1 files changed, 180 insertions, 0 deletions
diff --git a/kernel/sched/stop_task.c b/kernel/sched/stop_task.c
new file mode 100644
index 000000000000..3278c81cefb1
--- /dev/null
+++ b/kernel/sched/stop_task.c
@@ -0,0 +1,180 @@
+#include "sched.h"
+
+/*
+ * 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 task_struct *p, int cpu, int sd_flag, int flags,
+		    int sibling_count_hint)
+{
+	return task_cpu(p); /* stop tasks as never migrate */
+}
+#endif /* CONFIG_SMP */
+
+#ifdef CONFIG_SCHED_HMP
+
+static void
+inc_hmp_sched_stats_stop(struct rq *rq, struct task_struct *p)
+{
+	inc_cumulative_runnable_avg(&rq->hmp_stats, p);
+}
+
+static void
+dec_hmp_sched_stats_stop(struct rq *rq, struct task_struct *p)
+{
+	dec_cumulative_runnable_avg(&rq->hmp_stats, p);
+}
+
+static void
+fixup_hmp_sched_stats_stop(struct rq *rq, struct task_struct *p,
+			   u32 new_task_load, u32 new_pred_demand)
+{
+	s64 task_load_delta = (s64)new_task_load - task_load(p);
+	s64 pred_demand_delta = PRED_DEMAND_DELTA;
+
+	fixup_cumulative_runnable_avg(&rq->hmp_stats, p, task_load_delta,
+				      pred_demand_delta);
+}
+
+#else	/* CONFIG_SCHED_HMP */
+
+static inline void
+inc_hmp_sched_stats_stop(struct rq *rq, struct task_struct *p) { }
+
+static inline void
+dec_hmp_sched_stats_stop(struct rq *rq, struct task_struct *p) { }
+
+#endif	/* CONFIG_SCHED_HMP */
+
+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 *prev)
+{
+	struct task_struct *stop = rq->stop;
+
+	if (!stop || !task_on_rq_queued(stop))
+		return NULL;
+
+	put_prev_task(rq, prev);
+
+	stop->se.exec_start = rq_clock_task(rq);
+
+	return stop;
+}
+
+static void
+enqueue_task_stop(struct rq *rq, struct task_struct *p, int flags)
+{
+	add_nr_running(rq, 1);
+	inc_hmp_sched_stats_stop(rq, p);
+}
+
+static void
+dequeue_task_stop(struct rq *rq, struct task_struct *p, int flags)
+{
+	sub_nr_running(rq, 1);
+	dec_hmp_sched_stats_stop(rq, p);
+}
+
+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)
+{
+	struct task_struct *curr = rq->curr;
+	u64 delta_exec;
+
+	delta_exec = rq_clock_task(rq) - curr->se.exec_start;
+	if (unlikely((s64)delta_exec < 0))
+		delta_exec = 0;
+
+	schedstat_set(curr->se.statistics.exec_max,
+			max(curr->se.statistics.exec_max, delta_exec));
+
+	curr->se.sum_exec_runtime += delta_exec;
+	account_group_exec_runtime(curr, delta_exec);
+
+	curr->se.exec_start = rq_clock_task(rq);
+	cpuacct_charge(curr, delta_exec);
+}
+
+static void task_tick_stop(struct rq *rq, struct task_struct *curr, int queued)
+{
+}
+
+static void set_curr_task_stop(struct rq *rq)
+{
+	struct task_struct *stop = rq->stop;
+
+	stop->se.exec_start = rq_clock_task(rq);
+}
+
+static void switched_to_stop(struct rq *rq, struct task_struct *p)
+{
+	BUG(); /* its impossible to change to this class */
+}
+
+static void
+prio_changed_stop(struct rq *rq, struct task_struct *p, int oldprio)
+{
+	BUG(); /* how!?, what priority? */
+}
+
+static unsigned int
+get_rr_interval_stop(struct rq *rq, struct task_struct *task)
+{
+	return 0;
+}
+
+static void update_curr_stop(struct rq *rq)
+{
+}
+
+/*
+ * Simple, special scheduling class for the per-CPU stop tasks:
+ */
+const struct sched_class stop_sched_class = {
+	.next			= &dl_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,
+
+#ifdef CONFIG_SMP
+	.select_task_rq		= select_task_rq_stop,
+	.set_cpus_allowed	= set_cpus_allowed_common,
+#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,
+	.update_curr		= update_curr_stop,
+#ifdef CONFIG_SCHED_HMP
+	.inc_hmp_sched_stats	= inc_hmp_sched_stats_stop,
+	.dec_hmp_sched_stats	= dec_hmp_sched_stats_stop,
+	.fixup_hmp_sched_stats	= fixup_hmp_sched_stats_stop,
+#endif
+};