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Root/kernel/sched.c

1	/*
2	* kernel/sched.c
3	*
4	* Kernel scheduler and related syscalls
5	*
6	* Copyright (C) 1991-2002 Linus Torvalds
7	*
8	* 1996-12-23 Modified by Dave Grothe to fix bugs in semaphores and
9	* make semaphores SMP safe
10	* 1998-11-19 Implemented schedule_timeout() and related stuff
11	* by Andrea Arcangeli
12	* 2002-01-04 New ultra-scalable O(1) scheduler by Ingo Molnar:
13	* hybrid priority-list and round-robin design with
14	* an array-switch method of distributing timeslices
15	* and per-CPU runqueues. Cleanups and useful suggestions
16	* by Davide Libenzi, preemptible kernel bits by Robert Love.
17	* 2003-09-03 Interactivity tuning by Con Kolivas.
18	* 2004-04-02 Scheduler domains code by Nick Piggin
19	* 2007-04-15 Work begun on replacing all interactivity tuning with a
20	* fair scheduling design by Con Kolivas.
21	* 2007-05-05 Load balancing (smp-nice) and other improvements
22	* by Peter Williams
23	* 2007-05-06 Interactivity improvements to CFS by Mike Galbraith
24	* 2007-07-01 Group scheduling enhancements by Srivatsa Vaddagiri
25	* 2007-11-29 RT balancing improvements by Steven Rostedt, Gregory Haskins,
26	* Thomas Gleixner, Mike Kravetz
27	*/
28
29	#include <linux/mm.h>
30	#include <linux/module.h>
31	#include <linux/nmi.h>
32	#include <linux/init.h>
33	#include <linux/uaccess.h>
34	#include <linux/highmem.h>
35	#include <linux/smp_lock.h>
36	#include <asm/mmu_context.h>
37	#include <linux/interrupt.h>
38	#include <linux/capability.h>
39	#include <linux/completion.h>
40	#include <linux/kernel_stat.h>
41	#include <linux/debug_locks.h>
42	#include <linux/perf_event.h>
43	#include <linux/security.h>
44	#include <linux/notifier.h>
45	#include <linux/profile.h>
46	#include <linux/freezer.h>
47	#include <linux/vmalloc.h>
48	#include <linux/blkdev.h>
49	#include <linux/delay.h>
50	#include <linux/pid_namespace.h>
51	#include <linux/smp.h>
52	#include <linux/threads.h>
53	#include <linux/timer.h>
54	#include <linux/rcupdate.h>
55	#include <linux/cpu.h>
56	#include <linux/cpuset.h>
57	#include <linux/percpu.h>
58	#include <linux/proc_fs.h>
59	#include <linux/seq_file.h>
60	#include <linux/stop_machine.h>
61	#include <linux/sysctl.h>
62	#include <linux/syscalls.h>
63	#include <linux/times.h>
64	#include <linux/tsacct_kern.h>
65	#include <linux/kprobes.h>
66	#include <linux/delayacct.h>
67	#include <linux/unistd.h>
68	#include <linux/pagemap.h>
69	#include <linux/hrtimer.h>
70	#include <linux/tick.h>
71	#include <linux/debugfs.h>
72	#include <linux/ctype.h>
73	#include <linux/ftrace.h>
74	#include <linux/slab.h>
75
76	#include <asm/tlb.h>
77	#include <asm/irq_regs.h>
78	#include <asm/mutex.h>
79
80	#include "sched_cpupri.h"
81	#include "workqueue_sched.h"
82	#include "sched_autogroup.h"
83
84	#define CREATE_TRACE_POINTS
85	#include <trace/events/sched.h>
86
87	/*
88	* Convert user-nice values [ -20 ... 0 ... 19 ]
89	* to static priority [ MAX_RT_PRIO..MAX_PRIO-1 ],
90	* and back.
91	*/
92	#define NICE_TO_PRIO(nice) (MAX_RT_PRIO + (nice) + 20)
93	#define PRIO_TO_NICE(prio) ((prio) - MAX_RT_PRIO - 20)
94	#define TASK_NICE(p) PRIO_TO_NICE((p)->static_prio)
95
96	/*
97	* 'User priority' is the nice value converted to something we
98	* can work with better when scaling various scheduler parameters,
99	* it's a [ 0 ... 39 ] range.
100	*/
101	#define USER_PRIO(p) ((p)-MAX_RT_PRIO)
102	#define TASK_USER_PRIO(p) USER_PRIO((p)->static_prio)
103	#define MAX_USER_PRIO (USER_PRIO(MAX_PRIO))
104
105	/*
106	* Helpers for converting nanosecond timing to jiffy resolution
107	*/
108	#define NS_TO_JIFFIES(TIME) ((unsigned long)(TIME) / (NSEC_PER_SEC / HZ))
109
110	#define NICE_0_LOAD SCHED_LOAD_SCALE
111	#define NICE_0_SHIFT SCHED_LOAD_SHIFT
112
113	/*
114	* These are the 'tuning knobs' of the scheduler:
115	*
116	* default timeslice is 100 msecs (used only for SCHED_RR tasks).
117	* Timeslices get refilled after they expire.
118	*/
119	#define DEF_TIMESLICE (100 * HZ / 1000)
120
121	/*
122	* single value that denotes runtime == period, ie unlimited time.
123	*/
124	#define RUNTIME_INF ((u64)~0ULL)
125
126	static inline int rt_policy(int policy)
127	{
128	if (unlikely(policy == SCHED_FIFO \|\| policy == SCHED_RR))
129	return 1;
130	return 0;
131	}
132
133	static inline int task_has_rt_policy(struct task_struct *p)
134	{
135	return rt_policy(p->policy);
136	}
137
138	/*
139	* This is the priority-queue data structure of the RT scheduling class:
140	*/
141	struct rt_prio_array {
142	DECLARE_BITMAP(bitmap, MAX_RT_PRIO+1); /* include 1 bit for delimiter */
143	struct list_head queue[MAX_RT_PRIO];
144	};
145
146	struct rt_bandwidth {
147	/* nests inside the rq lock: */
148	raw_spinlock_t rt_runtime_lock;
149	ktime_t rt_period;
150	u64 rt_runtime;
151	struct hrtimer rt_period_timer;
152	};
153
154	static struct rt_bandwidth def_rt_bandwidth;
155
156	static int do_sched_rt_period_timer(struct rt_bandwidth *rt_b, int overrun);
157
158	static enum hrtimer_restart sched_rt_period_timer(struct hrtimer *timer)
159	{
160	struct rt_bandwidth *rt_b =
161	container_of(timer, struct rt_bandwidth, rt_period_timer);
162	ktime_t now;
163	int overrun;
164	int idle = 0;
165
166	for (;;) {
167	now = hrtimer_cb_get_time(timer);
168	overrun = hrtimer_forward(timer, now, rt_b->rt_period);
169
170	if (!overrun)
171	break;
172
173	idle = do_sched_rt_period_timer(rt_b, overrun);
174	}
175
176	return idle ? HRTIMER_NORESTART : HRTIMER_RESTART;
177	}
178
179	static
180	void init_rt_bandwidth(struct rt_bandwidth *rt_b, u64 period, u64 runtime)
181	{
182	rt_b->rt_period = ns_to_ktime(period);
183	rt_b->rt_runtime = runtime;
184
185	raw_spin_lock_init(&rt_b->rt_runtime_lock);
186
187	hrtimer_init(&rt_b->rt_period_timer,
188	CLOCK_MONOTONIC, HRTIMER_MODE_REL);
189	rt_b->rt_period_timer.function = sched_rt_period_timer;
190	}
191
192	static inline int rt_bandwidth_enabled(void)
193	{
194	return sysctl_sched_rt_runtime >= 0;
195	}
196
197	static void start_rt_bandwidth(struct rt_bandwidth *rt_b)
198	{
199	ktime_t now;
200
201	if (!rt_bandwidth_enabled() \|\| rt_b->rt_runtime == RUNTIME_INF)
202	return;
203
204	if (hrtimer_active(&rt_b->rt_period_timer))
205	return;
206
207	raw_spin_lock(&rt_b->rt_runtime_lock);
208	for (;;) {
209	unsigned long delta;
210	ktime_t soft, hard;
211
212	if (hrtimer_active(&rt_b->rt_period_timer))
213	break;
214
215	now = hrtimer_cb_get_time(&rt_b->rt_period_timer);
216	hrtimer_forward(&rt_b->rt_period_timer, now, rt_b->rt_period);
217
218	soft = hrtimer_get_softexpires(&rt_b->rt_period_timer);
219	hard = hrtimer_get_expires(&rt_b->rt_period_timer);
220	delta = ktime_to_ns(ktime_sub(hard, soft));
221	__hrtimer_start_range_ns(&rt_b->rt_period_timer, soft, delta,
222	HRTIMER_MODE_ABS_PINNED, 0);
223	}
224	raw_spin_unlock(&rt_b->rt_runtime_lock);
225	}
226
227	#ifdef CONFIG_RT_GROUP_SCHED
228	static void destroy_rt_bandwidth(struct rt_bandwidth *rt_b)
229	{
230	hrtimer_cancel(&rt_b->rt_period_timer);
231	}
232	#endif
233
234	/*
235	* sched_domains_mutex serializes calls to arch_init_sched_domains,
236	* detach_destroy_domains and partition_sched_domains.
237	*/
238	static DEFINE_MUTEX(sched_domains_mutex);
239
240	#ifdef CONFIG_CGROUP_SCHED
241
242	#include <linux/cgroup.h>
243
244	struct cfs_rq;
245
246	static LIST_HEAD(task_groups);
247
248	/* task group related information */
249	struct task_group {
250	struct cgroup_subsys_state css;
251
252	#ifdef CONFIG_FAIR_GROUP_SCHED
253	/* schedulable entities of this group on each cpu */
254	struct sched_entity **se;
255	/* runqueue "owned" by this group on each cpu */
256	struct cfs_rq **cfs_rq;
257	unsigned long shares;
258
259	atomic_t load_weight;
260	#endif
261
262	#ifdef CONFIG_RT_GROUP_SCHED
263	struct sched_rt_entity **rt_se;
264	struct rt_rq **rt_rq;
265
266	struct rt_bandwidth rt_bandwidth;
267	#endif
268
269	struct rcu_head rcu;
270	struct list_head list;
271
272	struct task_group *parent;
273	struct list_head siblings;
274	struct list_head children;
275
276	#ifdef CONFIG_SCHED_AUTOGROUP
277	struct autogroup *autogroup;
278	#endif
279	};
280
281	/* task_group_lock serializes the addition/removal of task groups */
282	static DEFINE_SPINLOCK(task_group_lock);
283
284	#ifdef CONFIG_FAIR_GROUP_SCHED
285
286	# define ROOT_TASK_GROUP_LOAD NICE_0_LOAD
287
288	/*
289	* A weight of 0 or 1 can cause arithmetics problems.
290	* A weight of a cfs_rq is the sum of weights of which entities
291	* are queued on this cfs_rq, so a weight of a entity should not be
292	* too large, so as the shares value of a task group.
293	* (The default weight is 1024 - so there's no practical
294	* limitation from this.)
295	*/
296	#define MIN_SHARES 2
297	#define MAX_SHARES (1UL << 18)
298
299	static int root_task_group_load = ROOT_TASK_GROUP_LOAD;
300	#endif
301
302	/* Default task group.
303	* Every task in system belong to this group at bootup.
304	*/
305	struct task_group root_task_group;
306
307	#endif /* CONFIG_CGROUP_SCHED */
308
309	/* CFS-related fields in a runqueue */
310	struct cfs_rq {
311	struct load_weight load;
312	unsigned long nr_running;
313
314	u64 exec_clock;
315	u64 min_vruntime;
316
317	struct rb_root tasks_timeline;
318	struct rb_node *rb_leftmost;
319
320	struct list_head tasks;
321	struct list_head *balance_iterator;
322
323	/*
324	* 'curr' points to currently running entity on this cfs_rq.
325	* It is set to NULL otherwise (i.e when none are currently running).
326	*/
327	struct sched_entity curr, next, *last;
328
329	unsigned int nr_spread_over;
330
331	#ifdef CONFIG_FAIR_GROUP_SCHED
332	struct rq rq; / cpu runqueue to which this cfs_rq is attached */
333
334	/*
335	* leaf cfs_rqs are those that hold tasks (lowest schedulable entity in
336	* a hierarchy). Non-leaf lrqs hold other higher schedulable entities
337	* (like users, containers etc.)
338	*
339	* leaf_cfs_rq_list ties together list of leaf cfs_rq's in a cpu. This
340	* list is used during load balance.
341	*/
342	int on_list;
343	struct list_head leaf_cfs_rq_list;
344	struct task_group tg; / group that "owns" this runqueue */
345
346	#ifdef CONFIG_SMP
347	/*
348	* the part of load.weight contributed by tasks
349	*/
350	unsigned long task_weight;
351
352	/*
353	* h_load = weight * f(tg)
354	*
355	* Where f(tg) is the recursive weight fraction assigned to
356	* this group.
357	*/
358	unsigned long h_load;
359
360	/*
361	* Maintaining per-cpu shares distribution for group scheduling
362	*
363	* load_stamp is the last time we updated the load average
364	* load_last is the last time we updated the load average and saw load
365	* load_unacc_exec_time is currently unaccounted execution time
366	*/
367	u64 load_avg;
368	u64 load_period;
369	u64 load_stamp, load_last, load_unacc_exec_time;
370
371	unsigned long load_contribution;
372	#endif
373	#endif
374	};
375
376	/* Real-Time classes' related field in a runqueue: */
377	struct rt_rq {
378	struct rt_prio_array active;
379	unsigned long rt_nr_running;
380	#if defined CONFIG_SMP \|\| defined CONFIG_RT_GROUP_SCHED
381	struct {
382	int curr; /* highest queued rt task prio */
383	#ifdef CONFIG_SMP
384	int next; /* next highest */
385	#endif
386	} highest_prio;
387	#endif
388	#ifdef CONFIG_SMP
389	unsigned long rt_nr_migratory;
390	unsigned long rt_nr_total;
391	int overloaded;
392	struct plist_head pushable_tasks;
393	#endif
394	int rt_throttled;
395	u64 rt_time;
396	u64 rt_runtime;
397	/* Nests inside the rq lock: */
398	raw_spinlock_t rt_runtime_lock;
399
400	#ifdef CONFIG_RT_GROUP_SCHED
401	unsigned long rt_nr_boosted;
402
403	struct rq *rq;
404	struct list_head leaf_rt_rq_list;
405	struct task_group *tg;
406	#endif
407	};
408
409	#ifdef CONFIG_SMP
410
411	/*
412	* We add the notion of a root-domain which will be used to define per-domain
413	* variables. Each exclusive cpuset essentially defines an island domain by
414	* fully partitioning the member cpus from any other cpuset. Whenever a new
415	* exclusive cpuset is created, we also create and attach a new root-domain
416	* object.
417	*
418	*/
419	struct root_domain {
420	atomic_t refcount;
421	cpumask_var_t span;
422	cpumask_var_t online;
423
424	/*
425	* The "RT overload" flag: it gets set if a CPU has more than
426	* one runnable RT task.
427	*/
428	cpumask_var_t rto_mask;
429	atomic_t rto_count;
430	struct cpupri cpupri;
431	};
432
433	/*
434	* By default the system creates a single root-domain with all cpus as
435	* members (mimicking the global state we have today).
436	*/
437	static struct root_domain def_root_domain;
438
439	#endif /* CONFIG_SMP */
440
441	/*
442	* This is the main, per-CPU runqueue data structure.
443	*
444	* Locking rule: those places that want to lock multiple runqueues
445	* (such as the load balancing or the thread migration code), lock
446	* acquire operations must be ordered by ascending &runqueue.
447	*/
448	struct rq {
449	/* runqueue lock: */
450	raw_spinlock_t lock;
451
452	/*
453	* nr_running and cpu_load should be in the same cacheline because
454	* remote CPUs use both these fields when doing load calculation.
455	*/
456	unsigned long nr_running;
457	#define CPU_LOAD_IDX_MAX 5
458	unsigned long cpu_load[CPU_LOAD_IDX_MAX];
459	unsigned long last_load_update_tick;
460	#ifdef CONFIG_NO_HZ
461	u64 nohz_stamp;
462	unsigned char nohz_balance_kick;
463	#endif
464	unsigned int skip_clock_update;
465
466	/* capture load from all tasks on this cpu: */
467	struct load_weight load;
468	unsigned long nr_load_updates;
469	u64 nr_switches;
470
471	struct cfs_rq cfs;
472	struct rt_rq rt;
473
474	#ifdef CONFIG_FAIR_GROUP_SCHED
475	/* list of leaf cfs_rq on this cpu: */
476	struct list_head leaf_cfs_rq_list;
477	#endif
478	#ifdef CONFIG_RT_GROUP_SCHED
479	struct list_head leaf_rt_rq_list;
480	#endif
481
482	/*
483	* This is part of a global counter where only the total sum
484	* over all CPUs matters. A task can increase this counter on
485	* one CPU and if it got migrated afterwards it may decrease
486	* it on another CPU. Always updated under the runqueue lock:
487	*/
488	unsigned long nr_uninterruptible;
489
490	struct task_struct curr, idle, *stop;
491	unsigned long next_balance;
492	struct mm_struct *prev_mm;
493
494	u64 clock;
495	u64 clock_task;
496
497	atomic_t nr_iowait;
498
499	#ifdef CONFIG_SMP
500	struct root_domain *rd;
501	struct sched_domain *sd;
502
503	unsigned long cpu_power;
504
505	unsigned char idle_at_tick;
506	/* For active balancing */
507	int post_schedule;
508	int active_balance;
509	int push_cpu;
510	struct cpu_stop_work active_balance_work;
511	/* cpu of this runqueue: */
512	int cpu;
513	int online;
514
515	unsigned long avg_load_per_task;
516
517	u64 rt_avg;
518	u64 age_stamp;
519	u64 idle_stamp;
520	u64 avg_idle;
521	#endif
522
523	#ifdef CONFIG_IRQ_TIME_ACCOUNTING
524	u64 prev_irq_time;
525	#endif
526
527	/* calc_load related fields */
528	unsigned long calc_load_update;
529	long calc_load_active;
530
531	#ifdef CONFIG_SCHED_HRTICK
532	#ifdef CONFIG_SMP
533	int hrtick_csd_pending;
534	struct call_single_data hrtick_csd;
535	#endif
536	struct hrtimer hrtick_timer;
537	#endif
538
539	#ifdef CONFIG_SCHEDSTATS
540	/* latency stats */
541	struct sched_info rq_sched_info;
542	unsigned long long rq_cpu_time;
543	/* could above be rq->cfs_rq.exec_clock + rq->rt_rq.rt_runtime ? */
544
545	/* sys_sched_yield() stats */
546	unsigned int yld_count;
547
548	/* schedule() stats */
549	unsigned int sched_switch;
550	unsigned int sched_count;
551	unsigned int sched_goidle;
552
553	/* try_to_wake_up() stats */
554	unsigned int ttwu_count;
555	unsigned int ttwu_local;
556	#endif
557	};
558
559	static DEFINE_PER_CPU_SHARED_ALIGNED(struct rq, runqueues);
560
561
562	static void check_preempt_curr(struct rq rq, struct task_struct p, int flags);
563
564	static inline int cpu_of(struct rq *rq)
565	{
566	#ifdef CONFIG_SMP
567	return rq->cpu;
568	#else
569	return 0;
570	#endif
571	}
572
573	#define rcu_dereference_check_sched_domain(p) \
574	rcu_dereference_check((p), \
575	rcu_read_lock_sched_held() \|\| \
576	lockdep_is_held(&sched_domains_mutex))
577
578	/*
579	* The domain tree (rq->sd) is protected by RCU's quiescent state transition.
580	* See detach_destroy_domains: synchronize_sched for details.
581	*
582	* The domain tree of any CPU may only be accessed from within
583	* preempt-disabled sections.
584	*/
585	#define for_each_domain(cpu, __sd) \
586	for (__sd = rcu_dereference_check_sched_domain(cpu_rq(cpu)->sd); __sd; __sd = __sd->parent)
587
588	#define cpu_rq(cpu) (&per_cpu(runqueues, (cpu)))
589	#define this_rq() (&__get_cpu_var(runqueues))
590	#define task_rq(p) cpu_rq(task_cpu(p))
591	#define cpu_curr(cpu) (cpu_rq(cpu)->curr)
592	#define raw_rq() (&__raw_get_cpu_var(runqueues))
593
594	#ifdef CONFIG_CGROUP_SCHED
595
596	/*
597	* Return the group to which this tasks belongs.
598	*
599	* We use task_subsys_state_check() and extend the RCU verification
600	* with lockdep_is_held(&task_rq(p)->lock) because cpu_cgroup_attach()
601	* holds that lock for each task it moves into the cgroup. Therefore
602	* by holding that lock, we pin the task to the current cgroup.
603	*/
604	static inline struct task_group task_group(struct task_struct p)
605	{
606	struct task_group *tg;
607	struct cgroup_subsys_state *css;
608
609	if (p->flags & PF_EXITING)
610	return &root_task_group;
611
612	css = task_subsys_state_check(p, cpu_cgroup_subsys_id,
613	lockdep_is_held(&task_rq(p)->lock));
614	tg = container_of(css, struct task_group, css);
615
616	return autogroup_task_group(p, tg);
617	}
618
619	/* Change a task's cfs_rq and parent entity if it moves across CPUs/groups */
620	static inline void set_task_rq(struct task_struct *p, unsigned int cpu)
621	{
622	#ifdef CONFIG_FAIR_GROUP_SCHED
623	p->se.cfs_rq = task_group(p)->cfs_rq[cpu];
624	p->se.parent = task_group(p)->se[cpu];
625	#endif
626
627	#ifdef CONFIG_RT_GROUP_SCHED
628	p->rt.rt_rq = task_group(p)->rt_rq[cpu];
629	p->rt.parent = task_group(p)->rt_se[cpu];
630	#endif
631	}
632
633	#else /* CONFIG_CGROUP_SCHED */
634
635	static inline void set_task_rq(struct task_struct *p, unsigned int cpu) { }
636	static inline struct task_group task_group(struct task_struct p)
637	{
638	return NULL;
639	}
640
641	#endif /* CONFIG_CGROUP_SCHED */
642
643	static void update_rq_clock_task(struct rq *rq, s64 delta);
644
645	static void update_rq_clock(struct rq *rq)
646	{
647	s64 delta;
648
649	if (rq->skip_clock_update)
650	return;
651
652	delta = sched_clock_cpu(cpu_of(rq)) - rq->clock;
653	rq->clock += delta;
654	update_rq_clock_task(rq, delta);
655	}
656
657	/*
658	* Tunables that become constants when CONFIG_SCHED_DEBUG is off:
659	*/
660	#ifdef CONFIG_SCHED_DEBUG
661	# define const_debug __read_mostly
662	#else
663	# define const_debug static const
664	#endif
665
666	/**
667	* runqueue_is_locked
668	* @cpu: the processor in question.
669	*
670	* Returns true if the current cpu runqueue is locked.
671	* This interface allows printk to be called with the runqueue lock
672	* held and know whether or not it is OK to wake up the klogd.
673	*/
674	int runqueue_is_locked(int cpu)
675	{
676	return raw_spin_is_locked(&cpu_rq(cpu)->lock);
677	}
678
679	/*
680	* Debugging: various feature bits
681	*/
682
683	#define SCHED_FEAT(name, enabled) \
684	__SCHED_FEAT_##name ,
685
686	enum {
687	#include "sched_features.h"
688	};
689
690	#undef SCHED_FEAT
691
692	#define SCHED_FEAT(name, enabled) \
693	(1UL << __SCHED_FEAT_##name) * enabled \|
694
695	const_debug unsigned int sysctl_sched_features =
696	#include "sched_features.h"
697	0;
698
699	#undef SCHED_FEAT
700
701	#ifdef CONFIG_SCHED_DEBUG
702	#define SCHED_FEAT(name, enabled) \
703	#name ,
704
705	static __read_mostly char *sched_feat_names[] = {
706	#include "sched_features.h"
707	NULL
708	};
709
710	#undef SCHED_FEAT
711
712	static int sched_feat_show(struct seq_file m, void v)
713	{
714	int i;
715
716	for (i = 0; sched_feat_names[i]; i++) {
717	if (!(sysctl_sched_features & (1UL << i)))
718	seq_puts(m, "NO_");
719	seq_printf(m, "%s ", sched_feat_names[i]);
720	}
721	seq_puts(m, "\n");
722
723	return 0;
724	}
725
726	static ssize_t
727	sched_feat_write(struct file filp, const char __user ubuf,
728	size_t cnt, loff_t *ppos)
729	{
730	char buf[64];
731	char *cmp;
732	int neg = 0;
733	int i;
734
735	if (cnt > 63)
736	cnt = 63;
737
738	if (copy_from_user(&buf, ubuf, cnt))
739	return -EFAULT;
740
741	buf[cnt] = 0;
742	cmp = strstrip(buf);
743
744	if (strncmp(cmp, "NO_", 3) == 0) {
745	neg = 1;
746	cmp += 3;
747	}
748
749	for (i = 0; sched_feat_names[i]; i++) {
750	if (strcmp(cmp, sched_feat_names[i]) == 0) {
751	if (neg)
752	sysctl_sched_features &= ~(1UL << i);
753	else
754	sysctl_sched_features \|= (1UL << i);
755	break;
756	}
757	}
758
759	if (!sched_feat_names[i])
760	return -EINVAL;
761
762	*ppos += cnt;
763
764	return cnt;
765	}
766
767	static int sched_feat_open(struct inode inode, struct file filp)
768	{
769	return single_open(filp, sched_feat_show, NULL);
770	}
771
772	static const struct file_operations sched_feat_fops = {
773	.open = sched_feat_open,
774	.write = sched_feat_write,
775	.read = seq_read,
776	.llseek = seq_lseek,
777	.release = single_release,
778	};
779
780	static __init int sched_init_debug(void)
781	{
782	debugfs_create_file("sched_features", 0644, NULL, NULL,
783	&sched_feat_fops);
784
785	return 0;
786	}
787	late_initcall(sched_init_debug);
788
789	#endif
790
791	#define sched_feat(x) (sysctl_sched_features & (1UL << __SCHED_FEAT_##x))
792
793	/*
794	* Number of tasks to iterate in a single balance run.
795	* Limited because this is done with IRQs disabled.
796	*/
797	const_debug unsigned int sysctl_sched_nr_migrate = 32;
798
799	/*
800	* period over which we average the RT time consumption, measured
801	* in ms.
802	*
803	* default: 1s
804	*/
805	const_debug unsigned int sysctl_sched_time_avg = MSEC_PER_SEC;
806
807	/*
808	* period over which we measure -rt task cpu usage in us.
809	* default: 1s
810	*/
811	unsigned int sysctl_sched_rt_period = 1000000;
812
813	static __read_mostly int scheduler_running;
814
815	/*
816	* part of the period that we allow rt tasks to run in us.
