v4.19.13 snapshot.
diff --git a/include/linux/smpboot.h b/include/linux/smpboot.h
new file mode 100644
index 0000000..d0884b5
--- /dev/null
+++ b/include/linux/smpboot.h
@@ -0,0 +1,49 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+#ifndef _LINUX_SMPBOOT_H
+#define _LINUX_SMPBOOT_H
+
+#include <linux/types.h>
+
+struct task_struct;
+/* Cookie handed to the thread_fn*/
+struct smpboot_thread_data;
+
+/**
+ * struct smp_hotplug_thread - CPU hotplug related thread descriptor
+ * @store: Pointer to per cpu storage for the task pointers
+ * @list: List head for core management
+ * @thread_should_run: Check whether the thread should run or not. Called with
+ * preemption disabled.
+ * @thread_fn: The associated thread function
+ * @create: Optional setup function, called when the thread gets
+ * created (Not called from the thread context)
+ * @setup: Optional setup function, called when the thread gets
+ * operational the first time
+ * @cleanup: Optional cleanup function, called when the thread
+ * should stop (module exit)
+ * @park: Optional park function, called when the thread is
+ * parked (cpu offline)
+ * @unpark: Optional unpark function, called when the thread is
+ * unparked (cpu online)
+ * @selfparking: Thread is not parked by the park function.
+ * @thread_comm: The base name of the thread
+ */
+struct smp_hotplug_thread {
+ struct task_struct __percpu **store;
+ struct list_head list;
+ int (*thread_should_run)(unsigned int cpu);
+ void (*thread_fn)(unsigned int cpu);
+ void (*create)(unsigned int cpu);
+ void (*setup)(unsigned int cpu);
+ void (*cleanup)(unsigned int cpu, bool online);
+ void (*park)(unsigned int cpu);
+ void (*unpark)(unsigned int cpu);
+ bool selfparking;
+ const char *thread_comm;
+};
+
+int smpboot_register_percpu_thread(struct smp_hotplug_thread *plug_thread);
+
+void smpboot_unregister_percpu_thread(struct smp_hotplug_thread *plug_thread);
+
+#endif