sched: Rename sync arguments
[linux-2.6.git] / kernel / sched_idletask.c
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 #ifdef CONFIG_SMP
9 static int select_task_rq_idle(struct task_struct *p, int sd_flag, int flags)
10 {
11         return task_cpu(p); /* IDLE tasks as never migrated */
12 }
13 #endif /* CONFIG_SMP */
14 /*
15  * Idle tasks are unconditionally rescheduled:
16  */
17 static void check_preempt_curr_idle(struct rq *rq, struct task_struct *p, int flags)
18 {
19         resched_task(rq->idle);
20 }
21
22 static struct task_struct *pick_next_task_idle(struct rq *rq)
23 {
24         schedstat_inc(rq, sched_goidle);
25         /* adjust the active tasks as we might go into a long sleep */
26         calc_load_account_active(rq);
27         return rq->idle;
28 }
29
30 /*
31  * It is not legal to sleep in the idle task - print a warning
32  * message if some code attempts to do it:
33  */
34 static void
35 dequeue_task_idle(struct rq *rq, struct task_struct *p, int sleep)
36 {
37         spin_unlock_irq(&rq->lock);
38         printk(KERN_ERR "bad: scheduling from the idle thread!\n");
39         dump_stack();
40         spin_lock_irq(&rq->lock);
41 }
42
43 static void put_prev_task_idle(struct rq *rq, struct task_struct *prev)
44 {
45 }
46
47 #ifdef CONFIG_SMP
48 static unsigned long
49 load_balance_idle(struct rq *this_rq, int this_cpu, struct rq *busiest,
50                   unsigned long max_load_move,
51                   struct sched_domain *sd, enum cpu_idle_type idle,
52                   int *all_pinned, int *this_best_prio)
53 {
54         return 0;
55 }
56
57 static int
58 move_one_task_idle(struct rq *this_rq, int this_cpu, struct rq *busiest,
59                    struct sched_domain *sd, enum cpu_idle_type idle)
60 {
61         return 0;
62 }
63 #endif
64
65 static void task_tick_idle(struct rq *rq, struct task_struct *curr, int queued)
66 {
67 }
68
69 static void set_curr_task_idle(struct rq *rq)
70 {
71 }
72
73 static void switched_to_idle(struct rq *rq, struct task_struct *p,
74                              int running)
75 {
76         /* Can this actually happen?? */
77         if (running)
78                 resched_task(rq->curr);
79         else
80                 check_preempt_curr(rq, p, 0);
81 }
82
83 static void prio_changed_idle(struct rq *rq, struct task_struct *p,
84                               int oldprio, int running)
85 {
86         /* This can happen for hot plug CPUS */
87
88         /*
89          * Reschedule if we are currently running on this runqueue and
90          * our priority decreased, or if we are not currently running on
91          * this runqueue and our priority is higher than the current's
92          */
93         if (running) {
94                 if (p->prio > oldprio)
95                         resched_task(rq->curr);
96         } else
97                 check_preempt_curr(rq, p, 0);
98 }
99
100 /*
101  * Simple, special scheduling class for the per-CPU idle tasks:
102  */
103 static const struct sched_class idle_sched_class = {
104         /* .next is NULL */
105         /* no enqueue/yield_task for idle tasks */
106
107         /* dequeue is not valid, we print a debug message there: */
108         .dequeue_task           = dequeue_task_idle,
109
110         .check_preempt_curr     = check_preempt_curr_idle,
111
112         .pick_next_task         = pick_next_task_idle,
113         .put_prev_task          = put_prev_task_idle,
114
115 #ifdef CONFIG_SMP
116         .select_task_rq         = select_task_rq_idle,
117
118         .load_balance           = load_balance_idle,
119         .move_one_task          = move_one_task_idle,
120 #endif
121
122         .set_curr_task          = set_curr_task_idle,
123         .task_tick              = task_tick_idle,
124
125         .prio_changed           = prio_changed_idle,
126         .switched_to            = switched_to_idle,
127
128         /* no .task_new for idle tasks */
129 };