kthread: add the helper function kthread_run_on_cpu()

Add a new helper function kthread_run_on_cpu(), which 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.

[[email protected]: export kthread_create_on_cpu to modules]

Link: https://lkml.kernel.org/r/[email protected]
Signed-off-by: Cai Huoqing <[email protected]>
Cc: Bernard Metzler <[email protected]>
Cc: Cai Huoqing <[email protected]>
Cc: Daniel Bristot de Oliveira <[email protected]>
Cc: Davidlohr Bueso <[email protected]>
Cc: Doug Ledford <[email protected]>
Cc: Ingo Molnar <[email protected]>
Cc: Jason Gunthorpe <[email protected]>
Cc: Joel Fernandes (Google) <[email protected]>
Cc: Josh Triplett <[email protected]>
Cc: Lai Jiangshan <[email protected]>
Cc: Mathieu Desnoyers <[email protected]>
Cc: "Paul E . McKenney" <[email protected]>
Cc: Steven Rostedt <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>

2 files changed, 26 insertions, 0 deletions

diff --git a/include/linux/kthread.h b/include/linux/kthread.h
index 346b0f269161..db47aae7c481 100644
--- a/include/linux/kthread.h
+++ b/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);
diff --git a/kernel/kthread.c b/kernel/kthread.c
index 7113003fab63..4ed9e7bce9e8 100644
--- a/kernel/kthread.c
+++ b/kernel/kthread.c
@@ -523,6 +523,7 @@ struct task_struct *kthread_create_on_cpu(int (*threadfn)(void *data),
 	to_kthread(p)->cpu = cpu;
 	return p;
 }
+EXPORT_SYMBOL(kthread_create_on_cpu);
 
 void kthread_set_per_cpu(struct task_struct *k, int cpu)
 {