#include <linux/config.h>
#include <linux/module.h>
#include <linux/init.h>
#include <linux/list.h>
#include <linux/spinlock.h>
#include <linux/sched.h>
#include <linux/kthread.h>
#include <linux/delay.h>
#include <linux/mm.h>

#include <asm/uaccess.h>

static spinlock_t t1 = SPIN_LOCK_UNLOCKED(t1);
static spinlock_t t2 = SPIN_LOCK_UNLOCKED(t2);

struct task_struct *threads[3];

static int run1(void *data)
{
	printk("thread 1 running\n");
	spin_lock(&t2);
	printk("thread 1 got lock t2\n");
	spin_lock(&t1);
	printk("thread 1 got lock t1\n");
	spin_unlock(&t1);
	spin_unlock(&t2);
	
	return 0;
}

static int run2(void *data)
{
	printk("thread 2 running\n");
	spin_lock(&t1);
	printk("thread 2 got lock t1\n");
	spin_unlock(&t1);
	return 0;
}

static int run3(void *data)
{
	printk("thread 3 running\n");
	spin_lock(&t2);
	printk("thread 3 got lock t2\n");
	spin_unlock(&t2);
	return 0;
}
static int pi_test_init(void)
{
	struct sched_param param = {.sched_priority = 10 };
	int n = 0;
	int i;

	printk("set sched myself\n");
	sched_setscheduler(current, SCHED_FIFO, 
			(struct sched_param __user*)&param);

	threads[n++] = kthread_create(run1, NULL, "thread1");
	threads[n++] = kthread_create(run2, NULL, "thread2");
	threads[n++] = kthread_create(run3, NULL, "thread3");

	spin_lock(&t1);

	for (i=0; i < n; i++) {
		param.sched_priority++;
		printk("set sched for thread[%d] %d\n",i,threads[i]->pid);
		sched_setscheduler(threads[i], SCHED_FIFO, 
				(struct sched_param __user*)&param);
	}

	/* first wake the middle process */
	wake_up_process(threads[1]);
	msleep(10);
	/* wake the lowest process that will block on the previous */
	wake_up_process(threads[0]);
	msleep(10);
	/* now wake the highest process which will block on the lowest
	 * but lets see who gets the lock when we let it go */
	wake_up_process(threads[2]);
	msleep(10);

	/* let the games begin! */
	printk("parent releasing the t1 lock!\n");
	spin_unlock(&t1);

	

	return 0;
}

static void pi_test_exit(void)
{
}

module_init(pi_test_init);
module_exit(pi_test_exit);

MODULE_LICENSE("GPL");