3 files changed, 7 insertions, 1 deletions

diff --git a/include/linux/smpboot.h b/include/linux/smpboot.h
index c65dee059913..13e929679550 100644
--- a/include/linux/smpboot.h
+++ b/include/linux/smpboot.h
@@ -24,6 +24,9 @@ struct smpboot_thread_data;
  *                      parked (cpu offline)
  * @unpark:             Optional unpark function, called when the thread is
  *                      unparked (cpu online)
+ * @pre_unpark:         Optional unpark function, called before the thread is
+ *                      unparked (cpu online). This is not guaranteed to be
+ *                      called on the target cpu of the thread. Careful!
  * @selfparking:        Thread is not parked by the park function.
  * @thread_comm:        The base name of the thread
  */
@@ -37,6 +40,7 @@ struct smp_hotplug_thread {
         void                            (*cleanup)(unsigned int cpu, bool online);
         void                            (*park)(unsigned int cpu);
         void                            (*unpark)(unsigned int cpu);
+        void                            (*pre_unpark)(unsigned int cpu);
         bool                            selfparking;
         const char                      *thread_comm;
 };
diff --git a/kernel/smpboot.c b/kernel/smpboot.c
index d4abac261779..8eaed9aa9cf0 100644
--- a/kernel/smpboot.c
+++ b/kernel/smpboot.c
@@ -209,6 +209,8 @@ static void smpboot_unpark_thread(struct smp_hotplug_thread *ht, unsigned int cp
 {
         struct task_struct *tsk = *per_cpu_ptr(ht->store, cpu);
 
+        if (ht->pre_unpark)
+                ht->pre_unpark(cpu);
         kthread_unpark(tsk);
 }
 
diff --git a/kernel/stop_machine.c b/kernel/stop_machine.c
index 95d178c62d5a..c09f2955ae30 100644
--- a/kernel/stop_machine.c
+++ b/kernel/stop_machine.c
@@ -336,7 +336,7 @@ static struct smp_hotplug_thread cpu_stop_threads = {
         .create                 = cpu_stop_create,
         .setup                  = cpu_stop_unpark,
         .park                   = cpu_stop_park,
-        .unpark                 = cpu_stop_unpark,
+        .pre_unpark             = cpu_stop_unpark,
         .selfparking            = true,
 };