#ifndef _LINUX_KTHREAD_H
  #define _LINUX_KTHREAD_H
  /* Simple interface for creating and stopping kernel threads without mess. */
  #include <linux/err.h>
  #include <linux/sched.h>

  struct task_struct *kthread_create_on_node(int (*threadfn)(void *data),
  					   void *data,
  					   int node,
  					   const char namefmt[], ...)
  	__attribute__((format(printf, 4, 5)));
  
  #define kthread_create(threadfn, data, namefmt, arg...) \
  	kthread_create_on_node(threadfn, data, -1, namefmt, ##arg)

  
  /**

   * kthread_run - create and wake a thread.

   * @threadfn: the function to run until signal_pending(current).
   * @data: data ptr for @threadfn.
   * @namefmt: printf-style name for the thread.
   *
   * Description: Convenient wrapper for kthread_create() followed by

   * wake_up_process().  Returns the kthread or ERR_PTR(-ENOMEM).
   */

  #define kthread_run(threadfn, data, namefmt, ...)			   \
  ({									   \
  	struct task_struct *__k						   \
  		= kthread_create(threadfn, data, namefmt, ## __VA_ARGS__); \
  	if (!IS_ERR(__k))						   \
  		wake_up_process(__k);					   \
  	__k;								   \
  })

  void kthread_bind(struct task_struct *k, unsigned int cpu);

  int kthread_stop(struct task_struct *k);

  int kthread_should_stop(void);

  void *kthread_data(struct task_struct *k);

  int kthreadd(void *unused);
  extern struct task_struct *kthreadd_task;

  extern int tsk_fork_get_node(struct task_struct *tsk);

  /*
   * Simple work processor based on kthread.
   *
   * This provides easier way to make use of kthreads.  A kthread_work
   * can be queued and flushed using queue/flush_kthread_work()
   * respectively.  Queued kthread_works are processed by a kthread
   * running kthread_worker_fn().
   *
   * A kthread_work can't be freed while it is executing.
   */
  struct kthread_work;
  typedef void (*kthread_work_func_t)(struct kthread_work *work);
  
  struct kthread_worker {
  	spinlock_t		lock;
  	struct list_head	work_list;
  	struct task_struct	*task;
  };
  
  struct kthread_work {
  	struct list_head	node;
  	kthread_work_func_t	func;
  	wait_queue_head_t	done;
  	atomic_t		flushing;
  	int			queue_seq;
  	int			done_seq;
  };
  
  #define KTHREAD_WORKER_INIT(worker)	{				\

  	.lock = __SPIN_LOCK_UNLOCKED((worker).lock),			\

  	.work_list = LIST_HEAD_INIT((worker).work_list),		\
  	}
  
  #define KTHREAD_WORK_INIT(work, fn)	{				\
  	.node = LIST_HEAD_INIT((work).node),				\
  	.func = (fn),							\
  	.done = __WAIT_QUEUE_HEAD_INITIALIZER((work).done),		\
  	.flushing = ATOMIC_INIT(0),					\
  	}
  
  #define DEFINE_KTHREAD_WORKER(worker)					\
  	struct kthread_worker worker = KTHREAD_WORKER_INIT(worker)
  
  #define DEFINE_KTHREAD_WORK(work, fn)					\
  	struct kthread_work work = KTHREAD_WORK_INIT(work, fn)

  /*
   * kthread_worker.lock and kthread_work.done need their own lockdep class
   * keys if they are defined on stack with lockdep enabled.  Use the
   * following macros when defining them on stack.
   */
  #ifdef CONFIG_LOCKDEP
  # define KTHREAD_WORKER_INIT_ONSTACK(worker)				\
  	({ init_kthread_worker(&worker); worker; })
  # define DEFINE_KTHREAD_WORKER_ONSTACK(worker)				\
  	struct kthread_worker worker = KTHREAD_WORKER_INIT_ONSTACK(worker)
  # define KTHREAD_WORK_INIT_ONSTACK(work, fn)				\
  	({ init_kthread_work((&work), fn); work; })
  # define DEFINE_KTHREAD_WORK_ONSTACK(work, fn)				\
  	struct kthread_work work = KTHREAD_WORK_INIT_ONSTACK(work, fn)
  #else
  # define DEFINE_KTHREAD_WORKER_ONSTACK(worker) DEFINE_KTHREAD_WORKER(worker)
  # define DEFINE_KTHREAD_WORK_ONSTACK(work, fn) DEFINE_KTHREAD_WORK(work, fn)
  #endif
  
  extern void __init_kthread_worker(struct kthread_worker *worker,
  			const char *name, struct lock_class_key *key);
  
  #define init_kthread_worker(worker)					\
  	do {								\
  		static struct lock_class_key __key;			\
  		__init_kthread_worker((worker), "("#worker")->lock", &__key); \
  	} while (0)
  
  #define init_kthread_work(work, fn)					\
  	do {								\
  		memset((work), 0, sizeof(struct kthread_work));		\
  		INIT_LIST_HEAD(&(work)->node);				\
  		(work)->func = (fn);					\
  		init_waitqueue_head(&(work)->done);			\
  	} while (0)

  
  int kthread_worker_fn(void *worker_ptr);
  
  bool queue_kthread_work(struct kthread_worker *worker,
  			struct kthread_work *work);
  void flush_kthread_work(struct kthread_work *work);
  void flush_kthread_worker(struct kthread_worker *worker);

  #endif /* _LINUX_KTHREAD_H */