Workqueue attempt, but fails to insmod, already loaded??

README.md

@@ -38,3 +38,4 @@ See also: <https://superuser.com/questions/351387/how-to-stop-kernel-messages-fr
         1. [hello2](kernel_module/hello2.c)
         1. [debugfs](kernel_module/debugfs.c)
         1. [fops](kernel_module/fops.c)
+        1. [workqueue](kernel_module/workqueue.c)

kernel_module/Makefile

@@ -1,4 +1,4 @@
-obj-m += debugfs.o fops.o hello.o hello2.o
+obj-m += $(addsuffix .o, $(notdir $(basename $(wildcard $(BR2_EXTERNAL_KERNEL_MODULE_PATH)/*.c))))
 ccflags-y := -Wno-declaration-after-statement -std=gnu99
 
 .PHONY: all clean

kernel_module/workqueue_cheat.c

@@ -0,0 +1,36 @@
+
+/*
+Usage:
+
+	insmod /workqueue.ko
+	# dmesg => worker
+	rmmod workqueue
+
+Creates a separate thread. So init_module can return, but some work will still get done.
+*/
+
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/workqueue.h>
+
+MODULE_LICENSE("GPL");
+
+static struct workqueue_struct *queue;
+
+static void worker_func(struct work_struct *work)
+{
+	printk(KERN_INFO "worker\n");
+}
+
+int init_module(void)
+{
+	DECLARE_WORK(work, worker_func);
+	queue = create_singlethread_workqueue("myworkqueue");
+	queue_work(queue, &work);
+	return 0;
+}
+
+void cleanup_module(void)
+{
+	destroy_workqueue(queue);
+}