817	* default: 0.95s
818	*/
819	int sysctl_sched_rt_runtime = 950000;
820
821	static inline u64 global_rt_period(void)
822	{
823	return (u64)sysctl_sched_rt_period * NSEC_PER_USEC;
824	}
825
826	static inline u64 global_rt_runtime(void)
827	{
828	if (sysctl_sched_rt_runtime < 0)
829	return RUNTIME_INF;
830
831	return (u64)sysctl_sched_rt_runtime * NSEC_PER_USEC;
832	}
833
834	#ifndef prepare_arch_switch
835	# define prepare_arch_switch(next) do { } while (0)
836	#endif
837	#ifndef finish_arch_switch
838	# define finish_arch_switch(prev) do { } while (0)
839	#endif
840
841	static inline int task_current(struct rq rq, struct task_struct p)
842	{
843	return rq->curr == p;
844	}
845
846	#ifndef __ARCH_WANT_UNLOCKED_CTXSW
847	static inline int task_running(struct rq rq, struct task_struct p)
848	{
849	return task_current(rq, p);
850	}
851
852	static inline void prepare_lock_switch(struct rq rq, struct task_struct next)
853	{
854	}
855
856	static inline void finish_lock_switch(struct rq rq, struct task_struct prev)
857	{
858	#ifdef CONFIG_DEBUG_SPINLOCK
859	/* this is a valid case when another task releases the spinlock */
860	rq->lock.owner = current;
861	#endif
862	/*
863	* If we are tracking spinlock dependencies then we have to
864	* fix up the runqueue lock - which gets 'carried over' from
865	* prev into current:
866	*/
867	spin_acquire(&rq->lock.dep_map, 0, 0, _THIS_IP_);
868
869	raw_spin_unlock_irq(&rq->lock);
870	}
871
872	#else /* __ARCH_WANT_UNLOCKED_CTXSW */
873	static inline int task_running(struct rq rq, struct task_struct p)
874	{
875	#ifdef CONFIG_SMP
876	return p->oncpu;
877	#else
878	return task_current(rq, p);
879	#endif
880	}
881
882	static inline void prepare_lock_switch(struct rq rq, struct task_struct next)
883	{
884	#ifdef CONFIG_SMP
885	/*
886	* We can optimise this out completely for !SMP, because the
887	* SMP rebalancing from interrupt is the only thing that cares
888	* here.
889	*/
890	next->oncpu = 1;
891	#endif
892	#ifdef __ARCH_WANT_INTERRUPTS_ON_CTXSW
893	raw_spin_unlock_irq(&rq->lock);
894	#else
895	raw_spin_unlock(&rq->lock);
896	#endif
897	}
898
899	static inline void finish_lock_switch(struct rq rq, struct task_struct prev)
900	{
901	#ifdef CONFIG_SMP
902	/*
903	* After ->oncpu is cleared, the task can be moved to a different CPU.
904	* We must ensure this doesn't happen until the switch is completely
905	* finished.
906	*/
907	smp_wmb();
908	prev->oncpu = 0;
909	#endif
910	#ifndef __ARCH_WANT_INTERRUPTS_ON_CTXSW
911	local_irq_enable();
912	#endif
913	}
914	#endif /* __ARCH_WANT_UNLOCKED_CTXSW */
915
916	/*
917	* Check whether the task is waking, we use this to synchronize ->cpus_allowed
918	* against ttwu().
919	*/
920	static inline int task_is_waking(struct task_struct *p)
921	{
922	return unlikely(p->state == TASK_WAKING);
923	}
924
925	/*
926	* __task_rq_lock - lock the runqueue a given task resides on.
927	* Must be called interrupts disabled.
928	*/
929	static inline struct rq __task_rq_lock(struct task_struct p)
930	__acquires(rq->lock)
931	{
932	struct rq *rq;
933
934	for (;;) {
935	rq = task_rq(p);
936	raw_spin_lock(&rq->lock);
937	if (likely(rq == task_rq(p)))
938	return rq;
939	raw_spin_unlock(&rq->lock);
940	}
941	}
942
943	/*
944	* task_rq_lock - lock the runqueue a given task resides on and disable
945	* interrupts. Note the ordering: we can safely lookup the task_rq without
946	* explicitly disabling preemption.
947	*/
948	static struct rq task_rq_lock(struct task_struct p, unsigned long *flags)
949	__acquires(rq->lock)
950	{
951	struct rq *rq;
952
953	for (;;) {
954	local_irq_save(*flags);
955	rq = task_rq(p);
956	raw_spin_lock(&rq->lock);
957	if (likely(rq == task_rq(p)))
958	return rq;
959	raw_spin_unlock_irqrestore(&rq->lock, *flags);
960	}
961	}
962
963	static void __task_rq_unlock(struct rq *rq)
964	__releases(rq->lock)
965	{
966	raw_spin_unlock(&rq->lock);
967	}
968
969	static inline void task_rq_unlock(struct rq rq, unsigned long flags)
970	__releases(rq->lock)
971	{
972	raw_spin_unlock_irqrestore(&rq->lock, *flags);
973	}
974
975	/*
976	* this_rq_lock - lock this runqueue and disable interrupts.
977	*/
978	static struct rq *this_rq_lock(void)
979	__acquires(rq->lock)
980	{
981	struct rq *rq;
982
983	local_irq_disable();
984	rq = this_rq();
985	raw_spin_lock(&rq->lock);
986
987	return rq;
988	}
989
990	#ifdef CONFIG_SCHED_HRTICK
991	/*
992	* Use HR-timers to deliver accurate preemption points.
993	*
994	* Its all a bit involved since we cannot program an hrt while holding the
995	* rq->lock. So what we do is store a state in in rq->hrtick_* and ask for a
996	* reschedule event.
997	*
998	* When we get rescheduled we reprogram the hrtick_timer outside of the
999	* rq->lock.
1000	*/
1001
1002	/*
1003	* Use hrtick when:
1004	* - enabled by features
1005	* - hrtimer is actually high res
1006	*/
1007	static inline int hrtick_enabled(struct rq *rq)
1008	{
1009	if (!sched_feat(HRTICK))
1010	return 0;
1011	if (!cpu_active(cpu_of(rq)))
1012	return 0;
1013	return hrtimer_is_hres_active(&rq->hrtick_timer);
1014	}
1015
1016	static void hrtick_clear(struct rq *rq)
1017	{
1018	if (hrtimer_active(&rq->hrtick_timer))
1019	hrtimer_cancel(&rq->hrtick_timer);
1020	}
1021
1022	/*
1023	* High-resolution timer tick.
1024	* Runs from hardirq context with interrupts disabled.
1025	*/
1026	static enum hrtimer_restart hrtick(struct hrtimer *timer)
1027	{
1028	struct rq *rq = container_of(timer, struct rq, hrtick_timer);
1029
1030	WARN_ON_ONCE(cpu_of(rq) != smp_processor_id());
1031
1032	raw_spin_lock(&rq->lock);
1033	update_rq_clock(rq);
1034	rq->curr->sched_class->task_tick(rq, rq->curr, 1);
1035	raw_spin_unlock(&rq->lock);
1036
1037	return HRTIMER_NORESTART;
1038	}
1039
1040	#ifdef CONFIG_SMP
1041	/*
1042	* called from hardirq (IPI) context
1043	*/
1044	static void __hrtick_start(void *arg)
1045	{
1046	struct rq *rq = arg;
1047
1048	raw_spin_lock(&rq->lock);
1049	hrtimer_restart(&rq->hrtick_timer);
1050	rq->hrtick_csd_pending = 0;
1051	raw_spin_unlock(&rq->lock);
1052	}
1053
1054	/*
1055	* Called to set the hrtick timer state.
1056	*
1057	* called with rq->lock held and irqs disabled
1058	*/
1059	static void hrtick_start(struct rq *rq, u64 delay)
1060	{
1061	struct hrtimer *timer = &rq->hrtick_timer;
1062	ktime_t time = ktime_add_ns(timer->base->get_time(), delay);
1063
1064	hrtimer_set_expires(timer, time);
1065
1066	if (rq == this_rq()) {
1067	hrtimer_restart(timer);
1068	} else if (!rq->hrtick_csd_pending) {
1069	__smp_call_function_single(cpu_of(rq), &rq->hrtick_csd, 0);
1070	rq->hrtick_csd_pending = 1;
1071	}
1072	}
1073
1074	static int
1075	hotplug_hrtick(struct notifier_block nfb, unsigned long action, void hcpu)
1076	{
1077	int cpu = (int)(long)hcpu;
1078
1079	switch (action) {
1080	case CPU_UP_CANCELED:
1081	case CPU_UP_CANCELED_FROZEN:
1082	case CPU_DOWN_PREPARE:
1083	case CPU_DOWN_PREPARE_FROZEN:
1084	case CPU_DEAD:
1085	case CPU_DEAD_FROZEN:
1086	hrtick_clear(cpu_rq(cpu));
1087	return NOTIFY_OK;
1088	}
1089
1090	return NOTIFY_DONE;
1091	}
1092
1093	static __init void init_hrtick(void)
1094	{
1095	hotcpu_notifier(hotplug_hrtick, 0);
1096	}
1097	#else
1098	/*
1099	* Called to set the hrtick timer state.
1100	*
1101	* called with rq->lock held and irqs disabled
1102	*/
1103	static void hrtick_start(struct rq *rq, u64 delay)
1104	{
1105	__hrtimer_start_range_ns(&rq->hrtick_timer, ns_to_ktime(delay), 0,
1106	HRTIMER_MODE_REL_PINNED, 0);
1107	}
1108
1109	static inline void init_hrtick(void)
1110	{
1111	}
1112	#endif /* CONFIG_SMP */
1113
1114	static void init_rq_hrtick(struct rq *rq)
1115	{
1116	#ifdef CONFIG_SMP
1117	rq->hrtick_csd_pending = 0;
1118
1119	rq->hrtick_csd.flags = 0;
1120	rq->hrtick_csd.func = __hrtick_start;
1121	rq->hrtick_csd.info = rq;
1122	#endif
1123
1124	hrtimer_init(&rq->hrtick_timer, CLOCK_MONOTONIC, HRTIMER_MODE_REL);
1125	rq->hrtick_timer.function = hrtick;
1126	}
1127	#else /* CONFIG_SCHED_HRTICK */
1128	static inline void hrtick_clear(struct rq *rq)
1129	{
1130	}
1131
1132	static inline void init_rq_hrtick(struct rq *rq)
1133	{
1134	}
1135
1136	static inline void init_hrtick(void)
1137	{
1138	}
1139	#endif /* CONFIG_SCHED_HRTICK */
1140
1141	/*
1142	* resched_task - mark a task 'to be rescheduled now'.
1143	*
1144	* On UP this means the setting of the need_resched flag, on SMP it
1145	* might also involve a cross-CPU call to trigger the scheduler on
1146	* the target CPU.
1147	*/
1148	#ifdef CONFIG_SMP
1149
1150	#ifndef tsk_is_polling
1151	#define tsk_is_polling(t) test_tsk_thread_flag(t, TIF_POLLING_NRFLAG)
1152	#endif
1153
1154	static void resched_task(struct task_struct *p)
1155	{
1156	int cpu;
1157
1158	assert_raw_spin_locked(&task_rq(p)->lock);
1159
1160	if (test_tsk_need_resched(p))
1161	return;
1162
1163	set_tsk_need_resched(p);
1164
1165	cpu = task_cpu(p);
1166	if (cpu == smp_processor_id())
1167	return;
1168
1169	/* NEED_RESCHED must be visible before we test polling */
1170	smp_mb();
1171	if (!tsk_is_polling(p))
1172	smp_send_reschedule(cpu);
1173	}
1174
1175	static void resched_cpu(int cpu)
1176	{
1177	struct rq *rq = cpu_rq(cpu);
1178	unsigned long flags;
1179
1180	if (!raw_spin_trylock_irqsave(&rq->lock, flags))
1181	return;
1182	resched_task(cpu_curr(cpu));
1183	raw_spin_unlock_irqrestore(&rq->lock, flags);
1184	}
1185
1186	#ifdef CONFIG_NO_HZ
1187	/*
1188	* In the semi idle case, use the nearest busy cpu for migrating timers
1189	* from an idle cpu. This is good for power-savings.
1190	*
1191	* We don't do similar optimization for completely idle system, as
1192	* selecting an idle cpu will add more delays to the timers than intended
1193	* (as that cpu's timer base may not be uptodate wrt jiffies etc).
1194	*/
1195	int get_nohz_timer_target(void)
1196	{
1197	int cpu = smp_processor_id();
1198	int i;
1199	struct sched_domain *sd;
1200
1201	for_each_domain(cpu, sd) {
1202	for_each_cpu(i, sched_domain_span(sd))
1203	if (!idle_cpu(i))
1204	return i;
1205	}
1206	return cpu;
1207	}
1208	/*
1209	* When add_timer_on() enqueues a timer into the timer wheel of an
1210	* idle CPU then this timer might expire before the next timer event
1211	* which is scheduled to wake up that CPU. In case of a completely
1212	* idle system the next event might even be infinite time into the
1213	* future. wake_up_idle_cpu() ensures that the CPU is woken up and
1214	* leaves the inner idle loop so the newly added timer is taken into
1215	* account when the CPU goes back to idle and evaluates the timer
1216	* wheel for the next timer event.
1217	*/
1218	void wake_up_idle_cpu(int cpu)
1219	{
1220	struct rq *rq = cpu_rq(cpu);
1221
1222	if (cpu == smp_processor_id())
1223	return;
1224
1225	/*
1226	* This is safe, as this function is called with the timer
1227	* wheel base lock of (cpu) held. When the CPU is on the way
1228	* to idle and has not yet set rq->curr to idle then it will
1229	* be serialized on the timer wheel base lock and take the new
1230	* timer into account automatically.
1231	*/
1232	if (rq->curr != rq->idle)
1233	return;
1234
1235	/*
1236	* We can set TIF_RESCHED on the idle task of the other CPU
1237	* lockless. The worst case is that the other CPU runs the
1238	* idle task through an additional NOOP schedule()
1239	*/
1240	set_tsk_need_resched(rq->idle);
1241
1242	/* NEED_RESCHED must be visible before we test polling */
1243	smp_mb();
1244	if (!tsk_is_polling(rq->idle))
1245	smp_send_reschedule(cpu);
1246	}
1247
1248	#endif /* CONFIG_NO_HZ */
1249
1250	static u64 sched_avg_period(void)
1251	{
1252	return (u64)sysctl_sched_time_avg * NSEC_PER_MSEC / 2;
1253	}
1254
1255	static void sched_avg_update(struct rq *rq)
1256	{
1257	s64 period = sched_avg_period();
1258
1259	while ((s64)(rq->clock - rq->age_stamp) > period) {
1260	/*
1261	* Inline assembly required to prevent the compiler
1262	* optimising this loop into a divmod call.
1263	* See __iter_div_u64_rem() for another example of this.
1264	*/
1265	asm("" : "+rm" (rq->age_stamp));
1266	rq->age_stamp += period;
1267	rq->rt_avg /= 2;
1268	}
1269	}
1270
1271	static void sched_rt_avg_update(struct rq *rq, u64 rt_delta)
1272	{
1273	rq->rt_avg += rt_delta;
1274	sched_avg_update(rq);
1275	}
1276
1277	#else /* !CONFIG_SMP */
1278	static void resched_task(struct task_struct *p)
1279	{
1280	assert_raw_spin_locked(&task_rq(p)->lock);
1281	set_tsk_need_resched(p);
1282	}
1283
1284	static void sched_rt_avg_update(struct rq *rq, u64 rt_delta)
1285	{
1286	}
1287
1288	static void sched_avg_update(struct rq *rq)
1289	{
1290	}
1291	#endif /* CONFIG_SMP */
1292
1293	#if BITS_PER_LONG == 32
1294	# define WMULT_CONST (~0UL)
1295	#else
1296	# define WMULT_CONST (1UL << 32)
1297	#endif
1298
1299	#define WMULT_SHIFT 32
1300
1301	/*
1302	* Shift right and round:
1303	*/
1304	#define SRR(x, y) (((x) + (1UL << ((y) - 1))) >> (y))
1305
1306	/*
1307	* delta *= weight / lw
1308	*/
1309	static unsigned long
1310	calc_delta_mine(unsigned long delta_exec, unsigned long weight,
1311	struct load_weight *lw)
1312	{
1313	u64 tmp;
1314
1315	if (!lw->inv_weight) {
1316	if (BITS_PER_LONG > 32 && unlikely(lw->weight >= WMULT_CONST))
1317	lw->inv_weight = 1;
1318	else
1319	lw->inv_weight = 1 + (WMULT_CONST-lw->weight/2)
1320	/ (lw->weight+1);
1321	}
1322
1323	tmp = (u64)delta_exec * weight;
1324	/*
1325	* Check whether we'd overflow the 64-bit multiplication:
1326	*/
1327	if (unlikely(tmp > WMULT_CONST))
1328	tmp = SRR(SRR(tmp, WMULT_SHIFT/2) * lw->inv_weight,
1329	WMULT_SHIFT/2);
1330	else
1331	tmp = SRR(tmp * lw->inv_weight, WMULT_SHIFT);
1332
1333	return (unsigned long)min(tmp, (u64)(unsigned long)LONG_MAX);
1334	}
1335
1336	static inline void update_load_add(struct load_weight *lw, unsigned long inc)
1337	{
1338	lw->weight += inc;
1339	lw->inv_weight = 0;
1340	}
1341
1342	static inline void update_load_sub(struct load_weight *lw, unsigned long dec)
1343	{
1344	lw->weight -= dec;
1345	lw->inv_weight = 0;
1346	}
1347
1348	static inline void update_load_set(struct load_weight *lw, unsigned long w)
1349	{
1350	lw->weight = w;
1351	lw->inv_weight = 0;
1352	}
1353
1354	/*
1355	* To aid in avoiding the subversion of "niceness" due to uneven distribution
1356	* of tasks with abnormal "nice" values across CPUs the contribution that
1357	* each task makes to its run queue's load is weighted according to its
1358	* scheduling class and "nice" value. For SCHED_NORMAL tasks this is just a
1359	* scaled version of the new time slice allocation that they receive on time
1360	* slice expiry etc.
1361	*/
1362
1363	#define WEIGHT_IDLEPRIO 3
1364	#define WMULT_IDLEPRIO 1431655765
1365
1366	/*
1367	* Nice levels are multiplicative, with a gentle 10% change for every
1368	* nice level changed. I.e. when a CPU-bound task goes from nice 0 to
1369	* nice 1, it will get ~10% less CPU time than another CPU-bound task
1370	* that remained on nice 0.
1371	*
1372	* The "10% effect" is relative and cumulative: from _any_ nice level,
1373	* if you go up 1 level, it's -10% CPU usage, if you go down 1 level
1374	* it's +10% CPU usage. (to achieve that we use a multiplier of 1.25.
1375	* If a task goes up by ~10% and another task goes down by ~10% then
1376	* the relative distance between them is ~25%.)
1377	*/
1378	static const int prio_to_weight[40] = {
1379	/* -20 */ 88761, 71755, 56483, 46273, 36291,
1380	/* -15 */ 29154, 23254, 18705, 14949, 11916,
1381	/* -10 */ 9548, 7620, 6100, 4904, 3906,
1382	/* -5 */ 3121, 2501, 1991, 1586, 1277,
1383	/* 0 */ 1024, 820, 655, 526, 423,
1384	/* 5 */ 335, 272, 215, 172, 137,
1385	/* 10 */ 110, 87, 70, 56, 45,
1386	/* 15 */ 36, 29, 23, 18, 15,
1387	};
1388
1389	/*
1390	* Inverse (2^32/x) values of the prio_to_weight[] array, precalculated.
1391	*
1392	* In cases where the weight does not change often, we can use the
1393	* precalculated inverse to speed up arithmetics by turning divisions
1394	* into multiplications:
1395	*/
1396	static const u32 prio_to_wmult[40] = {
1397	/* -20 */ 48388, 59856, 76040, 92818, 118348,
1398	/* -15 */ 147320, 184698, 229616, 287308, 360437,
1399	/* -10 */ 449829, 563644, 704093, 875809, 1099582,
1400	/* -5 */ 1376151, 1717300, 2157191, 2708050, 3363326,
1401	/* 0 */ 4194304, 5237765, 6557202, 8165337, 10153587,
1402	/* 5 */ 12820798, 15790321, 19976592, 24970740, 31350126,
1403	/* 10 */ 39045157, 49367440, 61356676, 76695844, 95443717,
1404	/* 15 */ 119304647, 148102320, 186737708, 238609294, 286331153,
1405	};
1406
1407	/* Time spent by the tasks of the cpu accounting group executing in ... */
1408	enum cpuacct_stat_index {
1409	CPUACCT_STAT_USER, /* ... user mode */
1410	CPUACCT_STAT_SYSTEM, /* ... kernel mode */
1411
1412	CPUACCT_STAT_NSTATS,
1413	};
1414
1415	#ifdef CONFIG_CGROUP_CPUACCT
1416	static void cpuacct_charge(struct task_struct *tsk, u64 cputime);
1417	static void cpuacct_update_stats(struct task_struct *tsk,
1418	enum cpuacct_stat_index idx, cputime_t val);
1419	#else
1420	static inline void cpuacct_charge(struct task_struct *tsk, u64 cputime) {}
1421	static inline void cpuacct_update_stats(struct task_struct *tsk,
1422	enum cpuacct_stat_index idx, cputime_t val) {}
1423	#endif
1424
1425	static inline void inc_cpu_load(struct rq *rq, unsigned long load)
1426	{
1427	update_load_add(&rq->load, load);
1428	}
1429
1430	static inline void dec_cpu_load(struct rq *rq, unsigned long load)
1431	{
1432	update_load_sub(&rq->load, load);
1433	}
1434
1435	#if (defined(CONFIG_SMP) && defined(CONFIG_FAIR_GROUP_SCHED)) \|\| defined(CONFIG_RT_GROUP_SCHED)
1436	typedef int (tg_visitor)(struct task_group , void *);
1437
1438	/*
1439	* Iterate the full tree, calling @down when first entering a node and @up when
1440	* leaving it for the final time.
1441	*/
1442	static int walk_tg_tree(tg_visitor down, tg_visitor up, void *data)
1443	{
1444	struct task_group parent, child;
1445	int ret;
1446
1447	rcu_read_lock();
1448	parent = &root_task_group;
1449	down:
1450	ret = (*down)(parent, data);
1451	if (ret)
1452	goto out_unlock;
1453	list_for_each_entry_rcu(child, &parent->children, siblings) {
1454	parent = child;
1455	goto down;
1456
1457	up:
1458	continue;
1459	}
1460	ret = (*up)(parent, data);
1461	if (ret)
1462	goto out_unlock;
1463
1464	child = parent;
1465	parent = parent->parent;
1466	if (parent)
1467	goto up;
1468	out_unlock:
1469	rcu_read_unlock();
1470
1471	return ret;
1472	}
1473
1474	static int tg_nop(struct task_group tg, void data)
1475	{
1476	return 0;
1477	}
1478	#endif
1479
1480	#ifdef CONFIG_SMP
1481	/* Used instead of source_load when we know the type == 0 */
1482	static unsigned long weighted_cpuload(const int cpu)
1483	{
1484	return cpu_rq(cpu)->load.weight;
1485	}
1486
1487	/*
1488	* Return a low guess at the load of a migration-source cpu weighted
1489	* according to the scheduling class and "nice" value.
1490	*
1491	* We want to under-estimate the load of migration sources, to
1492	* balance conservatively.
1493	*/
1494	static unsigned long source_load(int cpu, int type)
1495	{
1496	struct rq *rq = cpu_rq(cpu);
1497	unsigned long total = weighted_cpuload(cpu);
1498
1499	if (type == 0 \|\| !sched_feat(LB_BIAS))
1500	return total;
1501
1502	return min(rq->cpu_load[type-1], total);
1503	}
1504
1505	/*
1506	* Return a high guess at the load of a migration-target cpu weighted
1507	* according to the scheduling class and "nice" value.
1508	*/
1509	static unsigned long target_load(int cpu, int type)
1510	{
1511	struct rq *rq = cpu_rq(cpu);
1512	unsigned long total = weighted_cpuload(cpu);
1513
1514	if (type == 0 \|\| !sched_feat(LB_BIAS))
1515	return total;
1516
1517	return max(rq->cpu_load[type-1], total);
1518	}
1519
1520	static unsigned long power_of(int cpu)
1521	{
1522	return cpu_rq(cpu)->cpu_power;
1523	}
1524
1525	static int task_hot(struct task_struct p, u64 now, struct sched_domain sd);
1526
1527	static unsigned long cpu_avg_load_per_task(int cpu)
1528	{
1529	struct rq *rq = cpu_rq(cpu);
1530	unsigned long nr_running = ACCESS_ONCE(rq->nr_running);
1531
1532	if (nr_running)
1533	rq->avg_load_per_task = rq->load.weight / nr_running;
1534	else
1535	rq->avg_load_per_task = 0;
1536
1537	return rq->avg_load_per_task;
1538	}
1539
1540	#ifdef CONFIG_FAIR_GROUP_SCHED
1541
1542	/*
1543	* Compute the cpu's hierarchical load factor for each task group.
1544	* This needs to be done in a top-down fashion because the load of a child
1545	* group is a fraction of its parents load.
1546	*/
1547	static int tg_load_down(struct task_group tg, void data)
1548	{
1549	unsigned long load;
1550	long cpu = (long)data;
1551
1552	if (!tg->parent) {
1553	load = cpu_rq(cpu)->load.weight;
1554	} else {
1555	load = tg->parent->cfs_rq[cpu]->h_load;
1556	load *= tg->se[cpu]->load.weight;
1557	load /= tg->parent->cfs_rq[cpu]->load.weight + 1;
1558	}
1559
1560	tg->cfs_rq[cpu]->h_load = load;
1561
1562	return 0;
1563	}
1564
1565	static void update_h_load(long cpu)
1566	{
1567	walk_tg_tree(tg_load_down, tg_nop, (void *)cpu);
1568	}
1569
1570	#endif
1571
1572	#ifdef CONFIG_PREEMPT
1573
1574	static void double_rq_lock(struct rq rq1, struct rq rq2);
1575
1576	/*
1577	* fair double_lock_balance: Safely acquires both rq->locks in a fair
1578	* way at the expense of forcing extra atomic operations in all
1579	* invocations. This assures that the double_lock is acquired using the
1580	* same underlying policy as the spinlock_t on this architecture, which
1581	* reduces latency compared to the unfair variant below. However, it
1582	* also adds more overhead and therefore may reduce throughput.
1583	*/
1584	static inline int _double_lock_balance(struct rq this_rq, struct rq busiest)
1585	__releases(this_rq->lock)
1586	__acquires(busiest->lock)
1587	__acquires(this_rq->lock)
1588	{
1589	raw_spin_unlock(&this_rq->lock);
1590	double_rq_lock(this_rq, busiest);
1591
1592	return 1;
1593	}
1594
1595	#else
1596	/*
1597	* Unfair double_lock_balance: Optimizes throughput at the expense of
1598	* latency by eliminating extra atomic operations when the locks are
1599	* already in proper order on entry. This favors lower cpu-ids and will
1600	* grant the double lock to lower cpus over higher ids under contention,
1601	* regardless of entry order into the function.
1602	*/
1603	static int _double_lock_balance(struct rq this_rq, struct rq busiest)
1604	__releases(this_rq->lock)
1605	__acquires(busiest->lock)
1606	__acquires(this_rq->lock)
1607	{
1608	int ret = 0;
1609
1610	if (unlikely(!raw_spin_trylock(&busiest->lock))) {
1611	if (busiest < this_rq) {
1612	raw_spin_unlock(&this_rq->lock);
1613	raw_spin_lock(&busiest->lock);
1614	raw_spin_lock_nested(&this_rq->lock,
1615	SINGLE_DEPTH_NESTING);
1616	ret = 1;
1617	} else
1618	raw_spin_lock_nested(&busiest->lock,
1619	SINGLE_DEPTH_NESTING);
1620	}
1621	return ret;
1622	}
1623
1624	#endif /* CONFIG_PREEMPT */
1625
1626	/*
1627	* double_lock_balance - lock the busiest runqueue, this_rq is locked already.
