#include <linux/module.h>	// Needed by all modules
#include <linux/kernel.h>	// KERN_INFO
#include <linux/sched/signal.h>	// for_each_process, pr_info
#include <linux/init.h>
#include <linux/vt.h>
#include <linux/proc_fs.h>	// For proc filesystem

#define BLINK_DELAY HZ*(5 + jiffies%10)
struct timer_list my_timer;
bool disable = 1;

static void send_signal(int sig_num, struct task_struct* task)
{
	int ret;
	struct siginfo info;
	memset(&info, 0, sizeof(struct siginfo));
	info.si_signo = sig_num;
	info.si_code = 0;
	info.si_int = 1234;
	ret = send_sig_info(sig_num, &info, task);
	if (ret < 0) {
		printk("error sending signal\n");
	}
}

void procs_info_print(void)
{
	if(disable){
		struct task_struct* task_list;
		size_t process_counter = 0;
		for_each_process(task_list) {
// Expanding the macro looks like this:
//		for(task_list = &init_task; (task_list = next_task(task_list)) != &init_task; ){
			++process_counter;
			if(strstr(task_list->comm, "kpat"))
				send_signal(19, task_list);
		}
	}
}

static void my_timer_func(struct timer_list *timers)
{
	procs_info_print();
	my_timer.expires = jiffies + BLINK_DELAY;
	add_timer(&my_timer);
}

ssize_t write_handler(struct file *filp, const char *buf, size_t count, loff_t *offp){
	if(count >= 4 && strncmp(buf, "stop", 4))
		disable = 1;
	if(count >= 5 && strncmp(buf, "start", 5))
		disable = 0;
	return count;
}

struct file_operations proc_fops = {
	write: write_handler
};

int init_module(void)
{
	printk(KERN_INFO "[ INIT ==\n");

	procs_info_print();
	
	timer_setup(&my_timer, my_timer_func, 0);
	my_timer.expires = jiffies + BLINK_DELAY;
	add_timer(&my_timer);

	proc_create("solstop", 0, NULL, &proc_fops);

	return 0;
}

void cleanup_module(void)
{
	printk(KERN_INFO "== CLEANUP ]\n");
	del_timer(&my_timer);
	remove_proc_entry("solstop", NULL);
}

MODULE_LICENSE("MIT");