linux/kernel/sched.c
<<
>>
Prefs
   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 <asm/mmu_context.h>
  36#include <linux/interrupt.h>
  37#include <linux/capability.h>
  38#include <linux/completion.h>
  39#include <linux/kernel_stat.h>
  40#include <linux/debug_locks.h>
  41#include <linux/perf_event.h>
  42#include <linux/security.h>
  43#include <linux/notifier.h>
  44#include <linux/profile.h>
  45#include <linux/freezer.h>
  46#include <linux/vmalloc.h>
  47#include <linux/blkdev.h>
  48#include <linux/delay.h>
  49#include <linux/pid_namespace.h>
  50#include <linux/smp.h>
  51#include <linux/threads.h>
  52#include <linux/timer.h>
  53#include <linux/rcupdate.h>
  54#include <linux/cpu.h>
  55#include <linux/cpuset.h>
  56#include <linux/percpu.h>
  57#include <linux/proc_fs.h>
  58#include <linux/seq_file.h>
  59#include <linux/stop_machine.h>
  60#include <linux/sysctl.h>
  61#include <linux/syscalls.h>
  62#include <linux/times.h>
  63#include <linux/tsacct_kern.h>
  64#include <linux/kprobes.h>
  65#include <linux/delayacct.h>
  66#include <linux/unistd.h>
  67#include <linux/pagemap.h>
  68#include <linux/hrtimer.h>
  69#include <linux/tick.h>
  70#include <linux/debugfs.h>
  71#include <linux/ctype.h>
  72#include <linux/ftrace.h>
  73#include <linux/slab.h>
  74
  75#include <asm/tlb.h>
  76#include <asm/irq_regs.h>
  77#include <asm/mutex.h>
  78#ifdef CONFIG_PARAVIRT
  79#include <asm/paravirt.h>
  80#endif
  81
  82#include "sched_cpupri.h"
  83#include "workqueue_sched.h"
  84#include "sched_autogroup.h"
  85
  86#define CREATE_TRACE_POINTS
  87#include <trace/events/sched.h>
  88
  89/*
  90 * Convert user-nice values [ -20 ... 0 ... 19 ]
  91 * to static priority [ MAX_RT_PRIO..MAX_PRIO-1 ],
  92 * and back.
  93 */
  94#define NICE_TO_PRIO(nice)      (MAX_RT_PRIO + (nice) + 20)
  95#define PRIO_TO_NICE(prio)      ((prio) - MAX_RT_PRIO - 20)
  96#define TASK_NICE(p)            PRIO_TO_NICE((p)->static_prio)
  97
  98/*
  99 * 'User priority' is the nice value converted to something we
 100 * can work with better when scaling various scheduler parameters,
 101 * it's a [ 0 ... 39 ] range.
 102 */
 103#define USER_PRIO(p)            ((p)-MAX_RT_PRIO)
 104#define TASK_USER_PRIO(p)       USER_PRIO((p)->static_prio)
 105#define MAX_USER_PRIO           (USER_PRIO(MAX_PRIO))
 106
 107/*
 108 * Helpers for converting nanosecond timing to jiffy resolution
 109 */
 110#define NS_TO_JIFFIES(TIME)     ((unsigned long)(TIME) / (NSEC_PER_SEC / HZ))
 111
 112#define NICE_0_LOAD             SCHED_LOAD_SCALE
 113#define NICE_0_SHIFT            SCHED_LOAD_SHIFT
 114
 115/*
 116 * These are the 'tuning knobs' of the scheduler:
 117 *
 118 * default timeslice is 100 msecs (used only for SCHED_RR tasks).
 119 * Timeslices get refilled after they expire.
 120 */
 121#define DEF_TIMESLICE           (100 * HZ / 1000)
 122
 123/*
 124 * single value that denotes runtime == period, ie unlimited time.
 125 */
 126#define RUNTIME_INF     ((u64)~0ULL)
 127
 128static inline int rt_policy(int policy)
 129{
 130        if (policy == SCHED_FIFO || policy == SCHED_RR)
 131                return 1;
 132        return 0;
 133}
 134
 135static inline int task_has_rt_policy(struct task_struct *p)
 136{
 137        return rt_policy(p->policy);
 138}
 139
 140/*
 141 * This is the priority-queue data structure of the RT scheduling class:
 142 */
 143struct rt_prio_array {
 144        DECLARE_BITMAP(bitmap, MAX_RT_PRIO+1); /* include 1 bit for delimiter */
 145        struct list_head queue[MAX_RT_PRIO];
 146};
 147
 148struct rt_bandwidth {
 149        /* nests inside the rq lock: */
 150        raw_spinlock_t          rt_runtime_lock;
 151        ktime_t                 rt_period;
 152        u64                     rt_runtime;
 153        struct hrtimer          rt_period_timer;
 154};
 155
 156static struct rt_bandwidth def_rt_bandwidth;
 157
 158static int do_sched_rt_period_timer(struct rt_bandwidth *rt_b, int overrun);
 159
 160static enum hrtimer_restart sched_rt_period_timer(struct hrtimer *timer)
 161{
 162        struct rt_bandwidth *rt_b =
 163                container_of(timer, struct rt_bandwidth, rt_period_timer);
 164        ktime_t now;
 165        int overrun;
 166        int idle = 0;
 167
 168        for (;;) {
 169                now = hrtimer_cb_get_time(timer);
 170                overrun = hrtimer_forward(timer, now, rt_b->rt_period);
 171
 172                if (!overrun)
 173                        break;
 174
 175                idle = do_sched_rt_period_timer(rt_b, overrun);
 176        }
 177
 178        return idle ? HRTIMER_NORESTART : HRTIMER_RESTART;
 179}
 180
 181static
 182void init_rt_bandwidth(struct rt_bandwidth *rt_b, u64 period, u64 runtime)
 183{
 184        rt_b->rt_period = ns_to_ktime(period);
 185        rt_b->rt_runtime = runtime;
 186
 187        raw_spin_lock_init(&rt_b->rt_runtime_lock);
 188
 189        hrtimer_init(&rt_b->rt_period_timer,
 190                        CLOCK_MONOTONIC, HRTIMER_MODE_REL);
 191        rt_b->rt_period_timer.function = sched_rt_period_timer;
 192}
 193
 194static inline int rt_bandwidth_enabled(void)
 195{
 196        return sysctl_sched_rt_runtime >= 0;
 197}
 198
 199static void start_rt_bandwidth(struct rt_bandwidth *rt_b)
 200{
 201        ktime_t now;
 202
 203        if (!rt_bandwidth_enabled() || rt_b->rt_runtime == RUNTIME_INF)
 204                return;
 205
 206        if (hrtimer_active(&rt_b->rt_period_timer))
 207                return;
 208
 209        raw_spin_lock(&rt_b->rt_runtime_lock);
 210        for (;;) {
 211                unsigned long delta;
 212                ktime_t soft, hard;
 213
 214                if (hrtimer_active(&rt_b->rt_period_timer))
 215                        break;
 216
 217                now = hrtimer_cb_get_time(&rt_b->rt_period_timer);
 218                hrtimer_forward(&rt_b->rt_period_timer, now, rt_b->rt_period);
 219
 220                soft = hrtimer_get_softexpires(&rt_b->rt_period_timer);
 221                hard = hrtimer_get_expires(&rt_b->rt_period_timer);
 222                delta = ktime_to_ns(ktime_sub(hard, soft));
 223                __hrtimer_start_range_ns(&rt_b->rt_period_timer, soft, delta,
 224                                HRTIMER_MODE_ABS_PINNED, 0);
 225        }
 226        raw_spin_unlock(&rt_b->rt_runtime_lock);
 227}
 228
 229#ifdef CONFIG_RT_GROUP_SCHED
 230static void destroy_rt_bandwidth(struct rt_bandwidth *rt_b)
 231{
 232        hrtimer_cancel(&rt_b->rt_period_timer);
 233}
 234#endif
 235
 236/*
 237 * sched_domains_mutex serializes calls to init_sched_domains,
 238 * detach_destroy_domains and partition_sched_domains.
 239 */
 240static DEFINE_MUTEX(sched_domains_mutex);
 241
 242#ifdef CONFIG_CGROUP_SCHED
 243
 244#include <linux/cgroup.h>
 245
 246struct cfs_rq;
 247
 248static LIST_HEAD(task_groups);
 249
 250/* task group related information */
 251struct task_group {
 252        struct cgroup_subsys_state css;
 253
 254#ifdef CONFIG_FAIR_GROUP_SCHED
 255        /* schedulable entities of this group on each cpu */
 256        struct sched_entity **se;
 257        /* runqueue "owned" by this group on each cpu */
 258        struct cfs_rq **cfs_rq;
 259        unsigned long shares;
 260
 261        atomic_t load_weight;
 262#endif
 263
 264#ifdef CONFIG_RT_GROUP_SCHED
 265        struct sched_rt_entity **rt_se;
 266        struct rt_rq **rt_rq;
 267
 268        struct rt_bandwidth rt_bandwidth;
 269#endif
 270
 271        struct rcu_head rcu;
 272        struct list_head list;
 273
 274        struct task_group *parent;
 275        struct list_head siblings;
 276        struct list_head children;
 277
 278#ifdef CONFIG_SCHED_AUTOGROUP
 279        struct autogroup *autogroup;
 280#endif
 281};
 282
 283/* task_group_lock serializes the addition/removal of task groups */
 284static DEFINE_SPINLOCK(task_group_lock);
 285
 286#ifdef CONFIG_FAIR_GROUP_SCHED
 287
 288# define ROOT_TASK_GROUP_LOAD   NICE_0_LOAD
 289
 290/*
 291 * A weight of 0 or 1 can cause arithmetics problems.
 292 * A weight of a cfs_rq is the sum of weights of which entities
 293 * are queued on this cfs_rq, so a weight of a entity should not be
 294 * too large, so as the shares value of a task group.
 295 * (The default weight is 1024 - so there's no practical
 296 *  limitation from this.)
 297 */
 298#define MIN_SHARES      (1UL <<  1)
 299#define MAX_SHARES      (1UL << 18)
 300
 301static int root_task_group_load = ROOT_TASK_GROUP_LOAD;
 302#endif
 303
 304/* Default task group.
 305 *      Every task in system belong to this group at bootup.
 306 */
 307struct task_group root_task_group;
 308
 309#endif  /* CONFIG_CGROUP_SCHED */
 310
 311/* CFS-related fields in a runqueue */
 312struct cfs_rq {
 313        struct load_weight load;
 314        unsigned long nr_running;
 315
 316        u64 exec_clock;
 317        u64 min_vruntime;
 318#ifndef CONFIG_64BIT
 319        u64 min_vruntime_copy;
 320#endif
 321
 322        struct rb_root tasks_timeline;
 323        struct rb_node *rb_leftmost;
 324
 325        struct list_head tasks;
 326        struct list_head *balance_iterator;
 327
 328        /*
 329         * 'curr' points to currently running entity on this cfs_rq.
 330         * It is set to NULL otherwise (i.e when none are currently running).
 331         */
 332        struct sched_entity *curr, *next, *last, *skip;
 333
 334#ifdef  CONFIG_SCHED_DEBUG
 335        unsigned int nr_spread_over;
 336#endif
 337
 338#ifdef CONFIG_FAIR_GROUP_SCHED
 339        struct rq *rq;  /* cpu runqueue to which this cfs_rq is attached */
 340
 341        /*
 342         * leaf cfs_rqs are those that hold tasks (lowest schedulable entity in
 343         * a hierarchy). Non-leaf lrqs hold other higher schedulable entities
 344         * (like users, containers etc.)
 345         *
 346         * leaf_cfs_rq_list ties together list of leaf cfs_rq's in a cpu. This
 347         * list is used during load balance.
 348         */
 349        int on_list;
 350        struct list_head leaf_cfs_rq_list;
 351        struct task_group *tg;  /* group that "owns" this runqueue */
 352
 353#ifdef CONFIG_SMP
 354        /*
 355         * the part of load.weight contributed by tasks
 356         */
 357        unsigned long task_weight;
 358
 359        /*
 360         *   h_load = weight * f(tg)
 361         *
 362         * Where f(tg) is the recursive weight fraction assigned to
 363         * this group.
 364         */
 365        unsigned long h_load;
 366
 367        /*
 368         * Maintaining per-cpu shares distribution for group scheduling
 369         *
 370         * load_stamp is the last time we updated the load average
 371         * load_last is the last time we updated the load average and saw load
 372         * load_unacc_exec_time is currently unaccounted execution time
 373         */
 374        u64 load_avg;
 375        u64 load_period;
 376        u64 load_stamp, load_last, load_unacc_exec_time;
 377
 378        unsigned long load_contribution;
 379#endif
 380#endif
 381};
 382
 383/* Real-Time classes' related field in a runqueue: */
 384struct rt_rq {
 385        struct rt_prio_array active;
 386        unsigned long rt_nr_running;
 387#if defined CONFIG_SMP || defined CONFIG_RT_GROUP_SCHED
 388        struct {
 389                int curr; /* highest queued rt task prio */
 390#ifdef CONFIG_SMP
 391                int next; /* next highest */
 392#endif
 393        } highest_prio;
 394#endif
 395#ifdef CONFIG_SMP
 396        unsigned long rt_nr_migratory;
 397        unsigned long rt_nr_total;
 398        int overloaded;
 399        struct plist_head pushable_tasks;
 400#endif
 401        int rt_throttled;
 402        u64 rt_time;
 403        u64 rt_runtime;
 404        /* Nests inside the rq lock: */
 405        raw_spinlock_t rt_runtime_lock;
 406
 407#ifdef CONFIG_RT_GROUP_SCHED
 408        unsigned long rt_nr_boosted;
 409
 410        struct rq *rq;
 411        struct list_head leaf_rt_rq_list;
 412        struct task_group *tg;
 413#endif
 414};
 415
 416#ifdef CONFIG_SMP
 417
 418/*
 419 * We add the notion of a root-domain which will be used to define per-domain
 420 * variables. Each exclusive cpuset essentially defines an island domain by
 421 * fully partitioning the member cpus from any other cpuset. Whenever a new
 422 * exclusive cpuset is created, we also create and attach a new root-domain
 423 * object.
 424 *
 425 */
 426struct root_domain {
 427        atomic_t refcount;
 428        atomic_t rto_count;
 429        struct rcu_head rcu;
 430        cpumask_var_t span;
 431        cpumask_var_t online;
 432
 433        /*
 434         * The "RT overload" flag: it gets set if a CPU has more than
 435         * one runnable RT task.
 436         */
 437        cpumask_var_t rto_mask;
 438        struct cpupri cpupri;
 439};
 440
 441/*
 442 * By default the system creates a single root-domain with all cpus as
 443 * members (mimicking the global state we have today).
 444 */
 445static struct root_domain def_root_domain;
 446
 447#endif /* CONFIG_SMP */
 448
 449/*
 450 * This is the main, per-CPU runqueue data structure.
 451 *
 452 * Locking rule: those places that want to lock multiple runqueues
 453 * (such as the load balancing or the thread migration code), lock
 454 * acquire operations must be ordered by ascending &runqueue.
 455 */
 456struct rq {
 457        /* runqueue lock: */
 458        raw_spinlock_t lock;
 459
 460        /*
 461         * nr_running and cpu_load should be in the same cacheline because
 462         * remote CPUs use both these fields when doing load calculation.
 463         */
 464        unsigned long nr_running;
 465        #define CPU_LOAD_IDX_MAX 5
 466        unsigned long cpu_load[CPU_LOAD_IDX_MAX];
 467        unsigned long last_load_update_tick;
 468#ifdef CONFIG_NO_HZ
 469        u64 nohz_stamp;
 470        unsigned char nohz_balance_kick;
 471#endif
 472        int skip_clock_update;
 473
 474        /* capture load from *all* tasks on this cpu: */
 475        struct load_weight load;
 476        unsigned long nr_load_updates;
 477        u64 nr_switches;
 478
 479        struct cfs_rq cfs;
 480        struct rt_rq rt;
 481
 482#ifdef CONFIG_FAIR_GROUP_SCHED
 483        /* list of leaf cfs_rq on this cpu: */
 484        struct list_head leaf_cfs_rq_list;
 485#endif
 486#ifdef CONFIG_RT_GROUP_SCHED
 487        struct list_head leaf_rt_rq_list;
 488#endif
 489
 490        /*
 491         * This is part of a global counter where only the total sum
 492         * over all CPUs matters. A task can increase this counter on
 493         * one CPU and if it got migrated afterwards it may decrease
 494         * it on another CPU. Always updated under the runqueue lock:
 495         */
 496        unsigned long nr_uninterruptible;
 497
 498        struct task_struct *curr, *idle, *stop;
 499        unsigned long next_balance;
 500        struct mm_struct *prev_mm;
 501
 502        u64 clock;
 503        u64 clock_task;
 504
 505        atomic_t nr_iowait;
 506
 507#ifdef CONFIG_SMP
 508        struct root_domain *rd;
 509        struct sched_domain *sd;
 510
 511        unsigned long cpu_power;
 512
 513        unsigned char idle_at_tick;
 514        /* For active balancing */
 515        int post_schedule;
 516        int active_balance;
 517        int push_cpu;
 518        struct cpu_stop_work active_balance_work;
 519        /* cpu of this runqueue: */
 520        int cpu;
 521        int online;
 522
 523        unsigned long avg_load_per_task;
 524
 525        u64 rt_avg;
 526        u64 age_stamp;
 527        u64 idle_stamp;
 528        u64 avg_idle;
 529#endif
 530
 531#ifdef CONFIG_IRQ_TIME_ACCOUNTING
 532        u64 prev_irq_time;
 533#endif
 534#ifdef CONFIG_PARAVIRT
 535        u64 prev_steal_time;
 536#endif
 537#ifdef CONFIG_PARAVIRT_TIME_ACCOUNTING
 538        u64 prev_steal_time_rq;
 539#endif
 540
 541        /* calc_load related fields */
 542        unsigned long calc_load_update;
 543        long calc_load_active;
 544
 545#ifdef CONFIG_SCHED_HRTICK
 546#ifdef CONFIG_SMP
 547        int hrtick_csd_pending;
 548        struct call_single_data hrtick_csd;
 549#endif
 550        struct hrtimer hrtick_timer;
 551#endif
 552
 553#ifdef CONFIG_SCHEDSTATS
 554        /* latency stats */
 555        struct sched_info rq_sched_info;
 556        unsigned long long rq_cpu_time;
 557        /* could above be rq->cfs_rq.exec_clock + rq->rt_rq.rt_runtime ? */
 558
 559        /* sys_sched_yield() stats */
 560        unsigned int yld_count;
 561
 562        /* schedule() stats */
 563        unsigned int sched_switch;
 564        unsigned int sched_count;
 565        unsigned int sched_goidle;
 566
 567        /* try_to_wake_up() stats */
 568        unsigned int ttwu_count;
 569        unsigned int ttwu_local;
 570#endif
 571
 572#ifdef CONFIG_SMP
 573        struct task_struct *wake_list;
 574#endif
 575};
 576
 577static DEFINE_PER_CPU_SHARED_ALIGNED(struct rq, runqueues);
 578
 579
 580static void check_preempt_curr(struct rq *rq, struct task_struct *p, int flags);
 581
 582static inline int cpu_of(struct rq *rq)
 583{
 584#ifdef CONFIG_SMP
 585        return rq->cpu;
 586#else
 587        return 0;
 588#endif
 589}
 590
 591#define rcu_dereference_check_sched_domain(p) \
 592        rcu_dereference_check((p), \
 593                              lockdep_is_held(&sched_domains_mutex))
 594
 595/*
 596 * The domain tree (rq->sd) is protected by RCU's quiescent state transition.
 597 * See detach_destroy_domains: synchronize_sched for details.
 598 *
 599 * The domain tree of any CPU may only be accessed from within
 600 * preempt-disabled sections.
 601 */
 602#define for_each_domain(cpu, __sd) \
 603        for (__sd = rcu_dereference_check_sched_domain(cpu_rq(cpu)->sd); __sd; __sd = __sd->parent)
 604
 605#define cpu_rq(cpu)             (&per_cpu(runqueues, (cpu)))
 606#define this_rq()               (&__get_cpu_var(runqueues))
 607#define task_rq(p)              cpu_rq(task_cpu(p))
 608#define cpu_curr(cpu)           (cpu_rq(cpu)->curr)
 609#define raw_rq()                (&__raw_get_cpu_var(runqueues))
 610
 611#ifdef CONFIG_CGROUP_SCHED
 612
 613/*
 614 * Return the group to which this tasks belongs.
 615 *
 616 * We use task_subsys_state_check() and extend the RCU verification with
 617 * pi->lock and rq->lock because cpu_cgroup_attach() holds those locks for each
 618 * task it moves into the cgroup. Therefore by holding either of those locks,
 619 * we pin the task to the current cgroup.
 620 */
 621static inline struct task_group *task_group(struct task_struct *p)
 622{
 623        struct task_group *tg;
 624        struct cgroup_subsys_state *css;
 625
 626        css = task_subsys_state_check(p, cpu_cgroup_subsys_id,
 627                        lockdep_is_held(&p->pi_lock) ||
 628                        lockdep_is_held(&task_rq(p)->lock));
 629        tg = container_of(css, struct task_group, css);
 630
 631        return autogroup_task_group(p, tg);
 632}
 633
 634/* Change a task's cfs_rq and parent entity if it moves across CPUs/groups */
 635static inline void set_task_rq(struct task_struct *p, unsigned int cpu)
 636{
 637#ifdef CONFIG_FAIR_GROUP_SCHED
 638        p->se.cfs_rq = task_group(p)->cfs_rq[cpu];
 639        p->se.parent = task_group(p)->se[cpu];
 640#endif
 641
 642#ifdef CONFIG_RT_GROUP_SCHED
 643        p->rt.rt_rq  = task_group(p)->rt_rq[cpu];
 644        p->rt.parent = task_group(p)->rt_se[cpu];
 645#endif
 646}
 647
 648#else /* CONFIG_CGROUP_SCHED */
 649
 650static inline void set_task_rq(struct task_struct *p, unsigned int cpu) { }
 651static inline struct task_group *task_group(struct task_struct *p)
 652{
 653        return NULL;
 654}
 655
 656#endif /* CONFIG_CGROUP_SCHED */
 657
 658static void update_rq_clock_task(struct rq *rq, s64 delta);
 659
 660static void update_rq_clock(struct rq *rq)
 661{
 662        s64 delta;
 663
 664        if (rq->skip_clock_update > 0)
 665                return;
 666
 667        delta = sched_clock_cpu(cpu_of(rq)) - rq->clock;
 668        rq->clock += delta;
 669        update_rq_clock_task(rq, delta);
 670}
 671
 672/*
 673 * Tunables that become constants when CONFIG_SCHED_DEBUG is off:
 674 */
 675#ifdef CONFIG_SCHED_DEBUG
 676# define const_debug __read_mostly
 677#else
 678# define const_debug static const
 679#endif
 680
 681/**
 682 * runqueue_is_locked - Returns true if the current cpu runqueue is locked
 683 * @cpu: the processor in question.
 684 *
 685 * This interface allows printk to be called with the runqueue lock
 686 * held and know whether or not it is OK to wake up the klogd.
 687 */
 688int runqueue_is_locked(int cpu)
 689{
 690        return raw_spin_is_locked(&cpu_rq(cpu)->lock);
 691}
 692
 693/*
 694 * Debugging: various feature bits
 695 */
 696
 697#define SCHED_FEAT(name, enabled)       \
 698        __SCHED_FEAT_##name ,
 699
 700enum {
 701#include "sched_features.h"
 702};
 703
 704#undef SCHED_FEAT
 705
 706#define SCHED_FEAT(name, enabled)       \
 707        (1UL << __SCHED_FEAT_##name) * enabled |
 708
 709const_debug unsigned int sysctl_sched_features =
 710#include "sched_features.h"
 711        0;
 712
 713#undef SCHED_FEAT
 714
 715#ifdef CONFIG_SCHED_DEBUG
 716#define SCHED_FEAT(name, enabled)       \
 717        #name ,
 718
 719static __read_mostly char *sched_feat_names[] = {
 720#include "sched_features.h"
 721        NULL
 722};
 723
 724#undef SCHED_FEAT
 725
 726static int sched_feat_show(struct seq_file *m, void *v)
 727{
 728        int i;
 729
 730        for (i = 0; sched_feat_names[i]; i++) {
 731                if (!(sysctl_sched_features & (1UL << i)))
 732                        seq_puts(m, "NO_");
 733                seq_printf(m, "%s ", sched_feat_names[i]);
 734        }
 735        seq_puts(m, "\n");
 736
 737        return 0;
 738}
 739
 740static ssize_t
 741sched_feat_write(struct file *filp, const char __user *ubuf,
 742                size_t cnt, loff_t *ppos)
 743{
 744        char buf[64];
 745        char *cmp;
 746        int neg = 0;
 747        int i;
 748
 749        if (cnt > 63)
 750                cnt = 63;
 751
 752        if (copy_from_user(&buf, ubuf, cnt))
 753                return -EFAULT;
 754
 755        buf[cnt] = 0;
 756        cmp = strstrip(buf);
 757
 758        if (strncmp(cmp, "NO_", 3) == 0) {
 759                neg = 1;
 760                cmp += 3;
 761        }
 762
 763        for (i = 0; sched_feat_names[i]; i++) {
 764                if (strcmp(cmp, sched_feat_names[i]) == 0) {
 765                        if (neg)
 766                                sysctl_sched_features &= ~(1UL << i);
 767                        else
 768                                sysctl_sched_features |= (1UL << i);
 769                        break;
 770                }
 771        }
 772
 773        if (!sched_feat_names[i])
 774                return -EINVAL;
 775
 776        *ppos += cnt;
 777
 778        return cnt;
 779}
 780
 781static int sched_feat_open(struct inode *inode, struct file *filp)
 782{
 783        return single_open(filp, sched_feat_show, NULL);
 784}
 785
 786static const struct file_operations sched_feat_fops = {
 787        .open           = sched_feat_open,
 788        .write          = sched_feat_write,
 789        .read           = seq_read,
 790        .llseek         = seq_lseek,
 791        .release        = single_release,
 792};
 793
 794static __init int sched_init_debug(void)
 795{
 796        debugfs_create_file("sched_features", 0644, NULL, NULL,
 797                        &sched_feat_fops);
 798
 799        return 0;
 800}
 801late_initcall(sched_init_debug);
 802
 803#endif
 804
 805#define sched_feat(x) (sysctl_sched_features & (1UL << __SCHED_FEAT_##x))
 806
 807/*
 808 * Number of tasks to iterate in a single balance run.
