1 files changed, 99 insertions, 0 deletions

diff --git a/kernel/sched/idle_task.c b/kernel/sched/idle_task.c
new file mode 100644
index 000000000000..91b4c957f289
--- /dev/null
+++ b/kernel/sched/idle_task.c
@@ -0,0 +1,99 @@
+#include "sched.h"
+
+/*
+ * 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 flags)
+{
+        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 flags)
+{
+        resched_task(rq->idle);
+}
+
+static struct task_struct *pick_next_task_idle(struct rq *rq)
+{
+        schedstat_inc(rq, sched_goidle);
+        calc_load_account_idle(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 flags)
+{
+        raw_spin_unlock_irq(&rq->lock);
+        printk(KERN_ERR "bad: scheduling from the idle thread!\n");
+        dump_stack();
+        raw_spin_lock_irq(&rq->lock);
+}
+
+static void put_prev_task_idle(struct rq *rq, struct task_struct *prev)
+{
+}
+
+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)
+{
+        BUG();
+}
+
+static void
+prio_changed_idle(struct rq *rq, struct task_struct *p, int oldprio)
+{
+        BUG();
+}
+
+static unsigned int get_rr_interval_idle(struct rq *rq, struct task_struct *task)
+{
+        return 0;
+}
+
+/*
+ * Simple, special scheduling class for the per-CPU idle tasks:
+ */
+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,
+#endif
+
+        .set_curr_task          = set_curr_task_idle,
+        .task_tick              = task_tick_idle,
+
+        .get_rr_interval        = get_rr_interval_idle,
+
+        .prio_changed           = prio_changed_idle,
+        .switched_to            = switched_to_idle,
+};