kernel/sched/rt.c

// SPDX-License-Identifier: GPL-2.0
/*
 * Real-Time Scheduling Class (mapped to the SCHED_FIFO and SCHED_RR
 * policies)
 */

#include "sched.h"

#include <linux/slab.h>
#include <linux/irq_work.h>
#include "tune.h"
#include <linux/ems.h>

#include "walt.h"
#include <trace/events/sched.h>

#ifdef CONFIG_SCHED_USE_FLUID_RT
struct frt_dom {
	unsigned int		coverage_ratio;
	unsigned int		coverage_thr;
	unsigned int		active_ratio;
	unsigned int		active_thr;
	int			coregroup;
	struct cpumask		cpus;

	/* It is updated to relfect the system idle situation */
	struct cpumask		*activated_cpus;

	struct list_head	list;
	struct frt_dom		*next;
	/* kobject for sysfs group */
	struct kobject		kobj;
};
struct cpumask activated_mask;
unsigned int frt_disable_cpufreq;

LIST_HEAD(frt_list);
DEFINE_RAW_SPINLOCK(frt_lock);

DEFINE_PER_CPU_SHARED_ALIGNED(struct frt_dom *, frt_rqs);

static struct kobject *frt_kobj;
#define RATIO_SCALE_SHIFT	10
#define cpu_util(rq) (rq->cfs.avg.util_avg + rq->rt.avg.util_avg)
#define ratio_scale(v, r) (((v) * (r) * 10) >> RATIO_SCALE_SHIFT)

static int frt_set_coverage_ratio(int cpu);
static int frt_set_active_ratio(int cpu);
struct frt_attr {
	struct attribute attr;
	ssize_t (*show)(struct kobject *, char *);
	ssize_t (*store)(struct kobject *, const char *, size_t count);
};

#define frt_attr_rw(_name)				\
static struct frt_attr _name##_attr =			\
__ATTR(_name, 0644, show_##_name, store_##_name)

#define frt_show(_name)								\
static ssize_t show_##_name(struct kobject *k, char *buf)			\
{										\
	struct frt_dom *dom = container_of(k, struct frt_dom, kobj);		\
										\
	return sprintf(buf, "%u\n", (unsigned int)dom->_name);			\
}

#define frt_store(_name, _type, _max)						\
static ssize_t store_##_name(struct kobject *k, const char *buf, size_t count)	\
{										\
	unsigned int val;							\
	struct frt_dom *dom = container_of(k, struct frt_dom, kobj);		\
										\
	if (!sscanf(buf, "%u", &val))						\
		return -EINVAL;							\
										\
	val = val > _max ? _max : val;						\
	dom->_name = (_type)val;						\
	frt_set_##_name(cpumask_first(&dom->cpus));				\
										\
	return count;								\
}

static ssize_t show_coverage_ratio(struct kobject *k, char *buf)
{
	struct frt_dom *dom = container_of(k, struct frt_dom, kobj);

	return sprintf(buf, "%u (%u)\n", dom->coverage_ratio, dom->coverage_thr);
}

static ssize_t show_active_ratio(struct kobject *k, char *buf)
{
	struct frt_dom *dom = container_of(k, struct frt_dom, kobj);

	return sprintf(buf, "%u (%u)\n", dom->active_ratio, dom->active_thr);
}

frt_store(coverage_ratio, int, 100);
frt_attr_rw(coverage_ratio);
frt_store(active_ratio, int, 100);
frt_attr_rw(active_ratio);

static ssize_t show(struct kobject *kobj, struct attribute *at, char *buf)
{
	struct frt_attr *frtattr = container_of(at, struct frt_attr, attr);

	return frtattr->show(kobj, buf);
}

static ssize_t store(struct kobject *kobj, struct attribute *at,
		     const char *buf, size_t count)
{
	struct frt_attr *frtattr = container_of(at, struct frt_attr, attr);

	return frtattr->store(kobj, buf, count);
}

static const struct sysfs_ops frt_sysfs_ops = {
	.show	= show,
	.store	= store,
};

static struct attribute *dom_frt_attrs[] = {
	&coverage_ratio_attr.attr,
	&active_ratio_attr.attr,
	NULL
};
static struct kobj_type ktype_frt = {
	.sysfs_ops	= &frt_sysfs_ops,
	.default_attrs	= dom_frt_attrs,
};

static ssize_t store_disable_cpufreq(struct kobject *kobj,
		struct kobj_attribute *attr, const char *buf,
		size_t count)
{
	unsigned int val;
	if (!sscanf(buf, "%u", &val))
		return -EINVAL;
	frt_disable_cpufreq = val;
	return count;
}

static ssize_t show_disable_cpufreq(struct kobject *kobj,
		struct kobj_attribute *attr, char *buf)
{
	return sprintf(buf, "%u\n", frt_disable_cpufreq);
}

static struct kobj_attribute disable_cpufreq_attr =
__ATTR(disable_cpufreq, 0644, show_disable_cpufreq, store_disable_cpufreq);

static struct attribute *frt_attrs[] = {
	&disable_cpufreq_attr.attr,
	NULL,
};

static const struct attribute_group frt_group = {
	.attrs = frt_attrs,
};

static struct task_struct *pick_highest_pushable_task(struct rq *rq, int cpu);
static inline int has_pushable_tasks(struct rq *rq);

#define MIN_RUNNABLE_THRESHOLD	(500000)
static bool frt_short_runnable(struct task_struct *p)
{
	return ktime_get_ns() - p->last_waked_ns < MIN_RUNNABLE_THRESHOLD;
}

static bool frt_sched_runnable(struct rq *rq)
{
	return rq->rt.rt_queued > 0;
}

int frt_idle_pull_tasks(struct rq *dst_rq)
{
	struct rq *src_rq;
	struct task_struct *pulled_task;
	int cpu, src_cpu = -1, dst_cpu = dst_rq->cpu, ret = 0;

	if (frt_sched_runnable(dst_rq))
		return 0;

	for_each_possible_cpu(cpu) {
		if (has_pushable_tasks(cpu_rq(cpu))) {
			src_cpu = cpu;
			break;
		}
	}

	if (src_cpu == -1)
		return 0;

	src_rq = cpu_rq(src_cpu);
	double_lock_balance(dst_rq, src_rq);

	if (frt_sched_runnable(dst_rq))
		goto out;

	pulled_task = pick_highest_pushable_task(src_rq, dst_cpu);
	if (!pulled_task)
		goto out;

	if (frt_short_runnable(pulled_task))
		goto out;

	deactivate_task(src_rq, pulled_task, 0);
	pulled_task->on_rq = TASK_ON_RQ_MIGRATING;
	set_task_cpu(pulled_task, dst_cpu);
	pulled_task->on_rq = TASK_ON_RQ_QUEUED;
	activate_task(dst_rq, pulled_task, 0);
	ret = 1;

out:
	if (ret)
		trace_sched_frt_idle_pull_tasks(pulled_task, src_cpu, dst_cpu);

	double_unlock_balance(dst_rq, src_rq);

	return ret;
}

static int frt_find_prefer_cpu(struct task_struct *task)
{
	int cpu, allowed_cpu = 0;
	unsigned int coverage_thr;
	struct frt_dom *dom;

	list_for_each_entry(dom, &frt_list, list) {
		coverage_thr = per_cpu(frt_rqs, cpumask_first(&dom->cpus))->coverage_thr;
		for_each_cpu_and(cpu, &task->cpus_allowed, &dom->cpus) {
			allowed_cpu = cpu;
			if (task->rt.avg.util_avg < coverage_thr)
				return allowed_cpu;
		}
	}
	return allowed_cpu;
}

static int frt_set_active_ratio(int cpu)
{
	unsigned long capacity;
	struct frt_dom *dom = per_cpu(frt_rqs, cpu);

	if (!dom || !cpu_active(cpu))
		return -1;

	capacity = get_cpu_max_capacity(cpu) *
			cpumask_weight(cpu_coregroup_mask(cpu));
	dom->active_thr = ratio_scale(capacity, dom->active_ratio);

	return 0;
}

static int frt_set_coverage_ratio(int cpu)
{
	unsigned long capacity;
	struct frt_dom *dom = per_cpu(frt_rqs, cpu);

	if (!dom || !cpu_active(cpu))
		return -1;

	capacity = get_cpu_max_capacity(cpu);
	dom->coverage_thr = ratio_scale(capacity, dom->coverage_ratio);

	return 0;
}

static const struct cpumask *get_activated_cpus(void)
{
	struct frt_dom *dom = per_cpu(frt_rqs, 0);
	if (dom)
		return dom->activated_cpus;
	return cpu_active_mask;
}

static void update_activated_cpus(void)
{
	struct frt_dom *dom, *prev_idle_dom = NULL;
	struct cpumask mask;
	unsigned long flags;

	if (!raw_spin_trylock_irqsave(&frt_lock, flags))
		return;

	cpumask_setall(&mask);
	list_for_each_entry_reverse(dom, &frt_list, list) {
		unsigned long dom_util_sum = 0;
		unsigned long dom_active_thr = 0;
		unsigned long capacity;
		struct cpumask active_cpus;
		int first_cpu, cpu;

		cpumask_and(&active_cpus, &dom->cpus, cpu_active_mask);
		first_cpu = cpumask_first(&active_cpus);
		/* all cpus of domain is offed */
		if (first_cpu == NR_CPUS)
			continue;

		for_each_cpu(cpu, &active_cpus) {
			struct rq *rq = cpu_rq(cpu);
			dom_util_sum += cpu_util(rq);
		}

		capacity = get_cpu_max_capacity(first_cpu) * cpumask_weight(&active_cpus);
		dom_active_thr = ratio_scale(capacity, dom->active_ratio);

		/* domain is idle */
		if (dom_util_sum < dom_active_thr) {
			/* if prev domain is also idle, clear prev domain cpus */
			if (prev_idle_dom)
				cpumask_andnot(&mask, &mask, &prev_idle_dom->cpus);
			prev_idle_dom = dom;
		}

		trace_sched_fluid_activated_cpus(first_cpu, dom_util_sum,
			dom_active_thr, *(unsigned int *)cpumask_bits(&mask));

		/* this is first domain, do update activated_cpus */
		if (first_cpu == 0)
			cpumask_copy(dom->activated_cpus, &mask);
	}
	raw_spin_unlock_irqrestore(&frt_lock, flags);
}


static int __init frt_sysfs_init(void)
{
	struct frt_dom *dom;

	if (list_empty(&frt_list))
		return 0;

	frt_kobj = kobject_create_and_add("frt", ems_kobj);
	if (!frt_kobj)
		goto out;

	/* Add frt sysfs node for each coregroup */
	list_for_each_entry(dom, &frt_list, list) {
		if (kobject_init_and_add(&dom->kobj, &ktype_frt,
				frt_kobj, "coregroup%d", dom->coregroup))
			goto out;
	}

	/* add frt syfs for global control */
	if (sysfs_create_group(frt_kobj, &frt_group))
		goto out;

	return 0;

out:
	pr_err("FRT(%s): failed to create sysfs node\n", __func__);
	return -EINVAL;
}

static void frt_parse_dt(struct device_node *dn, struct frt_dom *dom, int cnt)
{
	struct device_node *frt, *coregroup;
	char name[15];

	frt = of_get_child_by_name(dn, "frt");
	if (!frt)
		goto disable;

	snprintf(name, sizeof(name), "coregroup%d", cnt);
	coregroup = of_get_child_by_name(frt, name);
	if (!coregroup)
		goto disable;
	dom->coregroup = cnt;

	of_property_read_u32(coregroup, "coverage-ratio", &dom->coverage_ratio);
	if (!dom->coverage_ratio)
		dom->coverage_ratio = 100;

	of_property_read_u32(coregroup, "active-ratio", &dom->active_ratio);
	if (!dom->active_ratio)
		dom->active_thr = 0;

	return;

disable:
	dom->coregroup = cnt;
	dom->coverage_ratio = 100;
	dom->active_thr = 0;
	pr_err("FRT(%s): failed to parse frt node\n", __func__);
}

static int __init init_frt(void)
{
	struct frt_dom *dom, *prev = NULL, *head = NULL;
	struct device_node *dn;
	int cpu, tcpu, cnt = 0;

	dn = of_find_node_by_path("/cpus/ems");
	if (!dn)
		return 0;

	INIT_LIST_HEAD(&frt_list);
	cpumask_setall(&activated_mask);

	for_each_possible_cpu(cpu) {
		if (cpu != cpumask_first(cpu_coregroup_mask(cpu)))
			continue;

		dom = kzalloc(sizeof(struct frt_dom), GFP_KERNEL);
		if (!dom) {
			pr_err("FRT(%s): failed to allocate dom\n", __func__);
			goto put_node;
		}

		if (head == NULL)
			head = dom;

		dom->activated_cpus = &activated_mask;

		cpumask_copy(&dom->cpus, cpu_coregroup_mask(cpu));

		frt_parse_dt(dn, dom, cnt++);

		dom->next = head;
		if (prev)
			prev->next = dom;
		prev = dom;

		for_each_cpu(tcpu, &dom->cpus)
			per_cpu(frt_rqs, tcpu) = dom;

		frt_set_coverage_ratio(cpu);
		frt_set_active_ratio(cpu);

		list_add_tail(&dom->list, &frt_list);
	}
	frt_sysfs_init();

put_node:
	of_node_put(dn);

	return 0;

} late_initcall(init_frt);
#else
static inline void update_activated_cpus(void) { };
#endif

int sched_rr_timeslice = RR_TIMESLICE;
int sysctl_sched_rr_timeslice = (MSEC_PER_SEC * RR_TIMESLICE) / HZ;

void update_rt_load_avg(u64 now, struct sched_rt_entity *rt_se);

static int do_sched_rt_period_timer(struct rt_bandwidth *rt_b, int overrun);

struct rt_bandwidth def_rt_bandwidth;

static enum hrtimer_restart sched_rt_period_timer(struct hrtimer *timer)
{
	struct rt_bandwidth *rt_b =
		container_of(timer, struct rt_bandwidth, rt_period_timer);
	int idle = 0;
	int overrun;

	raw_spin_lock(&rt_b->rt_runtime_lock);
	for (;;) {
		overrun = hrtimer_forward_now(timer, rt_b->rt_period);
		if (!overrun)
			break;

		raw_spin_unlock(&rt_b->rt_runtime_lock);
		idle = do_sched_rt_period_timer(rt_b, overrun);
		raw_spin_lock(&rt_b->rt_runtime_lock);
	}
	if (idle)
		rt_b->rt_period_active = 0;
	raw_spin_unlock(&rt_b->rt_runtime_lock);

	return idle ? HRTIMER_NORESTART : HRTIMER_RESTART;
}

void init_rt_bandwidth(struct rt_bandwidth *rt_b, u64 period, u64 runtime)
{
	rt_b->rt_period = ns_to_ktime(period);
	rt_b->rt_runtime = runtime;

	raw_spin_lock_init(&rt_b->rt_runtime_lock);

	hrtimer_init(&rt_b->rt_period_timer,
			CLOCK_MONOTONIC, HRTIMER_MODE_REL);
	rt_b->rt_period_timer.function = sched_rt_period_timer;
}

static inline void do_start_rt_bandwidth(struct rt_bandwidth *rt_b)
{
	raw_spin_lock(&rt_b->rt_runtime_lock);
	if (!rt_b->rt_period_active) {
		rt_b->rt_period_active = 1;
		/*
		 * SCHED_DEADLINE updates the bandwidth, as a run away
		 * RT task with a DL task could hog a CPU. But DL does
		 * not reset the period. If a deadline task was running
		 * without an RT task running, it can cause RT tasks to
		 * throttle when they start up. Kick the timer right away
		 * to update the period.
		 */
		hrtimer_forward_now(&rt_b->rt_period_timer, ns_to_ktime(0));
		hrtimer_start_expires(&rt_b->rt_period_timer, HRTIMER_MODE_ABS_PINNED);
	}
	raw_spin_unlock(&rt_b->rt_runtime_lock);
}

static void start_rt_bandwidth(struct rt_bandwidth *rt_b)
{
	if (!rt_bandwidth_enabled() || rt_b->rt_runtime == RUNTIME_INF)
		return;

	do_start_rt_bandwidth(rt_b);
}

void init_rt_rq(struct rt_rq *rt_rq)
{
	struct rt_prio_array *array;
	int i;

	array = &rt_rq->active;
	for (i = 0; i < MAX_RT_PRIO; i++) {
		INIT_LIST_HEAD(array->queue + i);
		__clear_bit(i, array->bitmap);
	}
	/* delimiter for bitsearch: */
	__set_bit(MAX_RT_PRIO, array->bitmap);

