perf: Fix double start/stop in x86_pmu_start()
[linux-2.6.git] / kernel / sched / 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 #endif /* CONFIG_SMP */
17 /*
18  * Idle tasks are unconditionally rescheduled:
19  */
20 static void check_preempt_curr_idle(struct rq *rq, struct task_struct *p, int flags)
21 {
22         resched_task(rq->idle);
23 }
24
25 static struct task_struct *pick_next_task_idle(struct rq *rq)
26 {
27         schedstat_inc(rq, sched_goidle);
28         calc_load_account_idle(rq);
29         return rq->idle;
30 }
31
32 /*
33  * It is not legal to sleep in the idle task - print a warning
34  * message if some code attempts to do it:
35  */
36 static void
37 dequeue_task_idle(struct rq *rq, struct task_struct *p, int flags)
38 {
39         raw_spin_unlock_irq(&rq->lock);
40         printk(KERN_ERR "bad: scheduling from the idle thread!\n");
41         dump_stack();
42         raw_spin_lock_irq(&rq->lock);
43 }
44
45 static void put_prev_task_idle(struct rq *rq, struct task_struct *prev)
46 {
47 }
48
49 static void task_tick_idle(struct rq *rq, struct task_struct *curr, int queued)
50 {
51 }
52
53 static void set_curr_task_idle(struct rq *rq)
54 {
55 }
56
57 static void switched_to_idle(struct rq *rq, struct task_struct *p)
58 {
59         BUG();
60 }
61
62 static void
63 prio_changed_idle(struct rq *rq, struct task_struct *p, int oldprio)
64 {
65         BUG();
66 }
67
68 static unsigned int get_rr_interval_idle(struct rq *rq, struct task_struct *task)
69 {
70         return 0;
71 }
72
73 /*
74  * Simple, special scheduling class for the per-CPU idle tasks:
75  */
76 const struct sched_class idle_sched_class = {
77         /* .next is NULL */
78         /* no enqueue/yield_task for idle tasks */
79
80         /* dequeue is not valid, we print a debug message there: */
81         .dequeue_task           = dequeue_task_idle,
82
83         .check_preempt_curr     = check_preempt_curr_idle,
84
85         .pick_next_task         = pick_next_task_idle,
86         .put_prev_task          = put_prev_task_idle,
87
88 #ifdef CONFIG_SMP
89         .select_task_rq         = select_task_rq_idle,
90 #endif
91
92         .set_curr_task          = set_curr_task_idle,
93         .task_tick              = task_tick_idle,
94
95         .get_rr_interval        = get_rr_interval_idle,
96
97         .prio_changed           = prio_changed_idle,
98         .switched_to            = switched_to_idle,
99 };