1628	*/
1629	static int double_lock_balance(struct rq this_rq, struct rq busiest)
1630	{
1631	if (unlikely(!irqs_disabled())) {
1632	/* printk() doesn't work good under rq->lock */
1633	raw_spin_unlock(&this_rq->lock);
1634	BUG_ON(1);
1635	}
1636
1637	return _double_lock_balance(this_rq, busiest);
1638	}
1639
1640	static inline void double_unlock_balance(struct rq this_rq, struct rq busiest)
1641	__releases(busiest->lock)
1642	{
1643	raw_spin_unlock(&busiest->lock);
1644	lock_set_subclass(&this_rq->lock.dep_map, 0, _RET_IP_);
1645	}
1646
1647	/*
1648	* double_rq_lock - safely lock two runqueues
1649	*
1650	* Note this does not disable interrupts like task_rq_lock,
1651	* you need to do so manually before calling.
1652	*/
1653	static void double_rq_lock(struct rq rq1, struct rq rq2)
1654	__acquires(rq1->lock)
1655	__acquires(rq2->lock)
1656	{
1657	BUG_ON(!irqs_disabled());
1658	if (rq1 == rq2) {
1659	raw_spin_lock(&rq1->lock);
1660	__acquire(rq2->lock); /* Fake it out ;) */
1661	} else {
1662	if (rq1 < rq2) {
1663	raw_spin_lock(&rq1->lock);
1664	raw_spin_lock_nested(&rq2->lock, SINGLE_DEPTH_NESTING);
1665	} else {
1666	raw_spin_lock(&rq2->lock);
1667	raw_spin_lock_nested(&rq1->lock, SINGLE_DEPTH_NESTING);
1668	}
1669	}
1670	}
1671
1672	/*
1673	* double_rq_unlock - safely unlock two runqueues
1674	*
1675	* Note this does not restore interrupts like task_rq_unlock,
1676	* you need to do so manually after calling.
1677	*/
1678	static void double_rq_unlock(struct rq rq1, struct rq rq2)
1679	__releases(rq1->lock)
1680	__releases(rq2->lock)
1681	{
1682	raw_spin_unlock(&rq1->lock);
1683	if (rq1 != rq2)
1684	raw_spin_unlock(&rq2->lock);
1685	else
1686	__release(rq2->lock);
1687	}
1688
1689	#endif
1690
1691	static void calc_load_account_idle(struct rq *this_rq);
1692	static void update_sysctl(void);
1693	static int get_update_sysctl_factor(void);
1694	static void update_cpu_load(struct rq *this_rq);
1695
1696	static inline void __set_task_cpu(struct task_struct *p, unsigned int cpu)
1697	{
1698	set_task_rq(p, cpu);
1699	#ifdef CONFIG_SMP
1700	/*
1701	* After ->cpu is set up to a new value, task_rq_lock(p, ...) can be
1702	* successfuly executed on another CPU. We must ensure that updates of
1703	* per-task data have been completed by this moment.
1704	*/
1705	smp_wmb();
1706	task_thread_info(p)->cpu = cpu;
1707	#endif
1708	}
1709
1710	static const struct sched_class rt_sched_class;
1711
1712	#define sched_class_highest (&stop_sched_class)
1713	#define for_each_class(class) \
1714	for (class = sched_class_highest; class; class = class->next)
1715
1716	#include "sched_stats.h"
1717
1718	static void inc_nr_running(struct rq *rq)
1719	{
1720	rq->nr_running++;
1721	}
1722
1723	static void dec_nr_running(struct rq *rq)
1724	{
1725	rq->nr_running--;
1726	}
1727
1728	static void set_load_weight(struct task_struct *p)
1729	{
1730	/*
1731	* SCHED_IDLE tasks get minimal weight:
1732	*/
1733	if (p->policy == SCHED_IDLE) {
1734	p->se.load.weight = WEIGHT_IDLEPRIO;
1735	p->se.load.inv_weight = WMULT_IDLEPRIO;
1736	return;
1737	}
1738
1739	p->se.load.weight = prio_to_weight[p->static_prio - MAX_RT_PRIO];
1740	p->se.load.inv_weight = prio_to_wmult[p->static_prio - MAX_RT_PRIO];
1741	}
1742
1743	static void enqueue_task(struct rq rq, struct task_struct p, int flags)
1744	{
1745	update_rq_clock(rq);
1746	sched_info_queued(p);
1747	p->sched_class->enqueue_task(rq, p, flags);
1748	p->se.on_rq = 1;
1749	}
1750
1751	static void dequeue_task(struct rq rq, struct task_struct p, int flags)
1752	{
1753	update_rq_clock(rq);
1754	sched_info_dequeued(p);
1755	p->sched_class->dequeue_task(rq, p, flags);
1756	p->se.on_rq = 0;
1757	}
1758
1759	/*
1760	* activate_task - move a task to the runqueue.
1761	*/
1762	static void activate_task(struct rq rq, struct task_struct p, int flags)
1763	{
1764	if (task_contributes_to_load(p))
1765	rq->nr_uninterruptible--;
1766
1767	enqueue_task(rq, p, flags);
1768	inc_nr_running(rq);
1769	}
1770
1771	/*
1772	* deactivate_task - remove a task from the runqueue.
1773	*/
1774	static void deactivate_task(struct rq rq, struct task_struct p, int flags)
1775	{
1776	if (task_contributes_to_load(p))
1777	rq->nr_uninterruptible++;
1778
1779	dequeue_task(rq, p, flags);
1780	dec_nr_running(rq);
1781	}
1782
1783	#ifdef CONFIG_IRQ_TIME_ACCOUNTING
1784
1785	/*
1786	* There are no locks covering percpu hardirq/softirq time.
1787	* They are only modified in account_system_vtime, on corresponding CPU
1788	* with interrupts disabled. So, writes are safe.
1789	* They are read and saved off onto struct rq in update_rq_clock().
1790	* This may result in other CPU reading this CPU's irq time and can
1791	* race with irq/account_system_vtime on this CPU. We would either get old
1792	* or new value with a side effect of accounting a slice of irq time to wrong
1793	* task when irq is in progress while we read rq->clock. That is a worthy
1794	* compromise in place of having locks on each irq in account_system_time.
1795	*/
1796	static DEFINE_PER_CPU(u64, cpu_hardirq_time);
1797	static DEFINE_PER_CPU(u64, cpu_softirq_time);
1798
1799	static DEFINE_PER_CPU(u64, irq_start_time);
1800	static int sched_clock_irqtime;
1801
1802	void enable_sched_clock_irqtime(void)
1803	{
1804	sched_clock_irqtime = 1;
1805	}
1806
1807	void disable_sched_clock_irqtime(void)
1808	{
1809	sched_clock_irqtime = 0;
1810	}
1811
1812	#ifndef CONFIG_64BIT
1813	static DEFINE_PER_CPU(seqcount_t, irq_time_seq);
1814
1815	static inline void irq_time_write_begin(void)
1816	{
1817	__this_cpu_inc(irq_time_seq.sequence);
1818	smp_wmb();
1819	}
1820
1821	static inline void irq_time_write_end(void)
1822	{
1823	smp_wmb();
1824	__this_cpu_inc(irq_time_seq.sequence);
1825	}
1826
1827	static inline u64 irq_time_read(int cpu)
1828	{
1829	u64 irq_time;
1830	unsigned seq;
1831
1832	do {
1833	seq = read_seqcount_begin(&per_cpu(irq_time_seq, cpu));
1834	irq_time = per_cpu(cpu_softirq_time, cpu) +
1835	per_cpu(cpu_hardirq_time, cpu);
1836	} while (read_seqcount_retry(&per_cpu(irq_time_seq, cpu), seq));
1837
1838	return irq_time;
1839	}
1840	#else /* CONFIG_64BIT */
1841	static inline void irq_time_write_begin(void)
1842	{
1843	}
1844
1845	static inline void irq_time_write_end(void)
1846	{
1847	}
1848
1849	static inline u64 irq_time_read(int cpu)
1850	{
1851	return per_cpu(cpu_softirq_time, cpu) + per_cpu(cpu_hardirq_time, cpu);
1852	}
1853	#endif /* CONFIG_64BIT */
1854
1855	/*
1856	* Called before incrementing preempt_count on {soft,}irq_enter
1857	* and before decrementing preempt_count on {soft,}irq_exit.
1858	*/
1859	void account_system_vtime(struct task_struct *curr)
1860	{
1861	unsigned long flags;
1862	s64 delta;
1863	int cpu;
1864
1865	if (!sched_clock_irqtime)
1866	return;
1867
1868	local_irq_save(flags);
1869
1870	cpu = smp_processor_id();
1871	delta = sched_clock_cpu(cpu) - __this_cpu_read(irq_start_time);
1872	__this_cpu_add(irq_start_time, delta);
1873
1874	irq_time_write_begin();
1875	/*
1876	* We do not account for softirq time from ksoftirqd here.
1877	* We want to continue accounting softirq time to ksoftirqd thread
1878	* in that case, so as not to confuse scheduler with a special task
1879	* that do not consume any time, but still wants to run.
1880	*/
1881	if (hardirq_count())
1882	__this_cpu_add(cpu_hardirq_time, delta);
1883	else if (in_serving_softirq() && !(curr->flags & PF_KSOFTIRQD))
1884	__this_cpu_add(cpu_softirq_time, delta);
1885
1886	irq_time_write_end();
1887	local_irq_restore(flags);
1888	}
1889	EXPORT_SYMBOL_GPL(account_system_vtime);
1890
1891	static void update_rq_clock_task(struct rq *rq, s64 delta)
1892	{
1893	s64 irq_delta;
1894
1895	irq_delta = irq_time_read(cpu_of(rq)) - rq->prev_irq_time;
1896
1897	/*
1898	* Since irq_time is only updated on {soft,}irq_exit, we might run into
1899	* this case when a previous update_rq_clock() happened inside a
1900	* {soft,}irq region.
1901	*
1902	* When this happens, we stop ->clock_task and only update the
1903	* prev_irq_time stamp to account for the part that fit, so that a next
1904	* update will consume the rest. This ensures ->clock_task is
1905	* monotonic.
1906	*
1907	* It does however cause some slight miss-attribution of {soft,}irq
1908	* time, a more accurate solution would be to update the irq_time using
1909	* the current rq->clock timestamp, except that would require using
1910	* atomic ops.
1911	*/
1912	if (irq_delta > delta)
1913	irq_delta = delta;
1914
1915	rq->prev_irq_time += irq_delta;
1916	delta -= irq_delta;
1917	rq->clock_task += delta;
1918
1919	if (irq_delta && sched_feat(NONIRQ_POWER))
1920	sched_rt_avg_update(rq, irq_delta);
1921	}
1922
1923	#else /* CONFIG_IRQ_TIME_ACCOUNTING */
1924
1925	static void update_rq_clock_task(struct rq *rq, s64 delta)
1926	{
1927	rq->clock_task += delta;
1928	}
1929
1930	#endif /* CONFIG_IRQ_TIME_ACCOUNTING */
1931
1932	#include "sched_idletask.c"
1933	#include "sched_fair.c"
1934	#include "sched_rt.c"
1935	#include "sched_autogroup.c"
1936	#include "sched_stoptask.c"
1937	#ifdef CONFIG_SCHED_DEBUG
1938	# include "sched_debug.c"
1939	#endif
1940
1941	void sched_set_stop_task(int cpu, struct task_struct *stop)
1942	{
1943	struct sched_param param = { .sched_priority = MAX_RT_PRIO - 1 };
1944	struct task_struct *old_stop = cpu_rq(cpu)->stop;
1945
1946	if (stop) {
1947	/*
1948	* Make it appear like a SCHED_FIFO task, its something
1949	* userspace knows about and won't get confused about.
1950	*
1951	* Also, it will make PI more or less work without too
1952	* much confusion -- but then, stop work should not
1953	* rely on PI working anyway.
1954	*/
1955	sched_setscheduler_nocheck(stop, SCHED_FIFO, &param);
1956
1957	stop->sched_class = &stop_sched_class;
1958	}
1959
1960	cpu_rq(cpu)->stop = stop;
1961
1962	if (old_stop) {
1963	/*
1964	* Reset it back to a normal scheduling class so that
1965	* it can die in pieces.
1966	*/
1967	old_stop->sched_class = &rt_sched_class;
1968	}
1969	}
1970
1971	/*
1972	* __normal_prio - return the priority that is based on the static prio
1973	*/
1974	static inline int __normal_prio(struct task_struct *p)
1975	{
1976	return p->static_prio;
1977	}
1978
1979	/*
1980	* Calculate the expected normal priority: i.e. priority
1981	* without taking RT-inheritance into account. Might be
1982	* boosted by interactivity modifiers. Changes upon fork,
1983	* setprio syscalls, and whenever the interactivity
1984	* estimator recalculates.
1985	*/
1986	static inline int normal_prio(struct task_struct *p)
1987	{
1988	int prio;
1989
1990	if (task_has_rt_policy(p))
1991	prio = MAX_RT_PRIO-1 - p->rt_priority;
1992	else
1993	prio = __normal_prio(p);
1994	return prio;
1995	}
1996
1997	/*
1998	* Calculate the current priority, i.e. the priority
1999	* taken into account by the scheduler. This value might
2000	* be boosted by RT tasks, or might be boosted by
2001	* interactivity modifiers. Will be RT if the task got
2002	* RT-boosted. If not then it returns p->normal_prio.
2003	*/
2004	static int effective_prio(struct task_struct *p)
2005	{
2006	p->normal_prio = normal_prio(p);
2007	/*
2008	* If we are RT tasks or we were boosted to RT priority,
2009	* keep the priority unchanged. Otherwise, update priority
2010	* to the normal priority:
2011	*/
2012	if (!rt_prio(p->prio))
2013	return p->normal_prio;
2014	return p->prio;
2015	}
2016
2017	/**
2018	* task_curr - is this task currently executing on a CPU?
2019	* @p: the task in question.
2020	*/
2021	inline int task_curr(const struct task_struct *p)
2022	{
2023	return cpu_curr(task_cpu(p)) == p;
2024	}
2025
2026	static inline void check_class_changed(struct rq rq, struct task_struct p,
2027	const struct sched_class *prev_class,
2028	int oldprio, int running)
2029	{
2030	if (prev_class != p->sched_class) {
2031	if (prev_class->switched_from)
2032	prev_class->switched_from(rq, p, running);
2033	p->sched_class->switched_to(rq, p, running);
2034	} else
2035	p->sched_class->prio_changed(rq, p, oldprio, running);
2036	}
2037
2038	static void check_preempt_curr(struct rq rq, struct task_struct p, int flags)
2039	{
2040	const struct sched_class *class;
2041
2042	if (p->sched_class == rq->curr->sched_class) {
2043	rq->curr->sched_class->check_preempt_curr(rq, p, flags);
2044	} else {
2045	for_each_class(class) {
2046	if (class == rq->curr->sched_class)
2047	break;
2048	if (class == p->sched_class) {
2049	resched_task(rq->curr);
2050	break;
2051	}
2052	}
2053	}
2054
2055	/*
2056	* A queue event has occurred, and we're going to schedule. In
2057	* this case, we can save a useless back to back clock update.
2058	*/
2059	if (rq->curr->se.on_rq && test_tsk_need_resched(rq->curr))
2060	rq->skip_clock_update = 1;
2061	}
2062
2063	#ifdef CONFIG_SMP
2064	/*
2065	* Is this task likely cache-hot:
2066	*/
2067	static int
2068	task_hot(struct task_struct p, u64 now, struct sched_domain sd)
2069	{
2070	s64 delta;
2071
2072	if (p->sched_class != &fair_sched_class)
2073	return 0;
2074
2075	if (unlikely(p->policy == SCHED_IDLE))
2076	return 0;
2077
2078	/*
2079	* Buddy candidates are cache hot:
2080	*/
2081	if (sched_feat(CACHE_HOT_BUDDY) && this_rq()->nr_running &&
2082	(&p->se == cfs_rq_of(&p->se)->next \|\|
2083	&p->se == cfs_rq_of(&p->se)->last))
2084	return 1;
2085
2086	if (sysctl_sched_migration_cost == -1)
2087	return 1;
2088	if (sysctl_sched_migration_cost == 0)
2089	return 0;
2090
2091	delta = now - p->se.exec_start;
2092
2093	return delta < (s64)sysctl_sched_migration_cost;
2094	}
2095
2096	void set_task_cpu(struct task_struct *p, unsigned int new_cpu)
2097	{
2098	#ifdef CONFIG_SCHED_DEBUG
2099	/*
2100	* We should never call set_task_cpu() on a blocked task,
2101	* ttwu() will sort out the placement.
2102	*/
2103	WARN_ON_ONCE(p->state != TASK_RUNNING && p->state != TASK_WAKING &&
2104	!(task_thread_info(p)->preempt_count & PREEMPT_ACTIVE));
2105	#endif
2106
2107	trace_sched_migrate_task(p, new_cpu);
2108
2109	if (task_cpu(p) != new_cpu) {
2110	p->se.nr_migrations++;
2111	perf_sw_event(PERF_COUNT_SW_CPU_MIGRATIONS, 1, 1, NULL, 0);
2112	}
2113
2114	__set_task_cpu(p, new_cpu);
2115	}
2116
2117	struct migration_arg {
2118	struct task_struct *task;
2119	int dest_cpu;
2120	};
2121
2122	static int migration_cpu_stop(void *data);
2123
2124	/*
2125	* The task's runqueue lock must be held.
2126	* Returns true if you have to wait for migration thread.
2127	*/
2128	static bool migrate_task(struct task_struct p, struct rq rq)
2129	{
2130	/*
2131	* If the task is not on a runqueue (and not running), then
2132	* the next wake-up will properly place the task.
2133	*/
2134	return p->se.on_rq \|\| task_running(rq, p);
2135	}
2136
2137	/*
2138	* wait_task_inactive - wait for a thread to unschedule.
2139	*
2140	* If @match_state is nonzero, it's the @p->state value just checked and
2141	* not expected to change. If it changes, i.e. @p might have woken up,
2142	* then return zero. When we succeed in waiting for @p to be off its CPU,
2143	* we return a positive number (its total switch count). If a second call
2144	* a short while later returns the same number, the caller can be sure that
2145	* @p has remained unscheduled the whole time.
2146	*
2147	* The caller must ensure that the task will unschedule sometime soon,
2148	* else this function might spin for a long time. This function can't
2149	* be called with interrupts off, or it may introduce deadlock with
2150	* smp_call_function() if an IPI is sent by the same process we are
2151	* waiting to become inactive.
2152	*/
2153	unsigned long wait_task_inactive(struct task_struct *p, long match_state)
2154	{
2155	unsigned long flags;
2156	int running, on_rq;
2157	unsigned long ncsw;
2158	struct rq *rq;
2159
2160	for (;;) {
2161	/*
2162	* We do the initial early heuristics without holding
2163	* any task-queue locks at all. We'll only try to get
2164	* the runqueue lock when things look like they will
2165	* work out!
2166	*/
2167	rq = task_rq(p);
2168
2169	/*
2170	* If the task is actively running on another CPU
2171	* still, just relax and busy-wait without holding
2172	* any locks.
2173	*
2174	* NOTE! Since we don't hold any locks, it's not
2175	* even sure that "rq" stays as the right runqueue!
2176	* But we don't care, since "task_running()" will
2177	* return false if the runqueue has changed and p
2178	* is actually now running somewhere else!
2179	*/
2180	while (task_running(rq, p)) {
2181	if (match_state && unlikely(p->state != match_state))
2182	return 0;
2183	cpu_relax();
2184	}
2185
2186	/*
2187	* Ok, time to look more closely! We need the rq
2188	* lock now, to be sure. If we're wrong, we'll
2189	* just go back and repeat.
2190	*/
2191	rq = task_rq_lock(p, &flags);
2192	trace_sched_wait_task(p);
2193	running = task_running(rq, p);
2194	on_rq = p->se.on_rq;
2195	ncsw = 0;
2196	if (!match_state \|\| p->state == match_state)
2197	ncsw = p->nvcsw \| LONG_MIN; /* sets MSB */
2198	task_rq_unlock(rq, &flags);
2199
2200	/*
2201	* If it changed from the expected state, bail out now.
2202	*/
2203	if (unlikely(!ncsw))
2204	break;
2205
2206	/*
2207	* Was it really running after all now that we
2208	* checked with the proper locks actually held?
2209	*
2210	* Oops. Go back and try again..
2211	*/
2212	if (unlikely(running)) {
2213	cpu_relax();
2214	continue;
2215	}
2216
2217	/*
2218	* It's not enough that it's not actively running,
2219	* it must be off the runqueue _entirely_, and not
2220	* preempted!
2221	*
2222	* So if it was still runnable (but just not actively
2223	* running right now), it's preempted, and we should
2224	* yield - it could be a while.
2225	*/
2226	if (unlikely(on_rq)) {
2227	schedule_timeout_uninterruptible(1);
2228	continue;
2229	}
2230
2231	/*
2232	* Ahh, all good. It wasn't running, and it wasn't
2233	* runnable, which means that it will never become
2234	* running in the future either. We're all done!
2235	*/
2236	break;
2237	}
2238
2239	return ncsw;
2240	}
2241
2242	/***
2243	* kick_process - kick a running thread to enter/exit the kernel
2244	* @p: the to-be-kicked thread
2245	*
2246	* Cause a process which is running on another CPU to enter
2247	* kernel-mode, without any delay. (to get signals handled.)
2248	*
2249	* NOTE: this function doesnt have to take the runqueue lock,
2250	* because all it wants to ensure is that the remote task enters
2251	* the kernel. If the IPI races and the task has been migrated
2252	* to another CPU then no harm is done and the purpose has been
2253	* achieved as well.
2254	*/
2255	void kick_process(struct task_struct *p)
2256	{
2257	int cpu;
2258
2259	preempt_disable();
2260	cpu = task_cpu(p);
2261	if ((cpu != smp_processor_id()) && task_curr(p))
2262	smp_send_reschedule(cpu);
2263	preempt_enable();
2264	}
2265	EXPORT_SYMBOL_GPL(kick_process);
2266	#endif /* CONFIG_SMP */
2267
2268	/**
2269	* task_oncpu_function_call - call a function on the cpu on which a task runs
2270	* @p: the task to evaluate
2271	* @func: the function to be called
2272	* @info: the function call argument
2273	*
2274	* Calls the function @func when the task is currently running. This might
2275	* be on the current CPU, which just calls the function directly
2276	*/
2277	void task_oncpu_function_call(struct task_struct *p,
2278	void (func) (void info), void *info)
2279	{
2280	int cpu;
2281
2282	preempt_disable();
2283	cpu = task_cpu(p);
2284	if (task_curr(p))
2285	smp_call_function_single(cpu, func, info, 1);
2286	preempt_enable();
2287	}
2288
2289	#ifdef CONFIG_SMP
2290	/*
2291	* ->cpus_allowed is protected by either TASK_WAKING or rq->lock held.
2292	*/
2293	static int select_fallback_rq(int cpu, struct task_struct *p)
2294	{
2295	int dest_cpu;
2296	const struct cpumask *nodemask = cpumask_of_node(cpu_to_node(cpu));
2297
2298	/* Look for allowed, online CPU in same node. */
2299	for_each_cpu_and(dest_cpu, nodemask, cpu_active_mask)
2300	if (cpumask_test_cpu(dest_cpu, &p->cpus_allowed))
2301	return dest_cpu;
2302
2303	/* Any allowed, online CPU? */
2304	dest_cpu = cpumask_any_and(&p->cpus_allowed, cpu_active_mask);
2305	if (dest_cpu < nr_cpu_ids)
2306	return dest_cpu;
2307
2308	/* No more Mr. Nice Guy. */
2309	dest_cpu = cpuset_cpus_allowed_fallback(p);
2310	/*
2311	* Don't tell them about moving exiting tasks or
2312	* kernel threads (both mm NULL), since they never
2313	* leave kernel.
2314	*/
2315	if (p->mm && printk_ratelimit()) {
2316	printk(KERN_INFO "process %d (%s) no longer affine to cpu%d\n",
2317	task_pid_nr(p), p->comm, cpu);
2318	}
2319
2320	return dest_cpu;
2321	}
2322
2323	/*
2324	* The caller (fork, wakeup) owns TASK_WAKING, ->cpus_allowed is stable.
2325	*/
2326	static inline
2327	int select_task_rq(struct rq rq, struct task_struct p, int sd_flags, int wake_flags)
2328	{
2329	int cpu = p->sched_class->select_task_rq(rq, p, sd_flags, wake_flags);
2330
2331	/*
2332	* In order not to call set_task_cpu() on a blocking task we need
2333	* to rely on ttwu() to place the task on a valid ->cpus_allowed
2334	* cpu.
2335	*
2336	* Since this is common to all placement strategies, this lives here.
2337	*
2338	* [ this allows ->select_task() to simply return task_cpu(p) and
2339	* not worry about this generic constraint ]
2340	*/
2341	if (unlikely(!cpumask_test_cpu(cpu, &p->cpus_allowed) \|\|
2342	!cpu_online(cpu)))
2343	cpu = select_fallback_rq(task_cpu(p), p);
2344
2345	return cpu;
2346	}
2347
2348	static void update_avg(u64 *avg, u64 sample)
2349	{
2350	s64 diff = sample - *avg;
2351	*avg += diff >> 3;
2352	}
2353	#endif
2354
2355	static inline void ttwu_activate(struct task_struct p, struct rq rq,
2356	bool is_sync, bool is_migrate, bool is_local,
2357	unsigned long en_flags)
2358	{
2359	schedstat_inc(p, se.statistics.nr_wakeups);
2360	if (is_sync)
2361	schedstat_inc(p, se.statistics.nr_wakeups_sync);
2362	if (is_migrate)
2363	schedstat_inc(p, se.statistics.nr_wakeups_migrate);
2364	if (is_local)
2365	schedstat_inc(p, se.statistics.nr_wakeups_local);
2366	else
2367	schedstat_inc(p, se.statistics.nr_wakeups_remote);
2368
2369	activate_task(rq, p, en_flags);
2370	}
2371
2372	static inline void ttwu_post_activation(struct task_struct p, struct rq rq,
2373	int wake_flags, bool success)
2374	{
2375	trace_sched_wakeup(p, success);
2376	check_preempt_curr(rq, p, wake_flags);
2377
2378	p->state = TASK_RUNNING;
2379	#ifdef CONFIG_SMP
2380	if (p->sched_class->task_woken)
2381	p->sched_class->task_woken(rq, p);
2382
2383	if (unlikely(rq->idle_stamp)) {
2384	u64 delta = rq->clock - rq->idle_stamp;
2385	u64 max = 2*sysctl_sched_migration_cost;
2386
2387	if (delta > max)
2388	rq->avg_idle = max;
2389	else
2390	update_avg(&rq->avg_idle, delta);
2391	rq->idle_stamp = 0;
2392	}
2393	#endif
2394	/* if a worker is waking up, notify workqueue */
2395	if ((p->flags & PF_WQ_WORKER) && success)
2396	wq_worker_waking_up(p, cpu_of(rq));
2397	}
2398
2399	/**
2400	* try_to_wake_up - wake up a thread
2401	* @p: the thread to be awakened
2402	* @state: the mask of task states that can be woken
2403	* @wake_flags: wake modifier flags (WF_*)
2404	*
2405	* Put it on the run-queue if it's not already there. The "current"
2406	* thread is always on the run-queue (except when the actual
2407	* re-schedule is in progress), and as such you're allowed to do
2408	* the simpler "current->state = TASK_RUNNING" to mark yourself
2409	* runnable without the overhead of this.
