From 67f669487e2a8615f3aecce8d154420ab67f0b9b Mon Sep 17 00:00:00 2001
From: Ciro Santilli <ciro.santilli@gmail.com>
Date: Sun, 14 May 2017 09:34:27 +0100
Subject: [PATCH] Workqueue attempt, but fails to insmod, already loaded??

---
 README.md                       |  1 +
 kernel_module/Makefile          |  2 +-
 kernel_module/workqueue_cheat.c | 36 +++++++++++++++++++++++++++++++++
 3 files changed, 38 insertions(+), 1 deletion(-)
 create mode 100644 kernel_module/workqueue_cheat.c

diff --git a/README.md b/README.md
index 04c6438..8032493 100644
--- a/README.md
+++ b/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)
diff --git a/kernel_module/Makefile b/kernel_module/Makefile
index 450e961..87d35c0 100644
--- a/kernel_module/Makefile
+++ b/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
diff --git a/kernel_module/workqueue_cheat.c b/kernel_module/workqueue_cheat.c
new file mode 100644
index 0000000..a8f1110
--- /dev/null
+++ b/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);
+}