 809 * Limited because this is done with IRQs disabled.
 810 */
 811const_debug unsigned int sysctl_sched_nr_migrate = 32;
 812
 813/*
 814 * period over which we average the RT time consumption, measured
 815 * in ms.
 816 *
 817 * default: 1s
 818 */
 819const_debug unsigned int sysctl_sched_time_avg = MSEC_PER_SEC;
 820
 821/*
 822 * period over which we measure -rt task cpu usage in us.
 823 * default: 1s
 824 */
 825unsigned int sysctl_sched_rt_period = 1000000;
 826
 827static __read_mostly int scheduler_running;
 828
 829/*
 830 * part of the period that we allow rt tasks to run in us.
 831 * default: 0.95s
 832 */
 833int sysctl_sched_rt_runtime = 950000;
 834
 835static inline u64 global_rt_period(void)
 836{
 837        return (u64)sysctl_sched_rt_period * NSEC_PER_USEC;
 838}
 839
 840static inline u64 global_rt_runtime(void)
 841{
 842        if (sysctl_sched_rt_runtime < 0)
 843                return RUNTIME_INF;
 844
 845        return (u64)sysctl_sched_rt_runtime * NSEC_PER_USEC;
 846}
 847
 848#ifndef prepare_arch_switch
 849# define prepare_arch_switch(next)      do { } while (0)
 850#endif
 851#ifndef finish_arch_switch
 852# define finish_arch_switch(prev)       do { } while (0)
 853#endif
 854
 855static inline int task_current(struct rq *rq, struct task_struct *p)
 856{
 857        return rq->curr == p;
 858}
 859
 860static inline int task_running(struct rq *rq, struct task_struct *p)
 861{
 862#ifdef CONFIG_SMP
 863        return p->on_cpu;
 864#else
 865        return task_current(rq, p);
 866#endif
 867}
 868
 869#ifndef __ARCH_WANT_UNLOCKED_CTXSW
 870static inline void prepare_lock_switch(struct rq *rq, struct task_struct *next)
 871{
 872#ifdef CONFIG_SMP
 873        /*
 874         * We can optimise this out completely for !SMP, because the
 875         * SMP rebalancing from interrupt is the only thing that cares
 876         * here.
 877         */
 878        next->on_cpu = 1;
 879#endif
 880}
 881
 882static inline void finish_lock_switch(struct rq *rq, struct task_struct *prev)
 883{
 884#ifdef CONFIG_SMP
 885        /*
 886         * After ->on_cpu is cleared, the task can be moved to a different CPU.
 887         * We must ensure this doesn't happen until the switch is completely
 888         * finished.
 889         */
 890        smp_wmb();
 891        prev->on_cpu = 0;
 892#endif
 893#ifdef CONFIG_DEBUG_SPINLOCK
 894        /* this is a valid case when another task releases the spinlock */
 895        rq->lock.owner = current;
 896#endif
 897        /*
 898         * If we are tracking spinlock dependencies then we have to
 899         * fix up the runqueue lock - which gets 'carried over' from
 900         * prev into current:
 901         */
 902        spin_acquire(&rq->lock.dep_map, 0, 0, _THIS_IP_);
 903
 904        raw_spin_unlock_irq(&rq->lock);
 905}
 906
 907#else /* __ARCH_WANT_UNLOCKED_CTXSW */
 908static inline void prepare_lock_switch(struct rq *rq, struct task_struct *next)
 909{
 910#ifdef CONFIG_SMP
 911        /*
 912         * We can optimise this out completely for !SMP, because the
 913         * SMP rebalancing from interrupt is the only thing that cares
 914         * here.
 915         */
 916        next->on_cpu = 1;
 917#endif
 918#ifdef __ARCH_WANT_INTERRUPTS_ON_CTXSW
 919        raw_spin_unlock_irq(&rq->lock);
 920#else
 921        raw_spin_unlock(&rq->lock);
 922#endif
 923}
 924
 925static inline void finish_lock_switch(struct rq *rq, struct task_struct *prev)
 926{
 927#ifdef CONFIG_SMP
 928        /*
 929         * After ->on_cpu is cleared, the task can be moved to a different CPU.
 930         * We must ensure this doesn't happen until the switch is completely
 931         * finished.
 932         */
 933        smp_wmb();
 934        prev->on_cpu = 0;
 935#endif
 936#ifndef __ARCH_WANT_INTERRUPTS_ON_CTXSW
 937        local_irq_enable();
 938#endif
 939}
 940#endif /* __ARCH_WANT_UNLOCKED_CTXSW */
 941
 942/*
 943 * __task_rq_lock - lock the rq @p resides on.
 944 */
 945static inline struct rq *__task_rq_lock(struct task_struct *p)
 946        __acquires(rq->lock)
 947{
 948        struct rq *rq;
 949
 950        lockdep_assert_held(&p->pi_lock);
 951
 952        for (;;) {
 953                rq = task_rq(p);
 954                raw_spin_lock(&rq->lock);
 955                if (likely(rq == task_rq(p)))
 956                        return rq;
 957                raw_spin_unlock(&rq->lock);
 958        }
 959}
 960
 961/*
 962 * task_rq_lock - lock p->pi_lock and lock the rq @p resides on.
 963 */
 964static struct rq *task_rq_lock(struct task_struct *p, unsigned long *flags)
 965        __acquires(p->pi_lock)
 966        __acquires(rq->lock)
 967{
 968        struct rq *rq;
 969
 970        for (;;) {
 971                raw_spin_lock_irqsave(&p->pi_lock, *flags);
 972                rq = task_rq(p);
 973                raw_spin_lock(&rq->lock);
 974                if (likely(rq == task_rq(p)))
 975                        return rq;
 976                raw_spin_unlock(&rq->lock);
 977                raw_spin_unlock_irqrestore(&p->pi_lock, *flags);
 978        }
 979}
 980
 981static void __task_rq_unlock(struct rq *rq)
 982        __releases(rq->lock)
 983{
 984        raw_spin_unlock(&rq->lock);
 985}
 986
 987static inline void
 988task_rq_unlock(struct rq *rq, struct task_struct *p, unsigned long *flags)
 989        __releases(rq->lock)
 990        __releases(p->pi_lock)
 991{
 992        raw_spin_unlock(&rq->lock);
 993        raw_spin_unlock_irqrestore(&p->pi_lock, *flags);
 994}
 995
 996/*
 997 * this_rq_lock - lock this runqueue and disable interrupts.
 998 */
 999static struct rq *this_rq_lock(void)
1000        __acquires(rq->lock)
1001{
1002        struct rq *rq;
1003
1004        local_irq_disable();
1005        rq = this_rq();
1006        raw_spin_lock(&rq->lock);
1007
1008        return rq;
1009}
1010
1011#ifdef CONFIG_SCHED_HRTICK
1012/*
1013 * Use HR-timers to deliver accurate preemption points.
1014 *
1015 * Its all a bit involved since we cannot program an hrt while holding the
1016 * rq->lock. So what we do is store a state in in rq->hrtick_* and ask for a
1017 * reschedule event.
1018 *
1019 * When we get rescheduled we reprogram the hrtick_timer outside of the
1020 * rq->lock.
1021 */
1022
1023/*
1024 * Use hrtick when:
1025 *  - enabled by features
1026 *  - hrtimer is actually high res
1027 */
1028static inline int hrtick_enabled(struct rq *rq)
1029{
1030        if (!sched_feat(HRTICK))
1031                return 0;
1032        if (!cpu_active(cpu_of(rq)))
1033                return 0;
1034        return hrtimer_is_hres_active(&rq->hrtick_timer);
1035}
1036
1037static void hrtick_clear(struct rq *rq)
1038{
1039        if (hrtimer_active(&rq->hrtick_timer))
1040                hrtimer_cancel(&rq->hrtick_timer);
1041}
1042
1043/*
1044 * High-resolution timer tick.
1045 * Runs from hardirq context with interrupts disabled.
1046 */
1047static enum hrtimer_restart hrtick(struct hrtimer *timer)
1048{
1049        struct rq *rq = container_of(timer, struct rq, hrtick_timer);
1050
1051        WARN_ON_ONCE(cpu_of(rq) != smp_processor_id());
1052
1053        raw_spin_lock(&rq->lock);
1054        update_rq_clock(rq);
1055        rq->curr->sched_class->task_tick(rq, rq->curr, 1);
1056        raw_spin_unlock(&rq->lock);
1057
1058        return HRTIMER_NORESTART;
1059}
1060
1061#ifdef CONFIG_SMP
1062/*
1063 * called from hardirq (IPI) context
1064 */
1065static void __hrtick_start(void *arg)
1066{
1067        struct rq *rq = arg;
1068
1069        raw_spin_lock(&rq->lock);
1070        hrtimer_restart(&rq->hrtick_timer);
1071        rq->hrtick_csd_pending = 0;
1072        raw_spin_unlock(&rq->lock);
1073}
1074
1075/*
1076 * Called to set the hrtick timer state.
1077 *
1078 * called with rq->lock held and irqs disabled
1079 */
1080static void hrtick_start(struct rq *rq, u64 delay)
1081{
1082        struct hrtimer *timer = &rq->hrtick_timer;
1083        ktime_t time = ktime_add_ns(timer->base->get_time(), delay);
1084
1085        hrtimer_set_expires(timer, time);
1086
1087        if (rq == this_rq()) {
1088                hrtimer_restart(timer);
1089        } else if (!rq->hrtick_csd_pending) {
1090                __smp_call_function_single(cpu_of(rq), &rq->hrtick_csd, 0);
1091                rq->hrtick_csd_pending = 1;
1092        }
1093}
1094
1095static int
1096hotplug_hrtick(struct notifier_block *nfb, unsigned long action, void *hcpu)
1097{
1098        int cpu = (int)(long)hcpu;
1099
1100        switch (action) {
1101        case CPU_UP_CANCELED:
1102        case CPU_UP_CANCELED_FROZEN:
1103        case CPU_DOWN_PREPARE:
1104        case CPU_DOWN_PREPARE_FROZEN:
1105        case CPU_DEAD:
1106        case CPU_DEAD_FROZEN:
1107                hrtick_clear(cpu_rq(cpu));
1108                return NOTIFY_OK;
1109        }
1110
1111        return NOTIFY_DONE;
1112}
1113
1114static __init void init_hrtick(void)
1115{
1116        hotcpu_notifier(hotplug_hrtick, 0);
1117}
1118#else
1119/*
1120 * Called to set the hrtick timer state.
1121 *
1122 * called with rq->lock held and irqs disabled
1123 */
1124static void hrtick_start(struct rq *rq, u64 delay)
1125{
1126        __hrtimer_start_range_ns(&rq->hrtick_timer, ns_to_ktime(delay), 0,
1127                        HRTIMER_MODE_REL_PINNED, 0);
1128}
1129
1130static inline void init_hrtick(void)
1131{
1132}
1133#endif /* CONFIG_SMP */
1134
1135static void init_rq_hrtick(struct rq *rq)
1136{
1137#ifdef CONFIG_SMP
1138        rq->hrtick_csd_pending = 0;
1139
1140        rq->hrtick_csd.flags = 0;
1141        rq->hrtick_csd.func = __hrtick_start;
1142        rq->hrtick_csd.info = rq;
1143#endif
1144
1145        hrtimer_init(&rq->hrtick_timer, CLOCK_MONOTONIC, HRTIMER_MODE_REL);
1146        rq->hrtick_timer.function = hrtick;
1147}
1148#else   /* CONFIG_SCHED_HRTICK */
1149static inline void hrtick_clear(struct rq *rq)
1150{
1151}
1152
1153static inline void init_rq_hrtick(struct rq *rq)
1154{
1155}
1156
1157static inline void init_hrtick(void)
1158{
1159}
1160#endif  /* CONFIG_SCHED_HRTICK */
1161
1162/*
1163 * resched_task - mark a task 'to be rescheduled now'.
1164 *
1165 * On UP this means the setting of the need_resched flag, on SMP it
1166 * might also involve a cross-CPU call to trigger the scheduler on
1167 * the target CPU.
1168 */
1169#ifdef CONFIG_SMP
1170
1171#ifndef tsk_is_polling
1172#define tsk_is_polling(t) test_tsk_thread_flag(t, TIF_POLLING_NRFLAG)
1173#endif
1174
1175static void resched_task(struct task_struct *p)
1176{
1177        int cpu;
1178
1179        assert_raw_spin_locked(&task_rq(p)->lock);
1180
1181        if (test_tsk_need_resched(p))
1182                return;
1183
1184        set_tsk_need_resched(p);
1185
1186        cpu = task_cpu(p);
1187        if (cpu == smp_processor_id())
1188                return;
1189
1190        /* NEED_RESCHED must be visible before we test polling */
1191        smp_mb();
1192        if (!tsk_is_polling(p))
1193                smp_send_reschedule(cpu);
1194}
1195
1196static void resched_cpu(int cpu)
1197{
1198        struct rq *rq = cpu_rq(cpu);
1199        unsigned long flags;
1200
1201        if (!raw_spin_trylock_irqsave(&rq->lock, flags))
1202                return;
1203        resched_task(cpu_curr(cpu));
1204        raw_spin_unlock_irqrestore(&rq->lock, flags);
1205}
1206
1207#ifdef CONFIG_NO_HZ
1208/*
1209 * In the semi idle case, use the nearest busy cpu for migrating timers
1210 * from an idle cpu.  This is good for power-savings.
1211 *
1212 * We don't do similar optimization for completely idle system, as
1213 * selecting an idle cpu will add more delays to the timers than intended
1214 * (as that cpu's timer base may not be uptodate wrt jiffies etc).
1215 */
1216int get_nohz_timer_target(void)
1217{
1218        int cpu = smp_processor_id();
1219        int i;
1220        struct sched_domain *sd;
1221
1222        rcu_read_lock();
1223        for_each_domain(cpu, sd) {
1224                for_each_cpu(i, sched_domain_span(sd)) {
1225                        if (!idle_cpu(i)) {
1226                                cpu = i;
1227                                goto unlock;
1228                        }
1229                }
1230        }
1231unlock:
1232        rcu_read_unlock();
1233        return cpu;
1234}
1235/*
1236 * When add_timer_on() enqueues a timer into the timer wheel of an
1237 * idle CPU then this timer might expire before the next timer event
1238 * which is scheduled to wake up that CPU. In case of a completely
1239 * idle system the next event might even be infinite time into the
1240 * future. wake_up_idle_cpu() ensures that the CPU is woken up and
1241 * leaves the inner idle loop so the newly added timer is taken into
1242 * account when the CPU goes back to idle and evaluates the timer
1243 * wheel for the next timer event.
1244 */
1245void wake_up_idle_cpu(int cpu)
1246{
1247        struct rq *rq = cpu_rq(cpu);
1248
1249        if (cpu == smp_processor_id())
1250                return;
1251
1252        /*
1253         * This is safe, as this function is called with the timer
1254         * wheel base lock of (cpu) held. When the CPU is on the way
1255         * to idle and has not yet set rq->curr to idle then it will
1256         * be serialized on the timer wheel base lock and take the new
1257         * timer into account automatically.
1258         */
1259        if (rq->curr != rq->idle)
1260                return;
1261
1262        /*
1263         * We can set TIF_RESCHED on the idle task of the other CPU
1264         * lockless. The worst case is that the other CPU runs the
1265         * idle task through an additional NOOP schedule()
1266         */
1267        set_tsk_need_resched(rq->idle);
1268
1269        /* NEED_RESCHED must be visible before we test polling */
1270        smp_mb();
1271        if (!tsk_is_polling(rq->idle))
1272                smp_send_reschedule(cpu);
1273}
1274
1275#endif /* CONFIG_NO_HZ */
1276
1277static u64 sched_avg_period(void)
1278{
1279        return (u64)sysctl_sched_time_avg * NSEC_PER_MSEC / 2;
1280}
1281
1282static void sched_avg_update(struct rq *rq)
1283{
1284        s64 period = sched_avg_period();
1285
1286        while ((s64)(rq->clock - rq->age_stamp) > period) {
1287                /*
1288                 * Inline assembly required to prevent the compiler
1289                 * optimising this loop into a divmod call.
1290                 * See __iter_div_u64_rem() for another example of this.
1291                 */
1292                asm("" : "+rm" (rq->age_stamp));
1293                rq->age_stamp += period;
1294                rq->rt_avg /= 2;
1295        }
1296}
1297
1298static void sched_rt_avg_update(struct rq *rq, u64 rt_delta)
1299{
1300        rq->rt_avg += rt_delta;
1301        sched_avg_update(rq);
1302}
1303
1304#else /* !CONFIG_SMP */
1305static void resched_task(struct task_struct *p)
1306{
1307        assert_raw_spin_locked(&task_rq(p)->lock);
1308        set_tsk_need_resched(p);
1309}
1310
1311static void sched_rt_avg_update(struct rq *rq, u64 rt_delta)
1312{
1313}
1314
1315static void sched_avg_update(struct rq *rq)
1316{
1317}
1318#endif /* CONFIG_SMP */
1319
1320#if BITS_PER_LONG == 32
1321# define WMULT_CONST    (~0UL)
1322#else
1323# define WMULT_CONST    (1UL << 32)
1324#endif
1325
1326#define WMULT_SHIFT     32
1327
1328/*
1329 * Shift right and round:
1330 */
1331#define SRR(x, y) (((x) + (1UL << ((y) - 1))) >> (y))
1332
1333/*
1334 * delta *= weight / lw
1335 */
1336static unsigned long
1337calc_delta_mine(unsigned long delta_exec, unsigned long weight,
1338                struct load_weight *lw)
1339{
1340        u64 tmp;
1341
1342        /*
1343         * weight can be less than 2^SCHED_LOAD_RESOLUTION for task group sched
1344         * entities since MIN_SHARES = 2. Treat weight as 1 if less than
1345         * 2^SCHED_LOAD_RESOLUTION.
1346         */
1347        if (likely(weight > (1UL << SCHED_LOAD_RESOLUTION)))
1348                tmp = (u64)delta_exec * scale_load_down(weight);
1349        else
1350                tmp = (u64)delta_exec;
1351
1352        if (!lw->inv_weight) {
1353                unsigned long w = scale_load_down(lw->weight);
1354
1355                if (BITS_PER_LONG > 32 && unlikely(w >= WMULT_CONST))
1356                        lw->inv_weight = 1;
1357                else if (unlikely(!w))
1358                        lw->inv_weight = WMULT_CONST;
1359                else
1360                        lw->inv_weight = WMULT_CONST / w;
1361        }
1362
1363        /*
1364         * Check whether we'd overflow the 64-bit multiplication:
1365         */
1366        if (unlikely(tmp > WMULT_CONST))
1367                tmp = SRR(SRR(tmp, WMULT_SHIFT/2) * lw->inv_weight,
1368                        WMULT_SHIFT/2);
1369        else
1370                tmp = SRR(tmp * lw->inv_weight, WMULT_SHIFT);
1371
1372        return (unsigned long)min(tmp, (u64)(unsigned long)LONG_MAX);
1373}
1374
1375static inline void update_load_add(struct load_weight *lw, unsigned long inc)
1376{
1377        lw->weight += inc;
1378        lw->inv_weight = 0;
1379}
1380
1381static inline void update_load_sub(struct load_weight *lw, unsigned long dec)
1382{
1383        lw->weight -= dec;
1384        lw->inv_weight = 0;
1385}
1386
1387static inline void update_load_set(struct load_weight *lw, unsigned long w)
1388{
1389        lw->weight = w;
1390        lw->inv_weight = 0;
1391}
1392
1393/*
1394 * To aid in avoiding the subversion of "niceness" due to uneven distribution
1395 * of tasks with abnormal "nice" values across CPUs the contribution that
1396 * each task makes to its run queue's load is weighted according to its
1397 * scheduling class and "nice" value. For SCHED_NORMAL tasks this is just a
1398 * scaled version of the new time slice allocation that they receive on time
1399 * slice expiry etc.
1400 */
1401
1402#define WEIGHT_IDLEPRIO                3
1403#define WMULT_IDLEPRIO         1431655765
1404
1405/*
1406 * Nice levels are multiplicative, with a gentle 10% change for every
1407 * nice level changed. I.e. when a CPU-bound task goes from nice 0 to
1408 * nice 1, it will get ~10% less CPU time than another CPU-bound task
1409 * that remained on nice 0.
1410 *
1411 * The "10% effect" is relative and cumulative: from _any_ nice level,
1412 * if you go up 1 level, it's -10% CPU usage, if you go down 1 level
1413 * it's +10% CPU usage. (to achieve that we use a multiplier of 1.25.
1414 * If a task goes up by ~10% and another task goes down by ~10% then
1415 * the relative distance between them is ~25%.)
1416 */
1417static const int prio_to_weight[40] = {
1418 /* -20 */     88761,     71755,     56483,     46273,     36291,
1419 /* -15 */     29154,     23254,     18705,     14949,     11916,
1420 /* -10 */      9548,      7620,      6100,      4904,      3906,
1421 /*  -5 */      3121,      2501,      1991,      1586,      1277,
1422 /*   0 */      1024,       820,       655,       526,       423,
1423 /*   5 */       335,       272,       215,       172,       137,
1424 /*  10 */       110,        87,        70,        56,        45,
1425 /*  15 */        36,        29,        23,        18,        15,
1426};
1427
1428/*
1429 * Inverse (2^32/x) values of the prio_to_weight[] array, precalculated.
1430 *
1431 * In cases where the weight does not change often, we can use the
1432 * precalculated inverse to speed up arithmetics by turning divisions
1433 * into multiplications:
1434 */
1435static const u32 prio_to_wmult[40] = {
1436 /* -20 */     48388,     59856,     76040,     92818,    118348,
1437 /* -15 */    147320,    184698,    229616,    287308,    360437,
1438 /* -10 */    449829,    563644,    704093,    875809,   1099582,
1439 /*  -5 */   1376151,   1717300,   2157191,   2708050,   3363326,
1440 /*   0 */   4194304,   5237765,   6557202,   8165337,  10153587,
1441 /*   5 */  12820798,  15790321,  19976592,  24970740,  31350126,
1442 /*  10 */  39045157,  49367440,  61356676,  76695844,  95443717,
1443 /*  15 */ 119304647, 148102320, 186737708, 238609294, 286331153,
1444};
1445
1446/* Time spent by the tasks of the cpu accounting group executing in ... */
1447enum cpuacct_stat_index {
1448        CPUACCT_STAT_USER,      /* ... user mode */
1449        CPUACCT_STAT_SYSTEM,    /* ... kernel mode */
1450
1451        CPUACCT_STAT_NSTATS,
1452};
1453
1454#ifdef CONFIG_CGROUP_CPUACCT
1455static void cpuacct_charge(struct task_struct *tsk, u64 cputime);
1456static void cpuacct_update_stats(struct task_struct *tsk,
1457                enum cpuacct_stat_index idx, cputime_t val);
1458#else
1459static inline void cpuacct_charge(struct task_struct *tsk, u64 cputime) {}
1460static inline void cpuacct_update_stats(struct task_struct *tsk,
1461                enum cpuacct_stat_index idx, cputime_t val) {}
1462#endif
1463
1464static inline void inc_cpu_load(struct rq *rq, unsigned long load)
1465{
1466        update_load_add(&rq->load, load);
1467}
1468
1469static inline void dec_cpu_load(struct rq *rq, unsigned long load)
1470{
1471        update_load_sub(&rq->load, load);
1472}
1473
1474#if (defined(CONFIG_SMP) && defined(CONFIG_FAIR_GROUP_SCHED)) || defined(CONFIG_RT_GROUP_SCHED)
1475typedef int (*tg_visitor)(struct task_group *, void *);
1476
1477/*
1478 * Iterate the full tree, calling @down when first entering a node and @up when
1479 * leaving it for the final time.
