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 11static int 12select_task_rq_idle(struct task_struct *p, int cpu, int sd_flag, int flags) 13{ 14 return task_cpu(p); /* IDLE tasks as never migrated */ 15} 16#endif /* CONFIG_SMP */ 17 18/* 19 * Idle tasks are unconditionally rescheduled: 20 */ 21static void check_preempt_curr_idle(struct rq *rq, struct task_struct *p, int flags) 22{ 23 resched_curr(rq); 24} 25 26static struct task_struct * 27pick_next_task_idle(struct rq *rq, struct task_struct *prev) 28{ 29 put_prev_task(rq, prev); 30 31 schedstat_inc(rq, sched_goidle); 32 return rq->idle; 33} 34 35/* 36 * It is not legal to sleep in the idle task - print a warning 37 * message if some code attempts to do it: 38 */ 39static void 40dequeue_task_idle(struct rq *rq, struct task_struct *p, int flags) 41{ 42 raw_spin_unlock_irq(&rq->lock); 43 printk(KERN_ERR "bad: scheduling from the idle thread!\n"); 44 dump_stack(); 45 raw_spin_lock_irq(&rq->lock); 46} 47 48static void put_prev_task_idle(struct rq *rq, struct task_struct *prev) 49{ 50 idle_exit_fair(rq); 51 rq_last_tick_reset(rq); 52} 53 54static void task_tick_idle(struct rq *rq, struct task_struct *curr, int queued) 55{ 56} 57 58static void set_curr_task_idle(struct rq *rq) 59{ 60} 61 62static void switched_to_idle(struct rq *rq, struct task_struct *p) 63{ 64 BUG(); 65} 66 67static void 68prio_changed_idle(struct rq *rq, struct task_struct *p, int oldprio) 69{ 70 BUG(); 71} 72 73static unsigned int get_rr_interval_idle(struct rq *rq, struct task_struct *task) 74{ 75 return 0; 76} 77 78static void update_curr_idle(struct rq *rq) 79{ 80} 81 82/* 83 * Simple, special scheduling class for the per-CPU idle tasks: 84 */ 85const struct sched_class idle_sched_class = { 86 /* .next is NULL */ 87 /* no enqueue/yield_task for idle tasks */ 88 89 /* dequeue is not valid, we print a debug message there: */ 90 .dequeue_task = dequeue_task_idle, 91 92 .check_preempt_curr = check_preempt_curr_idle, 93 94 .pick_next_task = pick_next_task_idle, 95 .put_prev_task = put_prev_task_idle, 96 97#ifdef CONFIG_SMP 98 .select_task_rq = select_task_rq_idle, 99#endif 100 101 .set_curr_task = set_curr_task_idle, 102 .task_tick = task_tick_idle, 103 104 .get_rr_interval = get_rr_interval_idle, 105 106 .prio_changed = prio_changed_idle, 107 .switched_to = switched_to_idle, 108 .update_curr = update_curr_idle, 109}; 110