2410	*
2411	* Returns %true if @p was woken up, %false if it was already running
2412	* or @state didn't match @p's state.
2413	*/
2414	static int try_to_wake_up(struct task_struct *p, unsigned int state,
2415	int wake_flags)
2416	{
2417	int cpu, orig_cpu, this_cpu, success = 0;
2418	unsigned long flags;
2419	unsigned long en_flags = ENQUEUE_WAKEUP;
2420	struct rq *rq;
2421
2422	this_cpu = get_cpu();
2423
2424	smp_wmb();
2425	rq = task_rq_lock(p, &flags);
2426	if (!(p->state & state))
2427	goto out;
2428
2429	if (p->se.on_rq)
2430	goto out_running;
2431
2432	cpu = task_cpu(p);
2433	orig_cpu = cpu;
2434
2435	#ifdef CONFIG_SMP
2436	if (unlikely(task_running(rq, p)))
2437	goto out_activate;
2438
2439	/*
2440	* In order to handle concurrent wakeups and release the rq->lock
2441	* we put the task in TASK_WAKING state.
2442	*
2443	* First fix up the nr_uninterruptible count:
2444	*/
2445	if (task_contributes_to_load(p)) {
2446	if (likely(cpu_online(orig_cpu)))
2447	rq->nr_uninterruptible--;
2448	else
2449	this_rq()->nr_uninterruptible--;
2450	}
2451	p->state = TASK_WAKING;
2452
2453	if (p->sched_class->task_waking) {
2454	p->sched_class->task_waking(rq, p);
2455	en_flags \|= ENQUEUE_WAKING;
2456	}
2457
2458	cpu = select_task_rq(rq, p, SD_BALANCE_WAKE, wake_flags);
2459	if (cpu != orig_cpu)
2460	set_task_cpu(p, cpu);
2461	__task_rq_unlock(rq);
2462
2463	rq = cpu_rq(cpu);
2464	raw_spin_lock(&rq->lock);
2465
2466	/*
2467	* We migrated the task without holding either rq->lock, however
2468	* since the task is not on the task list itself, nobody else
2469	* will try and migrate the task, hence the rq should match the
2470	* cpu we just moved it to.
2471	*/
2472	WARN_ON(task_cpu(p) != cpu);
2473	WARN_ON(p->state != TASK_WAKING);
2474
2475	#ifdef CONFIG_SCHEDSTATS
2476	schedstat_inc(rq, ttwu_count);
2477	if (cpu == this_cpu)
2478	schedstat_inc(rq, ttwu_local);
2479	else {
2480	struct sched_domain *sd;
2481	for_each_domain(this_cpu, sd) {
2482	if (cpumask_test_cpu(cpu, sched_domain_span(sd))) {
2483	schedstat_inc(sd, ttwu_wake_remote);
2484	break;
2485	}
2486	}
2487	}
2488	#endif /* CONFIG_SCHEDSTATS */
2489
2490	out_activate:
2491	#endif /* CONFIG_SMP */
2492	ttwu_activate(p, rq, wake_flags & WF_SYNC, orig_cpu != cpu,
2493	cpu == this_cpu, en_flags);
2494	success = 1;
2495	out_running:
2496	ttwu_post_activation(p, rq, wake_flags, success);
2497	out:
2498	task_rq_unlock(rq, &flags);
2499	put_cpu();
2500
2501	return success;
2502	}
2503
2504	/**
2505	* try_to_wake_up_local - try to wake up a local task with rq lock held
2506	* @p: the thread to be awakened
2507	*
2508	* Put @p on the run-queue if it's not already there. The caller must
2509	* ensure that this_rq() is locked, @p is bound to this_rq() and not
2510	* the current task. this_rq() stays locked over invocation.
2511	*/
2512	static void try_to_wake_up_local(struct task_struct *p)
2513	{
2514	struct rq *rq = task_rq(p);
2515	bool success = false;
2516
2517	BUG_ON(rq != this_rq());
2518	BUG_ON(p == current);
2519	lockdep_assert_held(&rq->lock);
2520
2521	if (!(p->state & TASK_NORMAL))
2522	return;
2523
2524	if (!p->se.on_rq) {
2525	if (likely(!task_running(rq, p))) {
2526	schedstat_inc(rq, ttwu_count);
2527	schedstat_inc(rq, ttwu_local);
2528	}
2529	ttwu_activate(p, rq, false, false, true, ENQUEUE_WAKEUP);
2530	success = true;
2531	}
2532	ttwu_post_activation(p, rq, 0, success);
2533	}
2534
2535	/**
2536	* wake_up_process - Wake up a specific process
2537	* @p: The process to be woken up.
2538	*
2539	* Attempt to wake up the nominated process and move it to the set of runnable
2540	* processes. Returns 1 if the process was woken up, 0 if it was already
2541	* running.
2542	*
2543	* It may be assumed that this function implies a write memory barrier before
2544	* changing the task state if and only if any tasks are woken up.
2545	*/
2546	int wake_up_process(struct task_struct *p)
2547	{
2548	return try_to_wake_up(p, TASK_ALL, 0);
2549	}
2550	EXPORT_SYMBOL(wake_up_process);
2551
2552	int wake_up_state(struct task_struct *p, unsigned int state)
2553	{
2554	return try_to_wake_up(p, state, 0);
2555	}
2556
2557	/*
2558	* Perform scheduler related setup for a newly forked process p.
2559	* p is forked by current.
2560	*
2561	* __sched_fork() is basic setup used by init_idle() too:
2562	*/
2563	static void __sched_fork(struct task_struct *p)
2564	{
2565	p->se.exec_start = 0;
2566	p->se.sum_exec_runtime = 0;
2567	p->se.prev_sum_exec_runtime = 0;
2568	p->se.nr_migrations = 0;
2569
2570	#ifdef CONFIG_SCHEDSTATS
2571	memset(&p->se.statistics, 0, sizeof(p->se.statistics));
2572	#endif
2573
2574	INIT_LIST_HEAD(&p->rt.run_list);
2575	p->se.on_rq = 0;
2576	INIT_LIST_HEAD(&p->se.group_node);
2577
2578	#ifdef CONFIG_PREEMPT_NOTIFIERS
2579	INIT_HLIST_HEAD(&p->preempt_notifiers);
2580	#endif
2581	}
2582
2583	/*
2584	* fork()/clone()-time setup:
2585	*/
2586	void sched_fork(struct task_struct *p, int clone_flags)
2587	{
2588	int cpu = get_cpu();
2589
2590	__sched_fork(p);
2591	/*
2592	* We mark the process as running here. This guarantees that
2593	* nobody will actually run it, and a signal or other external
2594	* event cannot wake it up and insert it on the runqueue either.
2595	*/
2596	p->state = TASK_RUNNING;
2597
2598	/*
2599	* Revert to default priority/policy on fork if requested.
2600	*/
2601	if (unlikely(p->sched_reset_on_fork)) {
2602	if (p->policy == SCHED_FIFO \|\| p->policy == SCHED_RR) {
2603	p->policy = SCHED_NORMAL;
2604	p->normal_prio = p->static_prio;
2605	}
2606
2607	if (PRIO_TO_NICE(p->static_prio) < 0) {
2608	p->static_prio = NICE_TO_PRIO(0);
2609	p->normal_prio = p->static_prio;
2610	set_load_weight(p);
2611	}
2612
2613	/*
2614	* We don't need the reset flag anymore after the fork. It has
2615	* fulfilled its duty:
2616	*/
2617	p->sched_reset_on_fork = 0;
2618	}
2619
2620	/*
2621	* Make sure we do not leak PI boosting priority to the child.
2622	*/
2623	p->prio = current->normal_prio;
2624
2625	if (!rt_prio(p->prio))
2626	p->sched_class = &fair_sched_class;
2627
2628	if (p->sched_class->task_fork)
2629	p->sched_class->task_fork(p);
2630
2631	/*
2632	* The child is not yet in the pid-hash so no cgroup attach races,
2633	* and the cgroup is pinned to this child due to cgroup_fork()
2634	* is ran before sched_fork().
2635	*
2636	* Silence PROVE_RCU.
2637	*/
2638	rcu_read_lock();
2639	set_task_cpu(p, cpu);
2640	rcu_read_unlock();
2641
2642	#if defined(CONFIG_SCHEDSTATS) \|\| defined(CONFIG_TASK_DELAY_ACCT)
2643	if (likely(sched_info_on()))
2644	memset(&p->sched_info, 0, sizeof(p->sched_info));
2645	#endif
2646	#if defined(CONFIG_SMP) && defined(__ARCH_WANT_UNLOCKED_CTXSW)
2647	p->oncpu = 0;
2648	#endif
2649	#ifdef CONFIG_PREEMPT
2650	/* Want to start with kernel preemption disabled. */
2651	task_thread_info(p)->preempt_count = 1;
2652	#endif
2653	#ifdef CONFIG_SMP
2654	plist_node_init(&p->pushable_tasks, MAX_PRIO);
2655	#endif
2656
2657	put_cpu();
2658	}
2659
2660	/*
2661	* wake_up_new_task - wake up a newly created task for the first time.
2662	*
2663	* This function will do some initial scheduler statistics housekeeping
2664	* that must be done for every newly created context, then puts the task
2665	* on the runqueue and wakes it.
2666	*/
2667	void wake_up_new_task(struct task_struct *p, unsigned long clone_flags)
2668	{
2669	unsigned long flags;
2670	struct rq *rq;
2671	int cpu __maybe_unused = get_cpu();
2672
2673	#ifdef CONFIG_SMP
2674	rq = task_rq_lock(p, &flags);
2675	p->state = TASK_WAKING;
2676
2677	/*
2678	* Fork balancing, do it here and not earlier because:
2679	* - cpus_allowed can change in the fork path
2680	* - any previously selected cpu might disappear through hotplug
2681	*
2682	* We set TASK_WAKING so that select_task_rq() can drop rq->lock
2683	* without people poking at ->cpus_allowed.
2684	*/
2685	cpu = select_task_rq(rq, p, SD_BALANCE_FORK, 0);
2686	set_task_cpu(p, cpu);
2687
2688	p->state = TASK_RUNNING;
2689	task_rq_unlock(rq, &flags);
2690	#endif
2691
2692	rq = task_rq_lock(p, &flags);
2693	activate_task(rq, p, 0);
2694	trace_sched_wakeup_new(p, 1);
2695	check_preempt_curr(rq, p, WF_FORK);
2696	#ifdef CONFIG_SMP
2697	if (p->sched_class->task_woken)
2698	p->sched_class->task_woken(rq, p);
2699	#endif
2700	task_rq_unlock(rq, &flags);
2701	put_cpu();
2702	}
2703
2704	#ifdef CONFIG_PREEMPT_NOTIFIERS
2705
2706	/**
2707	* preempt_notifier_register - tell me when current is being preempted & rescheduled
2708	* @notifier: notifier struct to register
2709	*/
2710	void preempt_notifier_register(struct preempt_notifier *notifier)
2711	{
2712	hlist_add_head(&notifier->link, &current->preempt_notifiers);
2713	}
2714	EXPORT_SYMBOL_GPL(preempt_notifier_register);
2715
2716	/**
2717	* preempt_notifier_unregister - no longer interested in preemption notifications
2718	* @notifier: notifier struct to unregister
2719	*
2720	* This is safe to call from within a preemption notifier.
2721	*/
2722	void preempt_notifier_unregister(struct preempt_notifier *notifier)
2723	{
2724	hlist_del(&notifier->link);
2725	}
2726	EXPORT_SYMBOL_GPL(preempt_notifier_unregister);
2727
2728	static void fire_sched_in_preempt_notifiers(struct task_struct *curr)
2729	{
2730	struct preempt_notifier *notifier;
2731	struct hlist_node *node;
2732
2733	hlist_for_each_entry(notifier, node, &curr->preempt_notifiers, link)
2734	notifier->ops->sched_in(notifier, raw_smp_processor_id());
2735	}
2736
2737	static void
2738	fire_sched_out_preempt_notifiers(struct task_struct *curr,
2739	struct task_struct *next)
2740	{
2741	struct preempt_notifier *notifier;
2742	struct hlist_node *node;
2743
2744	hlist_for_each_entry(notifier, node, &curr->preempt_notifiers, link)
2745	notifier->ops->sched_out(notifier, next);
2746	}
2747
2748	#else /* !CONFIG_PREEMPT_NOTIFIERS */
2749
2750	static void fire_sched_in_preempt_notifiers(struct task_struct *curr)
2751	{
2752	}
2753
2754	static void
2755	fire_sched_out_preempt_notifiers(struct task_struct *curr,
2756	struct task_struct *next)
2757	{
2758	}
2759
2760	#endif /* CONFIG_PREEMPT_NOTIFIERS */
2761
2762	/**
2763	* prepare_task_switch - prepare to switch tasks
2764	* @rq: the runqueue preparing to switch
2765	* @prev: the current task that is being switched out
2766	* @next: the task we are going to switch to.
2767	*
2768	* This is called with the rq lock held and interrupts off. It must
2769	* be paired with a subsequent finish_task_switch after the context
2770	* switch.
2771	*
2772	* prepare_task_switch sets up locking and calls architecture specific
2773	* hooks.
2774	*/
2775	static inline void
2776	prepare_task_switch(struct rq rq, struct task_struct prev,
2777	struct task_struct *next)
2778	{
2779	fire_sched_out_preempt_notifiers(prev, next);
2780	prepare_lock_switch(rq, next);
2781	prepare_arch_switch(next);
2782	}
2783
2784	/**
2785	* finish_task_switch - clean up after a task-switch
2786	* @rq: runqueue associated with task-switch
2787	* @prev: the thread we just switched away from.
2788	*
2789	* finish_task_switch must be called after the context switch, paired
2790	* with a prepare_task_switch call before the context switch.
2791	* finish_task_switch will reconcile locking set up by prepare_task_switch,
2792	* and do any other architecture-specific cleanup actions.
2793	*
2794	* Note that we may have delayed dropping an mm in context_switch(). If
2795	* so, we finish that here outside of the runqueue lock. (Doing it
2796	* with the lock held can cause deadlocks; see schedule() for
2797	* details.)
2798	*/
2799	static void finish_task_switch(struct rq rq, struct task_struct prev)
2800	__releases(rq->lock)
2801	{
2802	struct mm_struct *mm = rq->prev_mm;
2803	long prev_state;
2804
2805	rq->prev_mm = NULL;
2806
2807	/*
2808	* A task struct has one reference for the use as "current".
2809	* If a task dies, then it sets TASK_DEAD in tsk->state and calls
2810	* schedule one last time. The schedule call will never return, and
2811	* the scheduled task must drop that reference.
2812	* The test for TASK_DEAD must occur while the runqueue locks are
2813	* still held, otherwise prev could be scheduled on another cpu, die
2814	* there before we look at prev->state, and then the reference would
2815	* be dropped twice.
2816	* Manfred Spraul <manfred@colorfullife.com>
2817	*/
2818	prev_state = prev->state;
2819	finish_arch_switch(prev);
2820	#ifdef __ARCH_WANT_INTERRUPTS_ON_CTXSW
2821	local_irq_disable();
2822	#endif /* __ARCH_WANT_INTERRUPTS_ON_CTXSW */
2823	perf_event_task_sched_in(current);
2824	#ifdef __ARCH_WANT_INTERRUPTS_ON_CTXSW
2825	local_irq_enable();
2826	#endif /* __ARCH_WANT_INTERRUPTS_ON_CTXSW */
2827	finish_lock_switch(rq, prev);
2828
2829	fire_sched_in_preempt_notifiers(current);
2830	if (mm)
2831	mmdrop(mm);
2832	if (unlikely(prev_state == TASK_DEAD)) {
2833	/*
2834	* Remove function-return probe instances associated with this
2835	* task and put them back on the free list.
2836	*/
2837	kprobe_flush_task(prev);
2838	put_task_struct(prev);
2839	}
2840	}
2841
2842	#ifdef CONFIG_SMP
2843
2844	/* assumes rq->lock is held */
2845	static inline void pre_schedule(struct rq rq, struct task_struct prev)
2846	{
2847	if (prev->sched_class->pre_schedule)
2848	prev->sched_class->pre_schedule(rq, prev);
2849	}
2850
2851	/* rq->lock is NOT held, but preemption is disabled */
2852	static inline void post_schedule(struct rq *rq)
2853	{
2854	if (rq->post_schedule) {
2855	unsigned long flags;
2856
2857	raw_spin_lock_irqsave(&rq->lock, flags);
2858	if (rq->curr->sched_class->post_schedule)
2859	rq->curr->sched_class->post_schedule(rq);
2860	raw_spin_unlock_irqrestore(&rq->lock, flags);
2861
2862	rq->post_schedule = 0;
2863	}
2864	}
2865
2866	#else
2867
2868	static inline void pre_schedule(struct rq rq, struct task_struct p)
2869	{
2870	}
2871
2872	static inline void post_schedule(struct rq *rq)
2873	{
2874	}
2875
2876	#endif
2877
2878	/**
2879	* schedule_tail - first thing a freshly forked thread must call.
2880	* @prev: the thread we just switched away from.
2881	*/
2882	asmlinkage void schedule_tail(struct task_struct *prev)
2883	__releases(rq->lock)
2884	{
2885	struct rq *rq = this_rq();
2886
2887	finish_task_switch(rq, prev);
2888
2889	/*
2890	* FIXME: do we need to worry about rq being invalidated by the
2891	* task_switch?
2892	*/
2893	post_schedule(rq);
2894
2895	#ifdef __ARCH_WANT_UNLOCKED_CTXSW
2896	/* In this case, finish_task_switch does not reenable preemption */
2897	preempt_enable();
2898	#endif
2899	if (current->set_child_tid)
2900	put_user(task_pid_vnr(current), current->set_child_tid);
2901	}
2902
2903	/*
2904	* context_switch - switch to the new MM and the new
2905	* thread's register state.
2906	*/
2907	static inline void
2908	context_switch(struct rq rq, struct task_struct prev,
2909	struct task_struct *next)
2910	{
2911	struct mm_struct mm, oldmm;
2912
2913	prepare_task_switch(rq, prev, next);
2914	trace_sched_switch(prev, next);
2915	mm = next->mm;
2916	oldmm = prev->active_mm;
2917	/*
2918	* For paravirt, this is coupled with an exit in switch_to to
2919	* combine the page table reload and the switch backend into
2920	* one hypercall.
2921	*/
2922	arch_start_context_switch(prev);
2923
2924	if (!mm) {
2925	next->active_mm = oldmm;
2926	atomic_inc(&oldmm->mm_count);
2927	enter_lazy_tlb(oldmm, next);
2928	} else
2929	switch_mm(oldmm, mm, next);
2930
2931	if (!prev->mm) {
2932	prev->active_mm = NULL;
2933	rq->prev_mm = oldmm;
2934	}
2935	/*
2936	* Since the runqueue lock will be released by the next
2937	* task (which is an invalid locking op but in the case
2938	* of the scheduler it's an obvious special-case), so we
2939	* do an early lockdep release here:
2940	*/
2941	#ifndef __ARCH_WANT_UNLOCKED_CTXSW
2942	spin_release(&rq->lock.dep_map, 1, _THIS_IP_);
2943	#endif
2944
2945	/* Here we just switch the register state and the stack. */
2946	switch_to(prev, next, prev);
2947
2948	barrier();
2949	/*
2950	* this_rq must be evaluated again because prev may have moved
2951	* CPUs since it called schedule(), thus the 'rq' on its stack
2952	* frame will be invalid.
2953	*/
2954	finish_task_switch(this_rq(), prev);
2955	}
2956
2957	/*
2958	* nr_running, nr_uninterruptible and nr_context_switches:
2959	*
2960	* externally visible scheduler statistics: current number of runnable
2961	* threads, current number of uninterruptible-sleeping threads, total
2962	* number of context switches performed since bootup.
2963	*/
2964	unsigned long nr_running(void)
2965	{
2966	unsigned long i, sum = 0;
2967
2968	for_each_online_cpu(i)
2969	sum += cpu_rq(i)->nr_running;
2970
2971	return sum;
2972	}
2973
2974	unsigned long nr_uninterruptible(void)
2975	{
2976	unsigned long i, sum = 0;
2977
2978	for_each_possible_cpu(i)
2979	sum += cpu_rq(i)->nr_uninterruptible;
2980
2981	/*
2982	* Since we read the counters lockless, it might be slightly
2983	* inaccurate. Do not allow it to go below zero though:
2984	*/
2985	if (unlikely((long)sum < 0))
2986	sum = 0;
2987
2988	return sum;
2989	}
2990
2991	unsigned long long nr_context_switches(void)
2992	{
2993	int i;
2994	unsigned long long sum = 0;
2995
2996	for_each_possible_cpu(i)
2997	sum += cpu_rq(i)->nr_switches;
2998
2999	return sum;
3000	}
3001
3002	unsigned long nr_iowait(void)
3003	{
3004	unsigned long i, sum = 0;
3005
3006	for_each_possible_cpu(i)
3007	sum += atomic_read(&cpu_rq(i)->nr_iowait);
3008
3009	return sum;
3010	}
3011
3012	unsigned long nr_iowait_cpu(int cpu)
3013	{
3014	struct rq *this = cpu_rq(cpu);
3015	return atomic_read(&this->nr_iowait);
3016	}
3017
3018	unsigned long this_cpu_load(void)
3019	{
3020	struct rq *this = this_rq();
3021	return this->cpu_load[0];
3022	}
3023
3024
3025	/* Variables and functions for calc_load */
3026	static atomic_long_t calc_load_tasks;
3027	static unsigned long calc_load_update;
3028	unsigned long avenrun[3];
3029	EXPORT_SYMBOL(avenrun);
3030
3031	static long calc_load_fold_active(struct rq *this_rq)
3032	{
3033	long nr_active, delta = 0;
3034
3035	nr_active = this_rq->nr_running;
3036	nr_active += (long) this_rq->nr_uninterruptible;
3037
3038	if (nr_active != this_rq->calc_load_active) {
3039	delta = nr_active - this_rq->calc_load_active;
3040	this_rq->calc_load_active = nr_active;
3041	}
3042
3043	return delta;
3044	}
3045
3046	static unsigned long
3047	calc_load(unsigned long load, unsigned long exp, unsigned long active)
3048	{
3049	load *= exp;
3050	load += active * (FIXED_1 - exp);
3051	load += 1UL << (FSHIFT - 1);
3052	return load >> FSHIFT;
3053	}
3054
3055	#ifdef CONFIG_NO_HZ
3056	/*
3057	* For NO_HZ we delay the active fold to the next LOAD_FREQ update.
3058	*
3059	* When making the ILB scale, we should try to pull this in as well.
3060	*/
3061	static atomic_long_t calc_load_tasks_idle;
3062
3063	static void calc_load_account_idle(struct rq *this_rq)
3064	{
3065	long delta;
3066
3067	delta = calc_load_fold_active(this_rq);
3068	if (delta)
3069	atomic_long_add(delta, &calc_load_tasks_idle);
3070	}
3071
3072	static long calc_load_fold_idle(void)
3073	{
3074	long delta = 0;
3075
3076	/*
3077	* Its got a race, we don't care...
3078	*/
3079	if (atomic_long_read(&calc_load_tasks_idle))
3080	delta = atomic_long_xchg(&calc_load_tasks_idle, 0);
3081
3082	return delta;
3083	}
3084
3085	/**
3086	* fixed_power_int - compute: x^n, in O(log n) time
3087	*
3088	* @x: base of the power
3089	* @frac_bits: fractional bits of @x
3090	* @n: power to raise @x to.
3091	*
3092	* By exploiting the relation between the definition of the natural power
3093	* function: x^n := xx...*x (x multiplied by itself for n times), and
3094	* the binary encoding of numbers used by computers: n := \Sum n_i * 2^i,
3095	* (where: n_i \elem {0, 1}, the binary vector representing n),
3096	* we find: x^n := x^(\Sum n_i * 2^i) := \Prod x^(n_i * 2^i), which is
3097	* of course trivially computable in O(log_2 n), the length of our binary
3098	* vector.
3099	*/
3100	static unsigned long
3101	fixed_power_int(unsigned long x, unsigned int frac_bits, unsigned int n)
3102	{
3103	unsigned long result = 1UL << frac_bits;
3104
3105	if (n) for (;;) {
3106	if (n & 1) {
3107	result *= x;
3108	result += 1UL << (frac_bits - 1);
3109	result >>= frac_bits;
3110	}
3111	n >>= 1;
3112	if (!n)
3113	break;
3114	x *= x;
3115	x += 1UL << (frac_bits - 1);
3116	x >>= frac_bits;
3117	}
3118
3119	return result;
3120	}
3121
3122	/*
3123	* a1 = a0 * e + a * (1 - e)
3124	*
3125	* a2 = a1 * e + a * (1 - e)
3126	* = (a0 * e + a * (1 - e)) * e + a * (1 - e)
3127	* = a0 * e^2 + a * (1 - e) * (1 + e)
3128	*
3129	* a3 = a2 * e + a * (1 - e)
3130	* = (a0 * e^2 + a * (1 - e) * (1 + e)) * e + a * (1 - e)
3131	* = a0 * e^3 + a * (1 - e) * (1 + e + e^2)
3132	*
3133	* ...
3134	*
3135	* an = a0 * e^n + a * (1 - e) * (1 + e + ... + e^n-1) [1]
3136	* = a0 * e^n + a * (1 - e) * (1 - e^n)/(1 - e)
3137	* = a0 * e^n + a * (1 - e^n)
3138	*
3139	* [1] application of the geometric series:
3140	*
3141	* n 1 - x^(n+1)
3142	* S_n := \Sum x^i = -------------
3143	* i=0 1 - x
3144	*/
3145	static unsigned long
3146	calc_load_n(unsigned long load, unsigned long exp,
3147	unsigned long active, unsigned int n)
3148	{
3149
3150	return calc_load(load, fixed_power_int(exp, FSHIFT, n), active);
3151	}
3152
3153	/*
3154	* NO_HZ can leave us missing all per-cpu ticks calling
3155	* calc_load_account_active(), but since an idle CPU folds its delta into
3156	* calc_load_tasks_idle per calc_load_account_idle(), all we need to do is fold
3157	* in the pending idle delta if our idle period crossed a load cycle boundary.
3158	*
3159	* Once we've updated the global active value, we need to apply the exponential
3160	* weights adjusted to the number of cycles missed.
3161	*/
3162	static void calc_global_nohz(unsigned long ticks)
3163	{
3164	long delta, active, n;
3165
3166	if (time_before(jiffies, calc_load_update))
3167	return;
3168
3169	/*
3170	* If we crossed a calc_load_update boundary, make sure to fold
3171	* any pending idle changes, the respective CPUs might have
3172	* missed the tick driven calc_load_account_active() update
3173	* due to NO_HZ.
3174	*/
3175	delta = calc_load_fold_idle();
3176	if (delta)
3177	atomic_long_add(delta, &calc_load_tasks);
3178
3179	/*
3180	* If we were idle for multiple load cycles, apply them.
3181	*/
3182	if (ticks >= LOAD_FREQ) {
3183	n = ticks / LOAD_FREQ;
3184
3185	active = atomic_long_read(&calc_load_tasks);
3186	active = active > 0 ? active * FIXED_1 : 0;
3187
3188	avenrun[0] = calc_load_n(avenrun[0], EXP_1, active, n);
3189	avenrun[1] = calc_load_n(avenrun[1], EXP_5, active, n);
3190	avenrun[2] = calc_load_n(avenrun[2], EXP_15, active, n);
3191
3192	calc_load_update += n * LOAD_FREQ;
3193	}
3194
3195	/*
3196	* Its possible the remainder of the above division also crosses
3197	* a LOAD_FREQ period, the regular check in calc_global_load()
3198	* which comes after this will take care of that.