1480 */
1481static int walk_tg_tree(tg_visitor down, tg_visitor up, void *data)
1482{
1483        struct task_group *parent, *child;
1484        int ret;
1485
1486        rcu_read_lock();
1487        parent = &root_task_group;
1488down:
1489        ret = (*down)(parent, data);
1490        if (ret)
1491                goto out_unlock;
1492        list_for_each_entry_rcu(child, &parent->children, siblings) {
1493                parent = child;
1494                goto down;
1495
1496up:
1497                continue;
1498        }
1499        ret = (*up)(parent, data);
1500        if (ret)
1501                goto out_unlock;
1502
1503        child = parent;
1504        parent = parent->parent;
1505        if (parent)
1506                goto up;
1507out_unlock:
1508        rcu_read_unlock();
1509
1510        return ret;
1511}
1512
1513static int tg_nop(struct task_group *tg, void *data)
1514{
1515        return 0;
1516}
1517#endif
1518
1519#ifdef CONFIG_SMP
1520/* Used instead of source_load when we know the type == 0 */
1521static unsigned long weighted_cpuload(const int cpu)
1522{
1523        return cpu_rq(cpu)->load.weight;
1524}
1525
1526/*
1527 * Return a low guess at the load of a migration-source cpu weighted
1528 * according to the scheduling class and "nice" value.
1529 *
1530 * We want to under-estimate the load of migration sources, to
1531 * balance conservatively.
1532 */
1533static unsigned long source_load(int cpu, int type)
1534{
1535        struct rq *rq = cpu_rq(cpu);
1536        unsigned long total = weighted_cpuload(cpu);
1537
1538        if (type == 0 || !sched_feat(LB_BIAS))
1539                return total;
1540
1541        return min(rq->cpu_load[type-1], total);
1542}
1543
1544/*
1545 * Return a high guess at the load of a migration-target cpu weighted
1546 * according to the scheduling class and "nice" value.
1547 */
1548static unsigned long target_load(int cpu, int type)
1549{
1550        struct rq *rq = cpu_rq(cpu);
1551        unsigned long total = weighted_cpuload(cpu);
1552
1553        if (type == 0 || !sched_feat(LB_BIAS))
1554                return total;
1555
1556        return max(rq->cpu_load[type-1], total);
1557}
1558
1559static unsigned long power_of(int cpu)
1560{
1561        return cpu_rq(cpu)->cpu_power;
1562}
1563
1564static int task_hot(struct task_struct *p, u64 now, struct sched_domain *sd);
1565
1566static unsigned long cpu_avg_load_per_task(int cpu)
1567{
1568        struct rq *rq = cpu_rq(cpu);
1569        unsigned long nr_running = ACCESS_ONCE(rq->nr_running);
1570
1571        if (nr_running)
1572                rq->avg_load_per_task = rq->load.weight / nr_running;
1573        else
1574                rq->avg_load_per_task = 0;
1575
1576        return rq->avg_load_per_task;
1577}
1578
1579#ifdef CONFIG_PREEMPT
1580
1581static void double_rq_lock(struct rq *rq1, struct rq *rq2);
1582
1583/*
1584 * fair double_lock_balance: Safely acquires both rq->locks in a fair
1585 * way at the expense of forcing extra atomic operations in all
1586 * invocations.  This assures that the double_lock is acquired using the
1587 * same underlying policy as the spinlock_t on this architecture, which
1588 * reduces latency compared to the unfair variant below.  However, it
1589 * also adds more overhead and therefore may reduce throughput.
1590 */
1591static inline int _double_lock_balance(struct rq *this_rq, struct rq *busiest)
1592        __releases(this_rq->lock)
1593        __acquires(busiest->lock)
1594        __acquires(this_rq->lock)
1595{
1596        raw_spin_unlock(&this_rq->lock);
1597        double_rq_lock(this_rq, busiest);
1598
1599        return 1;
1600}
1601
1602#else
1603/*
1604 * Unfair double_lock_balance: Optimizes throughput at the expense of
1605 * latency by eliminating extra atomic operations when the locks are
1606 * already in proper order on entry.  This favors lower cpu-ids and will
1607 * grant the double lock to lower cpus over higher ids under contention,
1608 * regardless of entry order into the function.
1609 */
1610static int _double_lock_balance(struct rq *this_rq, struct rq *busiest)
1611        __releases(this_rq->lock)
1612        __acquires(busiest->lock)
1613        __acquires(this_rq->lock)
1614{
1615        int ret = 0;
1616
1617        if (unlikely(!raw_spin_trylock(&busiest->lock))) {
1618                if (busiest < this_rq) {
1619                        raw_spin_unlock(&this_rq->lock);
1620                        raw_spin_lock(&busiest->lock);
1621                        raw_spin_lock_nested(&this_rq->lock,
1622                                              SINGLE_DEPTH_NESTING);
1623                        ret = 1;
1624                } else
1625                        raw_spin_lock_nested(&busiest->lock,
1626                                              SINGLE_DEPTH_NESTING);
1627        }
1628        return ret;
1629}
1630
1631#endif /* CONFIG_PREEMPT */
1632
1633/*
1634 * double_lock_balance - lock the busiest runqueue, this_rq is locked already.
1635 */
1636static int double_lock_balance(struct rq *this_rq, struct rq *busiest)
1637{
1638        if (unlikely(!irqs_disabled())) {
1639                /* printk() doesn't work good under rq->lock */
1640                raw_spin_unlock(&this_rq->lock);
1641                BUG_ON(1);
1642        }
1643
1644        return _double_lock_balance(this_rq, busiest);
1645}
1646
1647static inline void double_unlock_balance(struct rq *this_rq, struct rq *busiest)
1648        __releases(busiest->lock)
1649{
1650        raw_spin_unlock(&busiest->lock);
1651        lock_set_subclass(&this_rq->lock.dep_map, 0, _RET_IP_);
1652}
1653
1654/*
1655 * double_rq_lock - safely lock two runqueues
1656 *
1657 * Note this does not disable interrupts like task_rq_lock,
1658 * you need to do so manually before calling.
1659 */
1660static void double_rq_lock(struct rq *rq1, struct rq *rq2)
1661        __acquires(rq1->lock)
1662        __acquires(rq2->lock)
1663{
1664        BUG_ON(!irqs_disabled());
1665        if (rq1 == rq2) {
1666                raw_spin_lock(&rq1->lock);
1667                __acquire(rq2->lock);   /* Fake it out ;) */
1668        } else {
1669                if (rq1 < rq2) {
1670                        raw_spin_lock(&rq1->lock);
1671                        raw_spin_lock_nested(&rq2->lock, SINGLE_DEPTH_NESTING);
1672                } else {
1673                        raw_spin_lock(&rq2->lock);
1674                        raw_spin_lock_nested(&rq1->lock, SINGLE_DEPTH_NESTING);
1675                }
1676        }
1677}
1678
1679/*
1680 * double_rq_unlock - safely unlock two runqueues
1681 *
1682 * Note this does not restore interrupts like task_rq_unlock,
1683 * you need to do so manually after calling.
1684 */
1685static void double_rq_unlock(struct rq *rq1, struct rq *rq2)
1686        __releases(rq1->lock)
1687        __releases(rq2->lock)
1688{
1689        raw_spin_unlock(&rq1->lock);
1690        if (rq1 != rq2)
1691                raw_spin_unlock(&rq2->lock);
1692        else
1693                __release(rq2->lock);
1694}
1695
1696#else /* CONFIG_SMP */
1697
1698/*
1699 * double_rq_lock - safely lock two runqueues
1700 *
1701 * Note this does not disable interrupts like task_rq_lock,
1702 * you need to do so manually before calling.
1703 */
1704static void double_rq_lock(struct rq *rq1, struct rq *rq2)
1705        __acquires(rq1->lock)
1706        __acquires(rq2->lock)
1707{
1708        BUG_ON(!irqs_disabled());
1709        BUG_ON(rq1 != rq2);
1710        raw_spin_lock(&rq1->lock);
1711        __acquire(rq2->lock);   /* Fake it out ;) */
1712}
1713
1714/*
1715 * double_rq_unlock - safely unlock two runqueues
1716 *
1717 * Note this does not restore interrupts like task_rq_unlock,
1718 * you need to do so manually after calling.
1719 */
1720static void double_rq_unlock(struct rq *rq1, struct rq *rq2)
1721        __releases(rq1->lock)
1722        __releases(rq2->lock)
1723{
1724        BUG_ON(rq1 != rq2);
1725        raw_spin_unlock(&rq1->lock);
1726        __release(rq2->lock);
1727}
1728
1729#endif
1730
1731static void calc_load_account_idle(struct rq *this_rq);
1732static void update_sysctl(void);
1733static int get_update_sysctl_factor(void);
1734static void update_cpu_load(struct rq *this_rq);
1735
1736static inline void __set_task_cpu(struct task_struct *p, unsigned int cpu)
1737{
1738        set_task_rq(p, cpu);
1739#ifdef CONFIG_SMP
1740        /*
1741         * After ->cpu is set up to a new value, task_rq_lock(p, ...) can be
1742         * successfuly executed on another CPU. We must ensure that updates of
1743         * per-task data have been completed by this moment.
1744         */
1745        smp_wmb();
1746        task_thread_info(p)->cpu = cpu;
1747#endif
1748}
1749
1750static const struct sched_class rt_sched_class;
1751
1752#define sched_class_highest (&stop_sched_class)
1753#define for_each_class(class) \
1754   for (class = sched_class_highest; class; class = class->next)
1755
1756#include "sched_stats.h"
1757
1758static void inc_nr_running(struct rq *rq)
1759{
1760        rq->nr_running++;
1761}
1762
1763static void dec_nr_running(struct rq *rq)
1764{
1765        rq->nr_running--;
1766}
1767
1768static void set_load_weight(struct task_struct *p)
1769{
1770        int prio = p->static_prio - MAX_RT_PRIO;
1771        struct load_weight *load = &p->se.load;
1772
1773        /*
1774         * SCHED_IDLE tasks get minimal weight:
1775         */
1776        if (p->policy == SCHED_IDLE) {
1777                load->weight = scale_load(WEIGHT_IDLEPRIO);
1778                load->inv_weight = WMULT_IDLEPRIO;
1779                return;
1780        }
1781
1782        load->weight = scale_load(prio_to_weight[prio]);
1783        load->inv_weight = prio_to_wmult[prio];
1784}
1785
1786static void enqueue_task(struct rq *rq, struct task_struct *p, int flags)
1787{
1788        update_rq_clock(rq);
1789        sched_info_queued(p);
1790        p->sched_class->enqueue_task(rq, p, flags);
1791}
1792
1793static void dequeue_task(struct rq *rq, struct task_struct *p, int flags)
1794{
1795        update_rq_clock(rq);
1796        sched_info_dequeued(p);
1797        p->sched_class->dequeue_task(rq, p, flags);
1798}
1799
1800/*
1801 * activate_task - move a task to the runqueue.
1802 */
1803static void activate_task(struct rq *rq, struct task_struct *p, int flags)
1804{
1805        if (task_contributes_to_load(p))
1806                rq->nr_uninterruptible--;
1807
1808        enqueue_task(rq, p, flags);
1809        inc_nr_running(rq);
1810}
1811
1812/*
1813 * deactivate_task - remove a task from the runqueue.
1814 */
1815static void deactivate_task(struct rq *rq, struct task_struct *p, int flags)
1816{
1817        if (task_contributes_to_load(p))
1818                rq->nr_uninterruptible++;
1819
1820        dequeue_task(rq, p, flags);
1821        dec_nr_running(rq);
1822}
1823
1824#ifdef CONFIG_IRQ_TIME_ACCOUNTING
1825
1826/*
1827 * There are no locks covering percpu hardirq/softirq time.
1828 * They are only modified in account_system_vtime, on corresponding CPU
1829 * with interrupts disabled. So, writes are safe.
1830 * They are read and saved off onto struct rq in update_rq_clock().
1831 * This may result in other CPU reading this CPU's irq time and can
1832 * race with irq/account_system_vtime on this CPU. We would either get old
1833 * or new value with a side effect of accounting a slice of irq time to wrong
1834 * task when irq is in progress while we read rq->clock. That is a worthy
1835 * compromise in place of having locks on each irq in account_system_time.
1836 */
1837static DEFINE_PER_CPU(u64, cpu_hardirq_time);
1838static DEFINE_PER_CPU(u64, cpu_softirq_time);
1839
1840static DEFINE_PER_CPU(u64, irq_start_time);
1841static int sched_clock_irqtime;
1842
1843void enable_sched_clock_irqtime(void)
1844{
1845        sched_clock_irqtime = 1;
1846}
1847
1848void disable_sched_clock_irqtime(void)
1849{
1850        sched_clock_irqtime = 0;
1851}
1852
1853#ifndef CONFIG_64BIT
1854static DEFINE_PER_CPU(seqcount_t, irq_time_seq);
1855
1856static inline void irq_time_write_begin(void)
1857{
1858        __this_cpu_inc(irq_time_seq.sequence);
1859        smp_wmb();
1860}
1861
1862static inline void irq_time_write_end(void)
1863{
1864        smp_wmb();
1865        __this_cpu_inc(irq_time_seq.sequence);
1866}
1867
1868static inline u64 irq_time_read(int cpu)
1869{
1870        u64 irq_time;
1871        unsigned seq;
1872
1873        do {
1874                seq = read_seqcount_begin(&per_cpu(irq_time_seq, cpu));
1875                irq_time = per_cpu(cpu_softirq_time, cpu) +
1876                           per_cpu(cpu_hardirq_time, cpu);
1877        } while (read_seqcount_retry(&per_cpu(irq_time_seq, cpu), seq));
1878
1879        return irq_time;
1880}
1881#else /* CONFIG_64BIT */
1882static inline void irq_time_write_begin(void)
1883{
1884}
1885
1886static inline void irq_time_write_end(void)
1887{
1888}
1889
1890static inline u64 irq_time_read(int cpu)
1891{
1892        return per_cpu(cpu_softirq_time, cpu) + per_cpu(cpu_hardirq_time, cpu);
1893}
1894#endif /* CONFIG_64BIT */
1895
1896/*
1897 * Called before incrementing preempt_count on {soft,}irq_enter
1898 * and before decrementing preempt_count on {soft,}irq_exit.
1899 */
1900void account_system_vtime(struct task_struct *curr)
1901{
1902        unsigned long flags;
1903        s64 delta;
1904        int cpu;
1905
1906        if (!sched_clock_irqtime)
1907                return;
1908
1909        local_irq_save(flags);
1910
1911        cpu = smp_processor_id();
1912        delta = sched_clock_cpu(cpu) - __this_cpu_read(irq_start_time);
1913        __this_cpu_add(irq_start_time, delta);
1914
1915        irq_time_write_begin();
1916        /*
1917         * We do not account for softirq time from ksoftirqd here.
1918         * We want to continue accounting softirq time to ksoftirqd thread
1919         * in that case, so as not to confuse scheduler with a special task
1920         * that do not consume any time, but still wants to run.
1921         */
1922        if (hardirq_count())
1923                __this_cpu_add(cpu_hardirq_time, delta);
1924        else if (in_serving_softirq() && curr != this_cpu_ksoftirqd())
1925                __this_cpu_add(cpu_softirq_time, delta);
1926
1927        irq_time_write_end();
1928        local_irq_restore(flags);
1929}
1930EXPORT_SYMBOL_GPL(account_system_vtime);
1931
1932#endif /* CONFIG_IRQ_TIME_ACCOUNTING */
1933
1934#ifdef CONFIG_PARAVIRT
1935static inline u64 steal_ticks(u64 steal)
1936{
1937        if (unlikely(steal > NSEC_PER_SEC))
1938                return div_u64(steal, TICK_NSEC);
1939
1940        return __iter_div_u64_rem(steal, TICK_NSEC, &steal);
1941}
1942#endif
1943
1944static void update_rq_clock_task(struct rq *rq, s64 delta)
1945{
1946/*
1947 * In theory, the compile should just see 0 here, and optimize out the call
1948 * to sched_rt_avg_update. But I don't trust it...
1949 */
1950#if defined(CONFIG_IRQ_TIME_ACCOUNTING) || defined(CONFIG_PARAVIRT_TIME_ACCOUNTING)
1951        s64 steal = 0, irq_delta = 0;
1952#endif
1953#ifdef CONFIG_IRQ_TIME_ACCOUNTING
1954        irq_delta = irq_time_read(cpu_of(rq)) - rq->prev_irq_time;
1955
1956        /*
1957         * Since irq_time is only updated on {soft,}irq_exit, we might run into
1958         * this case when a previous update_rq_clock() happened inside a
1959         * {soft,}irq region.
1960         *
1961         * When this happens, we stop ->clock_task and only update the
1962         * prev_irq_time stamp to account for the part that fit, so that a next
1963         * update will consume the rest. This ensures ->clock_task is
1964         * monotonic.
1965         *
1966         * It does however cause some slight miss-attribution of {soft,}irq
1967         * time, a more accurate solution would be to update the irq_time using
1968         * the current rq->clock timestamp, except that would require using
1969         * atomic ops.
1970         */
1971        if (irq_delta > delta)
1972                irq_delta = delta;
1973
1974        rq->prev_irq_time += irq_delta;
1975        delta -= irq_delta;
1976#endif
1977#ifdef CONFIG_PARAVIRT_TIME_ACCOUNTING
1978        if (static_branch((&paravirt_steal_rq_enabled))) {
1979                u64 st;
1980
1981                steal = paravirt_steal_clock(cpu_of(rq));
1982                steal -= rq->prev_steal_time_rq;
1983
1984                if (unlikely(steal > delta))
1985                        steal = delta;
1986
1987                st = steal_ticks(steal);
1988                steal = st * TICK_NSEC;
1989
1990                rq->prev_steal_time_rq += steal;
1991
1992                delta -= steal;
1993        }
1994#endif
1995
1996        rq->clock_task += delta;
1997
1998#if defined(CONFIG_IRQ_TIME_ACCOUNTING) || defined(CONFIG_PARAVIRT_TIME_ACCOUNTING)
1999        if ((irq_delta + steal) && sched_feat(NONTASK_POWER))
2000                sched_rt_avg_update(rq, irq_delta + steal);
2001#endif
2002}
2003
2004#ifdef CONFIG_IRQ_TIME_ACCOUNTING
2005static int irqtime_account_hi_update(void)
2006{
2007        struct cpu_usage_stat *cpustat = &kstat_this_cpu.cpustat;
2008        unsigned long flags;
2009        u64 latest_ns;
2010        int ret = 0;
2011
2012        local_irq_save(flags);
2013        latest_ns = this_cpu_read(cpu_hardirq_time);
2014        if (cputime64_gt(nsecs_to_cputime64(latest_ns), cpustat->irq))
2015                ret = 1;
2016        local_irq_restore(flags);
2017        return ret;
2018}
2019
2020static int irqtime_account_si_update(void)
2021{
2022        struct cpu_usage_stat *cpustat = &kstat_this_cpu.cpustat;
2023        unsigned long flags;
2024        u64 latest_ns;
2025        int ret = 0;
2026
2027        local_irq_save(flags);
2028        latest_ns = this_cpu_read(cpu_softirq_time);
2029        if (cputime64_gt(nsecs_to_cputime64(latest_ns), cpustat->softirq))
2030                ret = 1;
2031        local_irq_restore(flags);
2032        return ret;
2033}
2034
2035#else /* CONFIG_IRQ_TIME_ACCOUNTING */
2036
2037#define sched_clock_irqtime     (0)
2038
2039#endif
2040
2041#include "sched_idletask.c"
2042#include "sched_fair.c"
2043#include "sched_rt.c"
2044#include "sched_autogroup.c"
2045#include "sched_stoptask.c"
2046#ifdef CONFIG_SCHED_DEBUG
2047# include "sched_debug.c"
2048#endif
2049
2050void sched_set_stop_task(int cpu, struct task_struct *stop)
2051{
2052        struct sched_param param = { .sched_priority = MAX_RT_PRIO - 1 };
2053        struct task_struct *old_stop = cpu_rq(cpu)->stop;
2054
2055        if (stop) {
2056                /*
2057                 * Make it appear like a SCHED_FIFO task, its something
2058                 * userspace knows about and won't get confused about.
2059                 *
2060                 * Also, it will make PI more or less work without too
2061                 * much confusion -- but then, stop work should not
2062                 * rely on PI working anyway.
2063                 */
2064                sched_setscheduler_nocheck(stop, SCHED_FIFO, &param);
2065
2066                stop->sched_class = &stop_sched_class;
2067        }
2068
2069        cpu_rq(cpu)->stop = stop;
2070
2071        if (old_stop) {
2072                /*
2073                 * Reset it back to a normal scheduling class so that
2074                 * it can die in pieces.
2075                 */
2076                old_stop->sched_class = &rt_sched_class;
2077        }
2078}
2079
2080/*
2081 * __normal_prio - return the priority that is based on the static prio
2082 */
2083static inline int __normal_prio(struct task_struct *p)
2084{
2085        return p->static_prio;
2086}
2087
2088/*
2089 * Calculate the expected normal priority: i.e. priority
2090 * without taking RT-inheritance into account. Might be
2091 * boosted by interactivity modifiers. Changes upon fork,
2092 * setprio syscalls, and whenever the interactivity
2093 * estimator recalculates.
2094 */
2095static inline int normal_prio(struct task_struct *p)
2096{
2097        int prio;
2098
2099        if (task_has_rt_policy(p))
2100                prio = MAX_RT_PRIO-1 - p->rt_priority;
2101        else
2102                prio = __normal_prio(p);
2103        return prio;
2104}
2105
2106/*
2107 * Calculate the current priority, i.e. the priority
2108 * taken into account by the scheduler. This value might
2109 * be boosted by RT tasks, or might be boosted by
2110 * interactivity modifiers. Will be RT if the task got
2111 * RT-boosted. If not then it returns p->normal_prio.
2112 */
2113static int effective_prio(struct task_struct *p)
2114{
2115        p->normal_prio = normal_prio(p);
2116        /*
2117         * If we are RT tasks or we were boosted to RT priority,
2118         * keep the priority unchanged. Otherwise, update priority
2119         * to the normal priority:
2120         */
2121        if (!rt_prio(p->prio))
2122                return p->normal_prio;
2123        return p->prio;
2124}
2125
2126/**
2127 * task_curr - is this task currently executing on a CPU?
2128 * @p: the task in question.
2129 */
2130inline int task_curr(const struct task_struct *p)
2131{
2132        return cpu_curr(task_cpu(p)) == p;
2133}
2134
2135static inline void check_class_changed(struct rq *rq, struct task_struct *p,
2136                                       const struct sched_class *prev_class,
2137                                       int oldprio)
2138{
2139        if (prev_class != p->sched_class) {
2140                if (prev_class->switched_from)
2141                        prev_class->switched_from(rq, p);
2142                p->sched_class->switched_to(rq, p);
2143        } else if (oldprio != p->prio)
2144                p->sched_class->prio_changed(rq, p, oldprio);
2145}
2146
2147static void check_preempt_curr(struct rq *rq, struct task_struct *p, int flags)
2148{
2149        const struct sched_class *class;
2150
2151        if (p->sched_class == rq->curr->sched_class) {
2152                rq->curr->sched_class->check_preempt_curr(rq, p, flags);
2153        } else {
2154                for_each_class(class) {
2155                        if (class == rq->curr->sched_class)
2156                                break;
2157                        if (class == p->sched_class) {
2158                                resched_task(rq->curr);
2159                                break;
2160                        }
2161                }
2162        }
2163
2164        /*
2165         * A queue event has occurred, and we're going to schedule.  In
2166         * this case, we can save a useless back to back clock update.
2167         */
2168        if (rq->curr->on_rq && test_tsk_need_resched(rq->curr))
2169                rq->skip_clock_update = 1;
2170}
2171
2172#ifdef CONFIG_SMP
2173/*
2174 * Is this task likely cache-hot:
2175 */
2176static int
2177task_hot(struct task_struct *p, u64 now, struct sched_domain *sd)
2178{
2179        s64 delta;
2180
2181        if (p->sched_class != &fair_sched_class)
2182                return 0;
2183
2184        if (unlikely(p->policy == SCHED_IDLE))
2185                return 0;
2186
2187        /*
2188         * Buddy candidates are cache hot:
2189         */
2190        if (sched_feat(CACHE_HOT_BUDDY) && this_rq()->nr_running &&
2191                        (&p->se == cfs_rq_of(&p->se)->next ||
2192                         &p->se == cfs_rq_of(&p->se)->last))
2193                return 1;
2194
2195        if (sysctl_sched_migration_cost == -1)
2196                return 1;
2197        if (sysctl_sched_migration_cost == 0)
2198                return 0;
2199
2200        delta = now - p->se.exec_start;
2201
2202        return delta < (s64)sysctl_sched_migration_cost;
2203}
2204
2205void set_task_cpu(struct task_struct *p, unsigned int new_cpu)
2206{
2207#ifdef CONFIG_SCHED_DEBUG
2208        /*
2209         * We should never call set_task_cpu() on a blocked task,
2210         * ttwu() will sort out the placement.