#if defined CONFIG_SMP
	rt_rq->highest_prio.curr = MAX_RT_PRIO;
	rt_rq->highest_prio.next = MAX_RT_PRIO;
	rt_rq->rt_nr_migratory = 0;
	rt_rq->overloaded = 0;
	plist_head_init(&rt_rq->pushable_tasks);
	atomic_long_set(&rt_rq->removed_util_avg, 0);
	atomic_long_set(&rt_rq->removed_load_avg, 0);
#endif /* CONFIG_SMP */
	/* We start is dequeued state, because no RT tasks are queued */
	rt_rq->rt_queued = 0;

	rt_rq->rt_time = 0;
	rt_rq->rt_throttled = 0;
	rt_rq->rt_runtime = 0;
	raw_spin_lock_init(&rt_rq->rt_runtime_lock);
}

#ifdef CONFIG_RT_GROUP_SCHED
static void destroy_rt_bandwidth(struct rt_bandwidth *rt_b)
{
	hrtimer_cancel(&rt_b->rt_period_timer);
}

#define rt_entity_is_task(rt_se) (!(rt_se)->my_q)

static inline struct task_struct *rt_task_of(struct sched_rt_entity *rt_se)
{
#ifdef CONFIG_SCHED_DEBUG
	WARN_ON_ONCE(!rt_entity_is_task(rt_se));
#endif
	return container_of(rt_se, struct task_struct, rt);
}

static inline struct rq *rq_of_rt_rq(struct rt_rq *rt_rq)
{
	return rt_rq->rq;
}

static inline struct rt_rq *rt_rq_of_se(struct sched_rt_entity *rt_se)
{
	return rt_se->rt_rq;
}

static inline struct rq *rq_of_rt_se(struct sched_rt_entity *rt_se)
{
	struct rt_rq *rt_rq = rt_se->rt_rq;

	return rt_rq->rq;
}

void free_rt_sched_group(struct task_group *tg)
{
	int i;

	if (tg->rt_se)
		destroy_rt_bandwidth(&tg->rt_bandwidth);

	for_each_possible_cpu(i) {
		if (tg->rt_rq)
			kfree(tg->rt_rq[i]);
		if (tg->rt_se)
			kfree(tg->rt_se[i]);
	}

	kfree(tg->rt_rq);
	kfree(tg->rt_se);
}

void init_tg_rt_entry(struct task_group *tg, struct rt_rq *rt_rq,
		struct sched_rt_entity *rt_se, int cpu,
		struct sched_rt_entity *parent)
{
	struct rq *rq = cpu_rq(cpu);

	rt_rq->highest_prio.curr = MAX_RT_PRIO;
	rt_rq->rt_nr_boosted = 0;
	rt_rq->rq = rq;
	rt_rq->tg = tg;

	tg->rt_rq[cpu] = rt_rq;
	tg->rt_se[cpu] = rt_se;

	if (!rt_se)
		return;

	if (!parent)
		rt_se->rt_rq = &rq->rt;
	else
		rt_se->rt_rq = parent->my_q;

	rt_se->my_q = rt_rq;
	rt_se->parent = parent;
	INIT_LIST_HEAD(&rt_se->run_list);
}

int alloc_rt_sched_group(struct task_group *tg, struct task_group *parent)
{
	struct rt_rq *rt_rq;
	struct sched_rt_entity *rt_se;
	int i;

	tg->rt_rq = kzalloc(sizeof(rt_rq) * nr_cpu_ids, GFP_KERNEL);
	if (!tg->rt_rq)
		goto err;
	tg->rt_se = kzalloc(sizeof(rt_se) * nr_cpu_ids, GFP_KERNEL);
	if (!tg->rt_se)
		goto err;

	init_rt_bandwidth(&tg->rt_bandwidth,
			ktime_to_ns(def_rt_bandwidth.rt_period), 0);

	for_each_possible_cpu(i) {
		rt_rq = kzalloc_node(sizeof(struct rt_rq),
				     GFP_KERNEL, cpu_to_node(i));
		if (!rt_rq)
			goto err;

		rt_se = kzalloc_node(sizeof(struct sched_rt_entity),
				     GFP_KERNEL, cpu_to_node(i));
		if (!rt_se)
			goto err_free_rq;

		init_rt_rq(rt_rq);
		rt_rq->rt_runtime = tg->rt_bandwidth.rt_runtime;
		init_tg_rt_entry(tg, rt_rq, rt_se, i, parent->rt_se[i]);
		init_rt_entity_runnable_average(rt_se);
	}

	return 1;

err_free_rq:
	kfree(rt_rq);
err:
	return 0;
}

#else /* CONFIG_RT_GROUP_SCHED */

#define rt_entity_is_task(rt_se) (1)

static inline struct task_struct *rt_task_of(struct sched_rt_entity *rt_se)
{
	return container_of(rt_se, struct task_struct, rt);
}

static inline struct rq *rq_of_rt_rq(struct rt_rq *rt_rq)
{
	return container_of(rt_rq, struct rq, rt);
}

static inline struct rq *rq_of_rt_se(struct sched_rt_entity *rt_se)
{
	struct task_struct *p = rt_task_of(rt_se);

	return task_rq(p);
}

static inline struct rt_rq *rt_rq_of_se(struct sched_rt_entity *rt_se)
{
	struct rq *rq = rq_of_rt_se(rt_se);

	return &rq->rt;
}

void free_rt_sched_group(struct task_group *tg) { }

int alloc_rt_sched_group(struct task_group *tg, struct task_group *parent)
{
	return 1;
}
#endif /* CONFIG_RT_GROUP_SCHED */

#ifdef CONFIG_SMP

#include "sched-pelt.h"
#define entity_is_task(se)	(!se->my_q)

extern u64 decay_load(u64 val, u64 n);

static u32 __accumulate_pelt_segments_rt(u64 periods, u32 d1, u32 d3)
{
	u32 c1, c2, c3 = d3;

	c1 = decay_load((u64)d1, periods);

	c2 = LOAD_AVG_MAX - decay_load(LOAD_AVG_MAX, periods) - 1024;

	return c1 + c2 + c3;
}

#define cap_scale(v, s) ((v)*(s) >> SCHED_CAPACITY_SHIFT)

static __always_inline u32
accumulate_sum_rt(u64 delta, int cpu, struct sched_avg *sa,
	       unsigned long weight, int running)
{
	unsigned long scale_freq, scale_cpu;
	u32 contrib = (u32)delta;
	u64 periods;

	scale_freq = arch_scale_freq_capacity(NULL, cpu);
	scale_cpu = arch_scale_cpu_capacity(NULL, cpu);

	delta += sa->period_contrib;
	periods = delta / 1024;

	if (periods) {
		sa->load_sum = decay_load(sa->load_sum, periods);
		sa->util_sum = decay_load((u64)(sa->util_sum), periods);

		delta %= 1024;
		contrib = __accumulate_pelt_segments_rt(periods,
				1024 - sa->period_contrib, delta);
	}
	sa->period_contrib = delta;

	contrib = cap_scale(contrib, scale_freq);
	if (weight) {
		sa->load_sum += weight * contrib;
	}
	if (running)
		sa->util_sum += (u32)(contrib * scale_cpu);

	return periods;
}

/*
 * We can represent the historical contribution to runnable average as the
 * coefficients of a geometric series, exactly like fair task load.
 * refer the ___update_load_avg @ fair sched class
 */
static __always_inline int
__update_load_avg(u64 now, int cpu, struct sched_avg *sa,
	unsigned long weight, int running, struct rt_rq *rt_rq)
{
	u64 delta;

	delta = now - sa->last_update_time;

	if ((s64)delta < 0) {
		sa->last_update_time = now;
		return 0;
	}

	delta >>= 10;
	if (!delta)
		return 0;

	sa->last_update_time += delta << 10;

	if (!weight)
		running = 0;

	if (!accumulate_sum_rt(delta, cpu, sa, weight, running))
		return 0;

	sa->load_avg = div_u64(sa->load_sum, LOAD_AVG_MAX - 1024 + sa->period_contrib);
	sa->util_avg = sa->util_sum / (LOAD_AVG_MAX - 1024 + sa->period_contrib);

	return 1;
}

static void pull_rt_task(struct rq *this_rq);

static inline bool need_pull_rt_task(struct rq *rq, struct task_struct *prev)
{
	/* Try to pull RT tasks here if we lower this rq's prio */
	return rq->rt.highest_prio.curr > prev->prio;
}

static inline int rt_overloaded(struct rq *rq)
{
	return atomic_read(&rq->rd->rto_count);
}

static inline void rt_set_overload(struct rq *rq)
{
	if (!rq->online)
		return;

	cpumask_set_cpu(rq->cpu, rq->rd->rto_mask);
	/*
	 * Make sure the mask is visible before we set
	 * the overload count. That is checked to determine
	 * if we should look at the mask. It would be a shame
	 * if we looked at the mask, but the mask was not
	 * updated yet.
	 *
	 * Matched by the barrier in pull_rt_task().
	 */
	smp_wmb();
	atomic_inc(&rq->rd->rto_count);
}

static inline void rt_clear_overload(struct rq *rq)
{
	if (!rq->online)
		return;

	/* the order here really doesn't matter */
	atomic_dec(&rq->rd->rto_count);
	cpumask_clear_cpu(rq->cpu, rq->rd->rto_mask);
}

static void update_rt_migration(struct rt_rq *rt_rq)
{
	if (rt_rq->rt_nr_migratory && rt_rq->rt_nr_total > 1) {
		if (!rt_rq->overloaded) {
			rt_set_overload(rq_of_rt_rq(rt_rq));
			rt_rq->overloaded = 1;
		}
	} else if (rt_rq->overloaded) {
		rt_clear_overload(rq_of_rt_rq(rt_rq));
		rt_rq->overloaded = 0;
	}
}

static void inc_rt_migration(struct sched_rt_entity *rt_se, struct rt_rq *rt_rq)
{
	struct task_struct *p;

	if (!rt_entity_is_task(rt_se))
		return;

	p = rt_task_of(rt_se);
	rt_rq = &rq_of_rt_rq(rt_rq)->rt;

	rt_rq->rt_nr_total++;
	if (p->nr_cpus_allowed > 1)
		rt_rq->rt_nr_migratory++;

	update_rt_migration(rt_rq);
}

static void dec_rt_migration(struct sched_rt_entity *rt_se, struct rt_rq *rt_rq)
{
	struct task_struct *p;

	if (!rt_entity_is_task(rt_se))
		return;

	p = rt_task_of(rt_se);
	rt_rq = &rq_of_rt_rq(rt_rq)->rt;

	rt_rq->rt_nr_total--;
	if (p->nr_cpus_allowed > 1)
		rt_rq->rt_nr_migratory--;

	update_rt_migration(rt_rq);
}

static inline int has_pushable_tasks(struct rq *rq)
{
	return !plist_head_empty(&rq->rt.pushable_tasks);
}

static DEFINE_PER_CPU(struct callback_head, rt_push_head);
static DEFINE_PER_CPU(struct callback_head, rt_pull_head);

static void push_rt_tasks(struct rq *);
static void pull_rt_task(struct rq *);

static inline void queue_push_tasks(struct rq *rq)
{
	if (!has_pushable_tasks(rq))
		return;

	queue_balance_callback(rq, &per_cpu(rt_push_head, rq->cpu), push_rt_tasks);
}

static inline void queue_pull_task(struct rq *rq)
{
	queue_balance_callback(rq, &per_cpu(rt_pull_head, rq->cpu), pull_rt_task);
}

static void enqueue_pushable_task(struct rq *rq, struct task_struct *p)
{
	plist_del(&p->pushable_tasks, &rq->rt.pushable_tasks);
	plist_node_init(&p->pushable_tasks, p->prio);
	plist_add(&p->pushable_tasks, &rq->rt.pushable_tasks);

	/* Update the highest prio pushable task */
	if (p->prio < rq->rt.highest_prio.next)
		rq->rt.highest_prio.next = p->prio;
}

static void dequeue_pushable_task(struct rq *rq, struct task_struct *p)
{
	plist_del(&p->pushable_tasks, &rq->rt.pushable_tasks);

	/* Update the new highest prio pushable task */
	if (has_pushable_tasks(rq)) {
		p = plist_first_entry(&rq->rt.pushable_tasks,
				      struct task_struct, pushable_tasks);
		rq->rt.highest_prio.next = p->prio;
	} else
		rq->rt.highest_prio.next = MAX_RT_PRIO;
}

#else

static inline void enqueue_pushable_task(struct rq *rq, struct task_struct *p)
{
}

static inline void dequeue_pushable_task(struct rq *rq, struct task_struct *p)
{
}

static inline
void inc_rt_migration(struct sched_rt_entity *rt_se, struct rt_rq *rt_rq)
{
}

static inline
void dec_rt_migration(struct sched_rt_entity *rt_se, struct rt_rq *rt_rq)
{
}

static inline bool need_pull_rt_task(struct rq *rq, struct task_struct *prev)
{
	return false;
}

static inline void pull_rt_task(struct rq *this_rq)
{
}

static inline void queue_push_tasks(struct rq *rq)
{
}
#endif /* CONFIG_SMP */

static void enqueue_top_rt_rq(struct rt_rq *rt_rq);
static void dequeue_top_rt_rq(struct rt_rq *rt_rq);

static inline int on_rt_rq(struct sched_rt_entity *rt_se)
{
	return rt_se->on_rq;
}

#ifdef CONFIG_RT_GROUP_SCHED

static inline u64 sched_rt_runtime(struct rt_rq *rt_rq)
{
	if (!rt_rq->tg)
		return RUNTIME_INF;

	return rt_rq->rt_runtime;
}

static inline u64 sched_rt_period(struct rt_rq *rt_rq)
{
	return ktime_to_ns(rt_rq->tg->rt_bandwidth.rt_period);
}

typedef struct task_group *rt_rq_iter_t;

static inline struct task_group *next_task_group(struct task_group *tg)
{
	do {
		tg = list_entry_rcu(tg->list.next,
			typeof(struct task_group), list);
	} while (&tg->list != &task_groups && task_group_is_autogroup(tg));

	if (&tg->list == &task_groups)
		tg = NULL;

	return tg;
}

#define for_each_rt_rq(rt_rq, iter, rq)					\
	for (iter = container_of(&task_groups, typeof(*iter), list);	\
		(iter = next_task_group(iter)) &&			\
		(rt_rq = iter->rt_rq[cpu_of(rq)]);)

