linux-kernel-module-cheat/kernel_module/params.c

/*
Allows passing parameters at insertion time.

Those parameters can also be read and modified at runtime from /sys.

	insmod /params.ko
	# dmesg => 0
	cd /sys/module/params/parameters
	cat i
	# => 0
	printf 1 >i
	# dmesg => 1
	rmmod params
	insmod /params.ko i=1
	# dmesg => 1
*/

#include <linux/delay.h> /* usleep_range */
#include <linux/kernel.h>
#include <linux/kthread.h>
#include <linux/module.h>
#include <uapi/linux/stat.h> /* S_IRUSR | S_IWUSR */

MODULE_LICENSE("GPL");

static int i = 0;
module_param(i, int, S_IRUSR | S_IWUSR);
MODULE_PARM_DESC(i, "my favorite int");

static struct task_struct *kthread;

static int work_func(void *data)
{
	while (!kthread_should_stop()) {
		pr_info("%d\n", i);
		usleep_range(1000000, 1000001);
	}
	return 0;
}

int init_module(void)
{
	kthread = kthread_create(work_func, NULL, "mykthread");
	wake_up_process(kthread);
	return 0;
}

void cleanup_module(void)
{
	kthread_stop(kthread);
}