2211         */
2212        WARN_ON_ONCE(p->state != TASK_RUNNING && p->state != TASK_WAKING &&
2213                        !(task_thread_info(p)->preempt_count & PREEMPT_ACTIVE));
2214
2215#ifdef CONFIG_LOCKDEP
2216        /*
2217         * The caller should hold either p->pi_lock or rq->lock, when changing
2218         * a task's CPU. ->pi_lock for waking tasks, rq->lock for runnable tasks.
2219         *
2220         * sched_move_task() holds both and thus holding either pins the cgroup,
2221         * see set_task_rq().
2222         *
2223         * Furthermore, all task_rq users should acquire both locks, see
2224         * task_rq_lock().
2225         */
2226        WARN_ON_ONCE(debug_locks && !(lockdep_is_held(&p->pi_lock) ||
2227                                      lockdep_is_held(&task_rq(p)->lock)));
2228#endif
2229#endif
2230
2231        trace_sched_migrate_task(p, new_cpu);
2232
2233        if (task_cpu(p) != new_cpu) {
2234                p->se.nr_migrations++;
2235                perf_sw_event(PERF_COUNT_SW_CPU_MIGRATIONS, 1, NULL, 0);
2236        }
2237
2238        __set_task_cpu(p, new_cpu);
2239}
2240
2241struct migration_arg {
2242        struct task_struct *task;
2243        int dest_cpu;
2244};
2245
2246static int migration_cpu_stop(void *data);
2247
2248/*
2249 * wait_task_inactive - wait for a thread to unschedule.
2250 *
2251 * If @match_state is nonzero, it's the @p->state value just checked and
2252 * not expected to change.  If it changes, i.e. @p might have woken up,
2253 * then return zero.  When we succeed in waiting for @p to be off its CPU,
2254 * we return a positive number (its total switch count).  If a second call
2255 * a short while later returns the same number, the caller can be sure that
2256 * @p has remained unscheduled the whole time.
2257 *
2258 * The caller must ensure that the task *will* unschedule sometime soon,
2259 * else this function might spin for a *long* time. This function can't
2260 * be called with interrupts off, or it may introduce deadlock with
2261 * smp_call_function() if an IPI is sent by the same process we are
2262 * waiting to become inactive.
2263 */
2264unsigned long wait_task_inactive(struct task_struct *p, long match_state)
2265{
2266        unsigned long flags;
2267        int running, on_rq;
2268        unsigned long ncsw;
2269        struct rq *rq;
2270
2271        for (;;) {
2272                /*
2273                 * We do the initial early heuristics without holding
2274                 * any task-queue locks at all. We'll only try to get
2275                 * the runqueue lock when things look like they will
2276                 * work out!
2277                 */
2278                rq = task_rq(p);
2279
2280                /*
2281                 * If the task is actively running on another CPU
2282                 * still, just relax and busy-wait without holding
2283                 * any locks.
2284                 *
2285                 * NOTE! Since we don't hold any locks, it's not
2286                 * even sure that "rq" stays as the right runqueue!
2287                 * But we don't care, since "task_running()" will
2288                 * return false if the runqueue has changed and p
2289                 * is actually now running somewhere else!
2290                 */
2291                while (task_running(rq, p)) {
2292                        if (match_state && unlikely(p->state != match_state))
2293                                return 0;
2294                        cpu_relax();
2295                }
2296
2297                /*
2298                 * Ok, time to look more closely! We need the rq
2299                 * lock now, to be *sure*. If we're wrong, we'll
2300                 * just go back and repeat.
2301                 */
2302                rq = task_rq_lock(p, &flags);
2303                trace_sched_wait_task(p);
2304                running = task_running(rq, p);
2305                on_rq = p->on_rq;
2306                ncsw = 0;
2307                if (!match_state || p->state == match_state)
2308                        ncsw = p->nvcsw | LONG_MIN; /* sets MSB */
2309                task_rq_unlock(rq, p, &flags);
2310
2311                /*
2312                 * If it changed from the expected state, bail out now.
2313                 */
2314                if (unlikely(!ncsw))
2315                        break;
2316
2317                /*
2318                 * Was it really running after all now that we
2319                 * checked with the proper locks actually held?
2320                 *
2321                 * Oops. Go back and try again..
2322                 */
2323                if (unlikely(running)) {
2324                        cpu_relax();
2325                        continue;
2326                }
2327
2328                /*
2329                 * It's not enough that it's not actively running,
2330                 * it must be off the runqueue _entirely_, and not
2331                 * preempted!
2332                 *
2333                 * So if it was still runnable (but just not actively
2334                 * running right now), it's preempted, and we should
2335                 * yield - it could be a while.
2336                 */
2337                if (unlikely(on_rq)) {
2338                        ktime_t to = ktime_set(0, NSEC_PER_SEC/HZ);
2339
2340                        set_current_state(TASK_UNINTERRUPTIBLE);
2341                        schedule_hrtimeout(&to, HRTIMER_MODE_REL);
2342                        continue;
2343                }
2344
2345                /*
2346                 * Ahh, all good. It wasn't running, and it wasn't
2347                 * runnable, which means that it will never become
2348                 * running in the future either. We're all done!
2349                 */
2350                break;
2351        }
2352
2353        return ncsw;
2354}
2355
2356/***
2357 * kick_process - kick a running thread to enter/exit the kernel
2358 * @p: the to-be-kicked thread
2359 *
2360 * Cause a process which is running on another CPU to enter
2361 * kernel-mode, without any delay. (to get signals handled.)
2362 *
2363 * NOTE: this function doesn't have to take the runqueue lock,
2364 * because all it wants to ensure is that the remote task enters
2365 * the kernel. If the IPI races and the task has been migrated
2366 * to another CPU then no harm is done and the purpose has been
2367 * achieved as well.
2368 */
2369void kick_process(struct task_struct *p)
2370{
2371        int cpu;
2372
2373        preempt_disable();
2374        cpu = task_cpu(p);
2375        if ((cpu != smp_processor_id()) && task_curr(p))
2376                smp_send_reschedule(cpu);
2377        preempt_enable();
2378}
2379EXPORT_SYMBOL_GPL(kick_process);
2380#endif /* CONFIG_SMP */
2381
2382#ifdef CONFIG_SMP
2383/*
2384 * ->cpus_allowed is protected by both rq->lock and p->pi_lock
2385 */
2386static int select_fallback_rq(int cpu, struct task_struct *p)
2387{
2388        int dest_cpu;
2389        const struct cpumask *nodemask = cpumask_of_node(cpu_to_node(cpu));
2390
2391        /* Look for allowed, online CPU in same node. */
2392        for_each_cpu_and(dest_cpu, nodemask, cpu_active_mask)
2393                if (cpumask_test_cpu(dest_cpu, &p->cpus_allowed))
2394                        return dest_cpu;
2395
2396        /* Any allowed, online CPU? */
2397        dest_cpu = cpumask_any_and(&p->cpus_allowed, cpu_active_mask);
2398        if (dest_cpu < nr_cpu_ids)
2399                return dest_cpu;
2400
2401        /* No more Mr. Nice Guy. */
2402        dest_cpu = cpuset_cpus_allowed_fallback(p);
2403        /*
2404         * Don't tell them about moving exiting tasks or
2405         * kernel threads (both mm NULL), since they never
2406         * leave kernel.
2407         */
2408        if (p->mm && printk_ratelimit()) {
2409                printk(KERN_INFO "process %d (%s) no longer affine to cpu%d\n",
2410                                task_pid_nr(p), p->comm, cpu);
2411        }
2412
2413        return dest_cpu;
2414}
2415
2416/*
2417 * The caller (fork, wakeup) owns p->pi_lock, ->cpus_allowed is stable.
2418 */
2419static inline
2420int select_task_rq(struct task_struct *p, int sd_flags, int wake_flags)
2421{
2422        int cpu = p->sched_class->select_task_rq(p, sd_flags, wake_flags);
2423
2424        /*
2425         * In order not to call set_task_cpu() on a blocking task we need
2426         * to rely on ttwu() to place the task on a valid ->cpus_allowed
2427         * cpu.
2428         *
2429         * Since this is common to all placement strategies, this lives here.
2430         *
2431         * [ this allows ->select_task() to simply return task_cpu(p) and
2432         *   not worry about this generic constraint ]
2433         */
2434        if (unlikely(!cpumask_test_cpu(cpu, &p->cpus_allowed) ||
2435                     !cpu_online(cpu)))
2436                cpu = select_fallback_rq(task_cpu(p), p);
2437
2438        return cpu;
2439}
2440
2441static void update_avg(u64 *avg, u64 sample)
2442{
2443        s64 diff = sample - *avg;
2444        *avg += diff >> 3;
2445}
2446#endif
2447
2448static void
2449ttwu_stat(struct task_struct *p, int cpu, int wake_flags)
2450{
2451#ifdef CONFIG_SCHEDSTATS
2452        struct rq *rq = this_rq();
2453
2454#ifdef CONFIG_SMP
2455        int this_cpu = smp_processor_id();
2456
2457        if (cpu == this_cpu) {
2458                schedstat_inc(rq, ttwu_local);
2459                schedstat_inc(p, se.statistics.nr_wakeups_local);
2460        } else {
2461                struct sched_domain *sd;
2462
2463                schedstat_inc(p, se.statistics.nr_wakeups_remote);
2464                rcu_read_lock();
2465                for_each_domain(this_cpu, sd) {
2466                        if (cpumask_test_cpu(cpu, sched_domain_span(sd))) {
2467                                schedstat_inc(sd, ttwu_wake_remote);
2468                                break;
2469                        }
2470                }
2471                rcu_read_unlock();
2472        }
2473
2474        if (wake_flags & WF_MIGRATED)
2475                schedstat_inc(p, se.statistics.nr_wakeups_migrate);
2476
2477#endif /* CONFIG_SMP */
2478
2479        schedstat_inc(rq, ttwu_count);
2480        schedstat_inc(p, se.statistics.nr_wakeups);
2481
2482        if (wake_flags & WF_SYNC)
2483                schedstat_inc(p, se.statistics.nr_wakeups_sync);
2484
2485#endif /* CONFIG_SCHEDSTATS */
2486}
2487
2488static void ttwu_activate(struct rq *rq, struct task_struct *p, int en_flags)
2489{
2490        activate_task(rq, p, en_flags);
2491        p->on_rq = 1;
2492
2493        /* if a worker is waking up, notify workqueue */
2494        if (p->flags & PF_WQ_WORKER)
2495                wq_worker_waking_up(p, cpu_of(rq));
2496}
2497
2498/*
2499 * Mark the task runnable and perform wakeup-preemption.
2500 */
2501static void
2502ttwu_do_wakeup(struct rq *rq, struct task_struct *p, int wake_flags)
2503{
2504        trace_sched_wakeup(p, true);
2505        check_preempt_curr(rq, p, wake_flags);
2506
2507        p->state = TASK_RUNNING;
2508#ifdef CONFIG_SMP
2509        if (p->sched_class->task_woken)
2510                p->sched_class->task_woken(rq, p);
2511
2512        if (rq->idle_stamp) {
2513                u64 delta = rq->clock - rq->idle_stamp;
2514                u64 max = 2*sysctl_sched_migration_cost;
2515
2516                if (delta > max)
2517                        rq->avg_idle = max;
2518                else
2519                        update_avg(&rq->avg_idle, delta);
2520                rq->idle_stamp = 0;
2521        }
2522#endif
2523}
2524
2525static void
2526ttwu_do_activate(struct rq *rq, struct task_struct *p, int wake_flags)
2527{
2528#ifdef CONFIG_SMP
2529        if (p->sched_contributes_to_load)
2530                rq->nr_uninterruptible--;
2531#endif
2532
2533        ttwu_activate(rq, p, ENQUEUE_WAKEUP | ENQUEUE_WAKING);
2534        ttwu_do_wakeup(rq, p, wake_flags);
2535}
2536
2537/*
2538 * Called in case the task @p isn't fully descheduled from its runqueue,
2539 * in this case we must do a remote wakeup. Its a 'light' wakeup though,
2540 * since all we need to do is flip p->state to TASK_RUNNING, since
2541 * the task is still ->on_rq.
2542 */
2543static int ttwu_remote(struct task_struct *p, int wake_flags)
2544{
2545        struct rq *rq;
2546        int ret = 0;
2547
2548        rq = __task_rq_lock(p);
2549        if (p->on_rq) {
2550                ttwu_do_wakeup(rq, p, wake_flags);
2551                ret = 1;
2552        }
2553        __task_rq_unlock(rq);
2554
2555        return ret;
2556}
2557
2558#ifdef CONFIG_SMP
2559static void sched_ttwu_do_pending(struct task_struct *list)
2560{
2561        struct rq *rq = this_rq();
2562
2563        raw_spin_lock(&rq->lock);
2564
2565        while (list) {
2566                struct task_struct *p = list;
2567                list = list->wake_entry;
2568                ttwu_do_activate(rq, p, 0);
2569        }
2570
2571        raw_spin_unlock(&rq->lock);
2572}
2573
2574#ifdef CONFIG_HOTPLUG_CPU
2575
2576static void sched_ttwu_pending(void)
2577{
2578        struct rq *rq = this_rq();
2579        struct task_struct *list = xchg(&rq->wake_list, NULL);
2580
2581        if (!list)
2582                return;
2583
2584        sched_ttwu_do_pending(list);
2585}
2586
2587#endif /* CONFIG_HOTPLUG_CPU */
2588
2589void scheduler_ipi(void)
2590{
2591        struct rq *rq = this_rq();
2592        struct task_struct *list = xchg(&rq->wake_list, NULL);
2593
2594        if (!list)
2595                return;
2596
2597        /*
2598         * Not all reschedule IPI handlers call irq_enter/irq_exit, since
2599         * traditionally all their work was done from the interrupt return
2600         * path. Now that we actually do some work, we need to make sure
2601         * we do call them.
2602         *
2603         * Some archs already do call them, luckily irq_enter/exit nest
2604         * properly.
2605         *
2606         * Arguably we should visit all archs and update all handlers,
2607         * however a fair share of IPIs are still resched only so this would
2608         * somewhat pessimize the simple resched case.
2609         */
2610        irq_enter();
2611        sched_ttwu_do_pending(list);
2612        irq_exit();
2613}
2614
2615static void ttwu_queue_remote(struct task_struct *p, int cpu)
2616{
2617        struct rq *rq = cpu_rq(cpu);
2618        struct task_struct *next = rq->wake_list;
2619
2620        for (;;) {
2621                struct task_struct *old = next;
2622
2623                p->wake_entry = next;
2624                next = cmpxchg(&rq->wake_list, old, p);
2625                if (next == old)
2626                        break;
2627        }
2628
2629        if (!next)
2630                smp_send_reschedule(cpu);
2631}
2632
2633#ifdef __ARCH_WANT_INTERRUPTS_ON_CTXSW
2634static int ttwu_activate_remote(struct task_struct *p, int wake_flags)
2635{
2636        struct rq *rq;
2637        int ret = 0;
2638
2639        rq = __task_rq_lock(p);
2640        if (p->on_cpu) {
2641                ttwu_activate(rq, p, ENQUEUE_WAKEUP);
2642                ttwu_do_wakeup(rq, p, wake_flags);
2643                ret = 1;
2644        }
2645        __task_rq_unlock(rq);
2646
2647        return ret;
2648
2649}
2650#endif /* __ARCH_WANT_INTERRUPTS_ON_CTXSW */
2651#endif /* CONFIG_SMP */
2652
2653static void ttwu_queue(struct task_struct *p, int cpu)
2654{
2655        struct rq *rq = cpu_rq(cpu);
2656
2657#if defined(CONFIG_SMP)
2658        if (sched_feat(TTWU_QUEUE) && cpu != smp_processor_id()) {
2659                sched_clock_cpu(cpu); /* sync clocks x-cpu */
2660                ttwu_queue_remote(p, cpu);
2661                return;
2662        }
2663#endif
2664
2665        raw_spin_lock(&rq->lock);
2666        ttwu_do_activate(rq, p, 0);
2667        raw_spin_unlock(&rq->lock);
2668}
2669
2670/**
2671 * try_to_wake_up - wake up a thread
2672 * @p: the thread to be awakened
2673 * @state: the mask of task states that can be woken
2674 * @wake_flags: wake modifier flags (WF_*)
2675 *
2676 * Put it on the run-queue if it's not already there. The "current"
2677 * thread is always on the run-queue (except when the actual
2678 * re-schedule is in progress), and as such you're allowed to do
2679 * the simpler "current->state = TASK_RUNNING" to mark yourself
2680 * runnable without the overhead of this.
2681 *
2682 * Returns %true if @p was woken up, %false if it was already running
2683 * or @state didn't match @p's state.
2684 */
2685static int
2686try_to_wake_up(struct task_struct *p, unsigned int state, int wake_flags)
2687{
2688        unsigned long flags;
2689        int cpu, success = 0;
2690
2691        smp_wmb();
2692        raw_spin_lock_irqsave(&p->pi_lock, flags);
2693        if (!(p->state & state))
2694                goto out;
2695
2696        success = 1; /* we're going to change ->state */
2697        cpu = task_cpu(p);
2698
2699        if (p->on_rq && ttwu_remote(p, wake_flags))
2700                goto stat;
2701
2702#ifdef CONFIG_SMP
2703        /*
2704         * If the owning (remote) cpu is still in the middle of schedule() with
2705         * this task as prev, wait until its done referencing the task.
2706         */
2707        while (p->on_cpu) {
2708#ifdef __ARCH_WANT_INTERRUPTS_ON_CTXSW
2709                /*
2710                 * In case the architecture enables interrupts in
2711                 * context_switch(), we cannot busy wait, since that
2712                 * would lead to deadlocks when an interrupt hits and
2713                 * tries to wake up @prev. So bail and do a complete
2714                 * remote wakeup.
2715                 */
2716                if (ttwu_activate_remote(p, wake_flags))
2717                        goto stat;
2718#else
2719                cpu_relax();
2720#endif
2721        }
2722        /*
2723         * Pairs with the smp_wmb() in finish_lock_switch().
2724         */
2725        smp_rmb();
2726
2727        p->sched_contributes_to_load = !!task_contributes_to_load(p);
2728        p->state = TASK_WAKING;
2729
2730        if (p->sched_class->task_waking)
2731                p->sched_class->task_waking(p);
2732
2733        cpu = select_task_rq(p, SD_BALANCE_WAKE, wake_flags);
2734        if (task_cpu(p) != cpu) {
2735                wake_flags |= WF_MIGRATED;
2736                set_task_cpu(p, cpu);
2737        }
2738#endif /* CONFIG_SMP */
2739
2740        ttwu_queue(p, cpu);
2741stat:
2742        ttwu_stat(p, cpu, wake_flags);
2743out:
2744        raw_spin_unlock_irqrestore(&p->pi_lock, flags);
2745
2746        return success;
2747}
2748
2749/**
2750 * try_to_wake_up_local - try to wake up a local task with rq lock held
2751 * @p: the thread to be awakened
2752 *
2753 * Put @p on the run-queue if it's not already there. The caller must
2754 * ensure that this_rq() is locked, @p is bound to this_rq() and not
2755 * the current task.
2756 */
2757static void try_to_wake_up_local(struct task_struct *p)
2758{
2759        struct rq *rq = task_rq(p);
2760
2761        BUG_ON(rq != this_rq());
2762        BUG_ON(p == current);
2763        lockdep_assert_held(&rq->lock);
2764
2765        if (!raw_spin_trylock(&p->pi_lock)) {
2766                raw_spin_unlock(&rq->lock);
2767                raw_spin_lock(&p->pi_lock);
2768                raw_spin_lock(&rq->lock);
2769        }
2770
2771        if (!(p->state & TASK_NORMAL))
2772                goto out;
2773
2774        if (!p->on_rq)
2775                ttwu_activate(rq, p, ENQUEUE_WAKEUP);
2776
2777        ttwu_do_wakeup(rq, p, 0);
2778        ttwu_stat(p, smp_processor_id(), 0);
2779out:
2780        raw_spin_unlock(&p->pi_lock);
2781}
2782
2783/**
2784 * wake_up_process - Wake up a specific process
2785 * @p: The process to be woken up.
2786 *
2787 * Attempt to wake up the nominated process and move it to the set of runnable
2788 * processes.  Returns 1 if the process was woken up, 0 if it was already
2789 * running.
2790 *
2791 * It may be assumed that this function implies a write memory barrier before
2792 * changing the task state if and only if any tasks are woken up.
2793 */
2794int wake_up_process(struct task_struct *p)
2795{
2796        return try_to_wake_up(p, TASK_ALL, 0);
2797}
2798EXPORT_SYMBOL(wake_up_process);
2799
2800int wake_up_state(struct task_struct *p, unsigned int state)
2801{
2802        return try_to_wake_up(p, state, 0);
2803}
2804
2805/*
2806 * Perform scheduler related setup for a newly forked process p.
2807 * p is forked by current.
2808 *
2809 * __sched_fork() is basic setup used by init_idle() too:
2810 */
2811static void __sched_fork(struct task_struct *p)
2812{
2813        p->on_rq                        = 0;
2814
2815        p->se.on_rq                     = 0;
2816        p->se.exec_start                = 0;
2817        p->se.sum_exec_runtime          = 0;
2818        p->se.prev_sum_exec_runtime     = 0;
2819        p->se.nr_migrations             = 0;
2820        p->se.vruntime                  = 0;
2821        INIT_LIST_HEAD(&p->se.group_node);
2822
2823#ifdef CONFIG_SCHEDSTATS
2824        memset(&p->se.statistics, 0, sizeof(p->se.statistics));
2825#endif
2826
2827        INIT_LIST_HEAD(&p->rt.run_list);
2828
2829#ifdef CONFIG_PREEMPT_NOTIFIERS
2830        INIT_HLIST_HEAD(&p->preempt_notifiers);
2831#endif
2832}
2833
2834/*
2835 * fork()/clone()-time setup:
2836 */
2837void sched_fork(struct task_struct *p)
2838{
2839        unsigned long flags;
2840        int cpu = get_cpu();
2841
2842        __sched_fork(p);
2843        /*
2844         * We mark the process as running here. This guarantees that
2845         * nobody will actually run it, and a signal or other external
2846         * event cannot wake it up and insert it on the runqueue either.
2847         */
2848        p->state = TASK_RUNNING;
2849
2850        /*
2851         * Revert to default priority/policy on fork if requested.
2852         */
2853        if (unlikely(p->sched_reset_on_fork)) {
2854                if (p->policy == SCHED_FIFO || p->policy == SCHED_RR) {
2855                        p->policy = SCHED_NORMAL;
2856                        p->normal_prio = p->static_prio;
2857                }
2858
2859                if (PRIO_TO_NICE(p->static_prio) < 0) {
2860                        p->static_prio = NICE_TO_PRIO(0);
2861                        p->normal_prio = p->static_prio;
2862                        set_load_weight(p);
2863                }
2864
2865                /*
2866                 * We don't need the reset flag anymore after the fork. It has
2867                 * fulfilled its duty:
2868                 */
2869                p->sched_reset_on_fork = 0;
2870        }
2871
2872        /*
2873         * Make sure we do not leak PI boosting priority to the child.
2874         */
2875        p->prio = current->normal_prio;
2876
2877        if (!rt_prio(p->prio))
2878                p->sched_class = &fair_sched_class;
2879
2880        if (p->sched_class->task_fork)
2881                p->sched_class->task_fork(p);
2882
2883        /*
2884         * The child is not yet in the pid-hash so no cgroup attach races,
2885         * and the cgroup is pinned to this child due to cgroup_fork()
2886         * is ran before sched_fork().
2887         *
2888         * Silence PROVE_RCU.
2889         */
2890        raw_spin_lock_irqsave(&p->pi_lock, flags);
2891        set_task_cpu(p, cpu);
2892        raw_spin_unlock_irqrestore(&p->pi_lock, flags);
2893
2894#if defined(CONFIG_SCHEDSTATS) || defined(CONFIG_TASK_DELAY_ACCT)
2895        if (likely(sched_info_on()))
2896                memset(&p->sched_info, 0, sizeof(p->sched_info));
2897#endif
2898#if defined(CONFIG_SMP)
2899        p->on_cpu = 0;
2900#endif
2901#ifdef CONFIG_PREEMPT_COUNT
2902        /* Want to start with kernel preemption disabled. */
2903        task_thread_info(p)->preempt_count = 1;
2904#endif
2905#ifdef CONFIG_SMP
2906        plist_node_init(&p->pushable_tasks, MAX_PRIO);
2907#endif
2908
2909        put_cpu();
2910}
2911
2912/*
2913 * wake_up_new_task - wake up a newly created task for the first time.
