/*
 * kernel/edf_common.c
 *
 * Common functions for EDF based scheduler.
 */

#include <linux/percpu.h>
#include <linux/sched.h>
#include <linux/list.h>

#include <litmus/litmus.h>
#include <litmus/sched_plugin.h>
#include <litmus/sched_trace.h>

#ifdef CONFIG_LITMUS_NESTED_LOCKING
#include <litmus/locking.h>
#endif

#include <litmus/edf_common.h>



/* edf_higher_prio -  returns true if first has a higher EDF priority
 *                    than second. Deadline ties are broken by PID.
 *
 * both first and second may be NULL
 */
#ifdef CONFIG_LITMUS_NESTED_LOCKING
int __edf_higher_prio(
	struct task_struct* first, comparison_mode_t first_mode,
	struct task_struct* second, comparison_mode_t second_mode)
#else
int edf_higher_prio(struct task_struct* first, struct task_struct* second)
#endif
{
	struct task_struct *first_task = first;
	struct task_struct *second_task = second;

	/* There is no point in comparing a task to itself. */
	if (first && first == second) {
		TRACE_CUR("WARNING: pointless edf priority comparison: %s/%d\n", first->comm, first->pid);
		WARN_ON(1);
		return 0;
	}


	/* check for NULL tasks */
	if (!first || !second) {
		return first && !second;
	}

#ifdef CONFIG_LITMUS_LOCKING
	/* Check for EFFECTIVE priorities. Change task
	 * used for comparison in such a case.
	 */
	if (unlikely(first->rt_param.inh_task)
#ifdef CONFIG_LITMUS_NESTED_LOCKING
		&& (first_mode == EFFECTIVE)
#endif
		) {
		first_task = first->rt_param.inh_task;
	}
	if (unlikely(second->rt_param.inh_task)
#ifdef CONFIG_LITMUS_NESTED_LOCKING
		&& (second_mode == EFFECTIVE)
#endif
		) {
		second_task = second->rt_param.inh_task;
	}

	/* Check for priority boosting. Tie-break by start of boosting.
	 */
	if (unlikely(is_priority_boosted(first_task))) {
		/* first_task is boosted, how about second_task? */
		if (!is_priority_boosted(second_task) ||
		    lt_before(get_boost_start(first_task),
					  get_boost_start(second_task))) {
			return 1;
		}
		else {
			return 0;
		}
	}
	else if (unlikely(is_priority_boosted(second_task))) {
		/* second_task is boosted, first is not*/
		return 0;
	}

#endif

//	// rate-monotonic for testing
//	if (!is_realtime(second_task)) {
//		return true;
//	}
//
//	if (shorter_period(first_task, second_task)) {
//		return true;
//	}
//
//	if (get_period(first_task) == get_period(second_task)) {
//		if (first_task->pid < second_task->pid) {
//			return true;
//		}
//		else if (first_task->pid == second_task->pid) {
//			return !second->rt_param.inh_task;
//		}
//	}

	if (!is_realtime(second_task)) {
		return true;
	}

	if (earlier_deadline(first_task, second_task)) {
		return true;
	}
	if (get_deadline(first_task) == get_deadline(second_task)) {

		if (shorter_period(first_task, second_task)) {
			return true;
		}
		if (get_rt_period(first_task) == get_rt_period(second_task)) {
			if (first_task->pid < second_task->pid) {
				return true;
			}
			if (first_task->pid == second_task->pid) {
#ifdef CONFIG_LITMUS_SOFTIRQD
				if (first_task->rt_param.is_proxy_thread <
					second_task->rt_param.is_proxy_thread) {
					return true;
				}
				if(first_task->rt_param.is_proxy_thread == second_task->rt_param.is_proxy_thread) {
					return !second->rt_param.inh_task;
				}
#else
				return !second->rt_param.inh_task;
#endif
			}

		}
	}

	return false;
}


#ifdef CONFIG_LITMUS_NESTED_LOCKING
int edf_higher_prio(struct task_struct* first, struct task_struct* second)
{
	return __edf_higher_prio(first, EFFECTIVE, second, EFFECTIVE);
}

int edf_max_heap_order(struct binheap_node *a, struct binheap_node *b)
{
	struct nested_info *l_a = (struct nested_info *)binheap_entry(a, struct nested_info, hp_binheap_node);
	struct nested_info *l_b = (struct nested_info *)binheap_entry(b, struct nested_info, hp_binheap_node);

	return __edf_higher_prio(l_a->hp_waiter_eff_prio, EFFECTIVE, l_b->hp_waiter_eff_prio, EFFECTIVE);
}

int edf_min_heap_order(struct binheap_node *a, struct binheap_node *b)
{
	return edf_max_heap_order(b, a);  // swap comparison
}

int edf_max_heap_base_priority_order(struct binheap_node *a, struct binheap_node *b)
{
	struct nested_info *l_a = (struct nested_info *)binheap_entry(a, struct nested_info, hp_binheap_node);
	struct nested_info *l_b = (struct nested_info *)binheap_entry(b, struct nested_info, hp_binheap_node);

	return __edf_higher_prio(l_a->hp_waiter_eff_prio, BASE, l_b->hp_waiter_eff_prio, BASE);
}

int edf_min_heap_base_priority_order(struct binheap_node *a, struct binheap_node *b)
{
	return edf_max_heap_base_priority_order(b, a);  // swap comparison
}
#endif


int edf_ready_order(struct bheap_node* a, struct bheap_node* b)
{
	return edf_higher_prio(bheap2task(a), bheap2task(b));
}

void edf_domain_init(rt_domain_t* rt, check_resched_needed_t resched,
		      release_jobs_t release)
{
	rt_domain_init(rt,  edf_ready_order, resched, release);
}

/* need_to_preempt - check whether the task t needs to be preempted
 *                   call only with irqs disabled and with  ready_lock acquired
 *                   THIS DOES NOT TAKE NON-PREEMPTIVE SECTIONS INTO ACCOUNT!
 */
int edf_preemption_needed(rt_domain_t* rt, struct task_struct *t)
{
	/* we need the read lock for edf_ready_queue */
	/* no need to preempt if there is nothing pending */
	if (!__jobs_pending(rt))
		return 0;
	/* we need to reschedule if t doesn't exist */
	if (!t)
		return 1;

	/* NOTE: We cannot check for non-preemptibility since we
	 *       don't know what address space we're currently in.
	 */

	/* make sure to get non-rt stuff out of the way */
	return !is_realtime(t) || edf_higher_prio(__next_ready(rt), t);
}