diff --git a/include/linux/smp.h b/include/linux/smp.h
index e21278d66a4b..b0de11140ee3 100644
--- a/include/linux/smp.h
+++ b/include/linux/smp.h
@@ -101,6 +101,8 @@ extern void smp_cpus_done(unsigned int max_cpus);
 /*
  * Call a function on all other processors
  */
+int generic_exec_single(int cpu, struct __call_single_data *csd,
+			smp_call_func_t func, void *info);
 void smp_call_function(smp_call_func_t func, void *info, int wait);
 void smp_call_function_many(const struct cpumask *mask,
 			    smp_call_func_t func, void *info, bool wait);
diff --git a/kernel/smp.c b/kernel/smp.c
index 767a156b1bd2..67d671709b9e 100644
--- a/kernel/smp.c
+++ b/kernel/smp.c
@@ -128,7 +128,8 @@ static __always_inline void csd_lock(call_single_data_t *csd)
 
 static __always_inline void csd_unlock(call_single_data_t *csd)
 {
-	WARN_ON(!(csd->flags & CSD_FLAG_LOCK));
+	if (!(csd->flags & CSD_FLAG_LOCK))
+		return;
 
 	/*
 	 * ensure we're all done before releasing data:
@@ -145,7 +146,7 @@ extern void send_call_function_single_ipi(int cpu);
  * for execution on the given CPU. data must already have
  * ->func, ->info, and ->flags set.
  */
-static int generic_exec_single(int cpu, call_single_data_t *csd,
+int generic_exec_single(int cpu, call_single_data_t *csd,
 			       smp_call_func_t func, void *info)
 {
 	if (cpu == smp_processor_id()) {