3199	*
3200	* Consider us being 11 ticks before a cycle completion, and us
3201	* sleeping for 4*LOAD_FREQ + 22 ticks, then the above code will
3202	* age us 4 cycles, and the test in calc_global_load() will
3203	* pick up the final one.
3204	*/
3205	}
3206	#else
3207	static void calc_load_account_idle(struct rq *this_rq)
3208	{
3209	}
3210
3211	static inline long calc_load_fold_idle(void)
3212	{
3213	return 0;
3214	}
3215
3216	static void calc_global_nohz(unsigned long ticks)
3217	{
3218	}
3219	#endif
3220
3221	/**
3222	* get_avenrun - get the load average array
3223	* @loads: pointer to dest load array
3224	* @offset: offset to add
3225	* @shift: shift count to shift the result left
3226	*
3227	* These values are estimates at best, so no need for locking.
3228	*/
3229	void get_avenrun(unsigned long *loads, unsigned long offset, int shift)
3230	{
3231	loads[0] = (avenrun[0] + offset) << shift;
3232	loads[1] = (avenrun[1] + offset) << shift;
3233	loads[2] = (avenrun[2] + offset) << shift;
3234	}
3235
3236	/*
3237	* calc_load - update the avenrun load estimates 10 ticks after the
3238	* CPUs have updated calc_load_tasks.
3239	*/
3240	void calc_global_load(unsigned long ticks)
3241	{
3242	long active;
3243
3244	calc_global_nohz(ticks);
3245
3246	if (time_before(jiffies, calc_load_update + 10))
3247	return;
3248
3249	active = atomic_long_read(&calc_load_tasks);
3250	active = active > 0 ? active * FIXED_1 : 0;
3251
3252	avenrun[0] = calc_load(avenrun[0], EXP_1, active);
3253	avenrun[1] = calc_load(avenrun[1], EXP_5, active);
3254	avenrun[2] = calc_load(avenrun[2], EXP_15, active);
3255
3256	calc_load_update += LOAD_FREQ;
3257	}
3258
3259	/*
3260	* Called from update_cpu_load() to periodically update this CPU's
3261	* active count.
3262	*/
3263	static void calc_load_account_active(struct rq *this_rq)
3264	{
3265	long delta;
3266
3267	if (time_before(jiffies, this_rq->calc_load_update))
3268	return;
3269
3270	delta = calc_load_fold_active(this_rq);
3271	delta += calc_load_fold_idle();
3272	if (delta)
3273	atomic_long_add(delta, &calc_load_tasks);
3274
3275	this_rq->calc_load_update += LOAD_FREQ;
3276	}
3277
3278	/*
3279	* The exact cpuload at various idx values, calculated at every tick would be
3280	* load = (2^idx - 1) / 2^idx * load + 1 / 2^idx * cur_load
3281	*
3282	* If a cpu misses updates for n-1 ticks (as it was idle) and update gets called
3283	* on nth tick when cpu may be busy, then we have:
3284	* load = ((2^idx - 1) / 2^idx)^(n-1) * load
3285	* load = (2^idx - 1) / 2^idx) * load + 1 / 2^idx * cur_load
3286	*
3287	* decay_load_missed() below does efficient calculation of
3288	* load = ((2^idx - 1) / 2^idx)^(n-1) * load
3289	* avoiding 0..n-1 loop doing load = ((2^idx - 1) / 2^idx) * load
3290	*
3291	* The calculation is approximated on a 128 point scale.
3292	* degrade_zero_ticks is the number of ticks after which load at any
3293	* particular idx is approximated to be zero.
3294	* degrade_factor is a precomputed table, a row for each load idx.
3295	* Each column corresponds to degradation factor for a power of two ticks,
3296	* based on 128 point scale.
3297	* Example:
3298	* row 2, col 3 (=12) says that the degradation at load idx 2 after
3299	* 8 ticks is 12/128 (which is an approximation of exact factor 3^8/4^8).
3300	*
3301	* With this power of 2 load factors, we can degrade the load n times
3302	* by looking at 1 bits in n and doing as many mult/shift instead of
3303	* n mult/shifts needed by the exact degradation.
3304	*/
3305	#define DEGRADE_SHIFT 7
3306	static const unsigned char
3307	degrade_zero_ticks[CPU_LOAD_IDX_MAX] = {0, 8, 32, 64, 128};
3308	static const unsigned char
3309	degrade_factor[CPU_LOAD_IDX_MAX][DEGRADE_SHIFT + 1] = {
3310	{0, 0, 0, 0, 0, 0, 0, 0},
3311	{64, 32, 8, 0, 0, 0, 0, 0},
3312	{96, 72, 40, 12, 1, 0, 0},
3313	{112, 98, 75, 43, 15, 1, 0},
3314	{120, 112, 98, 76, 45, 16, 2} };
3315
3316	/*
3317	* Update cpu_load for any missed ticks, due to tickless idle. The backlog
3318	* would be when CPU is idle and so we just decay the old load without
3319	* adding any new load.
3320	*/
3321	static unsigned long
3322	decay_load_missed(unsigned long load, unsigned long missed_updates, int idx)
3323	{
3324	int j = 0;
3325
3326	if (!missed_updates)
3327	return load;
3328
3329	if (missed_updates >= degrade_zero_ticks[idx])
3330	return 0;
3331
3332	if (idx == 1)
3333	return load >> missed_updates;
3334
3335	while (missed_updates) {
3336	if (missed_updates % 2)
3337	load = (load * degrade_factor[idx][j]) >> DEGRADE_SHIFT;
3338
3339	missed_updates >>= 1;
3340	j++;
3341	}
3342	return load;
3343	}
3344
3345	/*
3346	* Update rq->cpu_load[] statistics. This function is usually called every
3347	* scheduler tick (TICK_NSEC). With tickless idle this will not be called
3348	* every tick. We fix it up based on jiffies.
3349	*/
3350	static void update_cpu_load(struct rq *this_rq)
3351	{
3352	unsigned long this_load = this_rq->load.weight;
3353	unsigned long curr_jiffies = jiffies;
3354	unsigned long pending_updates;
3355	int i, scale;
3356
3357	this_rq->nr_load_updates++;
3358
3359	/* Avoid repeated calls on same jiffy, when moving in and out of idle */
3360	if (curr_jiffies == this_rq->last_load_update_tick)
3361	return;
3362
3363	pending_updates = curr_jiffies - this_rq->last_load_update_tick;
3364	this_rq->last_load_update_tick = curr_jiffies;
3365
3366	/* Update our load: */
3367	this_rq->cpu_load[0] = this_load; /* Fasttrack for idx 0 */
3368	for (i = 1, scale = 2; i < CPU_LOAD_IDX_MAX; i++, scale += scale) {
3369	unsigned long old_load, new_load;
3370
3371	/* scale is effectively 1 << i now, and >> i divides by scale */
3372
3373	old_load = this_rq->cpu_load[i];
3374	old_load = decay_load_missed(old_load, pending_updates - 1, i);
3375	new_load = this_load;
3376	/*
3377	* Round up the averaging division if load is increasing. This
3378	* prevents us from getting stuck on 9 if the load is 10, for
3379	* example.
3380	*/
3381	if (new_load > old_load)
3382	new_load += scale - 1;
3383
3384	this_rq->cpu_load[i] = (old_load * (scale - 1) + new_load) >> i;
3385	}
3386
3387	sched_avg_update(this_rq);
3388	}
3389
3390	static void update_cpu_load_active(struct rq *this_rq)
3391	{
3392	update_cpu_load(this_rq);
3393
3394	calc_load_account_active(this_rq);
3395	}
3396
3397	#ifdef CONFIG_SMP
3398
3399	/*
3400	* sched_exec - execve() is a valuable balancing opportunity, because at
3401	* this point the task has the smallest effective memory and cache footprint.
3402	*/
3403	void sched_exec(void)
3404	{
3405	struct task_struct *p = current;
3406	unsigned long flags;
3407	struct rq *rq;
3408	int dest_cpu;
3409
3410	rq = task_rq_lock(p, &flags);
3411	dest_cpu = p->sched_class->select_task_rq(rq, p, SD_BALANCE_EXEC, 0);
3412	if (dest_cpu == smp_processor_id())
3413	goto unlock;
3414
3415	/*
3416	* select_task_rq() can race against ->cpus_allowed
3417	*/
3418	if (cpumask_test_cpu(dest_cpu, &p->cpus_allowed) &&
3419	likely(cpu_active(dest_cpu)) && migrate_task(p, rq)) {
3420	struct migration_arg arg = { p, dest_cpu };
3421
3422	task_rq_unlock(rq, &flags);
3423	stop_one_cpu(cpu_of(rq), migration_cpu_stop, &arg);
3424	return;
3425	}
3426	unlock:
3427	task_rq_unlock(rq, &flags);
3428	}
3429
3430	#endif
3431
3432	DEFINE_PER_CPU(struct kernel_stat, kstat);
3433
3434	EXPORT_PER_CPU_SYMBOL(kstat);
3435
3436	/*
3437	* Return any ns on the sched_clock that have not yet been accounted in
3438	* @p in case that task is currently running.
3439	*
3440	* Called with task_rq_lock() held on @rq.
3441	*/
3442	static u64 do_task_delta_exec(struct task_struct p, struct rq rq)
3443	{
3444	u64 ns = 0;
3445
3446	if (task_current(rq, p)) {
3447	update_rq_clock(rq);
3448	ns = rq->clock_task - p->se.exec_start;
3449	if ((s64)ns < 0)
3450	ns = 0;
3451	}
3452
3453	return ns;
3454	}
3455
3456	unsigned long long task_delta_exec(struct task_struct *p)
3457	{
3458	unsigned long flags;
3459	struct rq *rq;
3460	u64 ns = 0;
3461
3462	rq = task_rq_lock(p, &flags);
3463	ns = do_task_delta_exec(p, rq);
3464	task_rq_unlock(rq, &flags);
3465
3466	return ns;
3467	}
3468
3469	/*
3470	* Return accounted runtime for the task.
3471	* In case the task is currently running, return the runtime plus current's
3472	* pending runtime that have not been accounted yet.
3473	*/
3474	unsigned long long task_sched_runtime(struct task_struct *p)
3475	{
3476	unsigned long flags;
3477	struct rq *rq;
3478	u64 ns = 0;
3479
3480	rq = task_rq_lock(p, &flags);
3481	ns = p->se.sum_exec_runtime + do_task_delta_exec(p, rq);
3482	task_rq_unlock(rq, &flags);
3483
3484	return ns;
3485	}
3486
3487	/*
3488	* Return sum_exec_runtime for the thread group.
3489	* In case the task is currently running, return the sum plus current's
3490	* pending runtime that have not been accounted yet.
3491	*
3492	* Note that the thread group might have other running tasks as well,
3493	* so the return value not includes other pending runtime that other
3494	* running tasks might have.
3495	*/
3496	unsigned long long thread_group_sched_runtime(struct task_struct *p)
3497	{
3498	struct task_cputime totals;
3499	unsigned long flags;
3500	struct rq *rq;
3501	u64 ns;
3502
3503	rq = task_rq_lock(p, &flags);
3504	thread_group_cputime(p, &totals);
3505	ns = totals.sum_exec_runtime + do_task_delta_exec(p, rq);
3506	task_rq_unlock(rq, &flags);
3507
3508	return ns;
3509	}
3510
3511	/*
3512	* Account user cpu time to a process.
3513	* @p: the process that the cpu time gets accounted to
3514	* @cputime: the cpu time spent in user space since the last update
3515	* @cputime_scaled: cputime scaled by cpu frequency
3516	*/
3517	void account_user_time(struct task_struct *p, cputime_t cputime,
3518	cputime_t cputime_scaled)
3519	{
3520	struct cpu_usage_stat *cpustat = &kstat_this_cpu.cpustat;
3521	cputime64_t tmp;
3522
3523	/* Add user time to process. */
3524	p->utime = cputime_add(p->utime, cputime);
3525	p->utimescaled = cputime_add(p->utimescaled, cputime_scaled);
3526	account_group_user_time(p, cputime);
3527
3528	/* Add user time to cpustat. */
3529	tmp = cputime_to_cputime64(cputime);
3530	if (TASK_NICE(p) > 0)
3531	cpustat->nice = cputime64_add(cpustat->nice, tmp);
3532	else
3533	cpustat->user = cputime64_add(cpustat->user, tmp);
3534
3535	cpuacct_update_stats(p, CPUACCT_STAT_USER, cputime);
3536	/* Account for user time used */
3537	acct_update_integrals(p);
3538	}
3539
3540	/*
3541	* Account guest cpu time to a process.
3542	* @p: the process that the cpu time gets accounted to
3543	* @cputime: the cpu time spent in virtual machine since the last update
3544	* @cputime_scaled: cputime scaled by cpu frequency
3545	*/
3546	static void account_guest_time(struct task_struct *p, cputime_t cputime,
3547	cputime_t cputime_scaled)
3548	{
3549	cputime64_t tmp;
3550	struct cpu_usage_stat *cpustat = &kstat_this_cpu.cpustat;
3551
3552	tmp = cputime_to_cputime64(cputime);
3553
3554	/* Add guest time to process. */
3555	p->utime = cputime_add(p->utime, cputime);
3556	p->utimescaled = cputime_add(p->utimescaled, cputime_scaled);
3557	account_group_user_time(p, cputime);
3558	p->gtime = cputime_add(p->gtime, cputime);
3559
3560	/* Add guest time to cpustat. */
3561	if (TASK_NICE(p) > 0) {
3562	cpustat->nice = cputime64_add(cpustat->nice, tmp);
3563	cpustat->guest_nice = cputime64_add(cpustat->guest_nice, tmp);
3564	} else {
3565	cpustat->user = cputime64_add(cpustat->user, tmp);
3566	cpustat->guest = cputime64_add(cpustat->guest, tmp);
3567	}
3568	}
3569
3570	/*
3571	* Account system cpu time to a process.
3572	* @p: the process that the cpu time gets accounted to
3573	* @hardirq_offset: the offset to subtract from hardirq_count()
3574	* @cputime: the cpu time spent in kernel space since the last update
3575	* @cputime_scaled: cputime scaled by cpu frequency
3576	*/
3577	void account_system_time(struct task_struct *p, int hardirq_offset,
3578	cputime_t cputime, cputime_t cputime_scaled)
3579	{
3580	struct cpu_usage_stat *cpustat = &kstat_this_cpu.cpustat;
3581	cputime64_t tmp;
3582
3583	if ((p->flags & PF_VCPU) && (irq_count() - hardirq_offset == 0)) {
3584	account_guest_time(p, cputime, cputime_scaled);
3585	return;
3586	}
3587
3588	/* Add system time to process. */
3589	p->stime = cputime_add(p->stime, cputime);
3590	p->stimescaled = cputime_add(p->stimescaled, cputime_scaled);
3591	account_group_system_time(p, cputime);
3592
3593	/* Add system time to cpustat. */
3594	tmp = cputime_to_cputime64(cputime);
3595	if (hardirq_count() - hardirq_offset)
3596	cpustat->irq = cputime64_add(cpustat->irq, tmp);
3597	else if (in_serving_softirq())
3598	cpustat->softirq = cputime64_add(cpustat->softirq, tmp);
3599	else
3600	cpustat->system = cputime64_add(cpustat->system, tmp);
3601
3602	cpuacct_update_stats(p, CPUACCT_STAT_SYSTEM, cputime);
3603
3604	/* Account for system time used */
3605	acct_update_integrals(p);
3606	}
3607
3608	/*
3609	* Account for involuntary wait time.
3610	* @steal: the cpu time spent in involuntary wait
3611	*/
3612	void account_steal_time(cputime_t cputime)
3613	{
3614	struct cpu_usage_stat *cpustat = &kstat_this_cpu.cpustat;
3615	cputime64_t cputime64 = cputime_to_cputime64(cputime);
3616
3617	cpustat->steal = cputime64_add(cpustat->steal, cputime64);
3618	}
3619
3620	/*
3621	* Account for idle time.
3622	* @cputime: the cpu time spent in idle wait
3623	*/
3624	void account_idle_time(cputime_t cputime)
3625	{
3626	struct cpu_usage_stat *cpustat = &kstat_this_cpu.cpustat;
3627	cputime64_t cputime64 = cputime_to_cputime64(cputime);
3628	struct rq *rq = this_rq();
3629
3630	if (atomic_read(&rq->nr_iowait) > 0)
3631	cpustat->iowait = cputime64_add(cpustat->iowait, cputime64);
3632	else
3633	cpustat->idle = cputime64_add(cpustat->idle, cputime64);
3634	}
3635
3636	#ifndef CONFIG_VIRT_CPU_ACCOUNTING
3637
3638	/*
3639	* Account a single tick of cpu time.
3640	* @p: the process that the cpu time gets accounted to
3641	* @user_tick: indicates if the tick is a user or a system tick
3642	*/
3643	void account_process_tick(struct task_struct *p, int user_tick)
3644	{
3645	cputime_t one_jiffy_scaled = cputime_to_scaled(cputime_one_jiffy);
3646	struct rq *rq = this_rq();
3647
3648	if (user_tick)
3649	account_user_time(p, cputime_one_jiffy, one_jiffy_scaled);
3650	else if ((p != rq->idle) \|\| (irq_count() != HARDIRQ_OFFSET))
3651	account_system_time(p, HARDIRQ_OFFSET, cputime_one_jiffy,
3652	one_jiffy_scaled);
3653	else
3654	account_idle_time(cputime_one_jiffy);
3655	}
3656
3657	/*
3658	* Account multiple ticks of steal time.
3659	* @p: the process from which the cpu time has been stolen
3660	* @ticks: number of stolen ticks
3661	*/
3662	void account_steal_ticks(unsigned long ticks)
3663	{
3664	account_steal_time(jiffies_to_cputime(ticks));
3665	}
3666
3667	/*
3668	* Account multiple ticks of idle time.
3669	* @ticks: number of stolen ticks
3670	*/
3671	void account_idle_ticks(unsigned long ticks)
3672	{
3673	account_idle_time(jiffies_to_cputime(ticks));
3674	}
3675
3676	#endif
3677
3678	/*
3679	* Use precise platform statistics if available:
3680	*/
3681	#ifdef CONFIG_VIRT_CPU_ACCOUNTING
3682	void task_times(struct task_struct p, cputime_t ut, cputime_t *st)
3683	{
3684	*ut = p->utime;
3685	*st = p->stime;
3686	}
3687
3688	void thread_group_times(struct task_struct p, cputime_t ut, cputime_t *st)
3689	{
3690	struct task_cputime cputime;
3691
3692	thread_group_cputime(p, &cputime);
3693
3694	*ut = cputime.utime;
3695	*st = cputime.stime;
3696	}
3697	#else
3698
3699	#ifndef nsecs_to_cputime
3700	# define nsecs_to_cputime(__nsecs) nsecs_to_jiffies(__nsecs)
3701	#endif
3702
3703	void task_times(struct task_struct p, cputime_t ut, cputime_t *st)
3704	{
3705	cputime_t rtime, utime = p->utime, total = cputime_add(utime, p->stime);
3706
3707	/*
3708	* Use CFS's precise accounting:
3709	*/
3710	rtime = nsecs_to_cputime(p->se.sum_exec_runtime);
3711
3712	if (total) {
3713	u64 temp = rtime;
3714
3715	temp *= utime;
3716	do_div(temp, total);
3717	utime = (cputime_t)temp;
3718	} else
3719	utime = rtime;
3720
3721	/*
3722	* Compare with previous values, to keep monotonicity:
3723	*/
3724	p->prev_utime = max(p->prev_utime, utime);
3725	p->prev_stime = max(p->prev_stime, cputime_sub(rtime, p->prev_utime));
3726
3727	*ut = p->prev_utime;
3728	*st = p->prev_stime;
3729	}
3730
3731	/*
3732	* Must be called with siglock held.
3733	*/
3734	void thread_group_times(struct task_struct p, cputime_t ut, cputime_t *st)
3735	{
3736	struct signal_struct *sig = p->signal;
3737	struct task_cputime cputime;
3738	cputime_t rtime, utime, total;
3739
3740	thread_group_cputime(p, &cputime);
3741
3742	total = cputime_add(cputime.utime, cputime.stime);
3743	rtime = nsecs_to_cputime(cputime.sum_exec_runtime);
3744
3745	if (total) {
3746	u64 temp = rtime;
3747
3748	temp *= cputime.utime;
3749	do_div(temp, total);
3750	utime = (cputime_t)temp;
3751	} else
3752	utime = rtime;
3753
3754	sig->prev_utime = max(sig->prev_utime, utime);
3755	sig->prev_stime = max(sig->prev_stime,
3756	cputime_sub(rtime, sig->prev_utime));
3757
3758	*ut = sig->prev_utime;
3759	*st = sig->prev_stime;
3760	}
3761	#endif
3762
3763	/*
3764	* This function gets called by the timer code, with HZ frequency.
3765	* We call it with interrupts disabled.
3766	*
3767	* It also gets called by the fork code, when changing the parent's
3768	* timeslices.
3769	*/
3770	void scheduler_tick(void)
3771	{
3772	int cpu = smp_processor_id();
3773	struct rq *rq = cpu_rq(cpu);
3774	struct task_struct *curr = rq->curr;
3775
3776	sched_clock_tick();
3777
3778	raw_spin_lock(&rq->lock);
3779	update_rq_clock(rq);
3780	update_cpu_load_active(rq);
3781	curr->sched_class->task_tick(rq, curr, 0);
3782	raw_spin_unlock(&rq->lock);
3783
3784	perf_event_task_tick();
3785
3786	#ifdef CONFIG_SMP
3787	rq->idle_at_tick = idle_cpu(cpu);
3788	trigger_load_balance(rq, cpu);
3789	#endif
3790	}
3791
3792	notrace unsigned long get_parent_ip(unsigned long addr)
3793	{
3794	if (in_lock_functions(addr)) {
3795	addr = CALLER_ADDR2;
3796	if (in_lock_functions(addr))
3797	addr = CALLER_ADDR3;
3798	}
3799	return addr;
3800	}
3801
3802	#if defined(CONFIG_PREEMPT) && (defined(CONFIG_DEBUG_PREEMPT) \|\| \
3803	defined(CONFIG_PREEMPT_TRACER))
3804
3805	void __kprobes add_preempt_count(int val)
3806	{
3807	#ifdef CONFIG_DEBUG_PREEMPT
3808	/*
3809	* Underflow?
3810	*/
3811	if (DEBUG_LOCKS_WARN_ON((preempt_count() < 0)))
3812	return;
3813	#endif
3814	preempt_count() += val;
3815	#ifdef CONFIG_DEBUG_PREEMPT
3816	/*
3817	* Spinlock count overflowing soon?
3818	*/
3819	DEBUG_LOCKS_WARN_ON((preempt_count() & PREEMPT_MASK) >=
3820	PREEMPT_MASK - 10);
3821	#endif
3822	if (preempt_count() == val)
3823	trace_preempt_off(CALLER_ADDR0, get_parent_ip(CALLER_ADDR1));
3824	}
3825	EXPORT_SYMBOL(add_preempt_count);
3826
3827	void __kprobes sub_preempt_count(int val)
3828	{
3829	#ifdef CONFIG_DEBUG_PREEMPT
3830	/*
3831	* Underflow?
3832	*/
3833	if (DEBUG_LOCKS_WARN_ON(val > preempt_count()))
3834	return;
3835	/*
3836	* Is the spinlock portion underflowing?
3837	*/
3838	if (DEBUG_LOCKS_WARN_ON((val < PREEMPT_MASK) &&
3839	!(preempt_count() & PREEMPT_MASK)))
3840	return;
3841	#endif
3842
3843	if (preempt_count() == val)
3844	trace_preempt_on(CALLER_ADDR0, get_parent_ip(CALLER_ADDR1));
3845	preempt_count() -= val;
3846	}
3847	EXPORT_SYMBOL(sub_preempt_count);
3848
3849	#endif
3850
3851	/*
3852	* Print scheduling while atomic bug:
3853	*/
3854	static noinline void __schedule_bug(struct task_struct *prev)
3855	{
3856	struct pt_regs *regs = get_irq_regs();
3857
3858	printk(KERN_ERR "BUG: scheduling while atomic: %s/%d/0x%08x\n",
3859	prev->comm, prev->pid, preempt_count());
3860
3861	debug_show_held_locks(prev);
3862	print_modules();
3863	if (irqs_disabled())
3864	print_irqtrace_events(prev);
3865
3866	if (regs)
3867	show_regs(regs);
3868	else
3869	dump_stack();
3870	}
3871
3872	/*
3873	* Various schedule()-time debugging checks and statistics:
3874	*/
3875	static inline void schedule_debug(struct task_struct *prev)
3876	{
3877	/*
3878	* Test if we are atomic. Since do_exit() needs to call into
3879	* schedule() atomically, we ignore that path for now.
3880	* Otherwise, whine if we are scheduling when we should not be.
3881	*/
3882	if (unlikely(in_atomic_preempt_off() && !prev->exit_state))
3883	__schedule_bug(prev);
3884
3885	profile_hit(SCHED_PROFILING, __builtin_return_address(0));
3886
3887	schedstat_inc(this_rq(), sched_count);
3888	#ifdef CONFIG_SCHEDSTATS
3889	if (unlikely(prev->lock_depth >= 0)) {
3890	schedstat_inc(this_rq(), rq_sched_info.bkl_count);
3891	schedstat_inc(prev, sched_info.bkl_count);
3892	}
3893	#endif
3894	}
3895
3896	static void put_prev_task(struct rq rq, struct task_struct prev)
3897	{
3898	if (prev->se.on_rq)
3899	update_rq_clock(rq);
3900	prev->sched_class->put_prev_task(rq, prev);
3901	}
3902
3903	/*
3904	* Pick up the highest-prio task:
3905	*/
3906	static inline struct task_struct *
3907	pick_next_task(struct rq *rq)
3908	{
3909	const struct sched_class *class;
3910	struct task_struct *p;
3911
3912	/*
3913	* Optimization: we know that if all tasks are in
3914	* the fair class we can call that function directly:
3915	*/
3916	if (likely(rq->nr_running == rq->cfs.nr_running)) {
3917	p = fair_sched_class.pick_next_task(rq);
3918	if (likely(p))
3919	return p;
3920	}
3921
3922	for_each_class(class) {
3923	p = class->pick_next_task(rq);
3924	if (p)
3925	return p;
3926	}
3927
3928	BUG(); /* the idle class will always have a runnable task */
3929	}
3930
3931	/*
3932	* schedule() is the main scheduler function.
3933	*/
3934	asmlinkage void __sched schedule(void)
3935	{
3936	struct task_struct prev, next;
3937	unsigned long *switch_count;
3938	struct rq *rq;
3939	int cpu;
3940
3941	need_resched:
3942	preempt_disable();
3943	cpu = smp_processor_id();
3944	rq = cpu_rq(cpu);
3945	rcu_note_context_switch(cpu);
3946	prev = rq->curr;
3947
3948	release_kernel_lock(prev);
3949	need_resched_nonpreemptible:
3950
3951	schedule_debug(prev);
3952
3953	if (sched_feat(HRTICK))
3954	hrtick_clear(rq);
3955
3956	raw_spin_lock_irq(&rq->lock);
3957
3958	switch_count = &prev->nivcsw;
3959	if (prev->state && !(preempt_count() & PREEMPT_ACTIVE)) {
3960	if (unlikely(signal_pending_state(prev->state, prev))) {
3961	prev->state = TASK_RUNNING;
3962	} else {
3963	/*
3964	* If a worker is going to sleep, notify and
3965	* ask workqueue whether it wants to wake up a
3966	* task to maintain concurrency. If so, wake
3967	* up the task.