#define for_each_sched_rt_entity(rt_se) \
	for (; rt_se; rt_se = rt_se->parent)

static inline struct rt_rq *group_rt_rq(struct sched_rt_entity *rt_se)
{
	return rt_se->my_q;
}

static void enqueue_rt_entity(struct sched_rt_entity *rt_se, unsigned int flags);
static void dequeue_rt_entity(struct sched_rt_entity *rt_se, unsigned int flags);

static void sched_rt_rq_enqueue(struct rt_rq *rt_rq)
{
	struct task_struct *curr = rq_of_rt_rq(rt_rq)->curr;
	struct rq *rq = rq_of_rt_rq(rt_rq);
	struct sched_rt_entity *rt_se;

	int cpu = cpu_of(rq);

	rt_se = rt_rq->tg->rt_se[cpu];

	if (rt_rq->rt_nr_running) {
		if (!rt_se)
			enqueue_top_rt_rq(rt_rq);
		else if (!on_rt_rq(rt_se))
			enqueue_rt_entity(rt_se, 0);

		if (rt_rq->highest_prio.curr < curr->prio)
			resched_curr(rq);
	}
}

static void sched_rt_rq_dequeue(struct rt_rq *rt_rq)
{
	struct sched_rt_entity *rt_se;
	int cpu = cpu_of(rq_of_rt_rq(rt_rq));

	rt_se = rt_rq->tg->rt_se[cpu];

	if (!rt_se)
		dequeue_top_rt_rq(rt_rq);
	else if (on_rt_rq(rt_se))
		dequeue_rt_entity(rt_se, 0);
}

static inline int rt_rq_throttled(struct rt_rq *rt_rq)
{
	return rt_rq->rt_throttled && !rt_rq->rt_nr_boosted;
}

static int rt_se_boosted(struct sched_rt_entity *rt_se)
{
	struct rt_rq *rt_rq = group_rt_rq(rt_se);
	struct task_struct *p;

	if (rt_rq)
		return !!rt_rq->rt_nr_boosted;

	p = rt_task_of(rt_se);
	return p->prio != p->normal_prio;
}

#ifdef CONFIG_SMP
static inline const struct cpumask *sched_rt_period_mask(void)
{
	return this_rq()->rd->span;
}
#else
static inline const struct cpumask *sched_rt_period_mask(void)
{
	return cpu_online_mask;
}
#endif

static inline
struct rt_rq *sched_rt_period_rt_rq(struct rt_bandwidth *rt_b, int cpu)
{
	return container_of(rt_b, struct task_group, rt_bandwidth)->rt_rq[cpu];
}

static inline struct rt_bandwidth *sched_rt_bandwidth(struct rt_rq *rt_rq)
{
	return &rt_rq->tg->rt_bandwidth;
}

#else /* !CONFIG_RT_GROUP_SCHED */

static inline u64 sched_rt_runtime(struct rt_rq *rt_rq)
{
	return rt_rq->rt_runtime;
}

static inline u64 sched_rt_period(struct rt_rq *rt_rq)
{
	return ktime_to_ns(def_rt_bandwidth.rt_period);
}

typedef struct rt_rq *rt_rq_iter_t;

#define for_each_rt_rq(rt_rq, iter, rq) \
	for ((void) iter, rt_rq = &rq->rt; rt_rq; rt_rq = NULL)

#define for_each_sched_rt_entity(rt_se) \
	for (; rt_se; rt_se = NULL)

static inline struct rt_rq *group_rt_rq(struct sched_rt_entity *rt_se)
{
	return NULL;
}

static inline void sched_rt_rq_enqueue(struct rt_rq *rt_rq)
{
	struct rq *rq = rq_of_rt_rq(rt_rq);

	if (!rt_rq->rt_nr_running)
		return;

	enqueue_top_rt_rq(rt_rq);
	resched_curr(rq);
}

static inline void sched_rt_rq_dequeue(struct rt_rq *rt_rq)
{
	dequeue_top_rt_rq(rt_rq);
}

static inline int rt_rq_throttled(struct rt_rq *rt_rq)
{
	return rt_rq->rt_throttled;
}

static inline const struct cpumask *sched_rt_period_mask(void)
{
	return cpu_online_mask;
}

static inline
struct rt_rq *sched_rt_period_rt_rq(struct rt_bandwidth *rt_b, int cpu)
{
	return &cpu_rq(cpu)->rt;
}

static inline struct rt_bandwidth *sched_rt_bandwidth(struct rt_rq *rt_rq)
{
	return &def_rt_bandwidth;
}

#endif /* CONFIG_RT_GROUP_SCHED */

bool sched_rt_bandwidth_account(struct rt_rq *rt_rq)
{
	struct rt_bandwidth *rt_b = sched_rt_bandwidth(rt_rq);

	return (hrtimer_active(&rt_b->rt_period_timer) ||
		rt_rq->rt_time < rt_b->rt_runtime);
}

#ifdef CONFIG_SMP
/*
 * We ran out of runtime, see if we can borrow some from our neighbours.
 */
static void do_balance_runtime(struct rt_rq *rt_rq)
{
	struct rt_bandwidth *rt_b = sched_rt_bandwidth(rt_rq);
	struct root_domain *rd = rq_of_rt_rq(rt_rq)->rd;
	int i, weight;
	u64 rt_period;

	weight = cpumask_weight(rd->span);

	raw_spin_lock(&rt_b->rt_runtime_lock);
	rt_period = ktime_to_ns(rt_b->rt_period);
	for_each_cpu(i, rd->span) {
		struct rt_rq *iter = sched_rt_period_rt_rq(rt_b, i);
		s64 diff;

		if (iter == rt_rq)
			continue;

		raw_spin_lock(&iter->rt_runtime_lock);
		/*
		 * Either all rqs have inf runtime and there's nothing to steal
		 * or __disable_runtime() below sets a specific rq to inf to
		 * indicate its been disabled and disalow stealing.
		 */
		if (iter->rt_runtime == RUNTIME_INF)
			goto next;

		/*
		 * From runqueues with spare time, take 1/n part of their
		 * spare time, but no more than our period.
		 */
		diff = iter->rt_runtime - iter->rt_time;
		if (diff > 0) {
			diff = div_u64((u64)diff, weight);
			if (rt_rq->rt_runtime + diff > rt_period)
				diff = rt_period - rt_rq->rt_runtime;
			iter->rt_runtime -= diff;
			rt_rq->rt_runtime += diff;
			if (rt_rq->rt_runtime == rt_period) {
				raw_spin_unlock(&iter->rt_runtime_lock);
				break;
			}
		}
next:
		raw_spin_unlock(&iter->rt_runtime_lock);
	}
	raw_spin_unlock(&rt_b->rt_runtime_lock);
}

/*
 * Ensure this RQ takes back all the runtime it lend to its neighbours.
 */
static void __disable_runtime(struct rq *rq)
{
	struct root_domain *rd = rq->rd;
	rt_rq_iter_t iter;
	struct rt_rq *rt_rq;

	if (unlikely(!scheduler_running))
		return;

	for_each_rt_rq(rt_rq, iter, rq) {
		struct rt_bandwidth *rt_b = sched_rt_bandwidth(rt_rq);
		s64 want;
		int i;

		raw_spin_lock(&rt_b->rt_runtime_lock);
		raw_spin_lock(&rt_rq->rt_runtime_lock);
		/*
		 * Either we're all inf and nobody needs to borrow, or we're
		 * already disabled and thus have nothing to do, or we have
		 * exactly the right amount of runtime to take out.
		 */
		if (rt_rq->rt_runtime == RUNTIME_INF ||
				rt_rq->rt_runtime == rt_b->rt_runtime)
			goto balanced;
		raw_spin_unlock(&rt_rq->rt_runtime_lock);

		/*
		 * Calculate the difference between what we started out with
		 * and what we current have, that's the amount of runtime
		 * we lend and now have to reclaim.
		 */
		want = rt_b->rt_runtime - rt_rq->rt_runtime;

		/*
		 * Greedy reclaim, take back as much as we can.
		 */
		for_each_cpu(i, rd->span) {
			struct rt_rq *iter = sched_rt_period_rt_rq(rt_b, i);
			s64 diff;

			/*
			 * Can't reclaim from ourselves or disabled runqueues.
			 */
			if (iter == rt_rq || iter->rt_runtime == RUNTIME_INF)
				continue;

			raw_spin_lock(&iter->rt_runtime_lock);
			if (want > 0) {
				diff = min_t(s64, iter->rt_runtime, want);
				iter->rt_runtime -= diff;
				want -= diff;
			} else {
				iter->rt_runtime -= want;
				want -= want;
			}
			raw_spin_unlock(&iter->rt_runtime_lock);

			if (!want)
				break;
		}

		raw_spin_lock(&rt_rq->rt_runtime_lock);
		/*
		 * We cannot be left wanting - that would mean some runtime
		 * leaked out of the system.
		 */
		BUG_ON(want);
balanced:
		/*
		 * Disable all the borrow logic by pretending we have inf
		 * runtime - in which case borrowing doesn't make sense.
		 */
		rt_rq->rt_runtime = RUNTIME_INF;
		rt_rq->rt_throttled = 0;
		raw_spin_unlock(&rt_rq->rt_runtime_lock);
		raw_spin_unlock(&rt_b->rt_runtime_lock);

		/* Make rt_rq available for pick_next_task() */
		sched_rt_rq_enqueue(rt_rq);
	}
}

static void __enable_runtime(struct rq *rq)
{
	rt_rq_iter_t iter;
	struct rt_rq *rt_rq;

	if (unlikely(!scheduler_running))
		return;

	/*
	 * Reset each runqueue's bandwidth settings
	 */
	for_each_rt_rq(rt_rq, iter, rq) {
		struct rt_bandwidth *rt_b = sched_rt_bandwidth(rt_rq);

		raw_spin_lock(&rt_b->rt_runtime_lock);
		raw_spin_lock(&rt_rq->rt_runtime_lock);
		rt_rq->rt_runtime = rt_b->rt_runtime;
		rt_rq->rt_time = 0;
		rt_rq->rt_throttled = 0;
		raw_spin_unlock(&rt_rq->rt_runtime_lock);
		raw_spin_unlock(&rt_b->rt_runtime_lock);
	}
}

static void balance_runtime(struct rt_rq *rt_rq)
{
	if (!sched_feat(RT_RUNTIME_SHARE))
		return;

	if (rt_rq->rt_time > rt_rq->rt_runtime) {
		raw_spin_unlock(&rt_rq->rt_runtime_lock);
		do_balance_runtime(rt_rq);
		raw_spin_lock(&rt_rq->rt_runtime_lock);
	}
}
#else /* !CONFIG_SMP */
static inline void balance_runtime(struct rt_rq *rt_rq) {}
#endif /* CONFIG_SMP */

static int do_sched_rt_period_timer(struct rt_bandwidth *rt_b, int overrun)
{
	int i, idle = 1, throttled = 0;
	const struct cpumask *span;

	span = sched_rt_period_mask();
#ifdef CONFIG_RT_GROUP_SCHED
	/*
	 * FIXME: isolated CPUs should really leave the root task group,
	 * whether they are isolcpus or were isolated via cpusets, lest
	 * the timer run on a CPU which does not service all runqueues,
	 * potentially leaving other CPUs indefinitely throttled.  If
	 * isolation is really required, the user will turn the throttle
	 * off to kill the perturbations it causes anyway.  Meanwhile,
	 * this maintains functionality for boot and/or troubleshooting.
	 */
	if (rt_b == &root_task_group.rt_bandwidth)
		span = cpu_online_mask;
#endif
	for_each_cpu(i, span) {
		int enqueue = 0;
		struct rt_rq *rt_rq = sched_rt_period_rt_rq(rt_b, i);
		struct rq *rq = rq_of_rt_rq(rt_rq);
		int skip;

		/*
		 * When span == cpu_online_mask, taking each rq->lock
		 * can be time-consuming. Try to avoid it when possible.
		 */
		raw_spin_lock(&rt_rq->rt_runtime_lock);
		if (!sched_feat(RT_RUNTIME_SHARE) && rt_rq->rt_runtime != RUNTIME_INF)
			rt_rq->rt_runtime = rt_b->rt_runtime;
		skip = !rt_rq->rt_time && !rt_rq->rt_nr_running;
		raw_spin_unlock(&rt_rq->rt_runtime_lock);
		if (skip)
			continue;

		raw_spin_lock(&rq->lock);
		update_rq_clock(rq);

		if (rt_rq->rt_time) {
			u64 runtime;

			raw_spin_lock(&rt_rq->rt_runtime_lock);
			if (rt_rq->rt_throttled)
				balance_runtime(rt_rq);
			runtime = rt_rq->rt_runtime;
			rt_rq->rt_time -= min(rt_rq->rt_time, overrun*runtime);
			if (rt_rq->rt_throttled && rt_rq->rt_time < runtime) {
				rt_rq->rt_throttled = 0;
				enqueue = 1;

				/*
				 * When we're idle and a woken (rt) task is
				 * throttled check_preempt_curr() will set
				 * skip_update and the time between the wakeup
				 * and this unthrottle will get accounted as
				 * 'runtime'.
				 */
				if (rt_rq->rt_nr_running && rq->curr == rq->idle)
					rq_clock_skip_update(rq, false);
			}
			if (rt_rq->rt_time || rt_rq->rt_nr_running)
				idle = 0;
			raw_spin_unlock(&rt_rq->rt_runtime_lock);
		} else if (rt_rq->rt_nr_running) {
			idle = 0;
			if (!rt_rq_throttled(rt_rq))
				enqueue = 1;
		}
		if (rt_rq->rt_throttled)
			throttled = 1;

		if (enqueue)
			sched_rt_rq_enqueue(rt_rq);
		raw_spin_unlock(&rq->lock);
	}

	if (!throttled && (!rt_bandwidth_enabled() || rt_b->rt_runtime == RUNTIME_INF))
		return 1;

	return idle;
}

static inline int rt_se_prio(struct sched_rt_entity *rt_se)
{
#ifdef CONFIG_RT_GROUP_SCHED
	struct rt_rq *rt_rq = group_rt_rq(rt_se);

	if (rt_rq)
		return rt_rq->highest_prio.curr;
#endif

	return rt_task_of(rt_se)->prio;
}

static int sched_rt_runtime_exceeded(struct rt_rq *rt_rq)
{
	u64 runtime = sched_rt_runtime(rt_rq);

	if (rt_rq->rt_throttled)
		return rt_rq_throttled(rt_rq);

	if (runtime >= sched_rt_period(rt_rq))
		return 0;

	balance_runtime(rt_rq);
	runtime = sched_rt_runtime(rt_rq);
	if (runtime == RUNTIME_INF)
		return 0;

	if (rt_rq->rt_time > runtime) {
		struct rt_bandwidth *rt_b = sched_rt_bandwidth(rt_rq);

		/*
		 * Don't actually throttle groups that have no runtime assigned
		 * but accrue some time due to boosting.
		 */
		if (likely(rt_b->rt_runtime)) {
			rt_rq->rt_throttled = 1;
			printk_deferred_once("sched: RT throttling activated\n");
		} else {
			/*
			 * In case we did anyway, make it go away,
			 * replenishment is a joke, since it will replenish us
			 * with exactly 0 ns.
			 */
			rt_rq->rt_time = 0;
		}

		if (rt_rq_throttled(rt_rq)) {
			sched_rt_rq_dequeue(rt_rq);
			return 1;
		}
	}

	return 0;
}

/*
 * Update the current task's runtime statistics. Skip current tasks that
 * are not in our scheduling class.
 */
static void update_curr_rt(struct rq *rq)
{
	struct task_struct *curr = rq->curr;
	struct sched_rt_entity *rt_se = &curr->rt;
	u64 delta_exec;

	if (curr->sched_class != &rt_sched_class)
		return;

	delta_exec = rq_clock_task(rq) - curr->se.exec_start;
	if (unlikely((s64)delta_exec <= 0))
		return;

	/* Kick cpufreq (see the comment in kernel/sched/sched.h). */
	cpufreq_update_util(rq, SCHED_CPUFREQ_RT);

	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);

	sched_rt_avg_update(rq, delta_exec);

	if (!rt_bandwidth_enabled())
		return;

	for_each_sched_rt_entity(rt_se) {
		struct rt_rq *rt_rq = rt_rq_of_se(rt_se);
		int exceeded;

		if (sched_rt_runtime(rt_rq) != RUNTIME_INF) {
			raw_spin_lock(&rt_rq->rt_runtime_lock);
			rt_rq->rt_time += delta_exec;
			exceeded = sched_rt_runtime_exceeded(rt_rq);
			if (exceeded)
				resched_curr(rq);
			raw_spin_unlock(&rt_rq->rt_runtime_lock);
			if (exceeded)
				do_start_rt_bandwidth(sched_rt_bandwidth(rt_rq));
		}
	}
}

static void
dequeue_top_rt_rq(struct rt_rq *rt_rq)
{
	struct rq *rq = rq_of_rt_rq(rt_rq);

	BUG_ON(&rq->rt != rt_rq);

	if (!rt_rq->rt_queued)
		return;

