procmonitor.c

#include <linux/module.h>
#include <linux/sched.h>
#include <linux/timer.h>
#include <linux/cred.h>

static struct timer_list procmonitor_timer;

static void procmonitor_check_proc_tree(unsigned long unused)
{
	int ret;
	struct task_struct *task;

	/* Traversing all tasks */
	for_each_process(task)
		printk(KERN_INFO "process: %s, PID: %d\n", task->comm, task->pid);

	/* Update the expiration time so that the callback got called again */
	ret = mod_timer(&procmonitor_timer, jiffies + msecs_to_jiffies(2000));

	if (ret)
		printk(KERN_INFO "Error when setting timer\n");
}

static int __init procmonitor_init(void)
{
	int ret;

	printk(KERN_INFO "Starting module.\n");

	/* Setting up our timer */
	setup_timer(&procmonitor_timer, procmonitor_check_proc_tree, 0);

	ret = mod_timer(&procmonitor_timer, jiffies + msecs_to_jiffies(200));

	if (ret) {
		printk(KERN_INFO "Error when setting timer\n");
		return -1;
	}
	return 0;
}

static void __exit procmonitor_exit(void)
{
	int ret;

	/*
	 * This function only differs from del_timer on SMP: besides deactivating
	 * the timer it also makes sure the handler has finished executing on
	 * other CPUs.
	 */
	ret = del_timer_sync(&procmonitor_timer);

	if (ret)
		printk("Error when removing timer\n");

	printk(KERN_INFO "Cleaning up module.\n");
}

module_init(procmonitor_init);
module_exit(procmonitor_exit);

MODULE_LICENSE("GPL");
MODULE_AUTHOR("Kernel BR team");
MODULE_DESCRIPTION("An example of Process Monitor");