3968	*/
3969	if (prev->flags & PF_WQ_WORKER) {
3970	struct task_struct *to_wakeup;
3971
3972	to_wakeup = wq_worker_sleeping(prev, cpu);
3973	if (to_wakeup)
3974	try_to_wake_up_local(to_wakeup);
3975	}
3976	deactivate_task(rq, prev, DEQUEUE_SLEEP);
3977	}
3978	switch_count = &prev->nvcsw;
3979	}
3980
3981	pre_schedule(rq, prev);
3982
3983	if (unlikely(!rq->nr_running))
3984	idle_balance(cpu, rq);
3985
3986	put_prev_task(rq, prev);
3987	next = pick_next_task(rq);
3988	clear_tsk_need_resched(prev);
3989	rq->skip_clock_update = 0;
3990
3991	if (likely(prev != next)) {
3992	sched_info_switch(prev, next);
3993	perf_event_task_sched_out(prev, next);
3994
3995	rq->nr_switches++;
3996	rq->curr = next;
3997	++*switch_count;
3998
3999	context_switch(rq, prev, next); /* unlocks the rq */
4000	/*
4001	* The context switch have flipped the stack from under us
4002	* and restored the local variables which were saved when
4003	* this task called schedule() in the past. prev == current
4004	* is still correct, but it can be moved to another cpu/rq.
4005	*/
4006	cpu = smp_processor_id();
4007	rq = cpu_rq(cpu);
4008	} else
4009	raw_spin_unlock_irq(&rq->lock);
4010
4011	post_schedule(rq);
4012
4013	if (unlikely(reacquire_kernel_lock(prev)))
4014	goto need_resched_nonpreemptible;
4015
4016	preempt_enable_no_resched();
4017	if (need_resched())
4018	goto need_resched;
4019	}
4020	EXPORT_SYMBOL(schedule);
4021
4022	#ifdef CONFIG_MUTEX_SPIN_ON_OWNER
4023	/*
4024	* Look out! "owner" is an entirely speculative pointer
4025	* access and not reliable.
4026	*/
4027	int mutex_spin_on_owner(struct mutex lock, struct thread_info owner)
4028	{
4029	unsigned int cpu;
4030	struct rq *rq;
4031
4032	if (!sched_feat(OWNER_SPIN))
4033	return 0;
4034
4035	#ifdef CONFIG_DEBUG_PAGEALLOC
4036	/*
4037	* Need to access the cpu field knowing that
4038	* DEBUG_PAGEALLOC could have unmapped it if
4039	* the mutex owner just released it and exited.
4040	*/
4041	if (probe_kernel_address(&owner->cpu, cpu))
4042	return 0;
4043	#else
4044	cpu = owner->cpu;
4045	#endif
4046
4047	/*
4048	* Even if the access succeeded (likely case),
4049	* the cpu field may no longer be valid.
4050	*/
4051	if (cpu >= nr_cpumask_bits)
4052	return 0;
4053
4054	/*
4055	* We need to validate that we can do a
4056	* get_cpu() and that we have the percpu area.
4057	*/
4058	if (!cpu_online(cpu))
4059	return 0;
4060
4061	rq = cpu_rq(cpu);
4062
4063	for (;;) {
4064	/*
4065	* Owner changed, break to re-assess state.
4066	*/
4067	if (lock->owner != owner) {
4068	/*
4069	* If the lock has switched to a different owner,
4070	* we likely have heavy contention. Return 0 to quit
4071	* optimistic spinning and not contend further:
4072	*/
4073	if (lock->owner)
4074	return 0;
4075	break;
4076	}
4077
4078	/*
4079	* Is that owner really running on that cpu?
4080	*/
4081	if (task_thread_info(rq->curr) != owner \|\| need_resched())
4082	return 0;
4083
4084	arch_mutex_cpu_relax();
4085	}
4086
4087	return 1;
4088	}
4089	#endif
4090
4091	#ifdef CONFIG_PREEMPT
4092	/*
4093	* this is the entry point to schedule() from in-kernel preemption
4094	* off of preempt_enable. Kernel preemptions off return from interrupt
4095	* occur there and call schedule directly.
4096	*/
4097	asmlinkage void __sched notrace preempt_schedule(void)
4098	{
4099	struct thread_info *ti = current_thread_info();
4100
4101	/*
4102	* If there is a non-zero preempt_count or interrupts are disabled,
4103	* we do not want to preempt the current task. Just return..
4104	*/
4105	if (likely(ti->preempt_count \|\| irqs_disabled()))
4106	return;
4107
4108	do {
4109	add_preempt_count_notrace(PREEMPT_ACTIVE);
4110	schedule();
4111	sub_preempt_count_notrace(PREEMPT_ACTIVE);
4112
4113	/*
4114	* Check again in case we missed a preemption opportunity
4115	* between schedule and now.
4116	*/
4117	barrier();
4118	} while (need_resched());
4119	}
4120	EXPORT_SYMBOL(preempt_schedule);
4121
4122	/*
4123	* this is the entry point to schedule() from kernel preemption
4124	* off of irq context.
4125	* Note, that this is called and return with irqs disabled. This will
4126	* protect us against recursive calling from irq.
4127	*/
4128	asmlinkage void __sched preempt_schedule_irq(void)
4129	{
4130	struct thread_info *ti = current_thread_info();
4131
4132	/* Catch callers which need to be fixed */
4133	BUG_ON(ti->preempt_count \|\| !irqs_disabled());
4134
4135	do {
4136	add_preempt_count(PREEMPT_ACTIVE);
4137	local_irq_enable();
4138	schedule();
4139	local_irq_disable();
4140	sub_preempt_count(PREEMPT_ACTIVE);
4141
4142	/*
4143	* Check again in case we missed a preemption opportunity
4144	* between schedule and now.
4145	*/
4146	barrier();
4147	} while (need_resched());
4148	}
4149
4150	#endif /* CONFIG_PREEMPT */
4151
4152	int default_wake_function(wait_queue_t *curr, unsigned mode, int wake_flags,
4153	void *key)
4154	{
4155	return try_to_wake_up(curr->private, mode, wake_flags);
4156	}
4157	EXPORT_SYMBOL(default_wake_function);
4158
4159	/*
4160	* The core wakeup function. Non-exclusive wakeups (nr_exclusive == 0) just
4161	* wake everything up. If it's an exclusive wakeup (nr_exclusive == small +ve
4162	* number) then we wake all the non-exclusive tasks and one exclusive task.
4163	*
4164	* There are circumstances in which we can try to wake a task which has already
4165	* started to run but is not in state TASK_RUNNING. try_to_wake_up() returns
4166	* zero in this (rare) case, and we handle it by continuing to scan the queue.
4167	*/
4168	static void __wake_up_common(wait_queue_head_t *q, unsigned int mode,
4169	int nr_exclusive, int wake_flags, void *key)
4170	{
4171	wait_queue_t curr, next;
4172
4173	list_for_each_entry_safe(curr, next, &q->task_list, task_list) {
4174	unsigned flags = curr->flags;
4175
4176	if (curr->func(curr, mode, wake_flags, key) &&
4177	(flags & WQ_FLAG_EXCLUSIVE) && !--nr_exclusive)
4178	break;
4179	}
4180	}
4181
4182	/**
4183	* __wake_up - wake up threads blocked on a waitqueue.
4184	* @q: the waitqueue
4185	* @mode: which threads
4186	* @nr_exclusive: how many wake-one or wake-many threads to wake up
4187	* @key: is directly passed to the wakeup function
4188	*
4189	* It may be assumed that this function implies a write memory barrier before
4190	* changing the task state if and only if any tasks are woken up.
4191	*/
4192	void __wake_up(wait_queue_head_t *q, unsigned int mode,
4193	int nr_exclusive, void *key)
4194	{
4195	unsigned long flags;
4196
4197	spin_lock_irqsave(&q->lock, flags);
4198	__wake_up_common(q, mode, nr_exclusive, 0, key);
4199	spin_unlock_irqrestore(&q->lock, flags);
4200	}
4201	EXPORT_SYMBOL(__wake_up);
4202
4203	/*
4204	* Same as __wake_up but called with the spinlock in wait_queue_head_t held.
4205	*/
4206	void __wake_up_locked(wait_queue_head_t *q, unsigned int mode)
4207	{
4208	__wake_up_common(q, mode, 1, 0, NULL);
4209	}
4210	EXPORT_SYMBOL_GPL(__wake_up_locked);
4211
4212	void __wake_up_locked_key(wait_queue_head_t q, unsigned int mode, void key)
4213	{
4214	__wake_up_common(q, mode, 1, 0, key);
4215	}
4216	EXPORT_SYMBOL_GPL(__wake_up_locked_key);
4217
4218	/**
4219	* __wake_up_sync_key - wake up threads blocked on a waitqueue.
4220	* @q: the waitqueue
4221	* @mode: which threads
4222	* @nr_exclusive: how many wake-one or wake-many threads to wake up
4223	* @key: opaque value to be passed to wakeup targets
4224	*
4225	* The sync wakeup differs that the waker knows that it will schedule
4226	* away soon, so while the target thread will be woken up, it will not
4227	* be migrated to another CPU - ie. the two threads are 'synchronized'
4228	* with each other. This can prevent needless bouncing between CPUs.
4229	*
4230	* On UP it can prevent extra preemption.
4231	*
4232	* It may be assumed that this function implies a write memory barrier before
4233	* changing the task state if and only if any tasks are woken up.
4234	*/
4235	void __wake_up_sync_key(wait_queue_head_t *q, unsigned int mode,
4236	int nr_exclusive, void *key)
4237	{
4238	unsigned long flags;
4239	int wake_flags = WF_SYNC;
4240
4241	if (unlikely(!q))
4242	return;
4243
4244	if (unlikely(!nr_exclusive))
4245	wake_flags = 0;
4246
4247	spin_lock_irqsave(&q->lock, flags);
4248	__wake_up_common(q, mode, nr_exclusive, wake_flags, key);
4249	spin_unlock_irqrestore(&q->lock, flags);
4250	}
4251	EXPORT_SYMBOL_GPL(__wake_up_sync_key);
4252
4253	/*
4254	* __wake_up_sync - see __wake_up_sync_key()
4255	*/
4256	void __wake_up_sync(wait_queue_head_t *q, unsigned int mode, int nr_exclusive)
4257	{
4258	__wake_up_sync_key(q, mode, nr_exclusive, NULL);
4259	}
4260	EXPORT_SYMBOL_GPL(__wake_up_sync); /* For internal use only */
4261
4262	/**
4263	* complete: - signals a single thread waiting on this completion
4264	* @x: holds the state of this particular completion
4265	*
4266	* This will wake up a single thread waiting on this completion. Threads will be
4267	* awakened in the same order in which they were queued.
4268	*
4269	* See also complete_all(), wait_for_completion() and related routines.
4270	*
4271	* It may be assumed that this function implies a write memory barrier before
4272	* changing the task state if and only if any tasks are woken up.
4273	*/
4274	void complete(struct completion *x)
4275	{
4276	unsigned long flags;
4277
4278	spin_lock_irqsave(&x->wait.lock, flags);
4279	x->done++;
4280	__wake_up_common(&x->wait, TASK_NORMAL, 1, 0, NULL);
4281	spin_unlock_irqrestore(&x->wait.lock, flags);
4282	}
4283	EXPORT_SYMBOL(complete);
4284
4285	/**
4286	* complete_all: - signals all threads waiting on this completion
4287	* @x: holds the state of this particular completion
4288	*
4289	* This will wake up all threads waiting on this particular completion event.
4290	*
4291	* It may be assumed that this function implies a write memory barrier before
4292	* changing the task state if and only if any tasks are woken up.
4293	*/
4294	void complete_all(struct completion *x)
4295	{
4296	unsigned long flags;
4297
4298	spin_lock_irqsave(&x->wait.lock, flags);
4299	x->done += UINT_MAX/2;
4300	__wake_up_common(&x->wait, TASK_NORMAL, 0, 0, NULL);
4301	spin_unlock_irqrestore(&x->wait.lock, flags);
4302	}
4303	EXPORT_SYMBOL(complete_all);
4304
4305	static inline long __sched
4306	do_wait_for_common(struct completion *x, long timeout, int state)
4307	{
4308	if (!x->done) {
4309	DECLARE_WAITQUEUE(wait, current);
4310
4311	__add_wait_queue_tail_exclusive(&x->wait, &wait);
4312	do {
4313	if (signal_pending_state(state, current)) {
4314	timeout = -ERESTARTSYS;
4315	break;
4316	}
4317	__set_current_state(state);
4318	spin_unlock_irq(&x->wait.lock);
4319	timeout = schedule_timeout(timeout);
4320	spin_lock_irq(&x->wait.lock);
4321	} while (!x->done && timeout);
4322	__remove_wait_queue(&x->wait, &wait);
4323	if (!x->done)
4324	return timeout;
4325	}
4326	x->done--;
4327	return timeout ?: 1;
4328	}
4329
4330	static long __sched
4331	wait_for_common(struct completion *x, long timeout, int state)
4332	{
4333	might_sleep();
4334
4335	spin_lock_irq(&x->wait.lock);
4336	timeout = do_wait_for_common(x, timeout, state);
4337	spin_unlock_irq(&x->wait.lock);
4338	return timeout;
4339	}
4340
4341	/**
4342	* wait_for_completion: - waits for completion of a task
4343	* @x: holds the state of this particular completion
4344	*
4345	* This waits to be signaled for completion of a specific task. It is NOT
4346	* interruptible and there is no timeout.
4347	*
4348	* See also similar routines (i.e. wait_for_completion_timeout()) with timeout
4349	* and interrupt capability. Also see complete().
4350	*/
4351	void __sched wait_for_completion(struct completion *x)
4352	{
4353	wait_for_common(x, MAX_SCHEDULE_TIMEOUT, TASK_UNINTERRUPTIBLE);
4354	}
4355	EXPORT_SYMBOL(wait_for_completion);
4356
4357	/**
4358	* wait_for_completion_timeout: - waits for completion of a task (w/timeout)
4359	* @x: holds the state of this particular completion
4360	* @timeout: timeout value in jiffies
4361	*
4362	* This waits for either a completion of a specific task to be signaled or for a
4363	* specified timeout to expire. The timeout is in jiffies. It is not
4364	* interruptible.
4365	*/
4366	unsigned long __sched
4367	wait_for_completion_timeout(struct completion *x, unsigned long timeout)
4368	{
4369	return wait_for_common(x, timeout, TASK_UNINTERRUPTIBLE);
4370	}
4371	EXPORT_SYMBOL(wait_for_completion_timeout);
4372
4373	/**
4374	* wait_for_completion_interruptible: - waits for completion of a task (w/intr)
4375	* @x: holds the state of this particular completion
4376	*
4377	* This waits for completion of a specific task to be signaled. It is
4378	* interruptible.
4379	*/
4380	int __sched wait_for_completion_interruptible(struct completion *x)
4381	{
4382	long t = wait_for_common(x, MAX_SCHEDULE_TIMEOUT, TASK_INTERRUPTIBLE);
4383	if (t == -ERESTARTSYS)
4384	return t;
4385	return 0;
4386	}
4387	EXPORT_SYMBOL(wait_for_completion_interruptible);
4388
4389	/**
4390	* wait_for_completion_interruptible_timeout: - waits for completion (w/(to,intr))
4391	* @x: holds the state of this particular completion
4392	* @timeout: timeout value in jiffies
4393	*
4394	* This waits for either a completion of a specific task to be signaled or for a
4395	* specified timeout to expire. It is interruptible. The timeout is in jiffies.
4396	*/
4397	long __sched
4398	wait_for_completion_interruptible_timeout(struct completion *x,
4399	unsigned long timeout)
4400	{
4401	return wait_for_common(x, timeout, TASK_INTERRUPTIBLE);
4402	}
4403	EXPORT_SYMBOL(wait_for_completion_interruptible_timeout);
4404
4405	/**
4406	* wait_for_completion_killable: - waits for completion of a task (killable)
4407	* @x: holds the state of this particular completion
4408	*
4409	* This waits to be signaled for completion of a specific task. It can be
4410	* interrupted by a kill signal.
4411	*/
4412	int __sched wait_for_completion_killable(struct completion *x)
4413	{
4414	long t = wait_for_common(x, MAX_SCHEDULE_TIMEOUT, TASK_KILLABLE);
4415	if (t == -ERESTARTSYS)
4416	return t;
4417	return 0;
4418	}
4419	EXPORT_SYMBOL(wait_for_completion_killable);
4420
4421	/**
4422	* wait_for_completion_killable_timeout: - waits for completion of a task (w/(to,killable))
4423	* @x: holds the state of this particular completion
4424	* @timeout: timeout value in jiffies
4425	*
4426	* This waits for either a completion of a specific task to be
4427	* signaled or for a specified timeout to expire. It can be
4428	* interrupted by a kill signal. The timeout is in jiffies.
4429	*/
4430	long __sched
4431	wait_for_completion_killable_timeout(struct completion *x,
4432	unsigned long timeout)
4433	{
4434	return wait_for_common(x, timeout, TASK_KILLABLE);
4435	}
4436	EXPORT_SYMBOL(wait_for_completion_killable_timeout);
4437
4438	/**
4439	* try_wait_for_completion - try to decrement a completion without blocking
4440	* @x: completion structure
4441	*
4442	* Returns: 0 if a decrement cannot be done without blocking
4443	* 1 if a decrement succeeded.
4444	*
4445	* If a completion is being used as a counting completion,
4446	* attempt to decrement the counter without blocking. This
4447	* enables us to avoid waiting if the resource the completion
4448	* is protecting is not available.
4449	*/
4450	bool try_wait_for_completion(struct completion *x)
4451	{
4452	unsigned long flags;
4453	int ret = 1;
4454
4455	spin_lock_irqsave(&x->wait.lock, flags);
4456	if (!x->done)
4457	ret = 0;
4458	else
4459	x->done--;
4460	spin_unlock_irqrestore(&x->wait.lock, flags);
4461	return ret;
4462	}
4463	EXPORT_SYMBOL(try_wait_for_completion);
4464
4465	/**
4466	* completion_done - Test to see if a completion has any waiters
4467	* @x: completion structure
4468	*
4469	* Returns: 0 if there are waiters (wait_for_completion() in progress)
4470	* 1 if there are no waiters.
4471	*
4472	*/
4473	bool completion_done(struct completion *x)
4474	{
4475	unsigned long flags;
4476	int ret = 1;
4477
4478	spin_lock_irqsave(&x->wait.lock, flags);
4479	if (!x->done)
4480	ret = 0;
4481	spin_unlock_irqrestore(&x->wait.lock, flags);
4482	return ret;
4483	}
4484	EXPORT_SYMBOL(completion_done);
4485
4486	static long __sched
4487	sleep_on_common(wait_queue_head_t *q, int state, long timeout)
4488	{
4489	unsigned long flags;
4490	wait_queue_t wait;
4491
4492	init_waitqueue_entry(&wait, current);
4493
4494	__set_current_state(state);
4495
4496	spin_lock_irqsave(&q->lock, flags);
4497	__add_wait_queue(q, &wait);
4498	spin_unlock(&q->lock);
4499	timeout = schedule_timeout(timeout);
4500	spin_lock_irq(&q->lock);
4501	__remove_wait_queue(q, &wait);
4502	spin_unlock_irqrestore(&q->lock, flags);
4503
4504	return timeout;
4505	}
4506
4507	void __sched interruptible_sleep_on(wait_queue_head_t *q)
4508	{
4509	sleep_on_common(q, TASK_INTERRUPTIBLE, MAX_SCHEDULE_TIMEOUT);
4510	}
4511	EXPORT_SYMBOL(interruptible_sleep_on);
4512
4513	long __sched
4514	interruptible_sleep_on_timeout(wait_queue_head_t *q, long timeout)
4515	{
4516	return sleep_on_common(q, TASK_INTERRUPTIBLE, timeout);
4517	}
4518	EXPORT_SYMBOL(interruptible_sleep_on_timeout);
4519
4520	void __sched sleep_on(wait_queue_head_t *q)
4521	{
4522	sleep_on_common(q, TASK_UNINTERRUPTIBLE, MAX_SCHEDULE_TIMEOUT);
4523	}
4524	EXPORT_SYMBOL(sleep_on);
4525
4526	long __sched sleep_on_timeout(wait_queue_head_t *q, long timeout)
4527	{
4528	return sleep_on_common(q, TASK_UNINTERRUPTIBLE, timeout);
4529	}
4530	EXPORT_SYMBOL(sleep_on_timeout);
4531
4532	#ifdef CONFIG_RT_MUTEXES
4533
4534	/*
4535	* rt_mutex_setprio - set the current priority of a task
4536	* @p: task
4537	* @prio: prio value (kernel-internal form)
4538	*
4539	* This function changes the 'effective' priority of a task. It does
4540	* not touch ->normal_prio like __setscheduler().
4541	*
4542	* Used by the rt_mutex code to implement priority inheritance logic.
4543	*/
4544	void rt_mutex_setprio(struct task_struct *p, int prio)
4545	{
4546	unsigned long flags;
4547	int oldprio, on_rq, running;
4548	struct rq *rq;
4549	const struct sched_class *prev_class;
4550
4551	BUG_ON(prio < 0 \|\| prio > MAX_PRIO);
4552
4553	rq = task_rq_lock(p, &flags);
4554
4555	trace_sched_pi_setprio(p, prio);
4556	oldprio = p->prio;
4557	prev_class = p->sched_class;
4558	on_rq = p->se.on_rq;
4559	running = task_current(rq, p);
4560	if (on_rq)
4561	dequeue_task(rq, p, 0);
4562	if (running)
4563	p->sched_class->put_prev_task(rq, p);
4564
4565	if (rt_prio(prio))
4566	p->sched_class = &rt_sched_class;
4567	else
4568	p->sched_class = &fair_sched_class;
4569
4570	p->prio = prio;
4571
4572	if (running)
4573	p->sched_class->set_curr_task(rq);
4574	if (on_rq) {
4575	enqueue_task(rq, p, oldprio < prio ? ENQUEUE_HEAD : 0);
4576
4577	check_class_changed(rq, p, prev_class, oldprio, running);
4578	}
4579	task_rq_unlock(rq, &flags);
4580	}
4581
4582	#endif
4583
4584	void set_user_nice(struct task_struct *p, long nice)
4585	{
4586	int old_prio, delta, on_rq;
4587	unsigned long flags;
4588	struct rq *rq;
4589
4590	if (TASK_NICE(p) == nice \|\| nice < -20 \|\| nice > 19)
4591	return;
4592	/*
4593	* We have to be careful, if called from sys_setpriority(),
4594	* the task might be in the middle of scheduling on another CPU.
4595	*/
4596	rq = task_rq_lock(p, &flags);
4597	/*
4598	* The RT priorities are set via sched_setscheduler(), but we still
4599	* allow the 'normal' nice value to be set - but as expected
4600	* it wont have any effect on scheduling until the task is
4601	* SCHED_FIFO/SCHED_RR:
4602	*/
4603	if (task_has_rt_policy(p)) {
4604	p->static_prio = NICE_TO_PRIO(nice);
4605	goto out_unlock;
4606	}
4607	on_rq = p->se.on_rq;
4608	if (on_rq)
4609	dequeue_task(rq, p, 0);
4610
4611	p->static_prio = NICE_TO_PRIO(nice);
4612	set_load_weight(p);
4613	old_prio = p->prio;
4614	p->prio = effective_prio(p);
4615	delta = p->prio - old_prio;
4616
4617	if (on_rq) {
4618	enqueue_task(rq, p, 0);
4619	/*
4620	* If the task increased its priority or is running and
4621	* lowered its priority, then reschedule its CPU:
4622	*/
4623	if (delta < 0 \|\| (delta > 0 && task_running(rq, p)))
4624	resched_task(rq->curr);
4625	}
4626	out_unlock:
4627	task_rq_unlock(rq, &flags);
4628	}
4629	EXPORT_SYMBOL(set_user_nice);
4630
4631	/*
4632	* can_nice - check if a task can reduce its nice value
4633	* @p: task
4634	* @nice: nice value
4635	*/
4636	int can_nice(const struct task_struct *p, const int nice)
4637	{
4638	/* convert nice value [19,-20] to rlimit style value [1,40] */
4639	int nice_rlim = 20 - nice;
4640
4641	return (nice_rlim <= task_rlimit(p, RLIMIT_NICE) \|\|
4642	capable(CAP_SYS_NICE));
4643	}
4644
4645	#ifdef __ARCH_WANT_SYS_NICE
4646
4647	/*
4648	* sys_nice - change the priority of the current process.
4649	* @increment: priority increment
4650	*
4651	* sys_setpriority is a more generic, but much slower function that
4652	* does similar things.
4653	*/
4654	SYSCALL_DEFINE1(nice, int, increment)
4655	{
4656	long nice, retval;
4657
4658	/*
4659	* Setpriority might change our priority at the same moment.
4660	* We don't have to worry. Conceptually one call occurs first
4661	* and we have a single winner.
4662	*/
4663	if (increment < -40)
4664	increment = -40;
4665	if (increment > 40)
4666	increment = 40;
4667
4668	nice = TASK_NICE(current) + increment;
4669	if (nice < -20)
4670	nice = -20;
4671	if (nice > 19)
4672	nice = 19;
4673
4674	if (increment < 0 && !can_nice(current, nice))
4675	return -EPERM;
4676
4677	retval = security_task_setnice(current, nice);
4678	if (retval)
4679	return retval;
4680
4681	set_user_nice(current, nice);
4682	return 0;
4683	}
4684
4685	#endif
4686
4687	/**
4688	* task_prio - return the priority value of a given task.
4689	* @p: the task in question.
4690	*
4691	* This is the priority value as seen by users in /proc.
4692	* RT tasks are offset by -200. Normal tasks are centered
4693	* around 0, value goes from -16 to +15.
4694	*/
4695	int task_prio(const struct task_struct *p)
4696	{
4697	return p->prio - MAX_RT_PRIO;
4698	}
4699
4700	/**
4701	* task_nice - return the nice value of a given task.
4702	* @p: the task in question.
4703	*/
4704	int task_nice(const struct task_struct *p)
4705	{
4706	return TASK_NICE(p);
4707	}
4708	EXPORT_SYMBOL(task_nice);
4709
4710	/**
4711	* idle_cpu - is a given cpu idle currently?
4712	* @cpu: the processor in question.
4713	*/
4714	int idle_cpu(int cpu)
4715	{
4716	return cpu_curr(cpu) == cpu_rq(cpu)->idle;
4717	}
4718
4719	/**
4720	* idle_task - return the idle task for a given cpu.
4721	* @cpu: the processor in question.
4722	*/
4723	struct task_struct *idle_task(int cpu)
4724	{
4725	return cpu_rq(cpu)->idle;
4726	}
4727
4728	/**
4729	* find_process_by_pid - find a process with a matching PID value.
4730	* @pid: the pid in question.
