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/*
* idle-task scheduling class.
*
* (NOTE: these are not related to SCHED_IDLE tasks which are
* handled in sched_fair.c)
*/
#ifdef CONFIG_SMP
static int select_task_rq_idle(struct task_struct *p, int sd_flag, int sync)
{
return task_cpu(p); /* IDLE tasks as never migrated */
}
#endif /* CONFIG_SMP */
/*
* Idle tasks are unconditionally rescheduled:
*/
static void check_preempt_curr_idle(struct rq *rq, struct task_struct *p, int sync)
{
resched_task(rq->idle);
}
static struct task_struct *pick_next_task_idle(struct rq *rq)
{
schedstat_inc(rq, sched_goidle);
/* adjust the active tasks as we might go into a long sleep */
calc_load_account_active(rq);
return rq->idle;
}
/*
* It is not legal to sleep in the idle task - print a warning
* message if some code attempts to do it:
*/
static void
dequeue_task_idle(struct rq *rq, struct task_struct *p, int sleep)
{
spin_unlock_irq(&rq->lock);
printk(KERN_ERR "bad: scheduling from the idle thread!\n");
dump_stack();
spin_lock_irq(&rq->lock);
}
static void put_prev_task_idle(struct rq *rq, struct task_struct *prev)
{
}
#ifdef CONFIG_SMP
static unsigned long
load_balance_idle(struct rq *this_rq, int this_cpu, struct rq *busiest,
unsigned long max_load_move,
struct sched_domain *sd, enum cpu_idle_type idle,
int *all_pinned, int *this_best_prio)
{
return 0;
}
static int
move_one_task_idle(struct rq *this_rq, int this_cpu, struct rq *busiest,
struct sched_domain *sd, enum cpu_idle_type idle)
{
return 0;
}
#endif
static void task_tick_idle(struct rq *rq, struct task_struct *curr, int queued)
{
}
static void set_curr_task_idle(struct rq *rq)
{
}
static void switched_to_idle(struct rq *rq, struct task_struct *p,
int running)
{
/* Can this actually happen?? */
if (running)
resched_task(rq->curr);
else
check_preempt_curr(rq, p, 0);
}
static void prio_changed_idle(struct rq *rq, struct task_struct *p,
int oldprio, int running)
{
/* This can happen for hot plug CPUS */
/*
* Reschedule if we are currently running on this runqueue and
* our priority decreased, or if we are not currently running on
* this runqueue and our priority is higher than the current's
*/
if (running) {
if (p->prio > oldprio)
resched_task(rq->curr);
} else
check_preempt_curr(rq, p, 0);
}
/*
* Simple, special scheduling class for the per-CPU idle tasks:
*/
static const struct sched_class idle_sched_class = {
/* .next is NULL */
/* no enqueue/yield_task for idle tasks */
/* dequeue is not valid, we print a debug message there: */
.dequeue_task = dequeue_task_idle,
.check_preempt_curr = check_preempt_curr_idle,
.pick_next_task = pick_next_task_idle,
.put_prev_task = put_prev_task_idle,
#ifdef CONFIG_SMP
.select_task_rq = select_task_rq_idle,
.load_balance = load_balance_idle,
.move_one_task = move_one_task_idle,
#endif
.set_curr_task = set_curr_task_idle,
.task_tick = task_tick_idle,
.prio_changed = prio_changed_idle,
.switched_to = switched_to_idle,
/* no .task_new for idle tasks */
};
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