	BUG_ON(!rq->nr_running);

	sub_nr_running(rq, rt_rq->rt_nr_running);
	rt_rq->rt_queued = 0;
}

static void
enqueue_top_rt_rq(struct rt_rq *rt_rq)
{
	struct rq *rq = rq_of_rt_rq(rt_rq);

	BUG_ON(&rq->rt != rt_rq);

	if (rt_rq->rt_queued)
		return;
	if (rt_rq_throttled(rt_rq) || !rt_rq->rt_nr_running)
		return;

	add_nr_running(rq, rt_rq->rt_nr_running);
	rt_rq->rt_queued = 1;
}

#if defined CONFIG_SMP

static void
inc_rt_prio_smp(struct rt_rq *rt_rq, int prio, int prev_prio)
{
	struct rq *rq = rq_of_rt_rq(rt_rq);

#ifdef CONFIG_RT_GROUP_SCHED
	/*
	 * Change rq's cpupri only if rt_rq is the top queue.
	 */
	if (&rq->rt != rt_rq)
		return;
#endif
	if (rq->online && prio < prev_prio)
		cpupri_set(&rq->rd->cpupri, rq->cpu, prio);
}

static void
dec_rt_prio_smp(struct rt_rq *rt_rq, int prio, int prev_prio)
{
	struct rq *rq = rq_of_rt_rq(rt_rq);

#ifdef CONFIG_RT_GROUP_SCHED
	/*
	 * Change rq's cpupri only if rt_rq is the top queue.
	 */
	if (&rq->rt != rt_rq)
		return;
#endif
	if (rq->online && rt_rq->highest_prio.curr != prev_prio)
		cpupri_set(&rq->rd->cpupri, rq->cpu, rt_rq->highest_prio.curr);
}

#else /* CONFIG_SMP */

static inline
void inc_rt_prio_smp(struct rt_rq *rt_rq, int prio, int prev_prio) {}
static inline
void dec_rt_prio_smp(struct rt_rq *rt_rq, int prio, int prev_prio) {}

#endif /* CONFIG_SMP */

#if defined CONFIG_SMP || defined CONFIG_RT_GROUP_SCHED
static void
inc_rt_prio(struct rt_rq *rt_rq, int prio)
{
	int prev_prio = rt_rq->highest_prio.curr;

	if (prio < prev_prio)
		rt_rq->highest_prio.curr = prio;

	inc_rt_prio_smp(rt_rq, prio, prev_prio);
}

static void
dec_rt_prio(struct rt_rq *rt_rq, int prio)
{
	int prev_prio = rt_rq->highest_prio.curr;

	if (rt_rq->rt_nr_running) {

		WARN_ON(prio < prev_prio);

		/*
		 * This may have been our highest task, and therefore
		 * we may have some recomputation to do
		 */
		if (prio == prev_prio) {
			struct rt_prio_array *array = &rt_rq->active;

			rt_rq->highest_prio.curr =
				sched_find_first_bit(array->bitmap);
		}

	} else
		rt_rq->highest_prio.curr = MAX_RT_PRIO;

	dec_rt_prio_smp(rt_rq, prio, prev_prio);
}

#else

static inline void inc_rt_prio(struct rt_rq *rt_rq, int prio) {}
static inline void dec_rt_prio(struct rt_rq *rt_rq, int prio) {}

#endif /* CONFIG_SMP || CONFIG_RT_GROUP_SCHED */

#ifdef CONFIG_RT_GROUP_SCHED

static void
inc_rt_group(struct sched_rt_entity *rt_se, struct rt_rq *rt_rq)
{
	if (rt_se_boosted(rt_se))
		rt_rq->rt_nr_boosted++;

	if (rt_rq->tg)
		start_rt_bandwidth(&rt_rq->tg->rt_bandwidth);
}

static void
dec_rt_group(struct sched_rt_entity *rt_se, struct rt_rq *rt_rq)
{
	if (rt_se_boosted(rt_se))
		rt_rq->rt_nr_boosted--;

	WARN_ON(!rt_rq->rt_nr_running && rt_rq->rt_nr_boosted);
}

#else /* CONFIG_RT_GROUP_SCHED */

static void
inc_rt_group(struct sched_rt_entity *rt_se, struct rt_rq *rt_rq)
{
	start_rt_bandwidth(&def_rt_bandwidth);
}

static inline
void dec_rt_group(struct sched_rt_entity *rt_se, struct rt_rq *rt_rq) {}

#endif /* CONFIG_RT_GROUP_SCHED */

static inline
unsigned int rt_se_nr_running(struct sched_rt_entity *rt_se)
{
	struct rt_rq *group_rq = group_rt_rq(rt_se);

	if (group_rq)
		return group_rq->rt_nr_running;
	else
		return 1;
}

static inline
unsigned int rt_se_rr_nr_running(struct sched_rt_entity *rt_se)
{
	struct rt_rq *group_rq = group_rt_rq(rt_se);
	struct task_struct *tsk;

	if (group_rq)
		return group_rq->rr_nr_running;

	tsk = rt_task_of(rt_se);

	return (tsk->policy == SCHED_RR) ? 1 : 0;
}

static inline
void inc_rt_tasks(struct sched_rt_entity *rt_se, struct rt_rq *rt_rq)
{
	int prio = rt_se_prio(rt_se);

	WARN_ON(!rt_prio(prio));
	rt_rq->rt_nr_running += rt_se_nr_running(rt_se);
	rt_rq->rr_nr_running += rt_se_rr_nr_running(rt_se);

	inc_rt_prio(rt_rq, prio);
	inc_rt_migration(rt_se, rt_rq);
	inc_rt_group(rt_se, rt_rq);
}

static inline
void dec_rt_tasks(struct sched_rt_entity *rt_se, struct rt_rq *rt_rq)
{
	WARN_ON(!rt_prio(rt_se_prio(rt_se)));
	WARN_ON(!rt_rq->rt_nr_running);
	rt_rq->rt_nr_running -= rt_se_nr_running(rt_se);
	rt_rq->rr_nr_running -= rt_se_rr_nr_running(rt_se);

	dec_rt_prio(rt_rq, rt_se_prio(rt_se));
	dec_rt_migration(rt_se, rt_rq);
	dec_rt_group(rt_se, rt_rq);
}

#if defined(CONFIG_SMP) && defined(CONFIG_RT_GROUP_SCHED)
static void
attach_rt_entity_load_avg(struct rt_rq *rt_rq, struct sched_rt_entity *rt_se)
{
	rt_se->avg.last_update_time = rt_rq->avg.last_update_time;
	rt_rq->avg.util_avg += rt_se->avg.util_avg;
	rt_rq->avg.util_sum += rt_se->avg.util_sum;
	rt_rq->avg.load_avg += rt_se->avg.load_avg;
	rt_rq->avg.load_sum += rt_se->avg.load_sum;
	rt_rq->propagate_avg = 1;
	rt_rq_util_change(rt_rq);
}

static void
detach_rt_entity_load_avg(struct rt_rq *rt_rq, struct sched_rt_entity *rt_se)
{
	sub_positive(&rt_rq->avg.util_avg, rt_se->avg.util_avg);
	sub_positive(&rt_rq->avg.util_sum, rt_se->avg.util_sum);
	sub_positive(&rt_rq->avg.load_avg, rt_se->avg.load_avg);
	sub_positive(&rt_rq->avg.load_sum, rt_se->avg.load_sum);
	rt_rq->propagate_avg = 1;
	rt_rq_util_change(rt_rq);
}
#else
static inline void
attach_rt_entity_load_avg(struct rt_rq *rt_rq, struct sched_rt_entity *rt_se) {}
static inline void
detach_rt_entity_load_avg(struct rt_rq *rt_rq, struct sched_rt_entity *rt_se) {}
#endif

/*
 * Change rt_se->run_list location unless SAVE && !MOVE
 *
 * assumes ENQUEUE/DEQUEUE flags match
 */
static inline bool move_entity(unsigned int flags)
{
	if ((flags & (DEQUEUE_SAVE | DEQUEUE_MOVE)) == DEQUEUE_SAVE)
		return false;

	return true;
}

static void __delist_rt_entity(struct sched_rt_entity *rt_se, struct rt_prio_array *array)
{
	list_del_init(&rt_se->run_list);

	if (list_empty(array->queue + rt_se_prio(rt_se)))
		__clear_bit(rt_se_prio(rt_se), array->bitmap);

	rt_se->on_list = 0;
}

static void __enqueue_rt_entity(struct sched_rt_entity *rt_se, unsigned int flags)
{
	struct rt_rq *rt_rq = rt_rq_of_se(rt_se);
	struct rt_prio_array *array = &rt_rq->active;
	struct rt_rq *group_rq = group_rt_rq(rt_se);
	struct list_head *queue = array->queue + rt_se_prio(rt_se);

	/*
	 * Don't enqueue the group if its throttled, or when empty.
	 * The latter is a consequence of the former when a child group
	 * get throttled and the current group doesn't have any other
	 * active members.
	 */
	if (group_rq && (rt_rq_throttled(group_rq) || !group_rq->rt_nr_running)) {
		if (rt_se->on_list)
			__delist_rt_entity(rt_se, array);
		return;
	}

	if (move_entity(flags)) {
		WARN_ON_ONCE(rt_se->on_list);
		if (flags & ENQUEUE_HEAD)
			list_add(&rt_se->run_list, queue);
		else
			list_add_tail(&rt_se->run_list, queue);

		__set_bit(rt_se_prio(rt_se), array->bitmap);
		rt_se->on_list = 1;
	}
	rt_se->on_rq = 1;

	update_rt_load_avg(rq_clock_task(rq_of_rt_rq(rt_rq)), rt_se);

	if (rt_entity_is_task(rt_se) && !rt_se->avg.last_update_time)
		attach_rt_entity_load_avg(rt_rq, rt_se);

	inc_rt_tasks(rt_se, rt_rq);
}

static void __dequeue_rt_entity(struct sched_rt_entity *rt_se, unsigned int flags)
{
	struct rt_rq *rt_rq = rt_rq_of_se(rt_se);
	struct rt_prio_array *array = &rt_rq->active;

	if (move_entity(flags)) {
		WARN_ON_ONCE(!rt_se->on_list);
		__delist_rt_entity(rt_se, array);
	}
	rt_se->on_rq = 0;

	update_rt_load_avg(rq_clock_task(rq_of_rt_rq(rt_rq)), rt_se);

	dec_rt_tasks(rt_se, rt_rq);
}

/*
 * Because the prio of an upper entry depends on the lower
 * entries, we must remove entries top - down.
 */
static void dequeue_rt_stack(struct sched_rt_entity *rt_se, unsigned int flags)
{
	struct sched_rt_entity *back = NULL;

	for_each_sched_rt_entity(rt_se) {
		rt_se->back = back;
		back = rt_se;
	}

	dequeue_top_rt_rq(rt_rq_of_se(back));

	for (rt_se = back; rt_se; rt_se = rt_se->back) {
		if (on_rt_rq(rt_se))
			__dequeue_rt_entity(rt_se, flags);
	}
}

static void enqueue_rt_entity(struct sched_rt_entity *rt_se, unsigned int flags)
{
	struct rq *rq = rq_of_rt_se(rt_se);

	dequeue_rt_stack(rt_se, flags);
	for_each_sched_rt_entity(rt_se)
		__enqueue_rt_entity(rt_se, flags);
	enqueue_top_rt_rq(&rq->rt);
}

static void dequeue_rt_entity(struct sched_rt_entity *rt_se, unsigned int flags)
{
	struct rq *rq = rq_of_rt_se(rt_se);

	dequeue_rt_stack(rt_se, flags);

	for_each_sched_rt_entity(rt_se) {
		struct rt_rq *rt_rq = group_rt_rq(rt_se);

		if (rt_rq && rt_rq->rt_nr_running)
			__enqueue_rt_entity(rt_se, flags);
	}
	enqueue_top_rt_rq(&rq->rt);
}

/*
 * Adding/removing a task to/from a priority array:
 */
static void
enqueue_task_rt(struct rq *rq, struct task_struct *p, int flags)
{
	struct sched_rt_entity *rt_se = &p->rt;

	schedtune_enqueue_task(p, cpu_of(rq));

	if (flags & ENQUEUE_WAKEUP)
		rt_se->timeout = 0;

	enqueue_rt_entity(rt_se, flags);
	walt_inc_cumulative_runnable_avg(rq, p);

	if (!task_current(rq, p) && p->nr_cpus_allowed > 1)
		enqueue_pushable_task(rq, p);
}

static void dequeue_task_rt(struct rq *rq, struct task_struct *p, int flags)
{
	struct sched_rt_entity *rt_se = &p->rt;

	schedtune_dequeue_task(p, cpu_of(rq));

	update_curr_rt(rq);
	dequeue_rt_entity(rt_se, flags);
	walt_dec_cumulative_runnable_avg(rq, p);

	dequeue_pushable_task(rq, p);
}

/*
 * Put task to the head or the end of the run list without the overhead of
 * dequeue followed by enqueue.
 */
static void
requeue_rt_entity(struct rt_rq *rt_rq, struct sched_rt_entity *rt_se, int head)
{
	if (on_rt_rq(rt_se)) {
		struct rt_prio_array *array = &rt_rq->active;
		struct list_head *queue = array->queue + rt_se_prio(rt_se);

		if (head)
			list_move(&rt_se->run_list, queue);
		else
			list_move_tail(&rt_se->run_list, queue);
	}
}

static void requeue_task_rt(struct rq *rq, struct task_struct *p, int head)
{
	struct sched_rt_entity *rt_se = &p->rt;
	struct rt_rq *rt_rq;

	for_each_sched_rt_entity(rt_se) {
		rt_rq = rt_rq_of_se(rt_se);
		requeue_rt_entity(rt_rq, rt_se, head);
	}
}

static void yield_task_rt(struct rq *rq)
{
	requeue_task_rt(rq, rq->curr, 0);
}

#ifdef CONFIG_SMP

/* TODO:
 * attach/detach/migrate_task_rt_rq() for load tracking
 */

#ifdef CONFIG_SCHED_USE_FLUID_RT
static int find_lowest_rq(struct task_struct *task, int wake_flags);
#else
static int find_lowest_rq(struct task_struct *task);
#endif
static int
select_task_rq_rt(struct task_struct *p, int cpu, int sd_flag, int flags,
		  int sibling_count_hint)
{
	struct task_struct *curr;
	struct rq *rq;

	/* For anything but wake ups, just return the task_cpu */
	if (sd_flag != SD_BALANCE_WAKE && sd_flag != SD_BALANCE_FORK)
		goto out;

	rq = cpu_rq(cpu);

	rcu_read_lock();
	curr = READ_ONCE(rq->curr); /* unlocked access */

#ifdef CONFIG_SCHED_USE_FLUID_RT
	if (curr) {
		int target = find_lowest_rq(p, flags);
		/*
		 * Even though the destination CPU is running
		 * a higher priority task, FluidRT can bother moving it
		 * when its utilization is very small, and the other CPU is too busy
		 * to accomodate the p in the point of priority and utilization.
		 *
		 * BTW, if the curr has higher priority than p, FluidRT tries to find
		 * the other CPUs first. In the worst case, curr can be victim, if it
		 * has very small utilization.
		 */
		if (likely(target != -1)) {
			cpu = target;
		}
	}
#else

	/*
	 * If the current task on @p's runqueue is an RT task, then
	 * try to see if we can wake this RT task up on another
	 * runqueue. Otherwise simply start this RT task
	 * on its current runqueue.
	 *
	 * We want to avoid overloading runqueues. If the woken
	 * task is a higher priority, then it will stay on this CPU
	 * and the lower prio task should be moved to another CPU.
	 * Even though this will probably make the lower prio task
	 * lose its cache, we do not want to bounce a higher task
	 * around just because it gave up its CPU, perhaps for a
	 * lock?
	 *
	 * For equal prio tasks, we just let the scheduler sort it out.
	 *
	 * Otherwise, just let it ride on the affined RQ and the
	 * post-schedule router will push the preempted task away
	 *
	 * This test is optimistic, if we get it wrong the load-balancer
	 * will have to sort it out.
	 */
	if (curr && unlikely(rt_task(curr)) &&
	    (curr->nr_cpus_allowed < 2 ||
	     curr->prio <= p->prio)) {
		int target = find_lowest_rq(p);
		/*
		 * Don't bother moving it if the destination CPU is
		 * not running a lower priority task.
		 */
		if (target != -1 &&
		    p->prio < cpu_rq(target)->rt.highest_prio.curr)
			cpu = target;
	}
#endif
	rcu_read_unlock();

out:
#ifdef CONFIG_SCHED_USE_FLUID_RT
	if (cpu >= 6)
		trace_sched_fluid_stat(p, &p->rt.avg, cpu, "BIG_ASSIGED");
#endif
	return cpu;
}

