_dec(&parent->available_instances);
	}

	mdev = kzalloc(sizeof(*mdev), GFP_KERNEL);
	if (!mdev) {
	mutex_unlock(&mdev_list_lock);
	return -ENOMEM;
	}

	device_initialize(&mdev->dev);
	mdev->dev.parent = parent->dev;
	mdev->dev.bus = &mdev_bus_type;
	mdev->dev.release = mdev_device_release;
	mdev->dev.groups = mdev_device_groups;
	mdev->type = type;
	/* Pairs with the put in mdev_device_release() */
	kobject_get(&type->kobj);

	guid_copy(&mdev->uuid, uuid);
	list_add(&mdev->next, &mdev_list);
	mutex_unlock(&mdev_list_lock);

	ret = dev_set_name(&mdev->dev, "%pUl", uuid);
	if (ret)
	goto out_put_device;

	/* Check if parent unregistration has started */
	if (!down_read_trylock(&parent->unreg_sem)) {
	ret = -ENODEV;
	goto out_put_device;
	}

	ret = device_add(&mdev->dev);
	if (ret)
	goto out_unlock;

	ret = device_driver_attach(&drv->driver, &mdev->dev);
	if (ret)
	goto out_del;

	ret = mdev_create_sysfs_files(mdev);
	if (ret)
	goto out_del;

	mdev->active = true;
	dev_dbg(&mdev->dev, "MDEV: created\n");
	up_read(&parent->unreg_sem);

	return 0;

	out_del:
	device_del(&mdev->dev);
	out_unlock:
	up_read(&parent->unreg_sem);
	out_put_device:
	put_device(&mdev->dev);
	return ret;
	}

	int mdev_device_remove(struct mdev_device *mdev)
	{
	struct mdev_device *tmp;
	struct mdev_parent *parent = mdev->type->parent;

	mutex_lock(&mdev_list_lock);
	list_for_each_entry(tmp, &mdev_list, next) {
	if (tmp == mdev)
	break;
	}

	if (tmp != mdev) {
	mutex_unlock(&mdev_list_lock);
	return -ENODEV;
	}

	if (!mdev->active) {
	mutex_unlock(&mdev_list_lock);
	return -EAGAIN;
	}

	mdev->active = false;
	mutex_unlock(&mdev_list_lock);

	/* Check if parent unregistration has started */
	if (!down_read_trylock(&parent->unreg_sem))
	return -ENODEV;

	mdev_device_remove_common(mdev);
	up_read(&parent->unreg_sem);
	return 0;
	}

	static int __init mdev_init(void)
	{
	int ret;

	ret = bus_register(&mdev_bus_type);
	if (ret)
	return ret;

	mdev_bus_compat_class = class_compat_register("mdev_bus");
	if (!mdev_bus_compat_class) {
	bus_unregister(&mdev_bus_type);
	return -ENOMEM;
	}

	return 0;
	}

	static void __exit mdev_exit(void)
	{
	class_compat_unregister(mdev_bus_compat_class);
	bus_unregister(&mdev_bus_type);
	}

	subsys_initcall(mdev_init)
	module_exit(mdev_exit)

	MODULE_VERSION(DRIVER_VERSION);
	MODULE_LICENSE("GPL v2");
	MODULE_AUTHOR(DRIVER_AUTHOR);
	MODULE_DESCRIPTION(DRIVER_DESC);