cse3_sol.c

#include <linux/module.h>	/* modules */
#include <linux/kernel.h>	/* KERN_INFO */
#include <linux/workqueue.h>
#include <linux/slab.h>
#include <linux/smp.h>
#include <linux/timer.h>
#include <linux/wait.h>
#include <linux/sched.h>

MODULE_AUTHOR("CSE");
MODULE_LICENSE("GPL");

int ret, i;
int flag = 0;

struct work_struct *work1;
struct work_struct *work2;
struct timer_list my_timer;
static DECLARE_WAIT_QUEUE_HEAD(wq);

void my_timer_callback(struct timer_list *t)
{
        printk(KERN_DEBUG "CSE: my_timer_callback called (%ld).\n", jiffies);
}

void my_wq_function(struct work_struct *work) 
{
	printk(KERN_DEBUG "CSE: CPU id = %i, let's check condition\n", smp_processor_id());
        ret = wait_event_interruptible(wq, flag != 0);
		printk(KERN_DEBUG "CSE: res is %i\n", ret);
	kfree((void *)work);
	timer_setup(&my_timer, my_timer_callback, 0);
	ret = mod_timer(&my_timer, jiffies + msecs_to_jiffies(1000));
	printk(KERN_DEBUG "CSE: timer started at (%ld).\n", jiffies);
    	return;
}

void my_wq_function2(struct work_struct *work)
{
        printk(KERN_DEBUG "CSE: CPU id = %i, let's wake up the other guy to start the timer\n", smp_processor_id());
	flag = 1;
    	wake_up_interruptible(&wq);
        kfree((void *)work);
        return;
}

int init_cse(void)
{
	printk(KERN_DEBUG "CSE: Hello world\n");
	work1 = kmalloc(sizeof(struct work_struct), GFP_KERNEL);
	work2 = kmalloc(sizeof(struct work_struct), GFP_KERNEL);
  	if (work1) {
		INIT_WORK( (struct work_struct *)work1, my_wq_function);
		ret = schedule_work((struct work_struct *)work1);
	}
	if (work2) {
                INIT_WORK( (struct work_struct *)work2, my_wq_function2);
                ret = schedule_work((struct work_struct *)work2);
        }

	return 0;
}

void cleanup_cse(void)
{
	flush_work((struct work_struct *)work1);
	flush_work((struct work_struct *)work2);
	ret = del_timer(&my_timer);
	printk(KERN_INFO "CSE: Goodbye world\n");
}

module_init(init_cse);
module_exit(cleanup_cse);