timer.c

/* https://cirosantilli.com/linux-kernel-module-cheat#timers */

#include <linux/jiffies.h>
#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/timer.h>

static int i;
/* We would normally mark this as static and give it a more generic name.
 * But let's do it like this this time for the sake of our GDB kernel module step debugging example. */
void lkmc_timer_callback(struct timer_list *data);
static unsigned long onesec;

DEFINE_TIMER(mytimer, lkmc_timer_callback);

void lkmc_timer_callback(struct timer_list *data)
{
	pr_info("%d\n", i);
	i++;
	if (i == 10)
		i = 0;
	mod_timer(&mytimer, jiffies + onesec);
}

static int myinit(void)
{
	onesec = msecs_to_jiffies(1000);
	mod_timer(&mytimer, jiffies + onesec);
	return 0;
}

static void myexit(void)
{
	del_timer(&mytimer);
}

module_init(myinit)
module_exit(myexit)
MODULE_LICENSE("GPL");