2914 *
2915 * This function will do some initial scheduler statistics housekeeping
2916 * that must be done for every newly created context, then puts the task
2917 * on the runqueue and wakes it.
2918 */
2919void wake_up_new_task(struct task_struct *p)
2920{
2921        unsigned long flags;
2922        struct rq *rq;
2923
2924        raw_spin_lock_irqsave(&p->pi_lock, flags);
2925#ifdef CONFIG_SMP
2926        /*
2927         * Fork balancing, do it here and not earlier because:
2928         *  - cpus_allowed can change in the fork path
2929         *  - any previously selected cpu might disappear through hotplug
2930         */
2931        set_task_cpu(p, select_task_rq(p, SD_BALANCE_FORK, 0));
2932#endif
2933
2934        rq = __task_rq_lock(p);
2935        activate_task(rq, p, 0);
2936        p->on_rq = 1;
2937        trace_sched_wakeup_new(p, true);
2938        check_preempt_curr(rq, p, WF_FORK);
2939#ifdef CONFIG_SMP
2940        if (p->sched_class->task_woken)
2941                p->sched_class->task_woken(rq, p);
2942#endif
2943        task_rq_unlock(rq, p, &flags);
2944}
2945
2946#ifdef CONFIG_PREEMPT_NOTIFIERS
2947
2948/**
2949 * preempt_notifier_register - tell me when current is being preempted & rescheduled
2950 * @notifier: notifier struct to register
2951 */
2952void preempt_notifier_register(struct preempt_notifier *notifier)
2953{
2954        hlist_add_head(&notifier->link, &current->preempt_notifiers);
2955}
2956EXPORT_SYMBOL_GPL(preempt_notifier_register);
2957
2958/**
2959 * preempt_notifier_unregister - no longer interested in preemption notifications
2960 * @notifier: notifier struct to unregister
2961 *
2962 * This is safe to call from within a preemption notifier.
2963 */
2964void preempt_notifier_unregister(struct preempt_notifier *notifier)
2965{
2966        hlist_del(&notifier->link);
2967}
2968EXPORT_SYMBOL_GPL(preempt_notifier_unregister);
2969
2970static void fire_sched_in_preempt_notifiers(struct task_struct *curr)
2971{
2972        struct preempt_notifier *notifier;
2973        struct hlist_node *node;
2974
2975        hlist_for_each_entry(notifier, node, &curr->preempt_notifiers, link)
2976                notifier->ops->sched_in(notifier, raw_smp_processor_id());
2977}
2978
2979static void
2980fire_sched_out_preempt_notifiers(struct task_struct *curr,
2981                                 struct task_struct *next)
2982{
2983        struct preempt_notifier *notifier;
2984        struct hlist_node *node;
2985
2986        hlist_for_each_entry(notifier, node, &curr->preempt_notifiers, link)
2987                notifier->ops->sched_out(notifier, next);
2988}
2989
2990#else /* !CONFIG_PREEMPT_NOTIFIERS */
2991
2992static void fire_sched_in_preempt_notifiers(struct task_struct *curr)
2993{
2994}
2995
2996static void
2997fire_sched_out_preempt_notifiers(struct task_struct *curr,
2998                                 struct task_struct *next)
2999{
3000}
3001
3002#endif /* CONFIG_PREEMPT_NOTIFIERS */
3003
3004/**
3005 * prepare_task_switch - prepare to switch tasks
3006 * @rq: the runqueue preparing to switch
3007 * @prev: the current task that is being switched out
3008 * @next: the task we are going to switch to.
3009 *
3010 * This is called with the rq lock held and interrupts off. It must
3011 * be paired with a subsequent finish_task_switch after the context
3012 * switch.
3013 *
3014 * prepare_task_switch sets up locking and calls architecture specific
3015 * hooks.
3016 */
3017static inline void
3018prepare_task_switch(struct rq *rq, struct task_struct *prev,
3019                    struct task_struct *next)
3020{
3021        sched_info_switch(prev, next);
3022        perf_event_task_sched_out(prev, next);
3023        fire_sched_out_preempt_notifiers(prev, next);
3024        prepare_lock_switch(rq, next);
3025        prepare_arch_switch(next);
3026        trace_sched_switch(prev, next);
3027}
3028
3029/**
3030 * finish_task_switch - clean up after a task-switch
3031 * @rq: runqueue associated with task-switch
3032 * @prev: the thread we just switched away from.
3033 *
3034 * finish_task_switch must be called after the context switch, paired
3035 * with a prepare_task_switch call before the context switch.
3036 * finish_task_switch will reconcile locking set up by prepare_task_switch,
3037 * and do any other architecture-specific cleanup actions.
3038 *
3039 * Note that we may have delayed dropping an mm in context_switch(). If
3040 * so, we finish that here outside of the runqueue lock. (Doing it
3041 * with the lock held can cause deadlocks; see schedule() for
3042 * details.)
3043 */
3044static void finish_task_switch(struct rq *rq, struct task_struct *prev)
3045        __releases(rq->lock)
3046{
3047        struct mm_struct *mm = rq->prev_mm;
3048        long prev_state;
3049
3050        rq->prev_mm = NULL;
3051
3052        /*
3053         * A task struct has one reference for the use as "current".
3054         * If a task dies, then it sets TASK_DEAD in tsk->state and calls
3055         * schedule one last time. The schedule call will never return, and
3056         * the scheduled task must drop that reference.
3057         * The test for TASK_DEAD must occur while the runqueue locks are
3058         * still held, otherwise prev could be scheduled on another cpu, die
3059         * there before we look at prev->state, and then the reference would
3060         * be dropped twice.
3061         *              Manfred Spraul <manfred@colorfullife.com>
3062         */
3063        prev_state = prev->state;
3064        finish_arch_switch(prev);
3065#ifdef __ARCH_WANT_INTERRUPTS_ON_CTXSW
3066        local_irq_disable();
3067#endif /* __ARCH_WANT_INTERRUPTS_ON_CTXSW */
3068        perf_event_task_sched_in(prev, current);
3069#ifdef __ARCH_WANT_INTERRUPTS_ON_CTXSW
3070        local_irq_enable();
3071#endif /* __ARCH_WANT_INTERRUPTS_ON_CTXSW */
3072        finish_lock_switch(rq, prev);
3073
3074        fire_sched_in_preempt_notifiers(current);
3075        if (mm)
3076                mmdrop(mm);
3077        if (unlikely(prev_state == TASK_DEAD)) {
3078                /*
3079                 * Remove function-return probe instances associated with this
3080                 * task and put them back on the free list.
3081                 */
3082                kprobe_flush_task(prev);
3083                put_task_struct(prev);
3084        }
3085}
3086
3087#ifdef CONFIG_SMP
3088
3089/* assumes rq->lock is held */
3090static inline void pre_schedule(struct rq *rq, struct task_struct *prev)
3091{
3092        if (prev->sched_class->pre_schedule)
3093                prev->sched_class->pre_schedule(rq, prev);
3094}
3095
3096/* rq->lock is NOT held, but preemption is disabled */
3097static inline void post_schedule(struct rq *rq)
3098{
3099        if (rq->post_schedule) {
3100                unsigned long flags;
3101
3102                raw_spin_lock_irqsave(&rq->lock, flags);
3103                if (rq->curr->sched_class->post_schedule)
3104                        rq->curr->sched_class->post_schedule(rq);
3105                raw_spin_unlock_irqrestore(&rq->lock, flags);
3106
3107                rq->post_schedule = 0;
3108        }
3109}
3110
3111#else
3112
3113static inline void pre_schedule(struct rq *rq, struct task_struct *p)
3114{
3115}
3116
3117static inline void post_schedule(struct rq *rq)
3118{
3119}
3120
3121#endif
3122
3123/**
3124 * schedule_tail - first thing a freshly forked thread must call.
3125 * @prev: the thread we just switched away from.
3126 */
3127asmlinkage void schedule_tail(struct task_struct *prev)
3128        __releases(rq->lock)
3129{
3130        struct rq *rq = this_rq();
3131
3132        finish_task_switch(rq, prev);
3133
3134        /*
3135         * FIXME: do we need to worry about rq being invalidated by the
3136         * task_switch?
3137         */
3138        post_schedule(rq);
3139
3140#ifdef __ARCH_WANT_UNLOCKED_CTXSW
3141        /* In this case, finish_task_switch does not reenable preemption */
3142        preempt_enable();
3143#endif
3144        if (current->set_child_tid)
3145                put_user(task_pid_vnr(current), current->set_child_tid);
3146}
3147
3148/*
3149 * context_switch - switch to the new MM and the new
3150 * thread's register state.
3151 */
3152static inline void
3153context_switch(struct rq *rq, struct task_struct *prev,
3154               struct task_struct *next)
3155{
3156        struct mm_struct *mm, *oldmm;
3157
3158        prepare_task_switch(rq, prev, next);
3159
3160        mm = next->mm;
3161        oldmm = prev->active_mm;
3162        /*
3163         * For paravirt, this is coupled with an exit in switch_to to
3164         * combine the page table reload and the switch backend into
3165         * one hypercall.
3166         */
3167        arch_start_context_switch(prev);
3168
3169        if (!mm) {
3170                next->active_mm = oldmm;
3171                atomic_inc(&oldmm->mm_count);
3172                enter_lazy_tlb(oldmm, next);
3173        } else
3174                switch_mm(oldmm, mm, next);
3175
3176        if (!prev->mm) {
3177                prev->active_mm = NULL;
3178                rq->prev_mm = oldmm;
3179        }
3180        /*
3181         * Since the runqueue lock will be released by the next
3182         * task (which is an invalid locking op but in the case
3183         * of the scheduler it's an obvious special-case), so we
3184         * do an early lockdep release here:
3185         */
3186#ifndef __ARCH_WANT_UNLOCKED_CTXSW
3187        spin_release(&rq->lock.dep_map, 1, _THIS_IP_);
3188#endif
3189
3190        /* Here we just switch the register state and the stack. */
3191        switch_to(prev, next, prev);
3192
3193        barrier();
3194        /*
3195         * this_rq must be evaluated again because prev may have moved
3196         * CPUs since it called schedule(), thus the 'rq' on its stack
3197         * frame will be invalid.
3198         */
3199        finish_task_switch(this_rq(), prev);
3200}
3201
3202/*
3203 * nr_running, nr_uninterruptible and nr_context_switches:
3204 *
3205 * externally visible scheduler statistics: current number of runnable
3206 * threads, current number of uninterruptible-sleeping threads, total
3207 * number of context switches performed since bootup.
3208 */
3209unsigned long nr_running(void)
3210{
3211        unsigned long i, sum = 0;
3212
3213        for_each_online_cpu(i)
3214                sum += cpu_rq(i)->nr_running;
3215
3216        return sum;
3217}
3218
3219unsigned long nr_uninterruptible(void)
3220{
3221        unsigned long i, sum = 0;
3222
3223        for_each_possible_cpu(i)
3224                sum += cpu_rq(i)->nr_uninterruptible;
3225
3226        /*
3227         * Since we read the counters lockless, it might be slightly
3228         * inaccurate. Do not allow it to go below zero though:
3229         */
3230        if (unlikely((long)sum < 0))
3231                sum = 0;
3232
3233        return sum;
3234}
3235
3236unsigned long long nr_context_switches(void)
3237{
3238        int i;
3239        unsigned long long sum = 0;
3240
3241        for_each_possible_cpu(i)
3242                sum += cpu_rq(i)->nr_switches;
3243
3244        return sum;
3245}
3246
3247unsigned long nr_iowait(void)
3248{
3249        unsigned long i, sum = 0;
3250
3251        for_each_possible_cpu(i)
3252                sum += atomic_read(&cpu_rq(i)->nr_iowait);
3253
3254        return sum;
3255}
3256
3257unsigned long nr_iowait_cpu(int cpu)
3258{
3259        struct rq *this = cpu_rq(cpu);
3260        return atomic_read(&this->nr_iowait);
3261}
3262
3263unsigned long this_cpu_load(void)
3264{
3265        struct rq *this = this_rq();
3266        return this->cpu_load[0];
3267}
3268
3269
3270/* Variables and functions for calc_load */
3271static atomic_long_t calc_load_tasks;
3272static unsigned long calc_load_update;
3273unsigned long avenrun[3];
3274EXPORT_SYMBOL(avenrun);
3275
3276static long calc_load_fold_active(struct rq *this_rq)
3277{
3278        long nr_active, delta = 0;
3279
3280        nr_active = this_rq->nr_running;
3281        nr_active += (long) this_rq->nr_uninterruptible;
3282
3283        if (nr_active != this_rq->calc_load_active) {
3284                delta = nr_active - this_rq->calc_load_active;
3285                this_rq->calc_load_active = nr_active;
3286        }
3287
3288        return delta;
3289}
3290
3291static unsigned long
3292calc_load(unsigned long load, unsigned long exp, unsigned long active)
3293{
3294        load *= exp;
3295        load += active * (FIXED_1 - exp);
3296        load += 1UL << (FSHIFT - 1);
3297        return load >> FSHIFT;
3298}
3299
3300#ifdef CONFIG_NO_HZ
3301/*
3302 * For NO_HZ we delay the active fold to the next LOAD_FREQ update.
3303 *
3304 * When making the ILB scale, we should try to pull this in as well.
3305 */
3306static atomic_long_t calc_load_tasks_idle;
3307
3308static void calc_load_account_idle(struct rq *this_rq)
3309{
3310        long delta;
3311
3312        delta = calc_load_fold_active(this_rq);
3313        if (delta)
3314                atomic_long_add(delta, &calc_load_tasks_idle);
3315}
3316
3317static long calc_load_fold_idle(void)
3318{
3319        long delta = 0;
3320
3321        /*
3322         * Its got a race, we don't care...
3323         */
3324        if (atomic_long_read(&calc_load_tasks_idle))
3325                delta = atomic_long_xchg(&calc_load_tasks_idle, 0);
3326
3327        return delta;
3328}
3329
3330/**
3331 * fixed_power_int - compute: x^n, in O(log n) time
3332 *
3333 * @x:         base of the power
3334 * @frac_bits: fractional bits of @x
3335 * @n:         power to raise @x to.
3336 *
3337 * By exploiting the relation between the definition of the natural power
3338 * function: x^n := x*x*...*x (x multiplied by itself for n times), and
3339 * the binary encoding of numbers used by computers: n := \Sum n_i * 2^i,
3340 * (where: n_i \elem {0, 1}, the binary vector representing n),
3341 * we find: x^n := x^(\Sum n_i * 2^i) := \Prod x^(n_i * 2^i), which is
3342 * of course trivially computable in O(log_2 n), the length of our binary
3343 * vector.
3344 */
3345static unsigned long
3346fixed_power_int(unsigned long x, unsigned int frac_bits, unsigned int n)
3347{
3348        unsigned long result = 1UL << frac_bits;
3349
3350        if (n) for (;;) {
3351                if (n & 1) {
3352                        result *= x;
3353                        result += 1UL << (frac_bits - 1);
3354                        result >>= frac_bits;
3355                }
3356                n >>= 1;
3357                if (!n)
3358                        break;
3359                x *= x;
3360                x += 1UL << (frac_bits - 1);
3361                x >>= frac_bits;
3362        }
3363
3364        return result;
3365}
3366
3367/*
3368 * a1 = a0 * e + a * (1 - e)
3369 *
3370 * a2 = a1 * e + a * (1 - e)
3371 *    = (a0 * e + a * (1 - e)) * e + a * (1 - e)
3372 *    = a0 * e^2 + a * (1 - e) * (1 + e)
3373 *
3374 * a3 = a2 * e + a * (1 - e)
3375 *    = (a0 * e^2 + a * (1 - e) * (1 + e)) * e + a * (1 - e)
3376 *    = a0 * e^3 + a * (1 - e) * (1 + e + e^2)
3377 *
3378 *  ...
3379 *
3380 * an = a0 * e^n + a * (1 - e) * (1 + e + ... + e^n-1) [1]
3381 *    = a0 * e^n + a * (1 - e) * (1 - e^n)/(1 - e)
3382 *    = a0 * e^n + a * (1 - e^n)
3383 *
3384 * [1] application of the geometric series:
3385 *
3386 *              n         1 - x^(n+1)
3387 *     S_n := \Sum x^i = -------------
3388 *             i=0          1 - x
3389 */
3390static unsigned long
3391calc_load_n(unsigned long load, unsigned long exp,
3392            unsigned long active, unsigned int n)
3393{
3394
3395        return calc_load(load, fixed_power_int(exp, FSHIFT, n), active);
3396}
3397
3398/*
3399 * NO_HZ can leave us missing all per-cpu ticks calling
3400 * calc_load_account_active(), but since an idle CPU folds its delta into
3401 * calc_load_tasks_idle per calc_load_account_idle(), all we need to do is fold
3402 * in the pending idle delta if our idle period crossed a load cycle boundary.
3403 *
3404 * Once we've updated the global active value, we need to apply the exponential
3405 * weights adjusted to the number of cycles missed.
3406 */
3407static void calc_global_nohz(unsigned long ticks)
3408{
3409        long delta, active, n;
3410
3411        if (time_before(jiffies, calc_load_update))
3412                return;
3413
3414        /*
3415         * If we crossed a calc_load_update boundary, make sure to fold
3416         * any pending idle changes, the respective CPUs might have
3417         * missed the tick driven calc_load_account_active() update
3418         * due to NO_HZ.
3419         */
3420        delta = calc_load_fold_idle();
3421        if (delta)
3422                atomic_long_add(delta, &calc_load_tasks);
3423
3424        /*
3425         * If we were idle for multiple load cycles, apply them.
3426         */
3427        if (ticks >= LOAD_FREQ) {
3428                n = ticks / LOAD_FREQ;
3429
3430                active = atomic_long_read(&calc_load_tasks);
3431                active = active > 0 ? active * FIXED_1 : 0;
3432
3433                avenrun[0] = calc_load_n(avenrun[0], EXP_1, active, n);
3434                avenrun[1] = calc_load_n(avenrun[1], EXP_5, active, n);
3435                avenrun[2] = calc_load_n(avenrun[2], EXP_15, active, n);
3436
3437                calc_load_update += n * LOAD_FREQ;
3438        }
3439
3440        /*
3441         * Its possible the remainder of the above division also crosses
3442         * a LOAD_FREQ period, the regular check in calc_global_load()
3443         * which comes after this will take care of that.
3444         *
3445         * Consider us being 11 ticks before a cycle completion, and us
3446         * sleeping for 4*LOAD_FREQ + 22 ticks, then the above code will
3447         * age us 4 cycles, and the test in calc_global_load() will
3448         * pick up the final one.
3449         */
3450}
3451#else
3452static void calc_load_account_idle(struct rq *this_rq)
3453{
3454}
3455
3456static inline long calc_load_fold_idle(void)
3457{
3458        return 0;
3459}
3460
3461static void calc_global_nohz(unsigned long ticks)
3462{
3463}
3464#endif
3465
3466/**
3467 * get_avenrun - get the load average array
3468 * @loads:      pointer to dest load array
3469 * @offset:     offset to add
3470 * @shift:      shift count to shift the result left
3471 *
3472 * These values are estimates at best, so no need for locking.
3473 */
3474void get_avenrun(unsigned long *loads, unsigned long offset, int shift)
3475{
3476        loads[0] = (avenrun[0] + offset) << shift;
3477        loads[1] = (avenrun[1] + offset) << shift;
3478        loads[2] = (avenrun[2] + offset) << shift;
3479}
3480
3481/*
3482 * calc_load - update the avenrun load estimates 10 ticks after the
3483 * CPUs have updated calc_load_tasks.
3484 */
3485void calc_global_load(unsigned long ticks)
3486{
3487        long active;
3488
3489        calc_global_nohz(ticks);
3490
3491        if (time_before(jiffies, calc_load_update + 10))
3492                return;
3493
3494        active = atomic_long_read(&calc_load_tasks);
3495        active = active > 0 ? active * FIXED_1 : 0;
3496
3497        avenrun[0] = calc_load(avenrun[0], EXP_1, active);
3498        avenrun[1] = calc_load(avenrun[1], EXP_5, active);
3499        avenrun[2] = calc_load(avenrun[2], EXP_15, active);
3500
3501        calc_load_update += LOAD_FREQ;
3502}
3503
3504/*
3505 * Called from update_cpu_load() to periodically update this CPU's
3506 * active count.
3507 */
3508static void calc_load_account_active(struct rq *this_rq)
3509{
3510        long delta;
3511
3512        if (time_before(jiffies, this_rq->calc_load_update))
3513                return;
3514
3515        delta  = calc_load_fold_active(this_rq);
3516        delta += calc_load_fold_idle();
3517        if (delta)
3518                atomic_long_add(delta, &calc_load_tasks);
3519
3520        this_rq->calc_load_update += LOAD_FREQ;
3521}
3522
3523/*
3524 * The exact cpuload at various idx values, calculated at every tick would be
3525 * load = (2^idx - 1) / 2^idx * load + 1 / 2^idx * cur_load
3526 *
3527 * If a cpu misses updates for n-1 ticks (as it was idle) and update gets called
3528 * on nth tick when cpu may be busy, then we have:
3529 * load = ((2^idx - 1) / 2^idx)^(n-1) * load
3530 * load = (2^idx - 1) / 2^idx) * load + 1 / 2^idx * cur_load
3531 *
3532 * decay_load_missed() below does efficient calculation of
3533 * load = ((2^idx - 1) / 2^idx)^(n-1) * load
3534 * avoiding 0..n-1 loop doing load = ((2^idx - 1) / 2^idx) * load
3535 *
3536 * The calculation is approximated on a 128 point scale.
3537 * degrade_zero_ticks is the number of ticks after which load at any
3538 * particular idx is approximated to be zero.
3539 * degrade_factor is a precomputed table, a row for each load idx.
3540 * Each column corresponds to degradation factor for a power of two ticks,
3541 * based on 128 point scale.
3542 * Example:
3543 * row 2, col 3 (=12) says that the degradation at load idx 2 after
3544 * 8 ticks is 12/128 (which is an approximation of exact factor 3^8/4^8).
3545 *
3546 * With this power of 2 load factors, we can degrade the load n times
3547 * by looking at 1 bits in n and doing as many mult/shift instead of
3548 * n mult/shifts needed by the exact degradation.
3549 */
3550#define DEGRADE_SHIFT           7
3551static const unsigned char
3552                degrade_zero_ticks[CPU_LOAD_IDX_MAX] = {0, 8, 32, 64, 128};
3553static const unsigned char
3554                degrade_factor[CPU_LOAD_IDX_MAX][DEGRADE_SHIFT + 1] = {
3555                                        {0, 0, 0, 0, 0, 0, 0, 0},
3556                                        {64, 32, 8, 0, 0, 0, 0, 0},
3557                                        {96, 72, 40, 12, 1, 0, 0},
3558                                        {112, 98, 75, 43, 15, 1, 0},
3559                                        {120, 112, 98, 76, 45, 16, 2} };
3560
3561/*
3562 * Update cpu_load for any missed ticks, due to tickless idle. The backlog
3563 * would be when CPU is idle and so we just decay the old load without
3564 * adding any new load.
3565 */
3566static unsigned long
3567decay_load_missed(unsigned long load, unsigned long missed_updates, int idx)
3568{
3569        int j = 0;
3570
3571        if (!missed_updates)
3572                return load;
3573
3574        if (missed_updates >= degrade_zero_ticks[idx])
3575                return 0;
3576
3577        if (idx == 1)
3578                return load >> missed_updates;
3579
3580        while (missed_updates) {
3581                if (missed_updates % 2)
3582                        load = (load * degrade_factor[idx][j]) >> DEGRADE_SHIFT;
3583
3584                missed_updates >>= 1;
3585                j++;
3586        }
3587        return load;
3588}
3589
3590/*
3591 * Update rq->cpu_load[] statistics. This function is usually called every
3592 * scheduler tick (TICK_NSEC). With tickless idle this will not be called
3593 * every tick. We fix it up based on jiffies.
3594 */
3595static void update_cpu_load(struct rq *this_rq)
3596{
3597        unsigned long this_load = this_rq->load.weight;
3598        unsigned long curr_jiffies = jiffies;
3599        unsigned long pending_updates;
3600        int i, scale;
3601
3602        this_rq->nr_load_updates++;
3603
3604        /* Avoid repeated calls on same jiffy, when moving in and out of idle */
3605        if (curr_jiffies == this_rq->last_load_update_tick)
3606                return;
3607
3608        pending_updates = curr_jiffies - this_rq->last_load_update_tick;
3609        this_rq->last_load_update_tick = curr_jiffies;
3610
3611        /* Update our load: */
3612        this_rq->cpu_load[0] = this_load; /* Fasttrack for idx 0 */
3613        for (i = 1, scale = 2; i < CPU_LOAD_IDX_MAX; i++, scale += scale) {
3614                unsigned long old_load, new_load;
3615
3616                /* scale is effectively 1 << i now, and >> i divides by scale */
3617
3618                old_load = this_rq->cpu_load[i];
3619                old_load = decay_load_missed(old_load, pending_updates - 1, i);
3620                new_load = this_load;
3621                /*
3622                 * Round up the averaging division if load is increasing. This
3623                 * prevents us from getting stuck on 9 if the load is 10, for
3624                 * example.
