1/*
2 * idle-task scheduling class.
3 *
4 * (NOTE: these are not related to SCHED_IDLE tasks which are
5 *  handled in sched_fair.c)
6 */
7
8/*
9 * Idle tasks are unconditionally rescheduled:
10 */
11static void check_preempt_curr_idle(struct rq *rq, struct task_struct *p)
12{
13	resched_task(rq->idle);
14}
15
16static struct task_struct *pick_next_task_idle(struct rq *rq)
17{
18	schedstat_inc(rq, sched_goidle);
19
20	return rq->idle;
21}
22
23/*
24 * It is not legal to sleep in the idle task - print a warning
25 * message if some code attempts to do it:
26 */
27static void
28dequeue_task_idle(struct rq *rq, struct task_struct *p, int sleep)
29{
30	spin_unlock_irq(&rq->lock);
31	printk(KERN_ERR "bad: scheduling from the idle thread!\n");
32	dump_stack();
33	spin_lock_irq(&rq->lock);
34}
35
36static void put_prev_task_idle(struct rq *rq, struct task_struct *prev)
37{
38}
39
40#ifdef CONFIG_SMP
41static unsigned long
42load_balance_idle(struct rq *this_rq, int this_cpu, struct rq *busiest,
43		  unsigned long max_load_move,
44		  struct sched_domain *sd, enum cpu_idle_type idle,
45		  int *all_pinned, int *this_best_prio)
46{
47	return 0;
48}
49
50static int
51move_one_task_idle(struct rq *this_rq, int this_cpu, struct rq *busiest,
52		   struct sched_domain *sd, enum cpu_idle_type idle)
53{
54	return 0;
55}
56#endif
57
58static void task_tick_idle(struct rq *rq, struct task_struct *curr)
59{
60}
61
62static void set_curr_task_idle(struct rq *rq)
63{
64}
65
66/*
67 * Simple, special scheduling class for the per-CPU idle tasks:
68 */
69const struct sched_class idle_sched_class = {
70	/* .next is NULL */
71	/* no enqueue/yield_task for idle tasks */
72
73	/* dequeue is not valid, we print a debug message there: */
74	.dequeue_task		= dequeue_task_idle,
75
76	.check_preempt_curr	= check_preempt_curr_idle,
77
78	.pick_next_task		= pick_next_task_idle,
79	.put_prev_task		= put_prev_task_idle,
80
81#ifdef CONFIG_SMP
82	.load_balance		= load_balance_idle,
83	.move_one_task		= move_one_task_idle,
84#endif
85
86	.set_curr_task          = set_curr_task_idle,
87	.task_tick		= task_tick_idle,
88	/* no .task_new for idle tasks */
89};
90