#ifdef CONFIG_RT_GROUP_SCHED
/*
 * Called within set_task_rq() right before setting a task's cpu. The
 * caller only guarantees p->pi_lock is held; no other assumptions,
 * including the state of rq->lock, should be made.
 */
void set_task_rq_rt(struct sched_rt_entity *rt_se,
				    struct rt_rq *prev, struct rt_rq *next)
{
	u64 p_last_update_time;
	u64 n_last_update_time;

	if (!sched_feat(ATTACH_AGE_LOAD))
		return;
	/*
	 * We are supposed to update the task to "current" time, then its up to
	 * date and ready to go to new CPU/rt_rq. But we have difficulty in
	 * getting what current time is, so simply throw away the out-of-date
	 * time. This will result in the wakee task is less decayed, but giving
	 * the wakee more load sounds not bad.
	 */
	if (!(rt_se->avg.last_update_time && prev))
		return;
#ifndef CONFIG_64BIT
	{
		u64 p_last_update_time_copy;
		u64 n_last_update_time_copy;

		do {
			p_last_update_time_copy = prev->load_last_update_time_copy;
			n_last_update_time_copy = next->load_last_update_time_copy;

			smp_rmb();

			p_last_update_time = prev->avg.last_update_time;
			n_last_update_time = next->avg.last_update_time;

		} while (p_last_update_time != p_last_update_time_copy ||
			 n_last_update_time != n_last_update_time_copy);
	}
#else
	p_last_update_time = prev->avg.last_update_time;
	n_last_update_time = next->avg.last_update_time;
#endif
	__update_load_avg(p_last_update_time, cpu_of(rq_of_rt_rq(prev)),
		&rt_se->avg, scale_load_down(NICE_0_LOAD), 0, NULL);

	rt_se->avg.last_update_time = n_last_update_time;
}
#endif /* CONFIG_RT_GROUP_SCHED */

#ifndef CONFIG_64BIT
static inline u64 rt_rq_last_update_time(struct rt_rq *rt_rq)
{
	u64 last_update_time_copy;
	u64 last_update_time;

	do {
		last_update_time_copy = rt_rq->load_last_update_time_copy;
		smp_rmb();
		last_update_time = rt_rq->avg.last_update_time;
	} while (last_update_time != last_update_time_copy);

	return last_update_time;
}
#else
static inline u64 rt_rq_last_update_time(struct rt_rq *rt_rq)
{
	return rt_rq->avg.last_update_time;
}
#endif

/*
 * Synchronize entity load avg of dequeued entity without locking
 * the previous rq.
 */
void sync_rt_entity_load_avg(struct sched_rt_entity *rt_se)
{
	struct rt_rq *rt_rq = rt_rq_of_se(rt_se);
	u64 last_update_time;

	last_update_time = rt_rq_last_update_time(rt_rq);
	__update_load_avg(last_update_time, cpu_of(rq_of_rt_rq(rt_rq)),
		&rt_se->avg, scale_load_down(NICE_0_LOAD), rt_rq->curr == rt_se, NULL);
}

/*
 * Task first catches up with rt_rq, and then subtract
 * itself from the rt_rq (task must be off the queue now).
 */
static void remove_rt_entity_load_avg(struct sched_rt_entity *rt_se)
{
	struct rt_rq *rt_rq = rt_rq_of_se(rt_se);

	/*
	 * tasks cannot exit without having gone through wake_up_new_task() ->
	 * post_init_entity_util_avg() which will have added things to the
	 * rt_rq, so we can remove unconditionally.
	 *
	 * Similarly for groups, they will have passed through
	 * post_init_entity_util_avg() before unregister_sched_fair_group()
	 * calls this.
	 */

	sync_rt_entity_load_avg(rt_se);
	atomic_long_add(rt_se->avg.load_avg, &rt_rq->removed_load_avg);
	atomic_long_add(rt_se->avg.util_avg, &rt_rq->removed_util_avg);
}

#ifdef CONFIG_RT_GROUP_SCHED
static void attach_task_rt_rq(struct task_struct *p)
{
	struct sched_rt_entity *rt_se = &p->rt;
	struct rt_rq *rt_rq = rt_rq_of_se(rt_se);
	u64 now = rq_clock_task(rq_of_rt_rq(rt_rq));

	update_rt_load_avg(now, rt_se);
	attach_rt_entity_load_avg(rt_rq, rt_se);
}

static void detach_task_rt_rq(struct task_struct *p)
{
	struct sched_rt_entity *rt_se = &p->rt;
	struct rt_rq *rt_rq = rt_rq_of_se(rt_se);
	u64 now = rq_clock_task(rq_of_rt_rq(rt_rq));

	update_rt_load_avg(now, rt_se);
	detach_rt_entity_load_avg(rt_rq, rt_se);
}
#endif

static void migrate_task_rq_rt(struct task_struct *p)
{
	/*
	 * We are supposed to update the task to "current" time, then its up to date
	 * and ready to go to new CPU/cfs_rq. But we have difficulty in getting
	 * what current time is, so simply throw away the out-of-date time. This
	 * will result in the wakee task is less decayed, but giving the wakee more
	 * load sounds not bad.
	 */
	remove_rt_entity_load_avg(&p->rt);

	/* Tell new CPU we are migrated */
	p->rt.avg.last_update_time = 0;

	/* We have migrated, no longer consider this task hot */
	p->se.exec_start = 0;
}

static void task_dead_rt(struct task_struct *p)
{
	remove_rt_entity_load_avg(&p->rt);
}

#ifdef CONFIG_RT_GROUP_SCHED
static void task_set_group_rt(struct task_struct *p)
{
	set_task_rq(p, task_cpu(p));
}

static void task_move_group_rt(struct task_struct *p)
{
	detach_task_rt_rq(p);
	set_task_rq(p, task_cpu(p));

#ifdef CONFIG_SMP
	/* Tell se's cfs_rq has been changed -- migrated */
	p->se.avg.last_update_time = 0;
#endif
	attach_task_rt_rq(p);
}

static void task_change_group_rt(struct task_struct *p, int type)
{
	switch (type) {
	case TASK_SET_GROUP:
		task_set_group_rt(p);
		break;

	case TASK_MOVE_GROUP:
		task_move_group_rt(p);
		break;
	}
}
#endif

static void check_preempt_equal_prio(struct rq *rq, struct task_struct *p)
{
	/*
	 * Current can't be migrated, useless to reschedule,
	 * let's hope p can move out.
	 */
	if (rq->curr->nr_cpus_allowed == 1 ||
	    !cpupri_find(&rq->rd->cpupri, rq->curr, NULL))
		return;

	/*
	 * p is migratable, so let's not schedule it and
	 * see if it is pushed or pulled somewhere else.
	 */
	if (p->nr_cpus_allowed != 1
	    && cpupri_find(&rq->rd->cpupri, p, NULL))
		return;

	/*
	 * There appears to be other cpus that can accept
	 * current and none to run 'p', so lets reschedule
	 * to try and push current away:
	 */
	requeue_task_rt(rq, p, 1);
	resched_curr(rq);
}

/* Give new sched_entity start runnable values to heavy its load in infant time */
void init_rt_entity_runnable_average(struct sched_rt_entity *rt_se)
{
	struct sched_avg *sa = &rt_se->avg;

	sa->last_update_time = 0;

	sa->period_contrib = 1023;

	/*
	 * Tasks are intialized with zero load.
	 * Load is not actually used by RT, but can be inherited into fair task.
	 */
	sa->load_avg = 0;
	sa->load_sum = 0;
	/*
	 * At this point, util_avg won't be used in select_task_rq_rt anyway
	 */
	sa->util_avg = 0;
	sa->util_sum = 0;
	/* when this task enqueue'ed, it will contribute to its cfs_rq's load_avg */
}
#else
void init_rt_entity_runnable_average(struct sched_rt_entity *rt_se) { }
#endif /* CONFIG_SMP */

#ifdef CONFIG_SCHED_USE_FLUID_RT
static inline void set_victim_flag(struct task_struct *p)
{
	p->victim_flag = 1;
}

static inline void clear_victim_flag(struct task_struct *p)
{
	p->victim_flag = 0;
}

static inline bool test_victim_flag(struct task_struct *p)
{
	if (p->victim_flag)
		return true;
	else
		return false;
}
#else
static inline bool test_victim_flag(struct task_struct *p) { return false; }
static inline void clear_victim_flag(struct task_struct *p) {}
#endif
/*
 * Preempt the current task with a newly woken task if needed:
 */
static void check_preempt_curr_rt(struct rq *rq, struct task_struct *p, int flags)
{
	if (p->prio < rq->curr->prio) {
		resched_curr(rq);
		return;
	} else if (test_victim_flag(p)) {
		requeue_task_rt(rq, p, 1);
		resched_curr(rq);
		return;
	}

#ifdef CONFIG_SMP
	/*
	 * If:
	 *
	 * - the newly woken task is of equal priority to the current task
	 * - the newly woken task is non-migratable while current is migratable
	 * - current will be preempted on the next reschedule
	 *
	 * we should check to see if current can readily move to a different
	 * cpu.  If so, we will reschedule to allow the push logic to try
	 * to move current somewhere else, making room for our non-migratable
	 * task.
	 */
	if (p->prio == rq->curr->prio && !test_tsk_need_resched(rq->curr))
		check_preempt_equal_prio(rq, p);
#endif
}

static struct sched_rt_entity *pick_next_rt_entity(struct rq *rq,
						   struct rt_rq *rt_rq)
{
	struct rt_prio_array *array = &rt_rq->active;
	struct sched_rt_entity *next = NULL;
	struct list_head *queue;
	int idx;

	idx = sched_find_first_bit(array->bitmap);
	BUG_ON(idx >= MAX_RT_PRIO);

	queue = array->queue + idx;
	if (SCHED_WARN_ON(list_empty(queue)))
		return NULL;
	next = list_entry(queue->next, struct sched_rt_entity, run_list);

	return next;
}

static struct task_struct *_pick_next_task_rt(struct rq *rq)
{
	struct sched_rt_entity *rt_se;
	struct task_struct *p;
	struct rt_rq *rt_rq  = &rq->rt;
	u64 now = rq_clock_task(rq);

	do {
		rt_se = pick_next_rt_entity(rq, rt_rq);
		if (unlikely(!rt_se))
			return NULL;
		update_rt_load_avg(now, rt_se);
		rt_rq->curr = rt_se;
		rt_rq = group_rt_rq(rt_se);
	} while (rt_rq);

	p = rt_task_of(rt_se);
	p->se.exec_start = now;

	return p;
}

extern int update_rt_rq_load_avg(u64 now, int cpu, struct rt_rq *rt_rq, int running);

static struct task_struct *
pick_next_task_rt(struct rq *rq, struct task_struct *prev, struct rq_flags *rf)
{
	struct task_struct *p;
	struct rt_rq *rt_rq = &rq->rt;

	if (need_pull_rt_task(rq, prev)) {
		/*
		 * This is OK, because current is on_cpu, which avoids it being
		 * picked for load-balance and preemption/IRQs are still
		 * disabled avoiding further scheduler activity on it and we're
		 * being very careful to re-start the picking loop.
		 */
		rq_unpin_lock(rq, rf);
		pull_rt_task(rq);
		rq_repin_lock(rq, rf);
		/*
		 * pull_rt_task() can drop (and re-acquire) rq->lock; this
		 * means a dl or stop task can slip in, in which case we need
		 * to re-start task selection.
		 */
		if (unlikely((rq->stop && task_on_rq_queued(rq->stop)) ||
			     rq->dl.dl_nr_running))
			return RETRY_TASK;
	}

	/*
	 * We may dequeue prev's rt_rq in put_prev_task().
	 * So, we update time before rt_nr_running check.
	 */
	if (prev->sched_class == &rt_sched_class)
		update_curr_rt(rq);

	if (!rt_rq->rt_queued)
		return NULL;

	put_prev_task(rq, prev);

	p = _pick_next_task_rt(rq);

	/* The running task is never eligible for pushing */
	dequeue_pushable_task(rq, p);

	queue_push_tasks(rq);

	if (p)
		update_rt_rq_load_avg(rq_clock_task(rq), cpu_of(rq), rt_rq,
					rq->curr->sched_class == &rt_sched_class);

	clear_victim_flag(p);

	return p;
}

static void put_prev_task_rt(struct rq *rq, struct task_struct *p)
{
	struct sched_rt_entity *rt_se = &p->rt;
	u64 now = rq_clock_task(rq);

	update_curr_rt(rq);

	/*
	 * The previous task needs to be made eligible for pushing
	 * if it is still active
	 */
	if (on_rt_rq(&p->rt) && p->nr_cpus_allowed > 1)
		enqueue_pushable_task(rq, p);

	for_each_sched_rt_entity(rt_se) {
		struct rt_rq *rt_rq = rt_rq_of_se(rt_se);
		if (rt_se->on_rq)
			update_rt_load_avg(now, rt_se);

		rt_rq->curr = NULL;
	}
}

#ifdef CONFIG_SMP

#ifdef CONFIG_RT_GROUP_SCHED
void rt_rq_util_change(struct rt_rq *rt_rq)
{
	if (&this_rq()->rt == rt_rq)
		cpufreq_update_util(rt_rq->rq, SCHED_CPUFREQ_RT);
}

/* Take into account change of utilization of a child task group */
static inline void
update_tg_rt_util(struct rt_rq *cfs_rq, struct sched_rt_entity *rt_se)
{
	struct rt_rq *grt_rq = rt_se->my_q;
	long delta = grt_rq->avg.util_avg - rt_se->avg.util_avg;

	/* Nothing to update */
	if (!delta)
		return;

	/* Set new sched_rt_entity's utilization */
	rt_se->avg.util_avg = grt_rq->avg.util_avg;
	rt_se->avg.util_sum = rt_se->avg.util_avg * LOAD_AVG_MAX;

	/* Update parent rt_rq utilization */
	add_positive(&cfs_rq->avg.util_avg, delta);
	cfs_rq->avg.util_sum = cfs_rq->avg.util_avg * LOAD_AVG_MAX;
}


/* Take into account change of load of a child task group */
static inline void
update_tg_rt_load(struct rt_rq *rt_rq, struct sched_rt_entity *rt_se)
{
	struct rt_rq *grt_rq = rt_se->my_q;
	long delta = grt_rq->avg.load_avg - rt_se->avg.load_avg;

	/*
	 * TODO: Need to consider the TG group update
	 * for RT RQ
	 */

	/* Nothing to update */
	if (!delta)
		return;

	/* Set new sched_rt_entity's load */
	rt_se->avg.load_avg = grt_rq->avg.load_avg;
	rt_se->avg.load_sum = rt_se->avg.load_avg * LOAD_AVG_MAX;

	/* Update parent cfs_rq load */
	add_positive(&rt_rq->avg.load_avg, delta);
	rt_rq->avg.load_sum = rt_rq->avg.load_avg * LOAD_AVG_MAX;