3625                 */
3626                if (new_load > old_load)
3627                        new_load += scale - 1;
3628
3629                this_rq->cpu_load[i] = (old_load * (scale - 1) + new_load) >> i;
3630        }
3631
3632        sched_avg_update(this_rq);
3633}
3634
3635static void update_cpu_load_active(struct rq *this_rq)
3636{
3637        update_cpu_load(this_rq);
3638
3639        calc_load_account_active(this_rq);
3640}
3641
3642#ifdef CONFIG_SMP
3643
3644/*
3645 * sched_exec - execve() is a valuable balancing opportunity, because at
3646 * this point the task has the smallest effective memory and cache footprint.
3647 */
3648void sched_exec(void)
3649{
3650        struct task_struct *p = current;
3651        unsigned long flags;
3652        int dest_cpu;
3653
3654        raw_spin_lock_irqsave(&p->pi_lock, flags);
3655        dest_cpu = p->sched_class->select_task_rq(p, SD_BALANCE_EXEC, 0);
3656        if (dest_cpu == smp_processor_id())
3657                goto unlock;
3658
3659        if (likely(cpu_active(dest_cpu))) {
3660                struct migration_arg arg = { p, dest_cpu };
3661
3662                raw_spin_unlock_irqrestore(&p->pi_lock, flags);
3663                stop_one_cpu(task_cpu(p), migration_cpu_stop, &arg);
3664                return;
3665        }
3666unlock:
3667        raw_spin_unlock_irqrestore(&p->pi_lock, flags);
3668}
3669
3670#endif
3671
3672DEFINE_PER_CPU(struct kernel_stat, kstat);
3673
3674EXPORT_PER_CPU_SYMBOL(kstat);
3675
3676/*
3677 * Return any ns on the sched_clock that have not yet been accounted in
3678 * @p in case that task is currently running.
3679 *
3680 * Called with task_rq_lock() held on @rq.
3681 */
3682static u64 do_task_delta_exec(struct task_struct *p, struct rq *rq)
3683{
3684        u64 ns = 0;
3685
3686        if (task_current(rq, p)) {
3687                update_rq_clock(rq);
3688                ns = rq->clock_task - p->se.exec_start;
3689                if ((s64)ns < 0)
3690                        ns = 0;
3691        }
3692
3693        return ns;
3694}
3695
3696unsigned long long task_delta_exec(struct task_struct *p)
3697{
3698        unsigned long flags;
3699        struct rq *rq;
3700        u64 ns = 0;
3701
3702        rq = task_rq_lock(p, &flags);
3703        ns = do_task_delta_exec(p, rq);
3704        task_rq_unlock(rq, p, &flags);
3705
3706        return ns;
3707}
3708
3709/*
3710 * Return accounted runtime for the task.
3711 * In case the task is currently running, return the runtime plus current's
3712 * pending runtime that have not been accounted yet.
3713 */
3714unsigned long long task_sched_runtime(struct task_struct *p)
3715{
3716        unsigned long flags;
3717        struct rq *rq;
3718        u64 ns = 0;
3719
3720        rq = task_rq_lock(p, &flags);
3721        ns = p->se.sum_exec_runtime + do_task_delta_exec(p, rq);
3722        task_rq_unlock(rq, p, &flags);
3723
3724        return ns;
3725}
3726
3727/*
3728 * Account user cpu time to a process.
3729 * @p: the process that the cpu time gets accounted to
3730 * @cputime: the cpu time spent in user space since the last update
3731 * @cputime_scaled: cputime scaled by cpu frequency
3732 */
3733void account_user_time(struct task_struct *p, cputime_t cputime,
3734                       cputime_t cputime_scaled)
3735{
3736        struct cpu_usage_stat *cpustat = &kstat_this_cpu.cpustat;
3737        cputime64_t tmp;
3738
3739        /* Add user time to process. */
3740        p->utime = cputime_add(p->utime, cputime);
3741        p->utimescaled = cputime_add(p->utimescaled, cputime_scaled);
3742        account_group_user_time(p, cputime);
3743
3744        /* Add user time to cpustat. */
3745        tmp = cputime_to_cputime64(cputime);
3746        if (TASK_NICE(p) > 0)
3747                cpustat->nice = cputime64_add(cpustat->nice, tmp);
3748        else
3749                cpustat->user = cputime64_add(cpustat->user, tmp);
3750
3751        cpuacct_update_stats(p, CPUACCT_STAT_USER, cputime);
3752        /* Account for user time used */
3753        acct_update_integrals(p);
3754}
3755
3756/*
3757 * Account guest cpu time to a process.
3758 * @p: the process that the cpu time gets accounted to
3759 * @cputime: the cpu time spent in virtual machine since the last update
3760 * @cputime_scaled: cputime scaled by cpu frequency
3761 */
3762static void account_guest_time(struct task_struct *p, cputime_t cputime,
3763                               cputime_t cputime_scaled)
3764{
3765        cputime64_t tmp;
3766        struct cpu_usage_stat *cpustat = &kstat_this_cpu.cpustat;
3767
3768        tmp = cputime_to_cputime64(cputime);
3769
3770        /* Add guest time to process. */
3771        p->utime = cputime_add(p->utime, cputime);
3772        p->utimescaled = cputime_add(p->utimescaled, cputime_scaled);
3773        account_group_user_time(p, cputime);
3774        p->gtime = cputime_add(p->gtime, cputime);
3775
3776        /* Add guest time to cpustat. */
3777        if (TASK_NICE(p) > 0) {
3778                cpustat->nice = cputime64_add(cpustat->nice, tmp);
3779                cpustat->guest_nice = cputime64_add(cpustat->guest_nice, tmp);
3780        } else {
3781                cpustat->user = cputime64_add(cpustat->user, tmp);
3782                cpustat->guest = cputime64_add(cpustat->guest, tmp);
3783        }
3784}
3785
3786/*
3787 * Account system cpu time to a process and desired cpustat field
3788 * @p: the process that the cpu time gets accounted to
3789 * @cputime: the cpu time spent in kernel space since the last update
3790 * @cputime_scaled: cputime scaled by cpu frequency
3791 * @target_cputime64: pointer to cpustat field that has to be updated
3792 */
3793static inline
3794void __account_system_time(struct task_struct *p, cputime_t cputime,
3795                        cputime_t cputime_scaled, cputime64_t *target_cputime64)
3796{
3797        cputime64_t tmp = cputime_to_cputime64(cputime);
3798
3799        /* Add system time to process. */
3800        p->stime = cputime_add(p->stime, cputime);
3801        p->stimescaled = cputime_add(p->stimescaled, cputime_scaled);
3802        account_group_system_time(p, cputime);
3803
3804        /* Add system time to cpustat. */
3805        *target_cputime64 = cputime64_add(*target_cputime64, tmp);
3806        cpuacct_update_stats(p, CPUACCT_STAT_SYSTEM, cputime);
3807
3808        /* Account for system time used */
3809        acct_update_integrals(p);
3810}
3811
3812/*
3813 * Account system cpu time to a process.
3814 * @p: the process that the cpu time gets accounted to
3815 * @hardirq_offset: the offset to subtract from hardirq_count()
3816 * @cputime: the cpu time spent in kernel space since the last update
3817 * @cputime_scaled: cputime scaled by cpu frequency
3818 */
3819void account_system_time(struct task_struct *p, int hardirq_offset,
3820                         cputime_t cputime, cputime_t cputime_scaled)
3821{
3822        struct cpu_usage_stat *cpustat = &kstat_this_cpu.cpustat;
3823        cputime64_t *target_cputime64;
3824
3825        if ((p->flags & PF_VCPU) && (irq_count() - hardirq_offset == 0)) {
3826                account_guest_time(p, cputime, cputime_scaled);
3827                return;
3828        }
3829
3830        if (hardirq_count() - hardirq_offset)
3831                target_cputime64 = &cpustat->irq;
3832        else if (in_serving_softirq())
3833                target_cputime64 = &cpustat->softirq;
3834        else
3835                target_cputime64 = &cpustat->system;
3836
3837        __account_system_time(p, cputime, cputime_scaled, target_cputime64);
3838}
3839
3840/*
3841 * Account for involuntary wait time.
3842 * @cputime: the cpu time spent in involuntary wait
3843 */
3844void account_steal_time(cputime_t cputime)
3845{
3846        struct cpu_usage_stat *cpustat = &kstat_this_cpu.cpustat;
3847        cputime64_t cputime64 = cputime_to_cputime64(cputime);
3848
3849        cpustat->steal = cputime64_add(cpustat->steal, cputime64);
3850}
3851
3852/*
3853 * Account for idle time.
3854 * @cputime: the cpu time spent in idle wait
3855 */
3856void account_idle_time(cputime_t cputime)
3857{
3858        struct cpu_usage_stat *cpustat = &kstat_this_cpu.cpustat;
3859        cputime64_t cputime64 = cputime_to_cputime64(cputime);
3860        struct rq *rq = this_rq();
3861
3862        if (atomic_read(&rq->nr_iowait) > 0)
3863                cpustat->iowait = cputime64_add(cpustat->iowait, cputime64);
3864        else
3865                cpustat->idle = cputime64_add(cpustat->idle, cputime64);
3866}
3867
3868static __always_inline bool steal_account_process_tick(void)
3869{
3870#ifdef CONFIG_PARAVIRT
3871        if (static_branch(&paravirt_steal_enabled)) {
3872                u64 steal, st = 0;
3873
3874                steal = paravirt_steal_clock(smp_processor_id());
3875                steal -= this_rq()->prev_steal_time;
3876
3877                st = steal_ticks(steal);
3878                this_rq()->prev_steal_time += st * TICK_NSEC;
3879
3880                account_steal_time(st);
3881                return st;
3882        }
3883#endif
3884        return false;
3885}
3886
3887#ifndef CONFIG_VIRT_CPU_ACCOUNTING
3888
3889#ifdef CONFIG_IRQ_TIME_ACCOUNTING
3890/*
3891 * Account a tick to a process and cpustat
3892 * @p: the process that the cpu time gets accounted to
3893 * @user_tick: is the tick from userspace
3894 * @rq: the pointer to rq
3895 *
3896 * Tick demultiplexing follows the order
3897 * - pending hardirq update
3898 * - pending softirq update
3899 * - user_time
3900 * - idle_time
3901 * - system time
3902 *   - check for guest_time
3903 *   - else account as system_time
3904 *
3905 * Check for hardirq is done both for system and user time as there is
3906 * no timer going off while we are on hardirq and hence we may never get an
3907 * opportunity to update it solely in system time.
3908 * p->stime and friends are only updated on system time and not on irq
3909 * softirq as those do not count in task exec_runtime any more.
3910 */
3911static void irqtime_account_process_tick(struct task_struct *p, int user_tick,
3912                                                struct rq *rq)
3913{
3914        cputime_t one_jiffy_scaled = cputime_to_scaled(cputime_one_jiffy);
3915        cputime64_t tmp = cputime_to_cputime64(cputime_one_jiffy);
3916        struct cpu_usage_stat *cpustat = &kstat_this_cpu.cpustat;
3917
3918        if (steal_account_process_tick())
3919                return;
3920
3921        if (irqtime_account_hi_update()) {
3922                cpustat->irq = cputime64_add(cpustat->irq, tmp);
3923        } else if (irqtime_account_si_update()) {
3924                cpustat->softirq = cputime64_add(cpustat->softirq, tmp);
3925        } else if (this_cpu_ksoftirqd() == p) {
3926                /*
3927                 * ksoftirqd time do not get accounted in cpu_softirq_time.
3928                 * So, we have to handle it separately here.
3929                 * Also, p->stime needs to be updated for ksoftirqd.
3930                 */
3931                __account_system_time(p, cputime_one_jiffy, one_jiffy_scaled,
3932                                        &cpustat->softirq);
3933        } else if (user_tick) {
3934                account_user_time(p, cputime_one_jiffy, one_jiffy_scaled);
3935        } else if (p == rq->idle) {
3936                account_idle_time(cputime_one_jiffy);
3937        } else if (p->flags & PF_VCPU) { /* System time or guest time */
3938                account_guest_time(p, cputime_one_jiffy, one_jiffy_scaled);
3939        } else {
3940                __account_system_time(p, cputime_one_jiffy, one_jiffy_scaled,
3941                                        &cpustat->system);
3942        }
3943}
3944
3945static void irqtime_account_idle_ticks(int ticks)
3946{
3947        int i;
3948        struct rq *rq = this_rq();
3949
3950        for (i = 0; i < ticks; i++)
3951                irqtime_account_process_tick(current, 0, rq);
3952}
3953#else /* CONFIG_IRQ_TIME_ACCOUNTING */
3954static void irqtime_account_idle_ticks(int ticks) {}
3955static void irqtime_account_process_tick(struct task_struct *p, int user_tick,
3956                                                struct rq *rq) {}
3957#endif /* CONFIG_IRQ_TIME_ACCOUNTING */
3958
3959/*
3960 * Account a single tick of cpu time.
3961 * @p: the process that the cpu time gets accounted to
3962 * @user_tick: indicates if the tick is a user or a system tick
3963 */
3964void account_process_tick(struct task_struct *p, int user_tick)
3965{
3966        cputime_t one_jiffy_scaled = cputime_to_scaled(cputime_one_jiffy);
3967        struct rq *rq = this_rq();
3968
3969        if (sched_clock_irqtime) {
3970                irqtime_account_process_tick(p, user_tick, rq);
3971                return;
3972        }
3973
3974        if (steal_account_process_tick())
3975                return;
3976
3977        if (user_tick)
3978                account_user_time(p, cputime_one_jiffy, one_jiffy_scaled);
3979        else if ((p != rq->idle) || (irq_count() != HARDIRQ_OFFSET))
3980                account_system_time(p, HARDIRQ_OFFSET, cputime_one_jiffy,
3981                                    one_jiffy_scaled);
3982        else
3983                account_idle_time(cputime_one_jiffy);
3984}
3985
3986/*
3987 * Account multiple ticks of steal time.
3988 * @p: the process from which the cpu time has been stolen
3989 * @ticks: number of stolen ticks
3990 */
3991void account_steal_ticks(unsigned long ticks)
3992{
3993        account_steal_time(jiffies_to_cputime(ticks));
3994}
3995
3996/*
3997 * Account multiple ticks of idle time.
3998 * @ticks: number of stolen ticks
3999 */
4000void account_idle_ticks(unsigned long ticks)
4001{
4002
4003        if (sched_clock_irqtime) {
4004                irqtime_account_idle_ticks(ticks);
4005                return;
4006        }
4007
4008        account_idle_time(jiffies_to_cputime(ticks));
4009}
4010
4011#endif
4012
4013/*
4014 * Use precise platform statistics if available:
4015 */
4016#ifdef CONFIG_VIRT_CPU_ACCOUNTING
4017void task_times(struct task_struct *p, cputime_t *ut, cputime_t *st)
4018{
4019        *ut = p->utime;
4020        *st = p->stime;
4021}
4022
4023void thread_group_times(struct task_struct *p, cputime_t *ut, cputime_t *st)
4024{
4025        struct task_cputime cputime;
4026
4027        thread_group_cputime(p, &cputime);
4028
4029        *ut = cputime.utime;
4030        *st = cputime.stime;
4031}
4032#else
4033
4034#ifndef nsecs_to_cputime
4035# define nsecs_to_cputime(__nsecs)      nsecs_to_jiffies(__nsecs)
4036#endif
4037
4038void task_times(struct task_struct *p, cputime_t *ut, cputime_t *st)
4039{
4040        cputime_t rtime, utime = p->utime, total = cputime_add(utime, p->stime);
4041
4042        /*
4043         * Use CFS's precise accounting:
4044         */
4045        rtime = nsecs_to_cputime(p->se.sum_exec_runtime);
4046
4047        if (total) {
4048                u64 temp = rtime;
4049
4050                temp *= utime;
4051                do_div(temp, total);
4052                utime = (cputime_t)temp;
4053        } else
4054                utime = rtime;
4055
4056        /*
4057         * Compare with previous values, to keep monotonicity:
4058         */
4059        p->prev_utime = max(p->prev_utime, utime);
4060        p->prev_stime = max(p->prev_stime, cputime_sub(rtime, p->prev_utime));
4061
4062        *ut = p->prev_utime;
4063        *st = p->prev_stime;
4064}
4065
4066/*
4067 * Must be called with siglock held.
4068 */
4069void thread_group_times(struct task_struct *p, cputime_t *ut, cputime_t *st)
4070{
4071        struct signal_struct *sig = p->signal;
4072        struct task_cputime cputime;
4073        cputime_t rtime, utime, total;
4074
4075        thread_group_cputime(p, &cputime);
4076
4077        total = cputime_add(cputime.utime, cputime.stime);
4078        rtime = nsecs_to_cputime(cputime.sum_exec_runtime);
4079
4080        if (total) {
4081                u64 temp = rtime;
4082
4083                temp *= cputime.utime;
4084                do_div(temp, total);
4085                utime = (cputime_t)temp;
4086        } else
4087                utime = rtime;
4088
4089        sig->prev_utime = max(sig->prev_utime, utime);
4090        sig->prev_stime = max(sig->prev_stime,
4091                              cputime_sub(rtime, sig->prev_utime));
4092
4093        *ut = sig->prev_utime;
4094        *st = sig->prev_stime;
4095}
4096#endif
4097
4098/*
4099 * This function gets called by the timer code, with HZ frequency.
4100 * We call it with interrupts disabled.
4101 */
4102void scheduler_tick(void)
4103{
4104        int cpu = smp_processor_id();
4105        struct rq *rq = cpu_rq(cpu);
4106        struct task_struct *curr = rq->curr;
4107
4108        sched_clock_tick();
4109
4110        raw_spin_lock(&rq->lock);
4111        update_rq_clock(rq);
4112        update_cpu_load_active(rq);
4113        curr->sched_class->task_tick(rq, curr, 0);
4114        raw_spin_unlock(&rq->lock);
4115
4116        perf_event_task_tick();
4117
4118#ifdef CONFIG_SMP
4119        rq->idle_at_tick = idle_cpu(cpu);
4120        trigger_load_balance(rq, cpu);
4121#endif
4122}
4123
4124notrace unsigned long get_parent_ip(unsigned long addr)
4125{
4126        if (in_lock_functions(addr)) {
4127                addr = CALLER_ADDR2;
4128                if (in_lock_functions(addr))
4129                        addr = CALLER_ADDR3;
4130        }
4131        return addr;
4132}
4133
4134#if defined(CONFIG_PREEMPT) && (defined(CONFIG_DEBUG_PREEMPT) || \
4135                                defined(CONFIG_PREEMPT_TRACER))
4136
4137void __kprobes add_preempt_count(int val)
4138{
4139#ifdef CONFIG_DEBUG_PREEMPT
4140        /*
4141         * Underflow?
4142         */
4143        if (DEBUG_LOCKS_WARN_ON((preempt_count() < 0)))
4144                return;
4145#endif
4146        preempt_count() += val;
4147#ifdef CONFIG_DEBUG_PREEMPT
4148        /*
4149         * Spinlock count overflowing soon?
4150         */
4151        DEBUG_LOCKS_WARN_ON((preempt_count() & PREEMPT_MASK) >=
4152                                PREEMPT_MASK - 10);
4153#endif
4154        if (preempt_count() == val)
4155                trace_preempt_off(CALLER_ADDR0, get_parent_ip(CALLER_ADDR1));
4156}
4157EXPORT_SYMBOL(add_preempt_count);
4158
4159void __kprobes sub_preempt_count(int val)
4160{
4161#ifdef CONFIG_DEBUG_PREEMPT
4162        /*
4163         * Underflow?
4164         */
4165        if (DEBUG_LOCKS_WARN_ON(val > preempt_count()))
4166                return;
4167        /*
4168         * Is the spinlock portion underflowing?
4169         */
4170        if (DEBUG_LOCKS_WARN_ON((val < PREEMPT_MASK) &&
4171                        !(preempt_count() & PREEMPT_MASK)))
4172                return;
4173#endif
4174
4175        if (preempt_count() == val)
4176                trace_preempt_on(CALLER_ADDR0, get_parent_ip(CALLER_ADDR1));
4177        preempt_count() -= val;
4178}
4179EXPORT_SYMBOL(sub_preempt_count);
4180
4181#endif
4182
4183/*
4184 * Print scheduling while atomic bug:
4185 */
4186static noinline void __schedule_bug(struct task_struct *prev)
4187{
4188        struct pt_regs *regs = get_irq_regs();
4189
4190        printk(KERN_ERR "BUG: scheduling while atomic: %s/%d/0x%08x\n",
4191                prev->comm, prev->pid, preempt_count());
4192
4193        debug_show_held_locks(prev);
4194        print_modules();
4195        if (irqs_disabled())
4196                print_irqtrace_events(prev);
4197
4198        if (regs)
4199                show_regs(regs);
4200        else
4201                dump_stack();
4202}
4203
4204/*
4205 * Various schedule()-time debugging checks and statistics:
4206 */
4207static inline void schedule_debug(struct task_struct *prev)
4208{
4209        /*
4210         * Test if we are atomic. Since do_exit() needs to call into
4211         * schedule() atomically, we ignore that path for now.
4212         * Otherwise, whine if we are scheduling when we should not be.
4213         */
4214        if (unlikely(in_atomic_preempt_off() && !prev->exit_state))
4215                __schedule_bug(prev);
4216
4217        profile_hit(SCHED_PROFILING, __builtin_return_address(0));
4218
4219        schedstat_inc(this_rq(), sched_count);
4220}
4221
4222static void put_prev_task(struct rq *rq, struct task_struct *prev)
4223{
4224        if (prev->on_rq || rq->skip_clock_update < 0)
4225                update_rq_clock(rq);
4226        prev->sched_class->put_prev_task(rq, prev);
4227}
4228
4229/*
4230 * Pick up the highest-prio task:
4231 */
4232static inline struct task_struct *
4233pick_next_task(struct rq *rq)
4234{
4235        const struct sched_class *class;
4236        struct task_struct *p;
4237
4238        /*
4239         * Optimization: we know that if all tasks are in
4240         * the fair class we can call that function directly:
4241         */
4242        if (likely(rq->nr_running == rq->cfs.nr_running)) {
4243                p = fair_sched_class.pick_next_task(rq);
4244                if (likely(p))
4245                        return p;
4246        }
4247
4248        for_each_class(class) {
4249                p = class->pick_next_task(rq);
4250                if (p)
4251                        return p;
4252        }
4253
4254        BUG(); /* the idle class will always have a runnable task */
4255}
4256
4257/*
4258 * __schedule() is the main scheduler function.
4259 */
4260static void __sched __schedule(void)
4261{
4262        struct task_struct *prev, *next;
4263        unsigned long *switch_count;
4264        struct rq *rq;
4265        int cpu;
4266
4267need_resched:
4268        preempt_disable();
4269        cpu = smp_processor_id();
4270        rq = cpu_rq(cpu);
4271        rcu_note_context_switch(cpu);
4272        prev = rq->curr;
4273
4274        schedule_debug(prev);
4275
4276        if (sched_feat(HRTICK))
4277                hrtick_clear(rq);
4278
4279        raw_spin_lock_irq(&rq->lock);
4280
4281        switch_count = &prev->nivcsw;
4282        if (prev->state && !(preempt_count() & PREEMPT_ACTIVE)) {
4283                if (unlikely(signal_pending_state(prev->state, prev))) {
4284                        prev->state = TASK_RUNNING;
4285                } else {
4286                        deactivate_task(rq, prev, DEQUEUE_SLEEP);
4287                        prev->on_rq = 0;
4288
4289                        /*
4290                         * If a worker went to sleep, notify and ask workqueue
4291                         * whether it wants to wake up a task to maintain
4292                         * concurrency.
4293                         */
4294                        if (prev->flags & PF_WQ_WORKER) {
4295                                struct task_struct *to_wakeup;
4296
4297                                to_wakeup = wq_worker_sleeping(prev, cpu);
4298                                if (to_wakeup)
4299                                        try_to_wake_up_local(to_wakeup);
4300                        }
4301                }
4302                switch_count = &prev->nvcsw;
4303        }
4304
4305        pre_schedule(rq, prev);
4306
4307        if (unlikely(!rq->nr_running))
4308                idle_balance(cpu, rq);
4309
4310        put_prev_task(rq, prev);
4311        next = pick_next_task(rq);
4312        clear_tsk_need_resched(prev);
4313        rq->skip_clock_update = 0;
4314
4315        if (likely(prev != next)) {
4316                rq->nr_switches++;
4317                rq->curr = next;
4318                ++*switch_count;
4319
4320                context_switch(rq, prev, next); /* unlocks the rq */
4321                /*
4322                 * The context switch have flipped the stack from under us
4323                 * and restored the local variables which were saved when
4324                 * this task called schedule() in the past. prev == current
4325                 * is still correct, but it can be moved to another cpu/rq.
