Merge tag 'v3.11' into p/abusse/merge_upgrade
[projects/modsched/linux.git] / kernel / sched / cfs / idle_task.c
1 #include "sched.h"
2
3 /*
4  * idle-task scheduling class.
5  *
6  * (NOTE: these are not related to SCHED_IDLE tasks which are
7  *  handled in sched/fair.c)
8  */
9
10 #ifdef CONFIG_SMP
11 static int
12 select_task_rq_idle(struct task_struct *p, int sd_flag, int flags)
13 {
14         return task_cpu(p); /* IDLE tasks as never migrated */
15 }
16
17 static void pre_schedule_idle(struct rq *rq, struct task_struct *prev)
18 {
19         idle_exit_fair(rq);
20         rq_last_tick_reset(rq);
21 }
22
23 static void post_schedule_idle(struct rq *rq)
24 {
25         idle_enter_fair(rq);
26 }
27 #endif /* CONFIG_SMP */
28 /*
29  * Idle tasks are unconditionally rescheduled:
30  */
31 static void check_preempt_curr_idle(struct rq *rq, struct task_struct *p, int flags)
32 {
33         resched_task(rq->idle);
34 }
35
36 static struct task_struct *pick_next_task_idle(struct rq *rq)
37 {
38         schedstat_inc(rq, sched_goidle);
39 #ifdef CONFIG_SMP
40         /* Trigger the post schedule to do an idle_enter for CFS */
41         rq->post_schedule = 1;
42 #endif
43         return rq->idle;
44 }
45
46 /*
47  * It is not legal to sleep in the idle task - print a warning
48  * message if some code attempts to do it:
49  */
50 static void
51 dequeue_task_idle(struct rq *rq, struct task_struct *p, int flags)
52 {
53         raw_spin_unlock_irq(&rq->lock);
54         printk(KERN_ERR "bad: scheduling from the idle thread!\n");
55         dump_stack();
56         raw_spin_lock_irq(&rq->lock);
57 }
58
59 static void put_prev_task_idle(struct rq *rq, struct task_struct *prev)
60 {
61 }
62
63 static void task_tick_idle(struct rq *rq, struct task_struct *curr, int queued)
64 {
65 }
66
67 static void set_curr_task_idle(struct rq *rq)
68 {
69 }
70
71 static void switched_to_idle(struct rq *rq, struct task_struct *p)
72 {
73         BUG();
74 }
75
76 static void
77 prio_changed_idle(struct rq *rq, struct task_struct *p, int oldprio)
78 {
79         BUG();
80 }
81
82 static unsigned int get_rr_interval_idle(struct rq *rq, struct task_struct *task)
83 {
84         return 0;
85 }
86
87 /*
88  * Simple, special scheduling class for the per-CPU idle tasks:
89  */
90 const struct sched_class idle_sched_class = {
91         /* .next is NULL */
92         /* no enqueue/yield_task for idle tasks */
93
94         /* dequeue is not valid, we print a debug message there: */
95         .dequeue_task           = dequeue_task_idle,
96
97         .check_preempt_curr     = check_preempt_curr_idle,
98
99         .pick_next_task         = pick_next_task_idle,
100         .put_prev_task          = put_prev_task_idle,
101
102 #ifdef CONFIG_SMP
103         .select_task_rq         = select_task_rq_idle,
104         .pre_schedule           = pre_schedule_idle,
105         .post_schedule          = post_schedule_idle,
106 #endif
107
108         .set_curr_task          = set_curr_task_idle,
109         .task_tick              = task_tick_idle,
110
111         .get_rr_interval        = get_rr_interval_idle,
112
113         .prio_changed           = prio_changed_idle,
114         .switched_to            = switched_to_idle,
115 };