	/*
	 * TODO: If the sched_entity is already enqueued, should we have to update the
	 * runnable load avg.
	 */
}

static inline int test_and_clear_tg_rt_propagate(struct sched_rt_entity *rt_se)
{
	struct rt_rq *rt_rq = rt_se->my_q;

	if (!rt_rq->propagate_avg)
		return 0;

	rt_rq->propagate_avg = 0;
	return 1;
}

/* Update task and its cfs_rq load average */
static inline int propagate_entity_rt_load_avg(struct sched_rt_entity *rt_se)
{
	struct rt_rq *rt_rq;

	if (rt_entity_is_task(rt_se))
		return 0;

	if (!test_and_clear_tg_rt_propagate(rt_se))
		return 0;

	rt_rq = rt_rq_of_se(rt_se);

	rt_rq->propagate_avg = 1;

	update_tg_rt_util(rt_rq, rt_se);
	update_tg_rt_load(rt_rq, rt_se);

	return 1;
}
#else
static inline int propagate_entity_rt_load_avg(struct sched_rt_entity *rt_se) { return 1; };
#endif

void update_rt_load_avg(u64 now, struct sched_rt_entity *rt_se)
{
	struct rt_rq *rt_rq = rt_rq_of_se(rt_se);
	struct rq *rq = rq_of_rt_rq(rt_rq);
	int cpu = cpu_of(rq);
	/*
	 * Track task load average for carrying it to new CPU after migrated.
	 */
	if (rt_se->avg.last_update_time)
		__update_load_avg(now, cpu, &rt_se->avg, scale_load_down(NICE_0_LOAD),
			rt_rq->curr == rt_se, NULL);

	update_rt_rq_load_avg(now, cpu, rt_rq, rt_rq->curr == rt_se);
	propagate_entity_rt_load_avg(rt_se);

#ifdef CONFIG_RT_GROUP_SCHED
	if (entity_is_task(rt_se))
		trace_sched_rt_load_avg_task(rt_task_of(rt_se), &rt_se->avg);
#endif
}

/* Only try algorithms three times */
#define RT_MAX_TRIES 3

static int pick_rt_task(struct rq *rq, struct task_struct *p, int cpu)
{
	if (!task_running(rq, p) &&
	    cpumask_test_cpu(cpu, &p->cpus_allowed))
		return 1;
	return 0;
}

/*
 * Return the highest pushable rq's task, which is suitable to be executed
 * on the cpu, NULL otherwise
 */
static struct task_struct *pick_highest_pushable_task(struct rq *rq, int cpu)
{
	struct plist_head *head = &rq->rt.pushable_tasks;
	struct task_struct *p;

	if (!has_pushable_tasks(rq))
		return NULL;

	plist_for_each_entry(p, head, pushable_tasks) {
		if (pick_rt_task(rq, p, cpu))
			return p;
	}

	return NULL;
}

static DEFINE_PER_CPU(cpumask_var_t, local_cpu_mask);

#ifdef CONFIG_SCHED_USE_FLUID_RT
static inline int weight_from_rtprio(int prio)
{
	int idx = (prio >> 1);

	if (!rt_prio(prio))
		return sched_prio_to_weight[prio - MAX_RT_PRIO];

	if ((idx << 1) == prio)
		return rtprio_to_weight[idx];
	else
		return ((rtprio_to_weight[idx] + rtprio_to_weight[idx+1]) >> 1);
}

/* Affordable CPU:
 * to find the best CPU in which the data is kept in cache-hot
 *
 * In most of time, RT task is invoked because,
 *  Case - I : it is already scheduled some time ago, or
 *  Case - II: it is requested by some task without timedelay
 *
 * In case-I, it's hardly to find the best CPU in cache-hot if the time is relatively long.
 * But in case-II, waker CPU is likely to keep the cache-hot data useful to wakee RT task.
 */
static inline int affordable_cpu(int cpu, unsigned long task_load)
{
	/*
	 * If the task.state is 'TASK_INTERRUPTIBLE',
	 * she is likely to call 'schedule()' explicitely, for waking up RT task.
	 *   and have something in common with it.
	 */
	if (cpu_curr(cpu)->state != TASK_INTERRUPTIBLE)
		return 0;

	/*
	 * Waker CPU must accommodate the target RT task.
	 */
	if (capacity_of(cpu) <= task_load)
		return 0;

	/*
	 * Future work (More concerns if needed):
	 * - Min opportunity cost between the eviction of tasks and dismiss of target RT
	 *	: If evicted tasks are expecting too many damage for its execution,
	 *		Target RT should not be this CPU.
	 *	load(RT) >= Capa(CPU)/3 && load(evicted tasks) >= Capa(CPU)/3
	 * - Identifying the relation:
	 *	: Is it possible to identify the relation (such as mutex owner and waiter)
	 * -
	 */

	return 1;
}

extern unsigned long task_util(struct task_struct *p);
unsigned long frt_cpu_util_wake(int cpu, struct task_struct *p)
{
	struct cfs_rq *cfs_rq = &cpu_rq(cpu)->cfs;
	struct rt_rq *rt_rq = &cpu_rq(cpu)->rt;
	unsigned int util;

	util = READ_ONCE(cfs_rq->avg.util_avg) + READ_ONCE(rt_rq->avg.util_avg);

#ifdef CONFIG_SCHED_WALT
	/*
	 * WALT does not decay idle tasks in the same manner
	 * as PELT, so it makes little sense to subtract task
	 * utilization from cpu utilization. Instead just use
	 * cpu_util for this case.
	 */
	if (!walt_disabled && sysctl_sched_use_walt_cpu_util)
		return cpu_util(cpu);
#endif
	/* Task has no contribution or is new */
	if (cpu != task_cpu(p) || !READ_ONCE(p->se.avg.last_update_time))
		return util;

	/* Discount task's blocked util from CPU's util */
	util -= min_t(unsigned int, util, task_util(p));

	return min_t(unsigned long, util, capacity_orig_of(cpu));
}
static inline int cpu_selected(int cpu)	{ return (nr_cpu_ids > cpu && cpu >= 0); }
/*
 * Must find the victim or recessive (not in lowest_mask)
 *
 */
/* Future-safe accessor for struct task_struct's cpus_allowed. */
#define rttsk_cpus_allowed(tsk) (&(tsk)->cpus_allowed)

static int find_victim_rt_rq(struct task_struct *task, const struct cpumask *sg_cpus, int *best_cpu) {
	unsigned int i;
	unsigned long victim_rtweight, target_rtweight, min_rtweight;
	unsigned int victim_cpu_cap, min_cpu_cap = arch_scale_cpu_capacity(NULL, task_cpu(task));
	bool victim_rt = true;

	if (!rt_task(task))
		return *best_cpu;

	target_rtweight = task->rt.avg.util_avg * weight_from_rtprio(task->prio);
	min_rtweight = target_rtweight;

	for_each_cpu_and(i, sg_cpus, rttsk_cpus_allowed(task)) {
		struct task_struct *victim = cpu_rq(i)->curr;

		if (victim->nr_cpus_allowed < 2)
			continue;

		if (rt_task(victim)) {
			victim_cpu_cap = arch_scale_cpu_capacity(NULL, i);
			victim_rtweight = victim->rt.avg.util_avg * weight_from_rtprio(victim->prio);

			if (min_cpu_cap == victim_cpu_cap) {
				if (victim_rtweight < min_rtweight) {
					min_rtweight = victim_rtweight;
					*best_cpu = i;
					min_cpu_cap = victim_cpu_cap;
				}
			} else {
				/*
				 * It's necessary to un-cap the cpu capacity when comparing
				 * utilization of each CPU. This is why the Fluid RT tries to give
				 * the green light on big CPU to the long-run RT task
				 * in accordance with the priority.
				 */
				if (victim_rtweight * min_cpu_cap < min_rtweight * victim_cpu_cap) {
					min_rtweight = victim_rtweight;
					*best_cpu = i;
					min_cpu_cap = victim_cpu_cap;
				}
			}
		} else {
			/* If Non-RT CPU is exist, select it first. */
			*best_cpu = i;
			victim_rt = false;
			break;
		}
	}

	if (*best_cpu >= 0 && victim_rt) {
		set_victim_flag(cpu_rq(*best_cpu)->curr);
	}

	if (victim_rt)
		trace_sched_fluid_stat(task, &task->rt.avg, *best_cpu, "VICTIM-FAIR");
	else
		trace_sched_fluid_stat(task, &task->rt.avg, *best_cpu, "VICTIM-RT");

	return *best_cpu;

}

static int check_cache_hot(struct task_struct *task, int flags, int *best_cpu)
{
	int cpu = smp_processor_id();
	return false;
	/*
	 * 3. Cache hot : packing the callee and caller,
	 *	when there is nothing to run except callee, or
	 *	wake_flags are set.
	 */
	/* FUTURE WORK: Hierarchical cache hot */
	if (!(flags & WF_SYNC))
		return false;

	if (cpumask_test_cpu(*best_cpu, cpu_coregroup_mask(cpu))) {
		task->rt.sync_flag = 1;
		*best_cpu = cpu;
		trace_sched_fluid_stat(task, &task->rt.avg, *best_cpu, "CACHE-HOT");
		return true;
	}

	return false;
}

static int find_idle_cpu(struct task_struct *task, int wake_flags)
{
	int cpu, best_cpu = -1;
	int cpu_prio, max_prio = -1;
	u64 cpu_load, min_load = ULLONG_MAX;
	struct cpumask candidate_cpus;
	struct frt_dom *dom, *prefer_dom;

	cpu = frt_find_prefer_cpu(task);
	prefer_dom = dom = per_cpu(frt_rqs, cpu);
	if (unlikely(!dom))
		return best_cpu;

	cpumask_and(&candidate_cpus, &task->cpus_allowed, cpu_active_mask);
	cpumask_and(&candidate_cpus, &candidate_cpus, get_activated_cpus());
	if (unlikely(cpumask_empty(&candidate_cpus)))
		cpumask_copy(&candidate_cpus, &task->cpus_allowed);

	do {
		for_each_cpu_and(cpu, &dom->cpus, &candidate_cpus) {
			if (!idle_cpu(cpu))
				continue;
			cpu_prio = cpu_rq(cpu)->rt.highest_prio.curr;
			if (cpu_prio < max_prio)
				continue;

			cpu_load = frt_cpu_util_wake(cpu, task) + task_util(task);
			if (cpu_load > capacity_orig_of(cpu))
				continue;

			if ((cpu_prio > max_prio) || (cpu_load < min_load) ||
					(cpu_load == min_load && task_cpu(task) == cpu)) {
				min_load = cpu_load;
				max_prio = cpu_prio;
				best_cpu = cpu;
			}
		}

		if (cpu_selected(best_cpu)) {
			if (check_cache_hot(task, wake_flags, &best_cpu))
				return best_cpu;

			trace_sched_fluid_stat(task, &task->rt.avg, best_cpu, "IDLE-FIRST");
			return best_cpu;
		}

		dom = dom->next;
	} while (dom != prefer_dom);

	return best_cpu;
}

static int find_recessive_cpu(struct task_struct *task, int wake_flags)
{
	int cpu, best_cpu = -1;
	u64 cpu_load, min_load = ULLONG_MAX;
	struct cpumask *lowest_mask;
	struct cpumask candidate_cpus;
	struct frt_dom *dom, *prefer_dom;

	lowest_mask = this_cpu_cpumask_var_ptr(local_cpu_mask);
	/* Make sure the mask is initialized first */
	if (unlikely(!lowest_mask)) {
		trace_sched_fluid_stat(task, &task->rt.avg, best_cpu, "NA LOWESTMSK");
		return best_cpu;
	}
	/* update the per-cpu local_cpu_mask (lowest_mask) */
	cpupri_find(&task_rq(task)->rd->cpupri, task, lowest_mask);

	cpumask_and(&candidate_cpus, &task->cpus_allowed, lowest_mask);
	cpumask_and(&candidate_cpus, &candidate_cpus, cpu_active_mask);
	cpu = frt_find_prefer_cpu(task);
	prefer_dom = dom = per_cpu(frt_rqs, cpu);
	if (unlikely(!dom))
		return best_cpu;

	do {
		for_each_cpu_and(cpu, &dom->cpus, &candidate_cpus) {
			cpu_load = frt_cpu_util_wake(cpu, task) + task_util(task);

			if (cpu_load > capacity_orig_of(cpu))
				continue;

			if (cpu_load < min_load ||
				(cpu_load == min_load && task_cpu(task) == cpu)) {
				min_load = cpu_load;
				best_cpu = cpu;
			}
		}

		if (cpu_selected(best_cpu)) {
			if (check_cache_hot(task, wake_flags, &best_cpu))
				return best_cpu;

			trace_sched_fluid_stat(task, &task->rt.avg, best_cpu,
				rt_task(cpu_rq(best_cpu)->curr) ? "RT-RECESS" : "FAIR-RECESS");
			return best_cpu;
		}

		dom = dom->next;
	} while (dom != prefer_dom);

	return best_cpu;
}

static int find_lowest_rq_fluid(struct task_struct *task, int wake_flags)
{
	int cpu, best_cpu = -1;

	if (task->nr_cpus_allowed == 1) {
		trace_sched_fluid_stat(task, &task->rt.avg, best_cpu, "NA ALLOWED");
		goto out; /* No other targets possible */
	}

	/*
	 *
	 * Fluid Sched Core selection procedure:
	 *
	 * 1. idle CPU selection (cache-hot cpu  first)
	 * 2. recessive task first (cache-hot cpu first)
	 * 3. victim task first (prev_cpu first)
	 */

	/* 1. idle CPU selection */
	best_cpu = find_idle_cpu(task, wake_flags);
	if (cpu_selected(best_cpu))
		goto out;

	/* 2. recessive task first */
	best_cpu = find_recessive_cpu(task, wake_flags);
	if (cpu_selected(best_cpu))
		goto out;

	/*
	 * 3. victim task first
	 */
	for_each_cpu(cpu, cpu_active_mask) {
		if (cpu != cpumask_first(cpu_coregroup_mask(cpu)))
			continue;

		if (find_victim_rt_rq(task, cpu_coregroup_mask(cpu), &best_cpu) != -1)
			break;
	}
out:
	if (best_cpu == -1)
		best_cpu = task_rq(task)->cpu;

	if (!cpumask_test_cpu(best_cpu, cpu_online_mask)) {
		trace_sched_fluid_stat(task, &task->rt.avg, best_cpu, "NOTHING_VALID");
		best_cpu = -1;
	}

	return best_cpu;
}
#endif /* CONFIG_SCHED_USE_FLUID_RT */

#ifdef CONFIG_SCHED_USE_FLUID_RT
static int find_lowest_rq(struct task_struct *task, int wake_flags)
#else
static int find_lowest_rq(struct task_struct *task)
#endif
{
#ifdef CONFIG_SCHED_USE_FLUID_RT
	return find_lowest_rq_fluid(task, wake_flags);
#else
	struct sched_domain *sd;
	struct cpumask *lowest_mask = this_cpu_cpumask_var_ptr(local_cpu_mask);
	int this_cpu = smp_processor_id();
	int cpu      = task_cpu(task);

	/* Make sure the mask is initialized first */
	if (unlikely(!lowest_mask))
		return -1;

	if (task->nr_cpus_allowed == 1)
		return -1; /* No other targets possible */

	if (!cpupri_find(&task_rq(task)->rd->cpupri, task, lowest_mask))
		return -1; /* No targets found */

	/*
	 * At this point we have built a mask of cpus representing the
	 * lowest priority tasks in the system.  Now we want to elect
	 * the best one based on our affinity and topology.
	 *
	 * We prioritize the last cpu that the task executed on since
	 * it is most likely cache-hot in that location.
	 */
	if (cpumask_test_cpu(cpu, lowest_mask))
		return cpu;

	/*
	 * Otherwise, we consult the sched_domains span maps to figure
	 * out which cpu is logically closest to our hot cache data.
	 */
	if (!cpumask_test_cpu(this_cpu, lowest_mask))
		this_cpu = -1; /* Skip this_cpu opt if not among lowest */

	rcu_read_lock();
	for_each_domain(cpu, sd) {
		if (sd->flags & SD_WAKE_AFFINE) {
			int best_cpu;

			/*
			 * "this_cpu" is cheaper to preempt than a
			 * remote processor.
			 */
			if (this_cpu != -1 &&
			    cpumask_test_cpu(this_cpu, sched_domain_span(sd))) {
				rcu_read_unlock();
				return this_cpu;
			}

			best_cpu = cpumask_first_and(lowest_mask,
						     sched_domain_span(sd));
			if (best_cpu < nr_cpu_ids) {
				rcu_read_unlock();
				return best_cpu;
			}
		}
	}
	rcu_read_unlock();

