/*
* stop-task scheduling class.
*
* The stop task is the highest priority task in the system, it preempts
* everything and will be preempted by nothing.
* See kernel/stop_machine.c
*/
#ifdef CONFIG_SMP
static int
select_task_rq_stop(struct rq *rq, struct task_struct *p,
int sd_flag, int flags)
{
return task_cpu(p); /* stop tasks as never migrate */
}
#endif /* CONFIG_SMP */
static void
check_preempt_curr_stop(struct rq *rq, struct task_struct *p, int flags)
/* we're never preempted */
static struct task_struct *pick_next_task_stop(struct rq *rq)
struct task_struct *stop = rq->stop;
if (stop && stop->se.on_rq)
return stop;
return NULL;
enqueue_task_stop(struct rq *rq, struct task_struct *p, int flags)
dequeue_task_stop(struct rq *rq, struct task_struct *p, int flags)
static void yield_task_stop(struct rq *rq)
BUG(); /* the stop task should never yield, its pointless. */
static void put_prev_task_stop(struct rq *rq, struct task_struct *prev)
static void task_tick_stop(struct rq *rq, struct task_struct *curr, int queued)
static void set_curr_task_stop(struct rq *rq)
static void switched_to_stop(struct rq *rq, struct task_struct *p,
int running)
BUG(); /* its impossible to change to this class */
static void prio_changed_stop(struct rq *rq, struct task_struct *p,
int oldprio, int running)
BUG(); /* how!?, what priority? */
static unsigned int
get_rr_interval_stop(struct rq *rq, struct task_struct *task)
return 0;
* Simple, special scheduling class for the per-CPU stop tasks:
static const struct sched_class stop_sched_class = {
.next = &rt_sched_class,
.enqueue_task = enqueue_task_stop,
.dequeue_task = dequeue_task_stop,
.yield_task = yield_task_stop,
.check_preempt_curr = check_preempt_curr_stop,
.pick_next_task = pick_next_task_stop,
.put_prev_task = put_prev_task_stop,
.select_task_rq = select_task_rq_stop,
#endif
.set_curr_task = set_curr_task_stop,
.task_tick = task_tick_stop,
.get_rr_interval = get_rr_interval_stop,
.prio_changed = prio_changed_stop,
.switched_to = switched_to_stop,
/* no .task_new for stop tasks */
};