1 files changed, 90 insertions, 0 deletions
diff --git a/include/linux/kthread.h b/include/linux/kthread.h
index aabc8a13ba71..ce0775aa64c3 100644
--- a/include/linux/kthread.h
+++ b/include/linux/kthread.h
@@ -30,8 +30,98 @@ struct task_struct *kthread_create(int (*threadfn)(void *data),
 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;
 
+/*
+ * 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,					\
+	.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 */