	/*
	 * And finally, if there were no matches within the domains
	 * just give the caller *something* to work with from the compatible
	 * locations.
	 */
	if (this_cpu != -1)
		return this_cpu;

	cpu = cpumask_any(lowest_mask);
	if (cpu < nr_cpu_ids)
		return cpu;
	return -1;
#endif /* CONFIG_SCHED_USE_FLUID_RT */
}

/* Will lock the rq it finds */
static struct rq *find_lock_lowest_rq(struct task_struct *task, struct rq *rq)
{
	struct rq *lowest_rq = NULL;
	int tries;
	int cpu;

	for (tries = 0; tries < RT_MAX_TRIES; tries++) {
#ifdef CONFIG_SCHED_USE_FLUID_RT
		cpu = find_lowest_rq(task, 0);
#else
		cpu = find_lowest_rq(task);
#endif
		if ((cpu == -1) || (cpu == rq->cpu))
			break;

		lowest_rq = cpu_rq(cpu);
		if (lowest_rq->rt.highest_prio.curr <= task->prio)
		{
			/*
			 * Target rq has tasks of equal or higher priority,
			 * retrying does not release any lock and is unlikely
			 * to yield a different result.
			 */
			lowest_rq = NULL;
			break;
		}

		/* if the prio of this runqueue changed, try again */
		if (double_lock_balance(rq, lowest_rq)) {
			/*
			 * We had to unlock the run queue. In
			 * the mean time, task could have
			 * migrated already or had its affinity changed.
			 * Also make sure that it wasn't scheduled on its rq.
			 */
			if (unlikely(task_rq(task) != rq ||
				     !cpumask_test_cpu(lowest_rq->cpu, &task->cpus_allowed) ||
				     task_running(rq, task) ||
				     !rt_task(task) ||
				     !task_on_rq_queued(task))) {

				double_unlock_balance(rq, lowest_rq);
				lowest_rq = NULL;
				break;
			}
		}

		/* If this rq is still suitable use it. */
		if (lowest_rq->rt.highest_prio.curr > task->prio)
			break;

		/* try again */
		double_unlock_balance(rq, lowest_rq);
		lowest_rq = NULL;
	}

	return lowest_rq;
}

static struct task_struct *pick_next_pushable_task(struct rq *rq)
{
	struct task_struct *p;

	if (!has_pushable_tasks(rq))
		return NULL;

	p = plist_first_entry(&rq->rt.pushable_tasks,
			      struct task_struct, pushable_tasks);

	BUG_ON(rq->cpu != task_cpu(p));
	BUG_ON(task_current(rq, p));
	BUG_ON(p->nr_cpus_allowed <= 1);

	BUG_ON(!task_on_rq_queued(p));
	BUG_ON(!rt_task(p));

	return p;
}

/*
 * If the current CPU has more than one RT task, see if the non
 * running task can migrate over to a CPU that is running a task
 * of lesser priority.
 */
static int push_rt_task(struct rq *rq)
{
	struct task_struct *next_task;
	struct rq *lowest_rq;
	int ret = 0;

	if (!rq->rt.overloaded)
		return 0;

	next_task = pick_next_pushable_task(rq);
	if (!next_task)
		return 0;

retry:
	if (unlikely(next_task == rq->curr)) {
		WARN_ON(1);
		return 0;
	}

	/*
	 * It's possible that the next_task slipped in of
	 * higher priority than current. If that's the case
	 * just reschedule current.
	 */
	if (unlikely(next_task->prio < rq->curr->prio)) {
		resched_curr(rq);
		return 0;
	}

	/* We might release rq lock */
	get_task_struct(next_task);

	/* find_lock_lowest_rq locks the rq if found */
	lowest_rq = find_lock_lowest_rq(next_task, rq);
	if (!lowest_rq) {
		struct task_struct *task;
		/*
		 * find_lock_lowest_rq releases rq->lock
		 * so it is possible that next_task has migrated.
		 *
		 * We need to make sure that the task is still on the same
		 * run-queue and is also still the next task eligible for
		 * pushing.
		 */
		task = pick_next_pushable_task(rq);
		if (task == next_task) {
			/*
			 * The task hasn't migrated, and is still the next
			 * eligible task, but we failed to find a run-queue
			 * to push it to.  Do not retry in this case, since
			 * other cpus will pull from us when ready.
			 */
			goto out;
		}

		if (!task)
			/* No more tasks, just exit */
			goto out;

		/*
		 * Something has shifted, try again.
		 */
		put_task_struct(next_task);
		next_task = task;
		goto retry;
	}

	deactivate_task(rq, next_task, 0);
	next_task->on_rq = TASK_ON_RQ_MIGRATING;
	set_task_cpu(next_task, lowest_rq->cpu);
	next_task->on_rq = TASK_ON_RQ_QUEUED;
	activate_task(lowest_rq, next_task, 0);
	ret = 1;

	resched_curr(lowest_rq);

	double_unlock_balance(rq, lowest_rq);

out:
	put_task_struct(next_task);

	return ret;
}

static void push_rt_tasks(struct rq *rq)
{
	/* push_rt_task will return true if it moved an RT */
	while (push_rt_task(rq))
		;
}

#ifdef HAVE_RT_PUSH_IPI

/*
 * When a high priority task schedules out from a CPU and a lower priority
 * task is scheduled in, a check is made to see if there's any RT tasks
 * on other CPUs that are waiting to run because a higher priority RT task
 * is currently running on its CPU. In this case, the CPU with multiple RT
 * tasks queued on it (overloaded) needs to be notified that a CPU has opened
 * up that may be able to run one of its non-running queued RT tasks.
 *
 * All CPUs with overloaded RT tasks need to be notified as there is currently
 * no way to know which of these CPUs have the highest priority task waiting
 * to run. Instead of trying to take a spinlock on each of these CPUs,
 * which has shown to cause large latency when done on machines with many
 * CPUs, sending an IPI to the CPUs to have them push off the overloaded
 * RT tasks waiting to run.
 *
 * Just sending an IPI to each of the CPUs is also an issue, as on large
 * count CPU machines, this can cause an IPI storm on a CPU, especially
 * if its the only CPU with multiple RT tasks queued, and a large number
 * of CPUs scheduling a lower priority task at the same time.
 *
 * Each root domain has its own irq work function that can iterate over
 * all CPUs with RT overloaded tasks. Since all CPUs with overloaded RT
 * tassk must be checked if there's one or many CPUs that are lowering
 * their priority, there's a single irq work iterator that will try to
 * push off RT tasks that are waiting to run.
 *
 * When a CPU schedules a lower priority task, it will kick off the
 * irq work iterator that will jump to each CPU with overloaded RT tasks.
 * As it only takes the first CPU that schedules a lower priority task
 * to start the process, the rto_start variable is incremented and if
 * the atomic result is one, then that CPU will try to take the rto_lock.
 * This prevents high contention on the lock as the process handles all
 * CPUs scheduling lower priority tasks.
 *
 * All CPUs that are scheduling a lower priority task will increment the
 * rt_loop_next variable. This will make sure that the irq work iterator
 * checks all RT overloaded CPUs whenever a CPU schedules a new lower
 * priority task, even if the iterator is in the middle of a scan. Incrementing
 * the rt_loop_next will cause the iterator to perform another scan.
 *
 */
static int rto_next_cpu(struct root_domain *rd)
{
	int next;
	int cpu;

	/*
	 * When starting the IPI RT pushing, the rto_cpu is set to -1,
	 * rt_next_cpu() will simply return the first CPU found in
	 * the rto_mask.
	 *
	 * If rto_next_cpu() is called with rto_cpu is a valid cpu, it
	 * will return the next CPU found in the rto_mask.
	 *
	 * If there are no more CPUs left in the rto_mask, then a check is made
	 * against rto_loop and rto_loop_next. rto_loop is only updated with
	 * the rto_lock held, but any CPU may increment the rto_loop_next
	 * without any locking.
	 */
	for (;;) {

		/* When rto_cpu is -1 this acts like cpumask_first() */
		cpu = cpumask_next(rd->rto_cpu, rd->rto_mask);

		rd->rto_cpu = cpu;

		if (cpu < nr_cpu_ids)
			return cpu;

		rd->rto_cpu = -1;

		/*
		 * ACQUIRE ensures we see the @rto_mask changes
		 * made prior to the @next value observed.
		 *
		 * Matches WMB in rt_set_overload().
		 */
		next = atomic_read_acquire(&rd->rto_loop_next);

		if (rd->rto_loop == next)
			break;

		rd->rto_loop = next;
	}

	return -1;
}

static inline bool rto_start_trylock(atomic_t *v)
{
	return !atomic_cmpxchg_acquire(v, 0, 1);
}

static inline void rto_start_unlock(atomic_t *v)
{
	atomic_set_release(v, 0);
}

static void tell_cpu_to_push(struct rq *rq)
{
	int cpu = -1;

	/* Keep the loop going if the IPI is currently active */
	atomic_inc(&rq->rd->rto_loop_next);

	/* Only one CPU can initiate a loop at a time */
	if (!rto_start_trylock(&rq->rd->rto_loop_start))
		return;

	raw_spin_lock(&rq->rd->rto_lock);

	/*
	 * The rto_cpu is updated under the lock, if it has a valid cpu
	 * then the IPI is still running and will continue due to the
	 * update to loop_next, and nothing needs to be done here.
	 * Otherwise it is finishing up and an ipi needs to be sent.
	 */
	if (rq->rd->rto_cpu < 0)
		cpu = rto_next_cpu(rq->rd);

	raw_spin_unlock(&rq->rd->rto_lock);

	rto_start_unlock(&rq->rd->rto_loop_start);

	if (cpu >= 0) {
		/* Make sure the rd does not get freed while pushing */
		sched_get_rd(rq->rd);
		irq_work_queue_on(&rq->rd->rto_push_work, cpu);
	}
}

/* Called from hardirq context */
void rto_push_irq_work_func(struct irq_work *work)
{
	struct root_domain *rd =
		container_of(work, struct root_domain, rto_push_work);
	struct rq *rq;
	int cpu;

	rq = this_rq();

	/*
	 * We do not need to grab the lock to check for has_pushable_tasks.
	 * When it gets updated, a check is made if a push is possible.
	 */
	if (has_pushable_tasks(rq)) {
		raw_spin_lock(&rq->lock);
		push_rt_tasks(rq);
		raw_spin_unlock(&rq->lock);
	}

	raw_spin_lock(&rd->rto_lock);

	/* Pass the IPI to the next rt overloaded queue */
	cpu = rto_next_cpu(rd);

	raw_spin_unlock(&rd->rto_lock);

	if (cpu < 0) {
		sched_put_rd(rd);
		return;
	}

	/* Try the next RT overloaded CPU */
	irq_work_queue_on(&rd->rto_push_work, cpu);
}
#endif /* HAVE_RT_PUSH_IPI */

static void pull_rt_task(struct rq *this_rq)
{
	int this_cpu = this_rq->cpu, cpu;
	bool resched = false;
	struct task_struct *p;
	struct rq *src_rq;
	int rt_overload_count = rt_overloaded(this_rq);

	if (likely(!rt_overload_count))
		return;

	/*
	 * Match the barrier from rt_set_overloaded; this guarantees that if we
	 * see overloaded we must also see the rto_mask bit.
	 */
	smp_rmb();

	/* If we are the only overloaded CPU do nothing */
	if (rt_overload_count == 1 &&
	    cpumask_test_cpu(this_rq->cpu, this_rq->rd->rto_mask))
		return;

#ifdef HAVE_RT_PUSH_IPI
	if (sched_feat(RT_PUSH_IPI)) {
		tell_cpu_to_push(this_rq);
		return;
	}
#endif

	for_each_cpu(cpu, this_rq->rd->rto_mask) {
		if (this_cpu == cpu)
			continue;

		src_rq = cpu_rq(cpu);

		/*
		 * Don't bother taking the src_rq->lock if the next highest
		 * task is known to be lower-priority than our current task.
		 * This may look racy, but if this value is about to go
		 * logically higher, the src_rq will push this task away.
		 * And if its going logically lower, we do not care
		 */
		if (src_rq->rt.highest_prio.next >=
		    this_rq->rt.highest_prio.curr)
			continue;

		/*
		 * We can potentially drop this_rq's lock in
		 * double_lock_balance, and another CPU could
		 * alter this_rq
		 */
		double_lock_balance(this_rq, src_rq);

		/*
		 * We can pull only a task, which is pushable
		 * on its rq, and no others.
		 */
		p = pick_highest_pushable_task(src_rq, this_cpu);

		/*
		 * Do we have an RT task that preempts
		 * the to-be-scheduled task?
		 */
		if (p && (p->prio < this_rq->rt.highest_prio.curr)) {
			WARN_ON(p == src_rq->curr);
			WARN_ON(!task_on_rq_queued(p));

			/*
			 * There's a chance that p is higher in priority
			 * than what's currently running on its cpu.
			 * This is just that p is wakeing up and hasn't
			 * had a chance to schedule. We only pull
			 * p if it is lower in priority than the
			 * current task on the run queue
			 */
			if (p->prio < src_rq->curr->prio)
				goto skip;

			resched = true;

			deactivate_task(src_rq, p, 0);
			p->on_rq = TASK_ON_RQ_MIGRATING;
			set_task_cpu(p, this_cpu);
			p->on_rq = TASK_ON_RQ_QUEUED;
			activate_task(this_rq, p, 0);
			/*
			 * We continue with the search, just in
			 * case there's an even higher prio task
			 * in another runqueue. (low likelihood
			 * but possible)
			 */
		}
skip:
		double_unlock_balance(this_rq, src_rq);
	}

	if (resched)
		resched_curr(this_rq);
}

/*
 * If we are not running and we are not going to reschedule soon, we should
 * try to push tasks away now
 */
static void task_woken_rt(struct rq *rq, struct task_struct *p)
{
	if (!task_running(rq, p) &&
	    !test_tsk_need_resched(rq->curr) &&
	    p->nr_cpus_allowed > 1 &&
	    (dl_task(rq->curr) || rt_task(rq->curr)) &&
	    (rq->curr->nr_cpus_allowed < 2 ||
	     rq->curr->prio <= p->prio)) {
#ifdef CONFIG_SCHED_USE_FLUID_RT
		if (p->rt.sync_flag && rq->curr->prio < p->prio) {
			p->rt.sync_flag = 0;
			push_rt_tasks(rq);
		}
#else
		push_rt_tasks(rq);
#endif
	}
#ifdef CONFIG_SCHED_USE_FLUID_RT
	p->rt.sync_flag = 0;
#endif
}

/* Assumes rq->lock is held */
static void rq_online_rt(struct rq *rq)
{
	if (rq->rt.overloaded)
		rt_set_overload(rq);

	__enable_runtime(rq);

	cpupri_set(&rq->rd->cpupri, rq->cpu, rq->rt.highest_prio.curr);
}

/* Assumes rq->lock is held */
static void rq_offline_rt(struct rq *rq)
{
	if (rq->rt.overloaded)
		rt_clear_overload(rq);

	__disable_runtime(rq);

	cpupri_set(&rq->rd->cpupri, rq->cpu, CPUPRI_INVALID);
}

/*
 * When switch from the rt queue, we bring ourselves to a position
 * that we might want to pull RT tasks from other runqueues.
 */
static void switched_from_rt(struct rq *rq, struct task_struct *p)
{
#ifdef CONFIG_RT_GROUP_SCHED
	detach_task_rt_rq(p);
#endif
	/*
	 * If there are other RT tasks then we will reschedule
	 * and the scheduling of the other RT tasks will handle
	 * the balancing. But if we are the last RT task
	 * we may need to handle the pulling of RT tasks
	 * now.
	 */
	if (!task_on_rq_queued(p) || rq->rt.rt_nr_running)
		return;

	queue_pull_task(rq);
}

void __init init_sched_rt_class(void)
{
	unsigned int i;

	for_each_possible_cpu(i) {
		zalloc_cpumask_var_node(&per_cpu(local_cpu_mask, i),
					GFP_KERNEL, cpu_to_node(i));
	}
}
#else
void update_rt_load_avg(u64 now, struct sched_rt_entity *rt_se)
{
}
#endif /* CONFIG_SMP */

extern void
copy_sched_avg(struct sched_avg *from, struct sched_avg *to, unsigned int ratio);

