kthread: Add the helper function kthread_run_on_cpu()

the helper function kthread_run_on_cpu() includes
kthread_create_on_cpu/wake_up_process().
In some cases, use kthread_run_on_cpu() directly instead of
kthread_create_on_node/kthread_bind/wake_up_process() or
kthread_create_on_cpu/wake_up_process() or
kthreadd_create/kthread_bind/wake_up_process() to simplify the code.

Signed-off-by: Cai Huoqing <caihuoqing@baidu.com>

include/linux/kthread.h

@@ -56,6 +56,31 @@ bool kthread_is_per_cpu(struct task_struct *k);
 	__k;								   \
 })
 
+/**
+ * kthread_run_on_cpu - create and wake a cpu bound thread.
+ * @threadfn: the function to run until signal_pending(current).
+ * @data: data ptr for @threadfn.
+ * @cpu: The cpu on which the thread should be bound,
+ * @namefmt: printf-style name for the thread. Format is restricted
+ *	     to "name.*%u". Code fills in cpu number.
+ *
+ * Description: Convenient wrapper for kthread_create_on_cpu()
+ * followed by wake_up_process().  Returns the kthread or
+ * ERR_PTR(-ENOMEM).
+ */
+static inline struct task_struct *
+kthread_run_on_cpu(int (*threadfn)(void *data), void *data,
+			unsigned int cpu, const char *namefmt)
+{
+	struct task_struct *p;
+
+	p = kthread_create_on_cpu(threadfn, data, cpu, namefmt);
+	if (!IS_ERR(p))
+		wake_up_process(p);
+
+	return p;
+}
+
 void free_kthread_struct(struct task_struct *k);
 void kthread_bind(struct task_struct *k, unsigned int cpu);
 void kthread_bind_mask(struct task_struct *k, const struct cpumask *mask);