perf: Fix double start/stop in x86_pmu_start()
[linux-2.6.git] / kernel / sched / stop_task.c
1 #include "sched.h"
2
3 /*
4  * stop-task scheduling class.
5  *
6  * The stop task is the highest priority task in the system, it preempts
7  * everything and will be preempted by nothing.
8  *
9  * See kernel/stop_machine.c
10  */
11
12 #ifdef CONFIG_SMP
13 static int
14 select_task_rq_stop(struct task_struct *p, int sd_flag, int flags)
15 {
16         return task_cpu(p); /* stop tasks as never migrate */
17 }
18 #endif /* CONFIG_SMP */
19
20 static void
21 check_preempt_curr_stop(struct rq *rq, struct task_struct *p, int flags)
22 {
23         /* we're never preempted */
24 }
25
26 static struct task_struct *pick_next_task_stop(struct rq *rq)
27 {
28         struct task_struct *stop = rq->stop;
29
30         if (stop && stop->on_rq)
31                 return stop;
32
33         return NULL;
34 }
35
36 static void
37 enqueue_task_stop(struct rq *rq, struct task_struct *p, int flags)
38 {
39         inc_nr_running(rq);
40 }
41
42 static void
43 dequeue_task_stop(struct rq *rq, struct task_struct *p, int flags)
44 {
45         dec_nr_running(rq);
46 }
47
48 static void yield_task_stop(struct rq *rq)
49 {
50         BUG(); /* the stop task should never yield, its pointless. */
51 }
52
53 static void put_prev_task_stop(struct rq *rq, struct task_struct *prev)
54 {
55 }
56
57 static void task_tick_stop(struct rq *rq, struct task_struct *curr, int queued)
58 {
59 }
60
61 static void set_curr_task_stop(struct rq *rq)
62 {
63 }
64
65 static void switched_to_stop(struct rq *rq, struct task_struct *p)
66 {
67         BUG(); /* its impossible to change to this class */
68 }
69
70 static void
71 prio_changed_stop(struct rq *rq, struct task_struct *p, int oldprio)
72 {
73         BUG(); /* how!?, what priority? */
74 }
75
76 static unsigned int
77 get_rr_interval_stop(struct rq *rq, struct task_struct *task)
78 {
79         return 0;
80 }
81
82 /*
83  * Simple, special scheduling class for the per-CPU stop tasks:
84  */
85 const struct sched_class stop_sched_class = {
86         .next                   = &rt_sched_class,
87
88         .enqueue_task           = enqueue_task_stop,
89         .dequeue_task           = dequeue_task_stop,
90         .yield_task             = yield_task_stop,
91
92         .check_preempt_curr     = check_preempt_curr_stop,
93
94         .pick_next_task         = pick_next_task_stop,
95         .put_prev_task          = put_prev_task_stop,
96
97 #ifdef CONFIG_SMP
98         .select_task_rq         = select_task_rq_stop,
99 #endif
100
101         .set_curr_task          = set_curr_task_stop,
102         .task_tick              = task_tick_stop,
103
104         .get_rr_interval        = get_rr_interval_stop,
105
106         .prio_changed           = prio_changed_stop,
107         .switched_to            = switched_to_stop,
108 };