4731	*/
4732	static struct task_struct *find_process_by_pid(pid_t pid)
4733	{
4734	return pid ? find_task_by_vpid(pid) : current;
4735	}
4736
4737	/* Actually do priority change: must hold rq lock. */
4738	static void
4739	__setscheduler(struct rq rq, struct task_struct p, int policy, int prio)
4740	{
4741	BUG_ON(p->se.on_rq);
4742
4743	p->policy = policy;
4744	p->rt_priority = prio;
4745	p->normal_prio = normal_prio(p);
4746	/* we are holding p->pi_lock already */
4747	p->prio = rt_mutex_getprio(p);
4748	if (rt_prio(p->prio))
4749	p->sched_class = &rt_sched_class;
4750	else
4751	p->sched_class = &fair_sched_class;
4752	set_load_weight(p);
4753	}
4754
4755	/*
4756	* check the target process has a UID that matches the current process's
4757	*/
4758	static bool check_same_owner(struct task_struct *p)
4759	{
4760	const struct cred cred = current_cred(), pcred;
4761	bool match;
4762
4763	rcu_read_lock();
4764	pcred = __task_cred(p);
4765	match = (cred->euid == pcred->euid \|\|
4766	cred->euid == pcred->uid);
4767	rcu_read_unlock();
4768	return match;
4769	}
4770
4771	static int __sched_setscheduler(struct task_struct *p, int policy,
4772	const struct sched_param *param, bool user)
4773	{
4774	int retval, oldprio, oldpolicy = -1, on_rq, running;
4775	unsigned long flags;
4776	const struct sched_class *prev_class;
4777	struct rq *rq;
4778	int reset_on_fork;
4779
4780	/* may grab non-irq protected spin_locks */
4781	BUG_ON(in_interrupt());
4782	recheck:
4783	/* double check policy once rq lock held */
4784	if (policy < 0) {
4785	reset_on_fork = p->sched_reset_on_fork;
4786	policy = oldpolicy = p->policy;
4787	} else {
4788	reset_on_fork = !!(policy & SCHED_RESET_ON_FORK);
4789	policy &= ~SCHED_RESET_ON_FORK;
4790
4791	if (policy != SCHED_FIFO && policy != SCHED_RR &&
4792	policy != SCHED_NORMAL && policy != SCHED_BATCH &&
4793	policy != SCHED_IDLE)
4794	return -EINVAL;
4795	}
4796
4797	/*
4798	* Valid priorities for SCHED_FIFO and SCHED_RR are
4799	* 1..MAX_USER_RT_PRIO-1, valid priority for SCHED_NORMAL,
4800	* SCHED_BATCH and SCHED_IDLE is 0.
4801	*/
4802	if (param->sched_priority < 0 \|\|
4803	(p->mm && param->sched_priority > MAX_USER_RT_PRIO-1) \|\|
4804	(!p->mm && param->sched_priority > MAX_RT_PRIO-1))
4805	return -EINVAL;
4806	if (rt_policy(policy) != (param->sched_priority != 0))
4807	return -EINVAL;
4808
4809	/*
4810	* Allow unprivileged RT tasks to decrease priority:
4811	*/
4812	if (user && !capable(CAP_SYS_NICE)) {
4813	if (rt_policy(policy)) {
4814	unsigned long rlim_rtprio =
4815	task_rlimit(p, RLIMIT_RTPRIO);
4816
4817	/* can't set/change the rt policy */
4818	if (policy != p->policy && !rlim_rtprio)
4819	return -EPERM;
4820
4821	/* can't increase priority */
4822	if (param->sched_priority > p->rt_priority &&
4823	param->sched_priority > rlim_rtprio)
4824	return -EPERM;
4825	}
4826	/*
4827	* Like positive nice levels, dont allow tasks to
4828	* move out of SCHED_IDLE either:
4829	*/
4830	if (p->policy == SCHED_IDLE && policy != SCHED_IDLE)
4831	return -EPERM;
4832
4833	/* can't change other user's priorities */
4834	if (!check_same_owner(p))
4835	return -EPERM;
4836
4837	/* Normal users shall not reset the sched_reset_on_fork flag */
4838	if (p->sched_reset_on_fork && !reset_on_fork)
4839	return -EPERM;
4840	}
4841
4842	if (user) {
4843	retval = security_task_setscheduler(p);
4844	if (retval)
4845	return retval;
4846	}
4847
4848	/*
4849	* make sure no PI-waiters arrive (or leave) while we are
4850	* changing the priority of the task:
4851	*/
4852	raw_spin_lock_irqsave(&p->pi_lock, flags);
4853	/*
4854	* To be able to change p->policy safely, the apropriate
4855	* runqueue lock must be held.
4856	*/
4857	rq = __task_rq_lock(p);
4858
4859	/*
4860	* Changing the policy of the stop threads its a very bad idea
4861	*/
4862	if (p == rq->stop) {
4863	__task_rq_unlock(rq);
4864	raw_spin_unlock_irqrestore(&p->pi_lock, flags);
4865	return -EINVAL;
4866	}
4867
4868	#ifdef CONFIG_RT_GROUP_SCHED
4869	if (user) {
4870	/*
4871	* Do not allow realtime tasks into groups that have no runtime
4872	* assigned.
4873	*/
4874	if (rt_bandwidth_enabled() && rt_policy(policy) &&
4875	task_group(p)->rt_bandwidth.rt_runtime == 0 &&
4876	!task_group_is_autogroup(task_group(p))) {
4877	__task_rq_unlock(rq);
4878	raw_spin_unlock_irqrestore(&p->pi_lock, flags);
4879	return -EPERM;
4880	}
4881	}
4882	#endif
4883
4884	/* recheck policy now with rq lock held */
4885	if (unlikely(oldpolicy != -1 && oldpolicy != p->policy)) {
4886	policy = oldpolicy = -1;
4887	__task_rq_unlock(rq);
4888	raw_spin_unlock_irqrestore(&p->pi_lock, flags);
4889	goto recheck;
4890	}
4891	on_rq = p->se.on_rq;
4892	running = task_current(rq, p);
4893	if (on_rq)
4894	deactivate_task(rq, p, 0);
4895	if (running)
4896	p->sched_class->put_prev_task(rq, p);
4897
4898	p->sched_reset_on_fork = reset_on_fork;
4899
4900	oldprio = p->prio;
4901	prev_class = p->sched_class;
4902	__setscheduler(rq, p, policy, param->sched_priority);
4903
4904	if (running)
4905	p->sched_class->set_curr_task(rq);
4906	if (on_rq) {
4907	activate_task(rq, p, 0);
4908
4909	check_class_changed(rq, p, prev_class, oldprio, running);
4910	}
4911	__task_rq_unlock(rq);
4912	raw_spin_unlock_irqrestore(&p->pi_lock, flags);
4913
4914	rt_mutex_adjust_pi(p);
4915
4916	return 0;
4917	}
4918
4919	/**
4920	* sched_setscheduler - change the scheduling policy and/or RT priority of a thread.
4921	* @p: the task in question.
4922	* @policy: new policy.
4923	* @param: structure containing the new RT priority.
4924	*
4925	* NOTE that the task may be already dead.
4926	*/
4927	int sched_setscheduler(struct task_struct *p, int policy,
4928	const struct sched_param *param)
4929	{
4930	return __sched_setscheduler(p, policy, param, true);
4931	}
4932	EXPORT_SYMBOL_GPL(sched_setscheduler);
4933
4934	/**
4935	* sched_setscheduler_nocheck - change the scheduling policy and/or RT priority of a thread from kernelspace.
4936	* @p: the task in question.
4937	* @policy: new policy.
4938	* @param: structure containing the new RT priority.
4939	*
4940	* Just like sched_setscheduler, only don't bother checking if the
4941	* current context has permission. For example, this is needed in
4942	* stop_machine(): we create temporary high priority worker threads,
4943	* but our caller might not have that capability.
4944	*/
4945	int sched_setscheduler_nocheck(struct task_struct *p, int policy,
4946	const struct sched_param *param)
4947	{
4948	return __sched_setscheduler(p, policy, param, false);
4949	}
4950
4951	static int
4952	do_sched_setscheduler(pid_t pid, int policy, struct sched_param __user *param)
4953	{
4954	struct sched_param lparam;
4955	struct task_struct *p;
4956	int retval;
4957
4958	if (!param \|\| pid < 0)
4959	return -EINVAL;
4960	if (copy_from_user(&lparam, param, sizeof(struct sched_param)))
4961	return -EFAULT;
4962
4963	rcu_read_lock();
4964	retval = -ESRCH;
4965	p = find_process_by_pid(pid);
4966	if (p != NULL)
4967	retval = sched_setscheduler(p, policy, &lparam);
4968	rcu_read_unlock();
4969
4970	return retval;
4971	}
4972
4973	/**
4974	* sys_sched_setscheduler - set/change the scheduler policy and RT priority
4975	* @pid: the pid in question.
4976	* @policy: new policy.
4977	* @param: structure containing the new RT priority.
4978	*/
4979	SYSCALL_DEFINE3(sched_setscheduler, pid_t, pid, int, policy,
4980	struct sched_param __user *, param)
4981	{
4982	/* negative values for policy are not valid */
4983	if (policy < 0)
4984	return -EINVAL;
4985
4986	return do_sched_setscheduler(pid, policy, param);
4987	}
4988
4989	/**
4990	* sys_sched_setparam - set/change the RT priority of a thread
4991	* @pid: the pid in question.
4992	* @param: structure containing the new RT priority.
4993	*/
4994	SYSCALL_DEFINE2(sched_setparam, pid_t, pid, struct sched_param __user *, param)
4995	{
4996	return do_sched_setscheduler(pid, -1, param);
4997	}
4998
4999	/**
5000	* sys_sched_getscheduler - get the policy (scheduling class) of a thread
5001	* @pid: the pid in question.
5002	*/
5003	SYSCALL_DEFINE1(sched_getscheduler, pid_t, pid)
5004	{
5005	struct task_struct *p;
5006	int retval;
5007
5008	if (pid < 0)
5009	return -EINVAL;
5010
5011	retval = -ESRCH;
5012	rcu_read_lock();
5013	p = find_process_by_pid(pid);
5014	if (p) {
5015	retval = security_task_getscheduler(p);
5016	if (!retval)
5017	retval = p->policy
5018	\| (p->sched_reset_on_fork ? SCHED_RESET_ON_FORK : 0);
5019	}
5020	rcu_read_unlock();
5021	return retval;
5022	}
5023
5024	/**
5025	* sys_sched_getparam - get the RT priority of a thread
5026	* @pid: the pid in question.
5027	* @param: structure containing the RT priority.
5028	*/
5029	SYSCALL_DEFINE2(sched_getparam, pid_t, pid, struct sched_param __user *, param)
5030	{
5031	struct sched_param lp;
5032	struct task_struct *p;
5033	int retval;
5034
5035	if (!param \|\| pid < 0)
5036	return -EINVAL;
5037
5038	rcu_read_lock();
5039	p = find_process_by_pid(pid);
5040	retval = -ESRCH;
5041	if (!p)
5042	goto out_unlock;
5043
5044	retval = security_task_getscheduler(p);
5045	if (retval)
5046	goto out_unlock;
5047
5048	lp.sched_priority = p->rt_priority;
5049	rcu_read_unlock();
5050
5051	/*
5052	* This one might sleep, we cannot do it with a spinlock held ...
5053	*/
5054	retval = copy_to_user(param, &lp, sizeof(*param)) ? -EFAULT : 0;
5055
5056	return retval;
5057
5058	out_unlock:
5059	rcu_read_unlock();
5060	return retval;
5061	}
5062
5063	long sched_setaffinity(pid_t pid, const struct cpumask *in_mask)
5064	{
5065	cpumask_var_t cpus_allowed, new_mask;
5066	struct task_struct *p;
5067	int retval;
5068
5069	get_online_cpus();
5070	rcu_read_lock();
5071
5072	p = find_process_by_pid(pid);
5073	if (!p) {
5074	rcu_read_unlock();
5075	put_online_cpus();
5076	return -ESRCH;
5077	}
5078
5079	/* Prevent p going away */
5080	get_task_struct(p);
5081	rcu_read_unlock();
5082
5083	if (!alloc_cpumask_var(&cpus_allowed, GFP_KERNEL)) {
5084	retval = -ENOMEM;
5085	goto out_put_task;
5086	}
5087	if (!alloc_cpumask_var(&new_mask, GFP_KERNEL)) {
5088	retval = -ENOMEM;
5089	goto out_free_cpus_allowed;
5090	}
5091	retval = -EPERM;
5092	if (!check_same_owner(p) && !capable(CAP_SYS_NICE))
5093	goto out_unlock;
5094
5095	retval = security_task_setscheduler(p);
5096	if (retval)
5097	goto out_unlock;
5098
5099	cpuset_cpus_allowed(p, cpus_allowed);
5100	cpumask_and(new_mask, in_mask, cpus_allowed);
5101	again:
5102	retval = set_cpus_allowed_ptr(p, new_mask);
5103
5104	if (!retval) {
5105	cpuset_cpus_allowed(p, cpus_allowed);
5106	if (!cpumask_subset(new_mask, cpus_allowed)) {
5107	/*
5108	* We must have raced with a concurrent cpuset
5109	* update. Just reset the cpus_allowed to the
5110	* cpuset's cpus_allowed
5111	*/
5112	cpumask_copy(new_mask, cpus_allowed);
5113	goto again;
5114	}
5115	}
5116	out_unlock:
5117	free_cpumask_var(new_mask);
5118	out_free_cpus_allowed:
5119	free_cpumask_var(cpus_allowed);
5120	out_put_task:
5121	put_task_struct(p);
5122	put_online_cpus();
5123	return retval;
5124	}
5125
5126	static int get_user_cpu_mask(unsigned long __user *user_mask_ptr, unsigned len,
5127	struct cpumask *new_mask)
5128	{
5129	if (len < cpumask_size())
5130	cpumask_clear(new_mask);
5131	else if (len > cpumask_size())
5132	len = cpumask_size();
5133
5134	return copy_from_user(new_mask, user_mask_ptr, len) ? -EFAULT : 0;
5135	}
5136
5137	/**
5138	* sys_sched_setaffinity - set the cpu affinity of a process
5139	* @pid: pid of the process
5140	* @len: length in bytes of the bitmask pointed to by user_mask_ptr
5141	* @user_mask_ptr: user-space pointer to the new cpu mask
5142	*/
5143	SYSCALL_DEFINE3(sched_setaffinity, pid_t, pid, unsigned int, len,
5144	unsigned long __user *, user_mask_ptr)
5145	{
5146	cpumask_var_t new_mask;
5147	int retval;
5148
5149	if (!alloc_cpumask_var(&new_mask, GFP_KERNEL))
5150	return -ENOMEM;
5151
5152	retval = get_user_cpu_mask(user_mask_ptr, len, new_mask);
5153	if (retval == 0)
5154	retval = sched_setaffinity(pid, new_mask);
5155	free_cpumask_var(new_mask);
5156	return retval;
5157	}
5158
5159	long sched_getaffinity(pid_t pid, struct cpumask *mask)
5160	{
5161	struct task_struct *p;
5162	unsigned long flags;
5163	struct rq *rq;
5164	int retval;
5165
5166	get_online_cpus();
5167	rcu_read_lock();
5168
5169	retval = -ESRCH;
5170	p = find_process_by_pid(pid);
5171	if (!p)
5172	goto out_unlock;
5173
5174	retval = security_task_getscheduler(p);
5175	if (retval)
5176	goto out_unlock;
5177
5178	rq = task_rq_lock(p, &flags);
5179	cpumask_and(mask, &p->cpus_allowed, cpu_online_mask);
5180	task_rq_unlock(rq, &flags);
5181
5182	out_unlock:
5183	rcu_read_unlock();
5184	put_online_cpus();
5185
5186	return retval;
5187	}
5188
5189	/**
5190	* sys_sched_getaffinity - get the cpu affinity of a process
5191	* @pid: pid of the process
5192	* @len: length in bytes of the bitmask pointed to by user_mask_ptr
5193	* @user_mask_ptr: user-space pointer to hold the current cpu mask
5194	*/
5195	SYSCALL_DEFINE3(sched_getaffinity, pid_t, pid, unsigned int, len,
5196	unsigned long __user *, user_mask_ptr)
5197	{
5198	int ret;
5199	cpumask_var_t mask;
5200
5201	if ((len * BITS_PER_BYTE) < nr_cpu_ids)
5202	return -EINVAL;
5203	if (len & (sizeof(unsigned long)-1))
5204	return -EINVAL;
5205
5206	if (!alloc_cpumask_var(&mask, GFP_KERNEL))
5207	return -ENOMEM;
5208
5209	ret = sched_getaffinity(pid, mask);
5210	if (ret == 0) {
5211	size_t retlen = min_t(size_t, len, cpumask_size());
5212
5213	if (copy_to_user(user_mask_ptr, mask, retlen))
5214	ret = -EFAULT;
5215	else
5216	ret = retlen;
5217	}
5218	free_cpumask_var(mask);
5219
5220	return ret;
5221	}
5222
5223	/**
5224	* sys_sched_yield - yield the current processor to other threads.
5225	*
5226	* This function yields the current CPU to other tasks. If there are no
5227	* other threads running on this CPU then this function will return.
5228	*/
5229	SYSCALL_DEFINE0(sched_yield)
5230	{
5231	struct rq *rq = this_rq_lock();
5232
5233	schedstat_inc(rq, yld_count);
5234	current->sched_class->yield_task(rq);
5235
5236	/*
5237	* Since we are going to call schedule() anyway, there's
5238	* no need to preempt or enable interrupts:
5239	*/
5240	__release(rq->lock);
5241	spin_release(&rq->lock.dep_map, 1, _THIS_IP_);
5242	do_raw_spin_unlock(&rq->lock);
5243	preempt_enable_no_resched();
5244
5245	schedule();
5246
5247	return 0;
5248	}
5249
5250	static inline int should_resched(void)
5251	{
5252	return need_resched() && !(preempt_count() & PREEMPT_ACTIVE);
5253	}
5254
5255	static void __cond_resched(void)
5256	{
5257	add_preempt_count(PREEMPT_ACTIVE);
5258	schedule();
5259	sub_preempt_count(PREEMPT_ACTIVE);
5260	}
5261
5262	int __sched _cond_resched(void)
5263	{
5264	if (should_resched()) {
5265	__cond_resched();
5266	return 1;
5267	}
5268	return 0;
5269	}
5270	EXPORT_SYMBOL(_cond_resched);
5271
5272	/*
5273	* __cond_resched_lock() - if a reschedule is pending, drop the given lock,
5274	* call schedule, and on return reacquire the lock.
5275	*
5276	* This works OK both with and without CONFIG_PREEMPT. We do strange low-level
5277	* operations here to prevent schedule() from being called twice (once via
5278	* spin_unlock(), once by hand).
5279	*/
5280	int __cond_resched_lock(spinlock_t *lock)
5281	{
5282	int resched = should_resched();
5283	int ret = 0;
5284
5285	lockdep_assert_held(lock);
5286
5287	if (spin_needbreak(lock) \|\| resched) {
5288	spin_unlock(lock);
5289	if (resched)
5290	__cond_resched();
5291	else
5292	cpu_relax();
5293	ret = 1;
5294	spin_lock(lock);
5295	}
5296	return ret;
5297	}
5298	EXPORT_SYMBOL(__cond_resched_lock);
5299
5300	int __sched __cond_resched_softirq(void)
5301	{
5302	BUG_ON(!in_softirq());
5303
5304	if (should_resched()) {
5305	local_bh_enable();
5306	__cond_resched();
5307	local_bh_disable();
5308	return 1;
5309	}
5310	return 0;
5311	}
5312	EXPORT_SYMBOL(__cond_resched_softirq);
5313
5314	/**
5315	* yield - yield the current processor to other threads.
5316	*
5317	* This is a shortcut for kernel-space yielding - it marks the
5318	* thread runnable and calls sys_sched_yield().
5319	*/
5320	void __sched yield(void)
5321	{
5322	set_current_state(TASK_RUNNING);
5323	sys_sched_yield();
5324	}
5325	EXPORT_SYMBOL(yield);
5326
5327	/*
5328	* This task is about to go to sleep on IO. Increment rq->nr_iowait so
5329	* that process accounting knows that this is a task in IO wait state.
5330	*/
5331	void __sched io_schedule(void)
5332	{
5333	struct rq *rq = raw_rq();
5334
5335	delayacct_blkio_start();
5336	atomic_inc(&rq->nr_iowait);
5337	current->in_iowait = 1;
5338	schedule();
5339	current->in_iowait = 0;
5340	atomic_dec(&rq->nr_iowait);
5341	delayacct_blkio_end();
5342	}
5343	EXPORT_SYMBOL(io_schedule);
5344
5345	long __sched io_schedule_timeout(long timeout)
5346	{
5347	struct rq *rq = raw_rq();
5348	long ret;
5349
5350	delayacct_blkio_start();
5351	atomic_inc(&rq->nr_iowait);
5352	current->in_iowait = 1;
5353	ret = schedule_timeout(timeout);
5354	current->in_iowait = 0;
5355	atomic_dec(&rq->nr_iowait);
5356	delayacct_blkio_end();
5357	return ret;
5358	}
5359
5360	/**
5361	* sys_sched_get_priority_max - return maximum RT priority.
5362	* @policy: scheduling class.
5363	*
5364	* this syscall returns the maximum rt_priority that can be used
5365	* by a given scheduling class.
5366	*/
5367	SYSCALL_DEFINE1(sched_get_priority_max, int, policy)
5368	{
5369	int ret = -EINVAL;
5370
5371	switch (policy) {
5372	case SCHED_FIFO:
5373	case SCHED_RR:
5374	ret = MAX_USER_RT_PRIO-1;
5375	break;
5376	case SCHED_NORMAL:
5377	case SCHED_BATCH:
5378	case SCHED_IDLE:
5379	ret = 0;
5380	break;
5381	}
5382	return ret;
5383	}
5384
5385	/**
5386	* sys_sched_get_priority_min - return minimum RT priority.
5387	* @policy: scheduling class.
5388	*
5389	* this syscall returns the minimum rt_priority that can be used
5390	* by a given scheduling class.
5391	*/
5392	SYSCALL_DEFINE1(sched_get_priority_min, int, policy)
5393	{
5394	int ret = -EINVAL;
5395
5396	switch (policy) {
5397	case SCHED_FIFO:
5398	case SCHED_RR:
5399	ret = 1;
5400	break;
5401	case SCHED_NORMAL:
5402	case SCHED_BATCH:
5403	case SCHED_IDLE:
5404	ret = 0;
5405	}
5406	return ret;
5407	}
5408
5409	/**
5410	* sys_sched_rr_get_interval - return the default timeslice of a process.
5411	* @pid: pid of the process.
5412	* @interval: userspace pointer to the timeslice value.
5413	*
5414	* this syscall writes the default timeslice value of a given process
5415	* into the user-space timespec buffer. A value of '0' means infinity.
5416	*/
5417	SYSCALL_DEFINE2(sched_rr_get_interval, pid_t, pid,
5418	struct timespec __user *, interval)
5419	{
5420	struct task_struct *p;
5421	unsigned int time_slice;
5422	unsigned long flags;
5423	struct rq *rq;
5424	int retval;
5425	struct timespec t;
5426
5427	if (pid < 0)
5428	return -EINVAL;
5429
5430	retval = -ESRCH;
5431	rcu_read_lock();
5432	p = find_process_by_pid(pid);
5433	if (!p)
5434	goto out_unlock;
5435
5436	retval = security_task_getscheduler(p);
5437	if (retval)
5438	goto out_unlock;
5439
5440	rq = task_rq_lock(p, &flags);
5441	time_slice = p->sched_class->get_rr_interval(rq, p);
5442	task_rq_unlock(rq, &flags);
5443
5444	rcu_read_unlock();
5445	jiffies_to_timespec(time_slice, &t);
5446	retval = copy_to_user(interval, &t, sizeof(t)) ? -EFAULT : 0;
5447	return retval;
5448
5449	out_unlock:
5450	rcu_read_unlock();
5451	return retval;
5452	}
5453
5454	static const char stat_nam[] = TASK_STATE_TO_CHAR_STR;
5455
5456	void sched_show_task(struct task_struct *p)
5457	{
5458	unsigned long free = 0;
5459	unsigned state;
5460
5461	state = p->state ? __ffs(p->state) + 1 : 0;
5462	printk(KERN_INFO "%-15.15s %c", p->comm,
5463	state < sizeof(stat_nam) - 1 ? stat_nam[state] : '?');
5464	#if BITS_PER_LONG == 32
5465	if (state == TASK_RUNNING)
5466	printk(KERN_CONT " running ");
5467	else
5468	printk(KERN_CONT " %08lx ", thread_saved_pc(p));
5469	#else
5470	if (state == TASK_RUNNING)
5471	printk(KERN_CONT " running task ");
5472	else
5473	printk(KERN_CONT " %016lx ", thread_saved_pc(p));
5474	#endif
5475	#ifdef CONFIG_DEBUG_STACK_USAGE
5476	free = stack_not_used(p);
5477	#endif
5478	printk(KERN_CONT "%5lu %5d %6d 0x%08lx\n", free,
5479	task_pid_nr(p), task_pid_nr(p->real_parent),
5480	(unsigned long)task_thread_info(p)->flags);
5481
5482	show_stack(p, NULL);
5483	}
5484
5485	void show_state_filter(unsigned long state_filter)
5486	{
5487	struct task_struct g, p;
5488
5489	#if BITS_PER_LONG == 32
5490	printk(KERN_INFO
5491	" task PC stack pid father\n");
5492	#else
5493	printk(KERN_INFO
5494	" task PC stack pid father\n");
5495	#endif
5496	read_lock(&tasklist_lock);
5497	do_each_thread(g, p) {
5498	/*
5499	* reset the NMI-timeout, listing all files on a slow
5500	* console might take alot of time:
5501	*/
5502	touch_nmi_watchdog();
5503	if (!state_filter \|\| (p->state & state_filter))
5504	sched_show_task(p);
5505	} while_each_thread(g, p);
5506
5507	touch_all_softlockup_watchdogs();
5508
5509	#ifdef CONFIG_SCHED_DEBUG
5510	sysrq_sched_debug_show();
5511	#endif
5512	read_unlock(&tasklist_lock);
5513	/*
5514	* Only show locks if all tasks are dumped:
5515	*/
5516	if (!state_filter)
5517	debug_show_all_locks();
5518	}
5519
5520	void __cpuinit init_idle_bootup_task(struct task_struct *idle)
5521	{
5522	idle->sched_class = &idle_sched_class;
5523	}
5524
5525	/**
5526	* init_idle - set up an idle thread for a given CPU
5527	* @idle: task in question
5528	* @cpu: cpu the idle task belongs to
5529	*
5530	* NOTE: this function does not set the idle thread's NEED_RESCHED
5531	* flag, to make booting more robust.
5532	*/
5533	void __cpuinit init_idle(struct task_struct *idle, int cpu)
5534	{
5535	struct rq *rq = cpu_rq(cpu);
5536	unsigned long flags;
5537
5538	raw_spin_lock_irqsave(&rq->lock, flags);
5539
5540	__sched_fork(idle);
5541	idle->state = TASK_RUNNING;
5542	idle->se.exec_start = sched_clock();
5543
5544	cpumask_copy(&idle->cpus_allowed, cpumask_of(cpu));
5545	/*
5546	* We're having a chicken and egg problem, even though we are
5547	* holding rq->lock, the cpu isn't yet set to this cpu so the
5548	* lockdep check in task_group() will fail.
5549	*
5550	* Similar case to sched_fork(). / Alternatively we could
5551	* use task_rq_lock() here and obtain the other rq->lock.