4326                 */
4327                cpu = smp_processor_id();
4328                rq = cpu_rq(cpu);
4329        } else
4330                raw_spin_unlock_irq(&rq->lock);
4331
4332        post_schedule(rq);
4333
4334        preempt_enable_no_resched();
4335        if (need_resched())
4336                goto need_resched;
4337}
4338
4339static inline void sched_submit_work(struct task_struct *tsk)
4340{
4341        if (!tsk->state)
4342                return;
4343        /*
4344         * If we are going to sleep and we have plugged IO queued,
4345         * make sure to submit it to avoid deadlocks.
4346         */
4347        if (blk_needs_flush_plug(tsk))
4348                blk_schedule_flush_plug(tsk);
4349}
4350
4351asmlinkage void __sched schedule(void)
4352{
4353        struct task_struct *tsk = current;
4354
4355        sched_submit_work(tsk);
4356        __schedule();
4357}
4358EXPORT_SYMBOL(schedule);
4359
4360#ifdef CONFIG_MUTEX_SPIN_ON_OWNER
4361
4362static inline bool owner_running(struct mutex *lock, struct task_struct *owner)
4363{
4364        if (lock->owner != owner)
4365                return false;
4366
4367        /*
4368         * Ensure we emit the owner->on_cpu, dereference _after_ checking
4369         * lock->owner still matches owner, if that fails, owner might
4370         * point to free()d memory, if it still matches, the rcu_read_lock()
4371         * ensures the memory stays valid.
4372         */
4373        barrier();
4374
4375        return owner->on_cpu;
4376}
4377
4378/*
4379 * Look out! "owner" is an entirely speculative pointer
4380 * access and not reliable.
4381 */
4382int mutex_spin_on_owner(struct mutex *lock, struct task_struct *owner)
4383{
4384        if (!sched_feat(OWNER_SPIN))
4385                return 0;
4386
4387        rcu_read_lock();
4388        while (owner_running(lock, owner)) {
4389                if (need_resched())
4390                        break;
4391
4392                arch_mutex_cpu_relax();
4393        }
4394        rcu_read_unlock();
4395
4396        /*
4397         * We break out the loop above on need_resched() and when the
4398         * owner changed, which is a sign for heavy contention. Return
4399         * success only when lock->owner is NULL.
4400         */
4401        return lock->owner == NULL;
4402}
4403#endif
4404
4405#ifdef CONFIG_PREEMPT
4406/*
4407 * this is the entry point to schedule() from in-kernel preemption
4408 * off of preempt_enable. Kernel preemptions off return from interrupt
4409 * occur there and call schedule directly.
4410 */
4411asmlinkage void __sched notrace preempt_schedule(void)
4412{
4413        struct thread_info *ti = current_thread_info();
4414
4415        /*
4416         * If there is a non-zero preempt_count or interrupts are disabled,
4417         * we do not want to preempt the current task. Just return..
4418         */
4419        if (likely(ti->preempt_count || irqs_disabled()))
4420                return;
4421
4422        do {
4423                add_preempt_count_notrace(PREEMPT_ACTIVE);
4424                __schedule();
4425                sub_preempt_count_notrace(PREEMPT_ACTIVE);
4426
4427                /*
4428                 * Check again in case we missed a preemption opportunity
4429                 * between schedule and now.
4430                 */
4431                barrier();
4432        } while (need_resched());
4433}
4434EXPORT_SYMBOL(preempt_schedule);
4435
4436/*
4437 * this is the entry point to schedule() from kernel preemption
4438 * off of irq context.
4439 * Note, that this is called and return with irqs disabled. This will
4440 * protect us against recursive calling from irq.
4441 */
4442asmlinkage void __sched preempt_schedule_irq(void)
4443{
4444        struct thread_info *ti = current_thread_info();
4445
4446        /* Catch callers which need to be fixed */
4447        BUG_ON(ti->preempt_count || !irqs_disabled());
4448
4449        do {
4450                add_preempt_count(PREEMPT_ACTIVE);
4451                local_irq_enable();
4452                __schedule();
4453                local_irq_disable();
4454                sub_preempt_count(PREEMPT_ACTIVE);
4455
4456                /*
4457                 * Check again in case we missed a preemption opportunity
4458                 * between schedule and now.
4459                 */
4460                barrier();
4461        } while (need_resched());
4462}
4463
4464#endif /* CONFIG_PREEMPT */
4465
4466int default_wake_function(wait_queue_t *curr, unsigned mode, int wake_flags,
4467                          void *key)
4468{
4469        return try_to_wake_up(curr->private, mode, wake_flags);
4470}
4471EXPORT_SYMBOL(default_wake_function);
4472
4473/*
4474 * The core wakeup function. Non-exclusive wakeups (nr_exclusive == 0) just
4475 * wake everything up. If it's an exclusive wakeup (nr_exclusive == small +ve
4476 * number) then we wake all the non-exclusive tasks and one exclusive task.
4477 *
4478 * There are circumstances in which we can try to wake a task which has already
4479 * started to run but is not in state TASK_RUNNING. try_to_wake_up() returns
4480 * zero in this (rare) case, and we handle it by continuing to scan the queue.
4481 */
4482static void __wake_up_common(wait_queue_head_t *q, unsigned int mode,
4483                        int nr_exclusive, int wake_flags, void *key)
4484{
4485        wait_queue_t *curr, *next;
4486
4487        list_for_each_entry_safe(curr, next, &q->task_list, task_list) {
4488                unsigned flags = curr->flags;
4489
4490                if (curr->func(curr, mode, wake_flags, key) &&
4491                                (flags & WQ_FLAG_EXCLUSIVE) && !--nr_exclusive)
4492                        break;
4493        }
4494}
4495
4496/**
4497 * __wake_up - wake up threads blocked on a waitqueue.
4498 * @q: the waitqueue
4499 * @mode: which threads
4500 * @nr_exclusive: how many wake-one or wake-many threads to wake up
4501 * @key: is directly passed to the wakeup function
4502 *
4503 * It may be assumed that this function implies a write memory barrier before
4504 * changing the task state if and only if any tasks are woken up.
4505 */
4506void __wake_up(wait_queue_head_t *q, unsigned int mode,
4507                        int nr_exclusive, void *key)
4508{
4509        unsigned long flags;
4510
4511        spin_lock_irqsave(&q->lock, flags);
4512        __wake_up_common(q, mode, nr_exclusive, 0, key);
4513        spin_unlock_irqrestore(&q->lock, flags);
4514}
4515EXPORT_SYMBOL(__wake_up);
4516
4517/*
4518 * Same as __wake_up but called with the spinlock in wait_queue_head_t held.
4519 */
4520void __wake_up_locked(wait_queue_head_t *q, unsigned int mode)
4521{
4522        __wake_up_common(q, mode, 1, 0, NULL);
4523}
4524EXPORT_SYMBOL_GPL(__wake_up_locked);
4525
4526void __wake_up_locked_key(wait_queue_head_t *q, unsigned int mode, void *key)
4527{
4528        __wake_up_common(q, mode, 1, 0, key);
4529}
4530EXPORT_SYMBOL_GPL(__wake_up_locked_key);
4531
4532/**
4533 * __wake_up_sync_key - wake up threads blocked on a waitqueue.
4534 * @q: the waitqueue
4535 * @mode: which threads
4536 * @nr_exclusive: how many wake-one or wake-many threads to wake up
4537 * @key: opaque value to be passed to wakeup targets
4538 *
4539 * The sync wakeup differs that the waker knows that it will schedule
4540 * away soon, so while the target thread will be woken up, it will not
4541 * be migrated to another CPU - ie. the two threads are 'synchronized'
4542 * with each other. This can prevent needless bouncing between CPUs.
4543 *
4544 * On UP it can prevent extra preemption.
4545 *
4546 * It may be assumed that this function implies a write memory barrier before
4547 * changing the task state if and only if any tasks are woken up.
4548 */
4549void __wake_up_sync_key(wait_queue_head_t *q, unsigned int mode,
4550                        int nr_exclusive, void *key)
4551{
4552        unsigned long flags;
4553        int wake_flags = WF_SYNC;
4554
4555        if (unlikely(!q))
4556                return;
4557
4558        if (unlikely(!nr_exclusive))
4559                wake_flags = 0;
4560
4561        spin_lock_irqsave(&q->lock, flags);
4562        __wake_up_common(q, mode, nr_exclusive, wake_flags, key);
4563        spin_unlock_irqrestore(&q->lock, flags);
4564}
4565EXPORT_SYMBOL_GPL(__wake_up_sync_key);
4566
4567/*
4568 * __wake_up_sync - see __wake_up_sync_key()
4569 */
4570void __wake_up_sync(wait_queue_head_t *q, unsigned int mode, int nr_exclusive)
4571{
4572        __wake_up_sync_key(q, mode, nr_exclusive, NULL);
4573}
4574EXPORT_SYMBOL_GPL(__wake_up_sync);      /* For internal use only */
4575
4576/**
4577 * complete: - signals a single thread waiting on this completion
4578 * @x:  holds the state of this particular completion
4579 *
4580 * This will wake up a single thread waiting on this completion. Threads will be
4581 * awakened in the same order in which they were queued.
4582 *
4583 * See also complete_all(), wait_for_completion() and related routines.
4584 *
4585 * It may be assumed that this function implies a write memory barrier before
4586 * changing the task state if and only if any tasks are woken up.
4587 */
4588void complete(struct completion *x)
4589{
4590        unsigned long flags;
4591
4592        spin_lock_irqsave(&x->wait.lock, flags);
4593        x->done++;
4594        __wake_up_common(&x->wait, TASK_NORMAL, 1, 0, NULL);
4595        spin_unlock_irqrestore(&x->wait.lock, flags);
4596}
4597EXPORT_SYMBOL(complete);
4598
4599/**
4600 * complete_all: - signals all threads waiting on this completion
4601 * @x:  holds the state of this particular completion
4602 *
4603 * This will wake up all threads waiting on this particular completion event.
4604 *
4605 * It may be assumed that this function implies a write memory barrier before
4606 * changing the task state if and only if any tasks are woken up.
4607 */
4608void complete_all(struct completion *x)
4609{
4610        unsigned long flags;
4611
4612        spin_lock_irqsave(&x->wait.lock, flags);
4613        x->done += UINT_MAX/2;
4614        __wake_up_common(&x->wait, TASK_NORMAL, 0, 0, NULL);
4615        spin_unlock_irqrestore(&x->wait.lock, flags);
4616}
4617EXPORT_SYMBOL(complete_all);
4618
4619static inline long __sched
4620do_wait_for_common(struct completion *x, long timeout, int state)
4621{
4622        if (!x->done) {
4623                DECLARE_WAITQUEUE(wait, current);
4624
4625                __add_wait_queue_tail_exclusive(&x->wait, &wait);
4626                do {
4627                        if (signal_pending_state(state, current)) {
4628                                timeout = -ERESTARTSYS;
4629                                break;
4630                        }
4631                        __set_current_state(state);
4632                        spin_unlock_irq(&x->wait.lock);
4633                        timeout = schedule_timeout(timeout);
4634                        spin_lock_irq(&x->wait.lock);
4635                } while (!x->done && timeout);
4636                __remove_wait_queue(&x->wait, &wait);
4637                if (!x->done)
4638                        return timeout;
4639        }
4640        x->done--;
4641        return timeout ?: 1;
4642}
4643
4644static long __sched
4645wait_for_common(struct completion *x, long timeout, int state)
4646{
4647        might_sleep();
4648
4649        spin_lock_irq(&x->wait.lock);
4650        timeout = do_wait_for_common(x, timeout, state);
4651        spin_unlock_irq(&x->wait.lock);
4652        return timeout;
4653}
4654
4655/**
4656 * wait_for_completion: - waits for completion of a task
4657 * @x:  holds the state of this particular completion
4658 *
4659 * This waits to be signaled for completion of a specific task. It is NOT
4660 * interruptible and there is no timeout.
4661 *
4662 * See also similar routines (i.e. wait_for_completion_timeout()) with timeout
4663 * and interrupt capability. Also see complete().
4664 */
4665void __sched wait_for_completion(struct completion *x)
4666{
4667        wait_for_common(x, MAX_SCHEDULE_TIMEOUT, TASK_UNINTERRUPTIBLE);
4668}
4669EXPORT_SYMBOL(wait_for_completion);
4670
4671/**
4672 * wait_for_completion_timeout: - waits for completion of a task (w/timeout)
4673 * @x:  holds the state of this particular completion
4674 * @timeout:  timeout value in jiffies
4675 *
4676 * This waits for either a completion of a specific task to be signaled or for a
4677 * specified timeout to expire. The timeout is in jiffies. It is not
4678 * interruptible.
4679 */
4680unsigned long __sched
4681wait_for_completion_timeout(struct completion *x, unsigned long timeout)
4682{
4683        return wait_for_common(x, timeout, TASK_UNINTERRUPTIBLE);
4684}
4685EXPORT_SYMBOL(wait_for_completion_timeout);
4686
4687/**
4688 * wait_for_completion_interruptible: - waits for completion of a task (w/intr)
4689 * @x:  holds the state of this particular completion
4690 *
4691 * This waits for completion of a specific task to be signaled. It is
4692 * interruptible.
4693 */
4694int __sched wait_for_completion_interruptible(struct completion *x)
4695{
4696        long t = wait_for_common(x, MAX_SCHEDULE_TIMEOUT, TASK_INTERRUPTIBLE);
4697        if (t == -ERESTARTSYS)
4698                return t;
4699        return 0;
4700}
4701EXPORT_SYMBOL(wait_for_completion_interruptible);
4702
4703/**
4704 * wait_for_completion_interruptible_timeout: - waits for completion (w/(to,intr))
4705 * @x:  holds the state of this particular completion
4706 * @timeout:  timeout value in jiffies
4707 *
4708 * This waits for either a completion of a specific task to be signaled or for a
4709 * specified timeout to expire. It is interruptible. The timeout is in jiffies.
4710 */
4711long __sched
4712wait_for_completion_interruptible_timeout(struct completion *x,
4713                                          unsigned long timeout)
4714{
4715        return wait_for_common(x, timeout, TASK_INTERRUPTIBLE);
4716}
4717EXPORT_SYMBOL(wait_for_completion_interruptible_timeout);
4718
4719/**
4720 * wait_for_completion_killable: - waits for completion of a task (killable)
4721 * @x:  holds the state of this particular completion
4722 *
4723 * This waits to be signaled for completion of a specific task. It can be
4724 * interrupted by a kill signal.
4725 */
4726int __sched wait_for_completion_killable(struct completion *x)
4727{
4728        long t = wait_for_common(x, MAX_SCHEDULE_TIMEOUT, TASK_KILLABLE);
4729        if (t == -ERESTARTSYS)
4730                return t;
4731        return 0;
4732}
4733EXPORT_SYMBOL(wait_for_completion_killable);
4734
4735/**
4736 * wait_for_completion_killable_timeout: - waits for completion of a task (w/(to,killable))
4737 * @x:  holds the state of this particular completion
4738 * @timeout:  timeout value in jiffies
4739 *
4740 * This waits for either a completion of a specific task to be
4741 * signaled or for a specified timeout to expire. It can be
4742 * interrupted by a kill signal. The timeout is in jiffies.
4743 */
4744long __sched
4745wait_for_completion_killable_timeout(struct completion *x,
4746                                     unsigned long timeout)
4747{
4748        return wait_for_common(x, timeout, TASK_KILLABLE);
4749}
4750EXPORT_SYMBOL(wait_for_completion_killable_timeout);
4751
4752/**
4753 *      try_wait_for_completion - try to decrement a completion without blocking
4754 *      @x:     completion structure
4755 *
4756 *      Returns: 0 if a decrement cannot be done without blocking
4757 *               1 if a decrement succeeded.
4758 *
4759 *      If a completion is being used as a counting completion,
4760 *      attempt to decrement the counter without blocking. This
4761 *      enables us to avoid waiting if the resource the completion
4762 *      is protecting is not available.
4763 */
4764bool try_wait_for_completion(struct completion *x)
4765{
4766        unsigned long flags;
4767        int ret = 1;
4768
4769        spin_lock_irqsave(&x->wait.lock, flags);
4770        if (!x->done)
4771                ret = 0;
4772        else
4773                x->done--;
4774        spin_unlock_irqrestore(&x->wait.lock, flags);
4775        return ret;
4776}
4777EXPORT_SYMBOL(try_wait_for_completion);
4778
4779/**
4780 *      completion_done - Test to see if a completion has any waiters
4781 *      @x:     completion structure
4782 *
4783 *      Returns: 0 if there are waiters (wait_for_completion() in progress)
4784 *               1 if there are no waiters.
4785 *
4786 */
4787bool completion_done(struct completion *x)
4788{
4789        unsigned long flags;
4790        int ret = 1;
4791
4792        spin_lock_irqsave(&x->wait.lock, flags);
4793        if (!x->done)
4794                ret = 0;
4795        spin_unlock_irqrestore(&x->wait.lock, flags);
4796        return ret;
4797}
4798EXPORT_SYMBOL(completion_done);
4799
4800static long __sched
4801sleep_on_common(wait_queue_head_t *q, int state, long timeout)
4802{
4803        unsigned long flags;
4804        wait_queue_t wait;
4805
4806        init_waitqueue_entry(&wait, current);
4807
4808        __set_current_state(state);
4809
4810        spin_lock_irqsave(&q->lock, flags);
4811        __add_wait_queue(q, &wait);
4812        spin_unlock(&q->lock);
4813        timeout = schedule_timeout(timeout);
4814        spin_lock_irq(&q->lock);
4815        __remove_wait_queue(q, &wait);
4816        spin_unlock_irqrestore(&q->lock, flags);
4817
4818        return timeout;
4819}
4820
4821void __sched interruptible_sleep_on(wait_queue_head_t *q)
4822{
4823        sleep_on_common(q, TASK_INTERRUPTIBLE, MAX_SCHEDULE_TIMEOUT);
4824}
4825EXPORT_SYMBOL(interruptible_sleep_on);
4826
4827long __sched
4828interruptible_sleep_on_timeout(wait_queue_head_t *q, long timeout)
4829{
4830        return sleep_on_common(q, TASK_INTERRUPTIBLE, timeout);
4831}
4832EXPORT_SYMBOL(interruptible_sleep_on_timeout);
4833
4834void __sched sleep_on(wait_queue_head_t *q)
4835{
4836        sleep_on_common(q, TASK_UNINTERRUPTIBLE, MAX_SCHEDULE_TIMEOUT);
4837}
4838EXPORT_SYMBOL(sleep_on);
4839
4840long __sched sleep_on_timeout(wait_queue_head_t *q, long timeout)
4841{
4842        return sleep_on_common(q, TASK_UNINTERRUPTIBLE, timeout);
4843}
4844EXPORT_SYMBOL(sleep_on_timeout);
4845
4846#ifdef CONFIG_RT_MUTEXES
4847
4848/*
4849 * rt_mutex_setprio - set the current priority of a task
4850 * @p: task
4851 * @prio: prio value (kernel-internal form)
4852 *
4853 * This function changes the 'effective' priority of a task. It does
4854 * not touch ->normal_prio like __setscheduler().
4855 *
4856 * Used by the rt_mutex code to implement priority inheritance logic.
4857 */
4858void rt_mutex_setprio(struct task_struct *p, int prio)
4859{
4860        int oldprio, on_rq, running;
4861        struct rq *rq;
4862        const struct sched_class *prev_class;
4863
4864        BUG_ON(prio < 0 || prio > MAX_PRIO);
4865
4866        rq = __task_rq_lock(p);
4867
4868        trace_sched_pi_setprio(p, prio);
4869        oldprio = p->prio;
4870        prev_class = p->sched_class;
4871        on_rq = p->on_rq;
4872        running = task_current(rq, p);
4873        if (on_rq)
4874                dequeue_task(rq, p, 0);
4875        if (running)
4876                p->sched_class->put_prev_task(rq, p);
4877
4878        if (rt_prio(prio))
4879                p->sched_class = &rt_sched_class;
4880        else
4881                p->sched_class = &fair_sched_class;
4882
4883        p->prio = prio;
4884
4885        if (running)
4886                p->sched_class->set_curr_task(rq);
4887        if (on_rq)
4888                enqueue_task(rq, p, oldprio < prio ? ENQUEUE_HEAD : 0);
4889
4890        check_class_changed(rq, p, prev_class, oldprio);
4891        __task_rq_unlock(rq);
4892}
4893
4894#endif
4895
4896void set_user_nice(struct task_struct *p, long nice)
4897{
4898        int old_prio, delta, on_rq;
4899        unsigned long flags;
4900        struct rq *rq;
4901
4902        if (TASK_NICE(p) == nice || nice < -20 || nice > 19)
4903                return;
4904        /*
4905         * We have to be careful, if called from sys_setpriority(),
4906         * the task might be in the middle of scheduling on another CPU.
4907         */
4908        rq = task_rq_lock(p, &flags);
4909        /*
4910         * The RT priorities are set via sched_setscheduler(), but we still
4911         * allow the 'normal' nice value to be set - but as expected
4912         * it wont have any effect on scheduling until the task is
4913         * SCHED_FIFO/SCHED_RR:
4914         */
4915        if (task_has_rt_policy(p)) {
4916                p->static_prio = NICE_TO_PRIO(nice);
4917                goto out_unlock;
4918        }
4919        on_rq = p->on_rq;
4920        if (on_rq)
4921                dequeue_task(rq, p, 0);
4922
4923        p->static_prio = NICE_TO_PRIO(nice);
4924        set_load_weight(p);
4925        old_prio = p->prio;
4926        p->prio = effective_prio(p);
4927        delta = p->prio - old_prio;
4928
4929        if (on_rq) {
4930                enqueue_task(rq, p, 0);
4931                /*
4932                 * If the task increased its priority or is running and
4933                 * lowered its priority, then reschedule its CPU:
4934                 */
4935                if (delta < 0 || (delta > 0 && task_running(rq, p)))
4936                        resched_task(rq->curr);
4937        }
4938out_unlock:
4939        task_rq_unlock(rq, p, &flags);
4940}
4941EXPORT_SYMBOL(set_user_nice);
4942
4943/*
4944 * can_nice - check if a task can reduce its nice value
4945 * @p: task
4946 * @nice: nice value
4947 */
4948int can_nice(const struct task_struct *p, const int nice)
4949{
4950        /* convert nice value [19,-20] to rlimit style value [1,40] */
4951        int nice_rlim = 20 - nice;
4952
4953        return (nice_rlim <= task_rlimit(p, RLIMIT_NICE) ||
4954                capable(CAP_SYS_NICE));
4955}
4956
4957#ifdef __ARCH_WANT_SYS_NICE
4958
4959/*
4960 * sys_nice - change the priority of the current process.
4961 * @increment: priority increment
4962 *
4963 * sys_setpriority is a more generic, but much slower function that
4964 * does similar things.
4965 */
4966SYSCALL_DEFINE1(nice, int, increment)
4967{
4968        long nice, retval;
4969
4970        /*
4971         * Setpriority might change our priority at the same moment.
4972         * We don't have to worry. Conceptually one call occurs first
4973         * and we have a single winner.
4974         */
4975        if (increment < -40)
4976                increment = -40;
4977        if (increment > 40)
4978                increment = 40;
4979
4980        nice = TASK_NICE(current) + increment;
4981        if (nice < -20)
4982                nice = -20;
4983        if (nice > 19)
4984                nice = 19;
4985
4986        if (increment < 0 && !can_nice(current, nice))
4987                return -EPERM;
4988
4989        retval = security_task_setnice(current, nice);
4990        if (retval)
4991                return retval;
4992
4993        set_user_nice(current, nice);
4994        return 0;
4995}
4996
4997#endif
4998
4999/**
5000 * task_prio - return the priority value of a given task.
5001 * @p: the task in question.
5002 *
5003 * This is the priority value as seen by users in /proc.
5004 * RT tasks are offset by -200. Normal tasks are centered
5005 * around 0, value goes from -16 to +15.
5006 */
5007int task_prio(const struct task_struct *p)
5008{
5009        return p->prio - MAX_RT_PRIO;
5010}
5011
5012/**
5013 * task_nice - return the nice value of a given task.
5014 * @p: the task in question.
5015 */
5016int task_nice(const struct task_struct *p)
5017{
5018        return TASK_NICE(p);
5019}
5020EXPORT_SYMBOL(task_nice);
5021
5022/**
5023 * idle_cpu - is a given cpu idle currently?
5024 * @cpu: the processor in question.