/*
 * When switching a task to RT, we may overload the runqueue
 * with RT tasks. In this case we try to push them off to
 * other runqueues.
 */
static void switched_to_rt(struct rq *rq, struct task_struct *p)
{
	/* Copy fair sched avg into rt sched avg */
	copy_sched_avg(&p->se.avg, &p->rt.avg, 100);
	/*
	 * If we are already running, then there's nothing
	 * that needs to be done. But if we are not running
	 * we may need to preempt the current running task.
	 * If that current running task is also an RT task
	 * then see if we can move to another run queue.
	 */
	if (task_on_rq_queued(p) && rq->curr != p) {
#ifdef CONFIG_SMP
		if (p->nr_cpus_allowed > 1 && rq->rt.overloaded)
			queue_push_tasks(rq);
#endif /* CONFIG_SMP */
		if (p->prio < rq->curr->prio && cpu_online(cpu_of(rq)))
			resched_curr(rq);
	}
}

/*
 * Priority of the task has changed. This may cause
 * us to initiate a push or pull.
 */
static void
prio_changed_rt(struct rq *rq, struct task_struct *p, int oldprio)
{
	if (!task_on_rq_queued(p))
		return;

	if (rq->curr == p) {
#ifdef CONFIG_SMP
		/*
		 * If our priority decreases while running, we
		 * may need to pull tasks to this runqueue.
		 */
		if (oldprio < p->prio)
			queue_pull_task(rq);

		/*
		 * If there's a higher priority task waiting to run
		 * then reschedule.
		 */
		if (p->prio > rq->rt.highest_prio.curr)
			resched_curr(rq);
#else
		/* For UP simply resched on drop of prio */
		if (oldprio < p->prio)
			resched_curr(rq);
#endif /* CONFIG_SMP */
	} else {
		/*
		 * This task is not running, but if it is
		 * greater than the current running task
		 * then reschedule.
		 */
		if (p->prio < rq->curr->prio)
			resched_curr(rq);
	}
}

#ifdef CONFIG_POSIX_TIMERS
static void watchdog(struct rq *rq, struct task_struct *p)
{
	unsigned long soft, hard;

	/* max may change after cur was read, this will be fixed next tick */
	soft = task_rlimit(p, RLIMIT_RTTIME);
	hard = task_rlimit_max(p, RLIMIT_RTTIME);

	if (soft != RLIM_INFINITY) {
		unsigned long next;

		if (p->rt.watchdog_stamp != jiffies) {
			p->rt.timeout++;
			p->rt.watchdog_stamp = jiffies;
		}

		next = DIV_ROUND_UP(min(soft, hard), USEC_PER_SEC/HZ);
		if (p->rt.timeout > next)
			p->cputime_expires.sched_exp = p->se.sum_exec_runtime;
	}
}
#else
static inline void watchdog(struct rq *rq, struct task_struct *p) { }
#endif

static void task_tick_rt(struct rq *rq, struct task_struct *p, int queued)
{
	struct sched_rt_entity *rt_se = &p->rt;
	u64 now = rq_clock_task(rq);
	int cpu = cpu_of(rq);

	update_curr_rt(rq);

	for_each_sched_rt_entity(rt_se)
		update_rt_load_avg(now, rt_se);

	update_rt_rq_load_avg(now, cpu, &rq->rt, rq->curr != NULL);
	update_activated_cpus();
	watchdog(rq, p);

	/*
	 * RR tasks need a special form of timeslice management.
	 * FIFO tasks have no timeslices.
	 */
	if (p->policy != SCHED_RR)
		return;

	if (--p->rt.time_slice)
		return;

	p->rt.time_slice = sched_rr_timeslice;

	/*
	 * Requeue to the end of queue if we (and all of our ancestors) are not
	 * the only element on the queue
	 */
	for_each_sched_rt_entity(rt_se) {
		if (rt_se->run_list.prev != rt_se->run_list.next) {
			requeue_task_rt(rq, p, 0);
			resched_curr(rq);
			return;
		}
	}
}

static void set_curr_task_rt(struct rq *rq)
{
	struct task_struct *p = rq->curr;
	struct sched_rt_entity *rt_se = &p->rt;

	p->se.exec_start = rq_clock_task(rq);

	for_each_sched_rt_entity(rt_se) {
		struct rt_rq *rt_rq = rt_rq_of_se(rt_se);
		rt_rq->curr = rt_se;
	}

	/* The running task is never eligible for pushing */
	dequeue_pushable_task(rq, p);
}

static unsigned int get_rr_interval_rt(struct rq *rq, struct task_struct *task)
{
	/*
	 * Time slice is 0 for SCHED_FIFO tasks
	 */
	if (task->policy == SCHED_RR)
		return sched_rr_timeslice;
	else
		return 0;
}

const struct sched_class rt_sched_class = {
	.next			= &fair_sched_class,
	.enqueue_task		= enqueue_task_rt,
	.dequeue_task		= dequeue_task_rt,
	.yield_task		= yield_task_rt,

	.check_preempt_curr	= check_preempt_curr_rt,

	.pick_next_task		= pick_next_task_rt,
	.put_prev_task		= put_prev_task_rt,

#ifdef CONFIG_SMP
	.select_task_rq		= select_task_rq_rt,

	.migrate_task_rq		= migrate_task_rq_rt,
	.task_dead				= task_dead_rt,
	.set_cpus_allowed       = set_cpus_allowed_common,
	.rq_online              = rq_online_rt,
	.rq_offline             = rq_offline_rt,
	.task_woken		= task_woken_rt,
	.switched_from		= switched_from_rt,
#endif

	.set_curr_task          = set_curr_task_rt,
	.task_tick		= task_tick_rt,

	.get_rr_interval	= get_rr_interval_rt,

	.prio_changed		= prio_changed_rt,
	.switched_to		= switched_to_rt,

	.update_curr		= update_curr_rt,
#ifdef CONFIG_SCHED_WALT
	.fixup_cumulative_runnable_avg = walt_fixup_cumulative_runnable_avg,
#endif
#ifdef CONFIG_RT_GROUP_SCHED
	.task_change_group	= task_change_group_rt,
#endif
};

#ifdef CONFIG_RT_GROUP_SCHED
/*
 * Ensure that the real time constraints are schedulable.
 */
static DEFINE_MUTEX(rt_constraints_mutex);

/* Must be called with tasklist_lock held */
static inline int tg_has_rt_tasks(struct task_group *tg)
{
	struct task_struct *g, *p;

	/*
	 * Autogroups do not have RT tasks; see autogroup_create().
	 */
	if (task_group_is_autogroup(tg))
		return 0;

	for_each_process_thread(g, p) {
		if (rt_task(p) && task_group(p) == tg)
			return 1;
	}

	return 0;
}

struct rt_schedulable_data {
	struct task_group *tg;
	u64 rt_period;
	u64 rt_runtime;
};

static int tg_rt_schedulable(struct task_group *tg, void *data)
{
	struct rt_schedulable_data *d = data;
	struct task_group *child;
	unsigned long total, sum = 0;
	u64 period, runtime;

	period = ktime_to_ns(tg->rt_bandwidth.rt_period);
	runtime = tg->rt_bandwidth.rt_runtime;

	if (tg == d->tg) {
		period = d->rt_period;
		runtime = d->rt_runtime;
	}

	/*
	 * Cannot have more runtime than the period.
	 */
	if (runtime > period && runtime != RUNTIME_INF)
		return -EINVAL;

	/*
	 * Ensure we don't starve existing RT tasks.
	 */
	if (rt_bandwidth_enabled() && !runtime && tg_has_rt_tasks(tg))
		return -EBUSY;

	total = to_ratio(period, runtime);

	/*
	 * Nobody can have more than the global setting allows.
	 */
	if (total > to_ratio(global_rt_period(), global_rt_runtime()))
		return -EINVAL;

	/*
	 * The sum of our children's runtime should not exceed our own.
	 */
	list_for_each_entry_rcu(child, &tg->children, siblings) {
		period = ktime_to_ns(child->rt_bandwidth.rt_period);
		runtime = child->rt_bandwidth.rt_runtime;

		if (child == d->tg) {
			period = d->rt_period;
			runtime = d->rt_runtime;
		}

		sum += to_ratio(period, runtime);
	}

	if (sum > total)
		return -EINVAL;

	return 0;
}

static int __rt_schedulable(struct task_group *tg, u64 period, u64 runtime)
{
	int ret;

	struct rt_schedulable_data data = {
		.tg = tg,
		.rt_period = period,
		.rt_runtime = runtime,
	};

	rcu_read_lock();
	ret = walk_tg_tree(tg_rt_schedulable, tg_nop, &data);
	rcu_read_unlock();

	return ret;
}

static int tg_set_rt_bandwidth(struct task_group *tg,
		u64 rt_period, u64 rt_runtime)
{
	int i, err = 0;

	/*
	 * Disallowing the root group RT runtime is BAD, it would disallow the
	 * kernel creating (and or operating) RT threads.
	 */
	if (tg == &root_task_group && rt_runtime == 0)
		return -EINVAL;

	/* No period doesn't make any sense. */
	if (rt_period == 0)
		return -EINVAL;

	mutex_lock(&rt_constraints_mutex);
	read_lock(&tasklist_lock);
	err = __rt_schedulable(tg, rt_period, rt_runtime);
	if (err)
		goto unlock;

	raw_spin_lock_irq(&tg->rt_bandwidth.rt_runtime_lock);
	tg->rt_bandwidth.rt_period = ns_to_ktime(rt_period);
	tg->rt_bandwidth.rt_runtime = rt_runtime;

	for_each_possible_cpu(i) {
		struct rt_rq *rt_rq = tg->rt_rq[i];

		raw_spin_lock(&rt_rq->rt_runtime_lock);
		rt_rq->rt_runtime = rt_runtime;
		raw_spin_unlock(&rt_rq->rt_runtime_lock);
	}
	raw_spin_unlock_irq(&tg->rt_bandwidth.rt_runtime_lock);
unlock:
	read_unlock(&tasklist_lock);
	mutex_unlock(&rt_constraints_mutex);

	return err;
}

int sched_group_set_rt_runtime(struct task_group *tg, long rt_runtime_us)
{
	u64 rt_runtime, rt_period;

	rt_period = ktime_to_ns(tg->rt_bandwidth.rt_period);
	rt_runtime = (u64)rt_runtime_us * NSEC_PER_USEC;
	if (rt_runtime_us < 0)
		rt_runtime = RUNTIME_INF;
	else if ((u64)rt_runtime_us > U64_MAX / NSEC_PER_USEC)
		return -EINVAL;

	return tg_set_rt_bandwidth(tg, rt_period, rt_runtime);
}

long sched_group_rt_runtime(struct task_group *tg)
{
	u64 rt_runtime_us;

	if (tg->rt_bandwidth.rt_runtime == RUNTIME_INF)
		return -1;

	rt_runtime_us = tg->rt_bandwidth.rt_runtime;
	do_div(rt_runtime_us, NSEC_PER_USEC);
	return rt_runtime_us;
}

int sched_group_set_rt_period(struct task_group *tg, u64 rt_period_us)
{
	u64 rt_runtime, rt_period;

	if (rt_period_us > U64_MAX / NSEC_PER_USEC)
		return -EINVAL;

	rt_period = rt_period_us * NSEC_PER_USEC;
	rt_runtime = tg->rt_bandwidth.rt_runtime;

	return tg_set_rt_bandwidth(tg, rt_period, rt_runtime);
}

long sched_group_rt_period(struct task_group *tg)
{
	u64 rt_period_us;

	rt_period_us = ktime_to_ns(tg->rt_bandwidth.rt_period);
	do_div(rt_period_us, NSEC_PER_USEC);
	return rt_period_us;
}

static int sched_rt_global_constraints(void)
{
	int ret = 0;

	mutex_lock(&rt_constraints_mutex);
	read_lock(&tasklist_lock);
	ret = __rt_schedulable(NULL, 0, 0);
	read_unlock(&tasklist_lock);
	mutex_unlock(&rt_constraints_mutex);

	return ret;
}

int sched_rt_can_attach(struct task_group *tg, struct task_struct *tsk)
{
	/* Don't accept realtime tasks when there is no way for them to run */
	if (rt_task(tsk) && tg->rt_bandwidth.rt_runtime == 0)
		return 0;

	return 1;
}

#else /* !CONFIG_RT_GROUP_SCHED */
static int sched_rt_global_constraints(void)
{
	unsigned long flags;
	int i;

	raw_spin_lock_irqsave(&def_rt_bandwidth.rt_runtime_lock, flags);
	for_each_possible_cpu(i) {
		struct rt_rq *rt_rq = &cpu_rq(i)->rt;

		raw_spin_lock(&rt_rq->rt_runtime_lock);
		rt_rq->rt_runtime = global_rt_runtime();
		raw_spin_unlock(&rt_rq->rt_runtime_lock);
	}
	raw_spin_unlock_irqrestore(&def_rt_bandwidth.rt_runtime_lock, flags);

	return 0;
}
#endif /* CONFIG_RT_GROUP_SCHED */

static int sched_rt_global_validate(void)
{
	if ((sysctl_sched_rt_runtime != RUNTIME_INF) &&
		(sysctl_sched_rt_runtime > sysctl_sched_rt_period))
		return -EINVAL;

	return 0;
}

static void sched_rt_do_global(void)
{
	unsigned long flags;

	raw_spin_lock_irqsave(&def_rt_bandwidth.rt_runtime_lock, flags);
	def_rt_bandwidth.rt_runtime = global_rt_runtime();
	def_rt_bandwidth.rt_period = ns_to_ktime(global_rt_period());
	raw_spin_unlock_irqrestore(&def_rt_bandwidth.rt_runtime_lock, flags);
}

int sched_rt_handler(struct ctl_table *table, int write,
		void __user *buffer, size_t *lenp,
		loff_t *ppos)
{
	int old_period, old_runtime;
	static DEFINE_MUTEX(mutex);
	int ret;

	mutex_lock(&mutex);
	old_period = sysctl_sched_rt_period;
	old_runtime = sysctl_sched_rt_runtime;

	ret = proc_dointvec_minmax(table, write, buffer, lenp, ppos);

	if (!ret && write) {
		ret = sched_rt_global_validate();
		if (ret)
			goto undo;

		ret = sched_dl_global_validate();
		if (ret)
			goto undo;

		ret = sched_rt_global_constraints();
		if (ret)
			goto undo;

		sched_rt_do_global();
		sched_dl_do_global();
	}
	if (0) {
undo:
		sysctl_sched_rt_period = old_period;
		sysctl_sched_rt_runtime = old_runtime;
	}
	mutex_unlock(&mutex);

	return ret;
}

int sched_rr_handler(struct ctl_table *table, int write,
		void __user *buffer, size_t *lenp,
		loff_t *ppos)
{
	int ret;
	static DEFINE_MUTEX(mutex);

	mutex_lock(&mutex);
	ret = proc_dointvec(table, write, buffer, lenp, ppos);
	/*
	 * Make sure that internally we keep jiffies.
	 * Also, writing zero resets the timeslice to default:
	 */
	if (!ret && write) {
		sched_rr_timeslice =
			sysctl_sched_rr_timeslice <= 0 ? RR_TIMESLICE :
			msecs_to_jiffies(sysctl_sched_rr_timeslice);

		if (sysctl_sched_rr_timeslice <= 0)
			sysctl_sched_rr_timeslice = jiffies_to_msecs(RR_TIMESLICE);
	}
	mutex_unlock(&mutex);
	return ret;
}

#ifdef CONFIG_SCHED_DEBUG
void print_rt_stats(struct seq_file *m, int cpu)
{
	rt_rq_iter_t iter;
	struct rt_rq *rt_rq;

	rcu_read_lock();
	for_each_rt_rq(rt_rq, iter, cpu_rq(cpu))
		print_rt_rq(m, cpu, rt_rq);
	rcu_read_unlock();
}
#endif /* CONFIG_SCHED_DEBUG */