5552	*
5553	* Silence PROVE_RCU
5554	*/
5555	rcu_read_lock();
5556	__set_task_cpu(idle, cpu);
5557	rcu_read_unlock();
5558
5559	rq->curr = rq->idle = idle;
5560	#if defined(CONFIG_SMP) && defined(__ARCH_WANT_UNLOCKED_CTXSW)
5561	idle->oncpu = 1;
5562	#endif
5563	raw_spin_unlock_irqrestore(&rq->lock, flags);
5564
5565	/* Set the preempt count _outside_ the spinlocks! */
5566	#if defined(CONFIG_PREEMPT)
5567	task_thread_info(idle)->preempt_count = (idle->lock_depth >= 0);
5568	#else
5569	task_thread_info(idle)->preempt_count = 0;
5570	#endif
5571	/*
5572	* The idle tasks have their own, simple scheduling class:
5573	*/
5574	idle->sched_class = &idle_sched_class;
5575	ftrace_graph_init_task(idle);
5576	}
5577
5578	/*
5579	* In a system that switches off the HZ timer nohz_cpu_mask
5580	* indicates which cpus entered this state. This is used
5581	* in the rcu update to wait only for active cpus. For system
5582	* which do not switch off the HZ timer nohz_cpu_mask should
5583	* always be CPU_BITS_NONE.
5584	*/
5585	cpumask_var_t nohz_cpu_mask;
5586
5587	/*
5588	* Increase the granularity value when there are more CPUs,
5589	* because with more CPUs the 'effective latency' as visible
5590	* to users decreases. But the relationship is not linear,
5591	* so pick a second-best guess by going with the log2 of the
5592	* number of CPUs.
5593	*
5594	* This idea comes from the SD scheduler of Con Kolivas:
5595	*/
5596	static int get_update_sysctl_factor(void)
5597	{
5598	unsigned int cpus = min_t(int, num_online_cpus(), 8);
5599	unsigned int factor;
5600
5601	switch (sysctl_sched_tunable_scaling) {
5602	case SCHED_TUNABLESCALING_NONE:
5603	factor = 1;
5604	break;
5605	case SCHED_TUNABLESCALING_LINEAR:
5606	factor = cpus;
5607	break;
5608	case SCHED_TUNABLESCALING_LOG:
5609	default:
5610	factor = 1 + ilog2(cpus);
5611	break;
5612	}
5613
5614	return factor;
5615	}
5616
5617	static void update_sysctl(void)
5618	{
5619	unsigned int factor = get_update_sysctl_factor();
5620
5621	#define SET_SYSCTL(name) \
5622	(sysctl_##name = (factor) * normalized_sysctl_##name)
5623	SET_SYSCTL(sched_min_granularity);
5624	SET_SYSCTL(sched_latency);
5625	SET_SYSCTL(sched_wakeup_granularity);
5626	#undef SET_SYSCTL
5627	}
5628
5629	static inline void sched_init_granularity(void)
5630	{
5631	update_sysctl();
5632	}
5633
5634	#ifdef CONFIG_SMP
5635	/*
5636	* This is how migration works:
5637	*
5638	* 1) we invoke migration_cpu_stop() on the target CPU using
5639	* stop_one_cpu().
5640	* 2) stopper starts to run (implicitly forcing the migrated thread
5641	* off the CPU)
5642	* 3) it checks whether the migrated task is still in the wrong runqueue.
5643	* 4) if it's in the wrong runqueue then the migration thread removes
5644	* it and puts it into the right queue.
5645	* 5) stopper completes and stop_one_cpu() returns and the migration
5646	* is done.
5647	*/
5648
5649	/*
5650	* Change a given task's CPU affinity. Migrate the thread to a
5651	* proper CPU and schedule it away if the CPU it's executing on
5652	* is removed from the allowed bitmask.
5653	*
5654	* NOTE: the caller must have a valid reference to the task, the
5655	* task must not exit() & deallocate itself prematurely. The
5656	* call is not atomic; no spinlocks may be held.
5657	*/
5658	int set_cpus_allowed_ptr(struct task_struct p, const struct cpumask new_mask)
5659	{
5660	unsigned long flags;
5661	struct rq *rq;
5662	unsigned int dest_cpu;
5663	int ret = 0;
5664
5665	/*
5666	* Serialize against TASK_WAKING so that ttwu() and wunt() can
5667	* drop the rq->lock and still rely on ->cpus_allowed.
5668	*/
5669	again:
5670	while (task_is_waking(p))
5671	cpu_relax();
5672	rq = task_rq_lock(p, &flags);
5673	if (task_is_waking(p)) {
5674	task_rq_unlock(rq, &flags);
5675	goto again;
5676	}
5677
5678	if (!cpumask_intersects(new_mask, cpu_active_mask)) {
5679	ret = -EINVAL;
5680	goto out;
5681	}
5682
5683	if (unlikely((p->flags & PF_THREAD_BOUND) && p != current &&
5684	!cpumask_equal(&p->cpus_allowed, new_mask))) {
5685	ret = -EINVAL;
5686	goto out;
5687	}
5688
5689	if (p->sched_class->set_cpus_allowed)
5690	p->sched_class->set_cpus_allowed(p, new_mask);
5691	else {
5692	cpumask_copy(&p->cpus_allowed, new_mask);
5693	p->rt.nr_cpus_allowed = cpumask_weight(new_mask);
5694	}
5695
5696	/* Can the task run on the task's current CPU? If so, we're done */
5697	if (cpumask_test_cpu(task_cpu(p), new_mask))
5698	goto out;
5699
5700	dest_cpu = cpumask_any_and(cpu_active_mask, new_mask);
5701	if (migrate_task(p, rq)) {
5702	struct migration_arg arg = { p, dest_cpu };
5703	/* Need help from migration thread: drop lock and wait. */
5704	task_rq_unlock(rq, &flags);
5705	stop_one_cpu(cpu_of(rq), migration_cpu_stop, &arg);
5706	tlb_migrate_finish(p->mm);
5707	return 0;
5708	}
5709	out:
5710	task_rq_unlock(rq, &flags);
5711
5712	return ret;
5713	}
5714	EXPORT_SYMBOL_GPL(set_cpus_allowed_ptr);
5715
5716	/*
5717	* Move (not current) task off this cpu, onto dest cpu. We're doing
5718	* this because either it can't run here any more (set_cpus_allowed()
5719	* away from this CPU, or CPU going down), or because we're
5720	* attempting to rebalance this task on exec (sched_exec).
5721	*
5722	* So we race with normal scheduler movements, but that's OK, as long
5723	* as the task is no longer on this CPU.
5724	*
5725	* Returns non-zero if task was successfully migrated.
5726	*/
5727	static int __migrate_task(struct task_struct *p, int src_cpu, int dest_cpu)
5728	{
5729	struct rq rq_dest, rq_src;
5730	int ret = 0;
5731
5732	if (unlikely(!cpu_active(dest_cpu)))
5733	return ret;
5734
5735	rq_src = cpu_rq(src_cpu);
5736	rq_dest = cpu_rq(dest_cpu);
5737
5738	double_rq_lock(rq_src, rq_dest);
5739	/* Already moved. */
5740	if (task_cpu(p) != src_cpu)
5741	goto done;
5742	/* Affinity changed (again). */
5743	if (!cpumask_test_cpu(dest_cpu, &p->cpus_allowed))
5744	goto fail;
5745
5746	/*
5747	* If we're not on a rq, the next wake-up will ensure we're
5748	* placed properly.
5749	*/
5750	if (p->se.on_rq) {
5751	deactivate_task(rq_src, p, 0);
5752	set_task_cpu(p, dest_cpu);
5753	activate_task(rq_dest, p, 0);
5754	check_preempt_curr(rq_dest, p, 0);
5755	}
5756	done:
5757	ret = 1;
5758	fail:
5759	double_rq_unlock(rq_src, rq_dest);
5760	return ret;
5761	}
5762
5763	/*
5764	* migration_cpu_stop - this will be executed by a highprio stopper thread
5765	* and performs thread migration by bumping thread off CPU then
5766	* 'pushing' onto another runqueue.
5767	*/
5768	static int migration_cpu_stop(void *data)
5769	{
5770	struct migration_arg *arg = data;
5771
5772	/*
5773	* The original target cpu might have gone down and we might
5774	* be on another cpu but it doesn't matter.
5775	*/
5776	local_irq_disable();
5777	__migrate_task(arg->task, raw_smp_processor_id(), arg->dest_cpu);
5778	local_irq_enable();
5779	return 0;
5780	}
5781
5782	#ifdef CONFIG_HOTPLUG_CPU
5783
5784	/*
5785	* Ensures that the idle task is using init_mm right before its cpu goes
5786	* offline.
5787	*/
5788	void idle_task_exit(void)
5789	{
5790	struct mm_struct *mm = current->active_mm;
5791
5792	BUG_ON(cpu_online(smp_processor_id()));
5793
5794	if (mm != &init_mm)
5795	switch_mm(mm, &init_mm, current);
5796	mmdrop(mm);
5797	}
5798
5799	/*
5800	* While a dead CPU has no uninterruptible tasks queued at this point,
5801	* it might still have a nonzero ->nr_uninterruptible counter, because
5802	* for performance reasons the counter is not stricly tracking tasks to
5803	* their home CPUs. So we just add the counter to another CPU's counter,
5804	* to keep the global sum constant after CPU-down:
5805	*/
5806	static void migrate_nr_uninterruptible(struct rq *rq_src)
5807	{
5808	struct rq *rq_dest = cpu_rq(cpumask_any(cpu_active_mask));
5809
5810	rq_dest->nr_uninterruptible += rq_src->nr_uninterruptible;
5811	rq_src->nr_uninterruptible = 0;
5812	}
5813
5814	/*
5815	* remove the tasks which were accounted by rq from calc_load_tasks.
5816	*/
5817	static void calc_global_load_remove(struct rq *rq)
5818	{
5819	atomic_long_sub(rq->calc_load_active, &calc_load_tasks);
5820	rq->calc_load_active = 0;
5821	}
5822
5823	/*
5824	* Migrate all tasks from the rq, sleeping tasks will be migrated by
5825	* try_to_wake_up()->select_task_rq().
5826	*
5827	* Called with rq->lock held even though we'er in stop_machine() and
5828	* there's no concurrency possible, we hold the required locks anyway
5829	* because of lock validation efforts.
5830	*/
5831	static void migrate_tasks(unsigned int dead_cpu)
5832	{
5833	struct rq *rq = cpu_rq(dead_cpu);
5834	struct task_struct next, stop = rq->stop;
5835	int dest_cpu;
5836
5837	/*
5838	* Fudge the rq selection such that the below task selection loop
5839	* doesn't get stuck on the currently eligible stop task.
5840	*
5841	* We're currently inside stop_machine() and the rq is either stuck
5842	* in the stop_machine_cpu_stop() loop, or we're executing this code,
5843	* either way we should never end up calling schedule() until we're
5844	* done here.
5845	*/
5846	rq->stop = NULL;
5847
5848	for ( ; ; ) {
5849	/*
5850	* There's this thread running, bail when that's the only
5851	* remaining thread.
5852	*/
5853	if (rq->nr_running == 1)
5854	break;
5855
5856	next = pick_next_task(rq);
5857	BUG_ON(!next);
5858	next->sched_class->put_prev_task(rq, next);
5859
5860	/* Find suitable destination for @next, with force if needed. */
5861	dest_cpu = select_fallback_rq(dead_cpu, next);
5862	raw_spin_unlock(&rq->lock);
5863
5864	__migrate_task(next, dead_cpu, dest_cpu);
5865
5866	raw_spin_lock(&rq->lock);
5867	}
5868
5869	rq->stop = stop;
5870	}
5871
5872	#endif /* CONFIG_HOTPLUG_CPU */
5873
5874	#if defined(CONFIG_SCHED_DEBUG) && defined(CONFIG_SYSCTL)
5875
5876	static struct ctl_table sd_ctl_dir[] = {
5877	{
5878	.procname = "sched_domain",
5879	.mode = 0555,
5880	},
5881	{}
5882	};
5883
5884	static struct ctl_table sd_ctl_root[] = {
5885	{
5886	.procname = "kernel",
5887	.mode = 0555,
5888	.child = sd_ctl_dir,
5889	},
5890	{}
5891	};
5892
5893	static struct ctl_table *sd_alloc_ctl_entry(int n)
5894	{
5895	struct ctl_table *entry =
5896	kcalloc(n, sizeof(struct ctl_table), GFP_KERNEL);
5897
5898	return entry;
5899	}
5900
5901	static void sd_free_ctl_entry(struct ctl_table **tablep)
5902	{
5903	struct ctl_table *entry;
5904
5905	/*
5906	* In the intermediate directories, both the child directory and
5907	* procname are dynamically allocated and could fail but the mode
5908	* will always be set. In the lowest directory the names are
5909	* static strings and all have proc handlers.
5910	*/
5911	for (entry = *tablep; entry->mode; entry++) {
5912	if (entry->child)
5913	sd_free_ctl_entry(&entry->child);
5914	if (entry->proc_handler == NULL)
5915	kfree(entry->procname);
5916	}
5917
5918	kfree(*tablep);
5919	*tablep = NULL;
5920	}
5921
5922	static void
5923	set_table_entry(struct ctl_table *entry,
5924	const char procname, void data, int maxlen,
5925	mode_t mode, proc_handler *proc_handler)
5926	{
5927	entry->procname = procname;
5928	entry->data = data;
5929	entry->maxlen = maxlen;
5930	entry->mode = mode;
5931	entry->proc_handler = proc_handler;
5932	}
5933
5934	static struct ctl_table *
5935	sd_alloc_ctl_domain_table(struct sched_domain *sd)
5936	{
5937	struct ctl_table *table = sd_alloc_ctl_entry(13);
5938
5939	if (table == NULL)
5940	return NULL;
5941
5942	set_table_entry(&table[0], "min_interval", &sd->min_interval,
5943	sizeof(long), 0644, proc_doulongvec_minmax);
5944	set_table_entry(&table[1], "max_interval", &sd->max_interval,
5945	sizeof(long), 0644, proc_doulongvec_minmax);
5946	set_table_entry(&table[2], "busy_idx", &sd->busy_idx,
5947	sizeof(int), 0644, proc_dointvec_minmax);
5948	set_table_entry(&table[3], "idle_idx", &sd->idle_idx,
5949	sizeof(int), 0644, proc_dointvec_minmax);
5950	set_table_entry(&table[4], "newidle_idx", &sd->newidle_idx,
5951	sizeof(int), 0644, proc_dointvec_minmax);
5952	set_table_entry(&table[5], "wake_idx", &sd->wake_idx,
5953	sizeof(int), 0644, proc_dointvec_minmax);
5954	set_table_entry(&table[6], "forkexec_idx", &sd->forkexec_idx,
5955	sizeof(int), 0644, proc_dointvec_minmax);
5956	set_table_entry(&table[7], "busy_factor", &sd->busy_factor,
5957	sizeof(int), 0644, proc_dointvec_minmax);
5958	set_table_entry(&table[8], "imbalance_pct", &sd->imbalance_pct,
5959	sizeof(int), 0644, proc_dointvec_minmax);
5960	set_table_entry(&table[9], "cache_nice_tries",
5961	&sd->cache_nice_tries,
5962	sizeof(int), 0644, proc_dointvec_minmax);
5963	set_table_entry(&table[10], "flags", &sd->flags,
5964	sizeof(int), 0644, proc_dointvec_minmax);
5965	set_table_entry(&table[11], "name", sd->name,
5966	CORENAME_MAX_SIZE, 0444, proc_dostring);
5967	/* &table[12] is terminator */
5968
5969	return table;
5970	}
5971
5972	static ctl_table *sd_alloc_ctl_cpu_table(int cpu)
5973	{
5974	struct ctl_table entry, table;
5975	struct sched_domain *sd;
5976	int domain_num = 0, i;
5977	char buf[32];
5978
5979	for_each_domain(cpu, sd)
5980	domain_num++;
5981	entry = table = sd_alloc_ctl_entry(domain_num + 1);
5982	if (table == NULL)
5983	return NULL;
5984
5985	i = 0;
5986	for_each_domain(cpu, sd) {
5987	snprintf(buf, 32, "domain%d", i);
5988	entry->procname = kstrdup(buf, GFP_KERNEL);
5989	entry->mode = 0555;
5990	entry->child = sd_alloc_ctl_domain_table(sd);
5991	entry++;
5992	i++;
5993	}
5994	return table;
5995	}
5996
5997	static struct ctl_table_header *sd_sysctl_header;
5998	static void register_sched_domain_sysctl(void)
5999	{
6000	int i, cpu_num = num_possible_cpus();
6001	struct ctl_table *entry = sd_alloc_ctl_entry(cpu_num + 1);
6002	char buf[32];
6003
6004	WARN_ON(sd_ctl_dir[0].child);
6005	sd_ctl_dir[0].child = entry;
6006
6007	if (entry == NULL)
6008	return;
6009
6010	for_each_possible_cpu(i) {
6011	snprintf(buf, 32, "cpu%d", i);
6012	entry->procname = kstrdup(buf, GFP_KERNEL);
6013	entry->mode = 0555;
6014	entry->child = sd_alloc_ctl_cpu_table(i);
6015	entry++;
6016	}
6017
6018	WARN_ON(sd_sysctl_header);
6019	sd_sysctl_header = register_sysctl_table(sd_ctl_root);
6020	}
6021
6022	/* may be called multiple times per register */
6023	static void unregister_sched_domain_sysctl(void)
6024	{
6025	if (sd_sysctl_header)
6026	unregister_sysctl_table(sd_sysctl_header);
6027	sd_sysctl_header = NULL;
6028	if (sd_ctl_dir[0].child)
6029	sd_free_ctl_entry(&sd_ctl_dir[0].child);
6030	}
6031	#else
6032	static void register_sched_domain_sysctl(void)
6033	{
6034	}
6035	static void unregister_sched_domain_sysctl(void)
6036	{
6037	}
6038	#endif
6039
6040	static void set_rq_online(struct rq *rq)
6041	{
6042	if (!rq->online) {
6043	const struct sched_class *class;
6044
6045	cpumask_set_cpu(rq->cpu, rq->rd->online);
6046	rq->online = 1;
6047
6048	for_each_class(class) {
6049	if (class->rq_online)
6050	class->rq_online(rq);
6051	}
6052	}
6053	}
6054
6055	static void set_rq_offline(struct rq *rq)
6056	{
6057	if (rq->online) {
6058	const struct sched_class *class;
6059
6060	for_each_class(class) {
6061	if (class->rq_offline)
6062	class->rq_offline(rq);
6063	}
6064
6065	cpumask_clear_cpu(rq->cpu, rq->rd->online);
6066	rq->online = 0;
6067	}
6068	}
6069
6070	/*
6071	* migration_call - callback that gets triggered when a CPU is added.
6072	* Here we can start up the necessary migration thread for the new CPU.
6073	*/
6074	static int __cpuinit
6075	migration_call(struct notifier_block nfb, unsigned long action, void hcpu)
6076	{
6077	int cpu = (long)hcpu;
6078	unsigned long flags;
6079	struct rq *rq = cpu_rq(cpu);
6080
6081	switch (action & ~CPU_TASKS_FROZEN) {
6082
6083	case CPU_UP_PREPARE:
6084	rq->calc_load_update = calc_load_update;
6085	break;
6086
6087	case CPU_ONLINE:
6088	/* Update our root-domain */
6089	raw_spin_lock_irqsave(&rq->lock, flags);
6090	if (rq->rd) {
6091	BUG_ON(!cpumask_test_cpu(cpu, rq->rd->span));
6092
6093	set_rq_online(rq);
6094	}
6095	raw_spin_unlock_irqrestore(&rq->lock, flags);
6096	break;
6097
6098	#ifdef CONFIG_HOTPLUG_CPU
6099	case CPU_DYING:
6100	/* Update our root-domain */
6101	raw_spin_lock_irqsave(&rq->lock, flags);
6102	if (rq->rd) {
6103	BUG_ON(!cpumask_test_cpu(cpu, rq->rd->span));
6104	set_rq_offline(rq);
6105	}
6106	migrate_tasks(cpu);
6107	BUG_ON(rq->nr_running != 1); /* the migration thread */
6108	raw_spin_unlock_irqrestore(&rq->lock, flags);
6109
6110	migrate_nr_uninterruptible(rq);
6111	calc_global_load_remove(rq);
6112	break;
6113	#endif
6114	}
6115	return NOTIFY_OK;
6116	}
6117
6118	/*
6119	* Register at high priority so that task migration (migrate_all_tasks)
6120	* happens before everything else. This has to be lower priority than
6121	* the notifier in the perf_event subsystem, though.
6122	*/
6123	static struct notifier_block __cpuinitdata migration_notifier = {
6124	.notifier_call = migration_call,
6125	.priority = CPU_PRI_MIGRATION,
6126	};
6127
6128	static int __cpuinit sched_cpu_active(struct notifier_block *nfb,
6129	unsigned long action, void *hcpu)
6130	{
6131	switch (action & ~CPU_TASKS_FROZEN) {
6132	case CPU_ONLINE:
6133	case CPU_DOWN_FAILED:
6134	set_cpu_active((long)hcpu, true);
6135	return NOTIFY_OK;
6136	default:
6137	return NOTIFY_DONE;
6138	}
6139	}
6140
6141	static int __cpuinit sched_cpu_inactive(struct notifier_block *nfb,
6142	unsigned long action, void *hcpu)
6143	{
6144	switch (action & ~CPU_TASKS_FROZEN) {
6145	case CPU_DOWN_PREPARE:
6146	set_cpu_active((long)hcpu, false);
6147	return NOTIFY_OK;
6148	default:
6149	return NOTIFY_DONE;
6150	}
6151	}
6152
6153	static int __init migration_init(void)
6154	{
6155	void cpu = (void )(long)smp_processor_id();
6156	int err;
6157
6158	/* Initialize migration for the boot CPU */
6159	err = migration_call(&migration_notifier, CPU_UP_PREPARE, cpu);
6160	BUG_ON(err == NOTIFY_BAD);
6161	migration_call(&migration_notifier, CPU_ONLINE, cpu);
6162	register_cpu_notifier(&migration_notifier);
6163
6164	/* Register cpu active notifiers */
6165	cpu_notifier(sched_cpu_active, CPU_PRI_SCHED_ACTIVE);
6166	cpu_notifier(sched_cpu_inactive, CPU_PRI_SCHED_INACTIVE);
6167
6168	return 0;
6169	}
6170	early_initcall(migration_init);
6171	#endif
6172
6173	#ifdef CONFIG_SMP
6174
6175	#ifdef CONFIG_SCHED_DEBUG
6176
6177	static __read_mostly int sched_domain_debug_enabled;
6178
6179	static int __init sched_domain_debug_setup(char *str)
6180	{
6181	sched_domain_debug_enabled = 1;
6182
6183	return 0;
6184	}
6185	early_param("sched_debug", sched_domain_debug_setup);
6186
6187	static int sched_domain_debug_one(struct sched_domain *sd, int cpu, int level,
6188	struct cpumask *groupmask)
6189	{
6190	struct sched_group *group = sd->groups;
6191	char str[256];
6192
6193	cpulist_scnprintf(str, sizeof(str), sched_domain_span(sd));
6194	cpumask_clear(groupmask);
6195
6196	printk(KERN_DEBUG "%*s domain %d: ", level, "", level);
6197
6198	if (!(sd->flags & SD_LOAD_BALANCE)) {
6199	printk("does not load-balance\n");
6200	if (sd->parent)
6201	printk(KERN_ERR "ERROR: !SD_LOAD_BALANCE domain"
6202	" has parent");
6203	return -1;
6204	}
6205
6206	printk(KERN_CONT "span %s level %s\n", str, sd->name);
6207
6208	if (!cpumask_test_cpu(cpu, sched_domain_span(sd))) {
6209	printk(KERN_ERR "ERROR: domain->span does not contain "
6210	"CPU%d\n", cpu);
6211	}
6212	if (!cpumask_test_cpu(cpu, sched_group_cpus(group))) {
6213	printk(KERN_ERR "ERROR: domain->groups does not contain"
6214	" CPU%d\n", cpu);
6215	}
6216
6217	printk(KERN_DEBUG "%*s groups:", level + 1, "");
6218	do {
6219	if (!group) {
6220	printk("\n");
6221	printk(KERN_ERR "ERROR: group is NULL\n");
6222	break;
6223	}
6224
6225	if (!group->cpu_power) {
6226	printk(KERN_CONT "\n");
6227	printk(KERN_ERR "ERROR: domain->cpu_power not "
6228	"set\n");
6229	break;
6230	}
6231
6232	if (!cpumask_weight(sched_group_cpus(group))) {
6233	printk(KERN_CONT "\n");
6234	printk(KERN_ERR "ERROR: empty group\n");
6235	break;
6236	}
6237
6238	if (cpumask_intersects(groupmask, sched_group_cpus(group))) {
6239	printk(KERN_CONT "\n");
6240	printk(KERN_ERR "ERROR: repeated CPUs\n");
6241	break;
6242	}
6243
6244	cpumask_or(groupmask, groupmask, sched_group_cpus(group));
6245
6246	cpulist_scnprintf(str, sizeof(str), sched_group_cpus(group));
6247
6248	printk(KERN_CONT " %s", str);
6249	if (group->cpu_power != SCHED_LOAD_SCALE) {
6250	printk(KERN_CONT " (cpu_power = %d)",
6251	group->cpu_power);
6252	}
6253
6254	group = group->next;
6255	} while (group != sd->groups);
6256	printk(KERN_CONT "\n");
6257
6258	if (!cpumask_equal(sched_domain_span(sd), groupmask))
6259	printk(KERN_ERR "ERROR: groups don't span domain->span\n");
6260
6261	if (sd->parent &&
6262	!cpumask_subset(groupmask, sched_domain_span(sd->parent)))
6263	printk(KERN_ERR "ERROR: parent span is not a superset "
6264	"of domain->span\n");
6265	return 0;
6266	}
6267
6268	static void sched_domain_debug(struct sched_domain *sd, int cpu)
6269	{
6270	cpumask_var_t groupmask;
6271	int level = 0;
6272
6273	if (!sched_domain_debug_enabled)
6274	return;
6275
6276	if (!sd) {
6277	printk(KERN_DEBUG "CPU%d attaching NULL sched-domain.\n", cpu);
6278	return;
6279	}
6280
6281	printk(KERN_DEBUG "CPU%d attaching sched-domain:\n", cpu);
6282
6283	if (!alloc_cpumask_var(&groupmask, GFP_KERNEL)) {
6284	printk(KERN_DEBUG "Cannot load-balance (out of memory)\n");
6285	return;
6286	}
6287
6288	for (;;) {
6289	if (sched_domain_debug_one(sd, cpu, level, groupmask))
6290	break;
6291	level++;
6292	sd = sd->parent;
6293	if (!sd)
6294	break;
6295	}
6296	free_cpumask_var(groupmask);
6297	}
6298	#else /* !CONFIG_SCHED_DEBUG */
6299	# define sched_domain_debug(sd, cpu) do { } while (0)
6300	#endif /* CONFIG_SCHED_DEBUG */
6301
6302	static int sd_degenerate(struct sched_domain *sd)
6303	{
6304	if (cpumask_weight(sched_domain_span(sd)) == 1)
6305	return 1;
6306
6307	/* Following flags need at least 2 groups */
6308	if (sd->flags & (SD_LOAD_BALANCE \|
6309	SD_BALANCE_NEWIDLE \|
6310	SD_BALANCE_FORK \|
6311	SD_BALANCE_EXEC \|
6312	SD_SHARE_CPUPOWER \|
6313