5025 */
5026int idle_cpu(int cpu)
5027{
5028        return cpu_curr(cpu) == cpu_rq(cpu)->idle;
5029}
5030
5031/**
5032 * idle_task - return the idle task for a given cpu.
5033 * @cpu: the processor in question.
5034 */
5035struct task_struct *idle_task(int cpu)
5036{
5037        return cpu_rq(cpu)->idle;
5038}
5039
5040/**
5041 * find_process_by_pid - find a process with a matching PID value.
5042 * @pid: the pid in question.
5043 */
5044static struct task_struct *find_process_by_pid(pid_t pid)
5045{
5046        return pid ? find_task_by_vpid(pid) : current;
5047}
5048
5049/* Actually do priority change: must hold rq lock. */
5050static void
5051__setscheduler(struct rq *rq, struct task_struct *p, int policy, int prio)
5052{
5053        p->policy = policy;
5054        p->rt_priority = prio;
5055        p->normal_prio = normal_prio(p);
5056        /* we are holding p->pi_lock already */
5057        p->prio = rt_mutex_getprio(p);
5058        if (rt_prio(p->prio))
5059                p->sched_class = &rt_sched_class;
5060        else
5061                p->sched_class = &fair_sched_class;
5062        set_load_weight(p);
5063}
5064
5065/*
5066 * check the target process has a UID that matches the current process's
5067 */
5068static bool check_same_owner(struct task_struct *p)
5069{
5070        const struct cred *cred = current_cred(), *pcred;
5071        bool match;
5072
5073        rcu_read_lock();
5074        pcred = __task_cred(p);
5075        if (cred->user->user_ns == pcred->user->user_ns)
5076                match = (cred->euid == pcred->euid ||
5077                         cred->euid == pcred->uid);
5078        else
5079                match = false;
5080        rcu_read_unlock();
5081        return match;
5082}
5083
5084static int __sched_setscheduler(struct task_struct *p, int policy,
5085                                const struct sched_param *param, bool user)
5086{
5087        int retval, oldprio, oldpolicy = -1, on_rq, running;
5088        unsigned long flags;
5089        const struct sched_class *prev_class;
5090        struct rq *rq;
5091        int reset_on_fork;
5092
5093        /* may grab non-irq protected spin_locks */
5094        BUG_ON(in_interrupt());
5095recheck:
5096        /* double check policy once rq lock held */
5097        if (policy < 0) {
5098                reset_on_fork = p->sched_reset_on_fork;
5099                policy = oldpolicy = p->policy;
5100        } else {
5101                reset_on_fork = !!(policy & SCHED_RESET_ON_FORK);
5102                policy &= ~SCHED_RESET_ON_FORK;
5103
5104                if (policy != SCHED_FIFO && policy != SCHED_RR &&
5105                                policy != SCHED_NORMAL && policy != SCHED_BATCH &&
5106                                policy != SCHED_IDLE)
5107                        return -EINVAL;
5108        }
5109
5110        /*
5111         * Valid priorities for SCHED_FIFO and SCHED_RR are
5112         * 1..MAX_USER_RT_PRIO-1, valid priority for SCHED_NORMAL,
5113         * SCHED_BATCH and SCHED_IDLE is 0.
5114         */
5115        if (param->sched_priority < 0 ||
5116            (p->mm && param->sched_priority > MAX_USER_RT_PRIO-1) ||
5117            (!p->mm && param->sched_priority > MAX_RT_PRIO-1))
5118                return -EINVAL;
5119        if (rt_policy(policy) != (param->sched_priority != 0))
5120                return -EINVAL;
5121
5122        /*
5123         * Allow unprivileged RT tasks to decrease priority:
5124         */
5125        if (user && !capable(CAP_SYS_NICE)) {
5126                if (rt_policy(policy)) {
5127                        unsigned long rlim_rtprio =
5128                                        task_rlimit(p, RLIMIT_RTPRIO);
5129
5130                        /* can't set/change the rt policy */
5131                        if (policy != p->policy && !rlim_rtprio)
5132                                return -EPERM;
5133
5134                        /* can't increase priority */
5135                        if (param->sched_priority > p->rt_priority &&
5136                            param->sched_priority > rlim_rtprio)
5137                                return -EPERM;
5138                }
5139
5140                /*
5141                 * Treat SCHED_IDLE as nice 20. Only allow a switch to
5142                 * SCHED_NORMAL if the RLIMIT_NICE would normally permit it.
5143                 */
5144                if (p->policy == SCHED_IDLE && policy != SCHED_IDLE) {
5145                        if (!can_nice(p, TASK_NICE(p)))
5146                                return -EPERM;
5147                }
5148
5149                /* can't change other user's priorities */
5150                if (!check_same_owner(p))
5151                        return -EPERM;
5152
5153                /* Normal users shall not reset the sched_reset_on_fork flag */
5154                if (p->sched_reset_on_fork && !reset_on_fork)
5155                        return -EPERM;
5156        }
5157
5158        if (user) {
5159                retval = security_task_setscheduler(p);
5160                if (retval)
5161                        return retval;
5162        }
5163
5164        /*
5165         * make sure no PI-waiters arrive (or leave) while we are
5166         * changing the priority of the task:
5167         *
5168         * To be able to change p->policy safely, the appropriate
5169         * runqueue lock must be held.
5170         */
5171        rq = task_rq_lock(p, &flags);
5172
5173        /*
5174         * Changing the policy of the stop threads its a very bad idea
5175         */
5176        if (p == rq->stop) {
5177                task_rq_unlock(rq, p, &flags);
5178                return -EINVAL;
5179        }
5180
5181        /*
5182         * If not changing anything there's no need to proceed further:
5183         */
5184        if (unlikely(policy == p->policy && (!rt_policy(policy) ||
5185                        param->sched_priority == p->rt_priority))) {
5186
5187                __task_rq_unlock(rq);
5188                raw_spin_unlock_irqrestore(&p->pi_lock, flags);
5189                return 0;
5190        }
5191
5192#ifdef CONFIG_RT_GROUP_SCHED
5193        if (user) {
5194                /*
5195                 * Do not allow realtime tasks into groups that have no runtime
5196                 * assigned.
5197                 */
5198                if (rt_bandwidth_enabled() && rt_policy(policy) &&
5199                                task_group(p)->rt_bandwidth.rt_runtime == 0 &&
5200                                !task_group_is_autogroup(task_group(p))) {
5201                        task_rq_unlock(rq, p, &flags);
5202                        return -EPERM;
5203                }
5204        }
5205#endif
5206
5207        /* recheck policy now with rq lock held */
5208        if (unlikely(oldpolicy != -1 && oldpolicy != p->policy)) {
5209                policy = oldpolicy = -1;
5210                task_rq_unlock(rq, p, &flags);
5211                goto recheck;
5212        }
5213        on_rq = p->on_rq;
5214        running = task_current(rq, p);
5215        if (on_rq)
5216                deactivate_task(rq, p, 0);
5217        if (running)
5218                p->sched_class->put_prev_task(rq, p);
5219
5220        p->sched_reset_on_fork = reset_on_fork;
5221
5222        oldprio = p->prio;
5223        prev_class = p->sched_class;
5224        __setscheduler(rq, p, policy, param->sched_priority);
5225
5226        if (running)
5227                p->sched_class->set_curr_task(rq);
5228        if (on_rq)
5229                activate_task(rq, p, 0);
5230
5231        check_class_changed(rq, p, prev_class, oldprio);
5232        task_rq_unlock(rq, p, &flags);
5233
5234        rt_mutex_adjust_pi(p);
5235
5236        return 0;
5237}
5238
5239/**
5240 * sched_setscheduler - change the scheduling policy and/or RT priority of a thread.
5241 * @p: the task in question.
5242 * @policy: new policy.
5243 * @param: structure containing the new RT priority.
5244 *
5245 * NOTE that the task may be already dead.
5246 */
5247int sched_setscheduler(struct task_struct *p, int policy,
5248                       const struct sched_param *param)
5249{
5250        return __sched_setscheduler(p, policy, param, true);
5251}
5252EXPORT_SYMBOL_GPL(sched_setscheduler);
5253
5254/**
5255 * sched_setscheduler_nocheck - change the scheduling policy and/or RT priority of a thread from kernelspace.
5256 * @p: the task in question.
5257 * @policy: new policy.
5258 * @param: structure containing the new RT priority.
5259 *
5260 * Just like sched_setscheduler, only don't bother checking if the
5261 * current context has permission.  For example, this is needed in
5262 * stop_machine(): we create temporary high priority worker threads,
5263 * but our caller might not have that capability.
5264 */
5265int sched_setscheduler_nocheck(struct task_struct *p, int policy,
5266                               const struct sched_param *param)
5267{
5268        return __sched_setscheduler(p, policy, param, false);
5269}
5270
5271static int
5272do_sched_setscheduler(pid_t pid, int policy, struct sched_param __user *param)
5273{
5274        struct sched_param lparam;
5275        struct task_struct *p;
5276        int retval;
5277
5278        if (!param || pid < 0)
5279                return -EINVAL;
5280        if (copy_from_user(&lparam, param, sizeof(struct sched_param)))
5281                return -EFAULT;
5282
5283        rcu_read_lock();
5284        retval = -ESRCH;
5285        p = find_process_by_pid(pid);
5286        if (p != NULL)
5287                retval = sched_setscheduler(p, policy, &lparam);
5288        rcu_read_unlock();
5289
5290        return retval;
5291}
5292
5293/**
5294 * sys_sched_setscheduler - set/change the scheduler policy and RT priority
5295 * @pid: the pid in question.
5296 * @policy: new policy.
5297 * @param: structure containing the new RT priority.
5298 */
5299SYSCALL_DEFINE3(sched_setscheduler, pid_t, pid, int, policy,
5300                struct sched_param __user *, param)
5301{
5302        /* negative values for policy are not valid */
5303        if (policy < 0)
5304                return -EINVAL;
5305
5306        return do_sched_setscheduler(pid, policy, param);
5307}
5308
5309/**
5310 * sys_sched_setparam - set/change the RT priority of a thread
5311 * @pid: the pid in question.
5312 * @param: structure containing the new RT priority.
5313 */
5314SYSCALL_DEFINE2(sched_setparam, pid_t, pid, struct sched_param __user *, param)
5315{
5316        return do_sched_setscheduler(pid, -1, param);
5317}
5318
5319/**
5320 * sys_sched_getscheduler - get the policy (scheduling class) of a thread
5321 * @pid: the pid in question.
5322 */
5323SYSCALL_DEFINE1(sched_getscheduler, pid_t, pid)
5324{
5325        struct task_struct *p;
5326        int retval;
5327
5328        if (pid < 0)
5329                return -EINVAL;
5330
5331        retval = -ESRCH;
5332        rcu_read_lock();
5333        p = find_process_by_pid(pid);
5334        if (p) {
5335                retval = security_task_getscheduler(p);
5336                if (!retval)
5337                        retval = p->policy
5338                                | (p->sched_reset_on_fork ? SCHED_RESET_ON_FORK : 0);
5339        }
5340        rcu_read_unlock();
5341        return retval;
5342}
5343
5344/**
5345 * sys_sched_getparam - get the RT priority of a thread
5346 * @pid: the pid in question.
5347 * @param: structure containing the RT priority.
5348 */
5349SYSCALL_DEFINE2(sched_getparam, pid_t, pid, struct sched_param __user *, param)
5350{
5351        struct sched_param lp;
5352        struct task_struct *p;
5353        int retval;
5354
5355        if (!param || pid < 0)
5356                return -EINVAL;
5357
5358        rcu_read_lock();
5359        p = find_process_by_pid(pid);
5360        retval = -ESRCH;
5361        if (!p)
5362                goto out_unlock;
5363
5364        retval = security_task_getscheduler(p);
5365        if (retval)
5366                goto out_unlock;
5367
5368        lp.sched_priority = p->rt_priority;
5369        rcu_read_unlock();
5370
5371        /*
5372         * This one might sleep, we cannot do it with a spinlock held ...
5373         */
5374        retval = copy_to_user(param, &lp, sizeof(*param)) ? -EFAULT : 0;
5375
5376        return retval;
5377
5378out_unlock:
5379        rcu_read_unlock();
5380        return retval;
5381}
5382
5383long sched_setaffinity(pid_t pid, const struct cpumask *in_mask)
5384{
5385        cpumask_var_t cpus_allowed, new_mask;
5386        struct task_struct *p;
5387        int retval;
5388
5389        get_online_cpus();
5390        rcu_read_lock();
5391
5392        p = find_process_by_pid(pid);
5393        if (!p) {
5394                rcu_read_unlock();
5395                put_online_cpus();
5396                return -ESRCH;
5397        }
5398
5399        /* Prevent p going away */
5400        get_task_struct(p);
5401        rcu_read_unlock();
5402
5403        if (!alloc_cpumask_var(&cpus_allowed, GFP_KERNEL)) {
5404                retval = -ENOMEM;
5405                goto out_put_task;
5406        }
5407        if (!alloc_cpumask_var(&new_mask, GFP_KERNEL)) {
5408                retval = -ENOMEM;
5409                goto out_free_cpus_allowed;
5410        }
5411        retval = -EPERM;
5412        if (!check_same_owner(p) && !task_ns_capable(p, CAP_SYS_NICE))
5413                goto out_unlock;
5414
5415        retval = security_task_setscheduler(p);
5416        if (retval)
5417                goto out_unlock;
5418
5419        cpuset_cpus_allowed(p, cpus_allowed);
5420        cpumask_and(new_mask, in_mask, cpus_allowed);
5421again:
5422        retval = set_cpus_allowed_ptr(p, new_mask);
5423
5424        if (!retval) {
5425                cpuset_cpus_allowed(p, cpus_allowed);
5426                if (!cpumask_subset(new_mask, cpus_allowed)) {
5427                        /*
5428                         * We must have raced with a concurrent cpuset
5429                         * update. Just reset the cpus_allowed to the
5430                         * cpuset's cpus_allowed
5431                         */
5432                        cpumask_copy(new_mask, cpus_allowed);
5433                        goto again;
5434                }
5435        }
5436out_unlock:
5437        free_cpumask_var(new_mask);
5438out_free_cpus_allowed:
5439        free_cpumask_var(cpus_allowed);
5440out_put_task:
5441        put_task_struct(p);
5442        put_online_cpus();
5443        return retval;
5444}
5445
5446static int get_user_cpu_mask(unsigned long __user *user_mask_ptr, unsigned len,
5447                             struct cpumask *new_mask)
5448{
5449        if (len < cpumask_size())
5450                cpumask_clear(new_mask);
5451        else if (len > cpumask_size())
5452                len = cpumask_size();
5453
5454        return copy_from_user(new_mask, user_mask_ptr, len) ? -EFAULT : 0;
5455}
5456
5457/**
5458 * sys_sched_setaffinity - set the cpu affinity of a process
5459 * @pid: pid of the process
5460 * @len: length in bytes of the bitmask pointed to by user_mask_ptr
5461 * @user_mask_ptr: user-space pointer to the new cpu mask
5462 */
5463SYSCALL_DEFINE3(sched_setaffinity, pid_t, pid, unsigned int, len,
5464                unsigned long __user *, user_mask_ptr)
5465{
5466        cpumask_var_t new_mask;
5467        int retval;
5468
5469        if (!alloc_cpumask_var(&new_mask, GFP_KERNEL))
5470                return -ENOMEM;
5471
5472        retval = get_user_cpu_mask(user_mask_ptr, len, new_mask);
5473        if (retval == 0)
5474                retval = sched_setaffinity(pid, new_mask);
5475        free_cpumask_var(new_mask);
5476        return retval;
5477}
5478
5479long sched_getaffinity(pid_t pid, struct cpumask *mask)
5480{
5481        struct task_struct *p;
5482        unsigned long flags;
5483        int retval;
5484
5485        get_online_cpus();
5486        rcu_read_lock();
5487
5488        retval = -ESRCH;
5489        p = find_process_by_pid(pid);
5490        if (!p)
5491                goto out_unlock;
5492
5493        retval = security_task_getscheduler(p);
5494        if (retval)
5495                goto out_unlock;
5496
5497        raw_spin_lock_irqsave(&p->pi_lock, flags);
5498        cpumask_and(mask, &p->cpus_allowed, cpu_online_mask);
5499        raw_spin_unlock_irqrestore(&p->pi_lock, flags);
5500
5501out_unlock:
5502        rcu_read_unlock();
5503        put_online_cpus();
5504
5505        return retval;
5506}
5507
5508/**
5509 * sys_sched_getaffinity - get the cpu affinity of a process
5510 * @pid: pid of the process
5511 * @len: length in bytes of the bitmask pointed to by user_mask_ptr
5512 * @user_mask_ptr: user-space pointer to hold the current cpu mask
5513 */
5514SYSCALL_DEFINE3(sched_getaffinity, pid_t, pid, unsigned int, len,
5515                unsigned long __user *, user_mask_ptr)
5516{
5517        int ret;
5518        cpumask_var_t mask;
5519
5520        if ((len * BITS_PER_BYTE) < nr_cpu_ids)
5521                return -EINVAL;
5522        if (len & (sizeof(unsigned long)-1))
5523                return -EINVAL;
5524
5525        if (!alloc_cpumask_var(&mask, GFP_KERNEL))
5526                return -ENOMEM;
5527
5528        ret = sched_getaffinity(pid, mask);
5529        if (ret == 0) {
5530                size_t retlen = min_t(size_t, len, cpumask_size());
5531
5532                if (copy_to_user(user_mask_ptr, mask, retlen))
5533                        ret = -EFAULT;
5534                else
5535                        ret = retlen;
5536        }
5537        free_cpumask_var(mask);
5538
5539        return ret;
5540}
5541
5542/**
5543 * sys_sched_yield - yield the current processor to other threads.
5544 *
5545 * This function yields the current CPU to other tasks. If there are no
5546 * other threads running on this CPU then this function will return.
5547 */
5548SYSCALL_DEFINE0(sched_yield)
5549{
5550        struct rq *rq = this_rq_lock();
5551
5552        schedstat_inc(rq, yld_count);
5553        current->sched_class->yield_task(rq);
5554
5555        /*
5556         * Since we are going to call schedule() anyway, there's
5557         * no need to preempt or enable interrupts:
5558         */
5559        __release(rq->lock);
5560        spin_release(&rq->lock.dep_map, 1, _THIS_IP_);
5561        do_raw_spin_unlock(&rq->lock);
5562        preempt_enable_no_resched();
5563
5564        schedule();
5565
5566        return 0;
5567}
5568
5569static inline int should_resched(void)
5570{
5571        return need_resched() && !(preempt_count() & PREEMPT_ACTIVE);
5572}
5573
5574static void __cond_resched(void)
5575{
5576        add_preempt_count(PREEMPT_ACTIVE);
5577        __schedule();
5578        sub_preempt_count(PREEMPT_ACTIVE);
5579}
5580
5581int __sched _cond_resched(void)
5582{
5583        if (should_resched()) {
5584                __cond_resched();
5585                return 1;
5586        }
5587        return 0;
5588}
5589EXPORT_SYMBOL(_cond_resched);
5590
5591/*
5592 * __cond_resched_lock() - if a reschedule is pending, drop the given lock,
5593 * call schedule, and on return reacquire the lock.
5594 *
5595 * This works OK both with and without CONFIG_PREEMPT. We do strange low-level
5596 * operations here to prevent schedule() from being called twice (once via
5597 * spin_unlock(), once by hand).
5598 */
5599int __cond_resched_lock(spinlock_t *lock)
5600{
5601        int resched = should_resched();
5602        int ret = 0;
5603
5604        lockdep_assert_held(lock);
5605
5606        if (spin_needbreak(lock) || resched) {
5607                spin_unlock(lock);
5608                if (resched)
5609                        __cond_resched();
5610                else
5611                        cpu_relax();
5612                ret = 1;
5613                spin_lock(lock);
5614        }
5615        return ret;
5616}
5617EXPORT_SYMBOL(__cond_resched_lock);
5618
5619int __sched __cond_resched_softirq(void)
5620{
5621        BUG_ON(!in_softirq());
5622
5623        if (should_resched()) {
5624                local_bh_enable();
5625                __cond_resched();
5626                local_bh_disable();
5627                return 1;
5628        }
5629        return 0;
5630}
5631EXPORT_SYMBOL(__cond_resched_softirq);
5632
5633/**
5634 * yield - yield the current processor to other threads.
5635 *
5636 * This is a shortcut for kernel-space yielding - it marks the
5637 * thread runnable and calls sys_sched_yield().
5638 */
5639void __sched yield(void)
5640{
5641        set_current_state(TASK_RUNNING);
5642        sys_sched_yield();
5643}
5644EXPORT_SYMBOL(yield);
5645
5646/**
5647 * yield_to - yield the current processor to another thread in
5648 * your thread group, or accelerate that thread toward the
5649 * processor it's on.
5650 * @p: target task
5651 * @preempt: whether task preemption is allowed or not
5652 *
5653 * It's the caller's job to ensure that the target task struct
5654 * can't go away on us before we can do any checks.
5655 *
5656 * Returns true if we indeed boosted the target task.
5657 */
5658bool __sched yield_to(struct task_struct *p, bool preempt)
5659{
5660        struct task_struct *curr = current;
5661        struct rq *rq, *p_rq;
5662        unsigned long flags;
5663        bool yielded = 0;
5664
5665        local_irq_save(flags);
5666        rq = this_rq();
5667
5668again:
5669        p_rq = task_rq(p);
5670        double_rq_lock(rq, p_rq);
5671        while (task_rq(p) != p_rq) {
5672                double_rq_unlock(rq, p_rq);
5673                goto again;
5674        }
5675
5676        if (!curr->sched_class->yield_to_task)
5677                goto out;
5678
5679        if (curr->sched_class != p->sched_class)
5680                goto out;
5681
5682        if (task_running(p_rq, p) || p->state)
5683                goto out;
5684
5685        yielded = curr->sched_class->yield_to_task(rq, p, preempt);
5686        if (yielded) {
5687                schedstat_inc(rq, yld_count);
5688                /*
5689                 * Make p's CPU reschedule; pick_next_entity takes care of
5690                 * fairness.
5691                 */
5692                if (preempt && rq != p_rq)
5693                        resched_task(p_rq->curr);
5694        }
5695
5696out:
5697        double_rq_unlock(rq, p_rq);
5698        local_irq_restore(flags);
5699
5700        if (yielded)
5701                schedule();
5702
5703        return yielded;
5704}
5705EXPORT_SYMBOL_GPL(yield_to);
5706
5707/*
5708 * This task is about to go to sleep on IO. Increment rq->nr_iowait so
5709 * that process accounting knows that this is a task in IO wait state.
5710 */
5711void __sched io_schedule(void)
5712{
5713        struct rq *rq = raw_rq();
5714
5715        delayacct_blkio_start();
5716        atomic_inc(&rq->nr_iowait);
5717        blk_flush_plug(current);
5718        current->in_iowait = 1;
5719        schedule();
5720        current->in_iowait = 0;
5721        atomic_dec(&rq->nr_iowait);
5722        delayacct_blkio_end();
5723}
5724EXPORT_SYMBOL(io_schedule);
5725
5726long __sched io_schedule_timeout(long timeout)
5727{
5728        struct rq *rq = raw_rq();
5729        long ret;
5730
5731        delayacct_blkio_start();
5732        atomic_inc(&rq->nr_iowait);
5733        blk_flush_plug(current);
5734        current->in_iowait = 1;
5735        ret = schedule_timeout(timeout);
5736        current->in_iowait = 0;
5737        atomic_dec(&rq->nr_iowait);
5738        delayacct_blkio_end();
5739        return ret;
5740}
5741
5742/**
5743 * sys_sched_get_priority_max - return maximum RT priority.
5744 * @policy: scheduling class.
5745 *
5746 * this syscall returns the maximum rt_priority that can be used
5747 * by a given scheduling class.
5748 */
5749SYSCALL_DEFINE1(sched_get_priority_max, int, policy)
5750{
5751        int ret = -EINVAL;
5752
5753        switch (policy) {
5754        case SCHED_FIFO:
5755        case SCHED_RR:
5756                ret = MAX_USER_RT_PRIO-1;
5757                break;
5758        case SCHED_NORMAL:
5759        case SCHED_BATCH:
5760        case SCHED_IDLE:
5761                ret = 0;
5762                break;
5763        }
5764        return ret;
5765}
5766
5767/**
5768 * sys_sched_get_priority_min - return minimum RT priority.
5769 * @policy: scheduling class.
5770 *
5771 * this syscall returns the minimum rt_priority that can be used
5772 * by a given scheduling class.
5773 */
5774SYSCALL_DEFINE1(sched_get_priority_min, int, policy)
5775{
5776        int ret = -EINVAL;
5777
5778        switch (policy) {
5779        case SCHED_FIFO:
5780        case SCHED_RR:
5781                ret = 1;
5782                break;
5783        case SCHED_NORMAL:
5784        case SCHED_BATCH:
5785        case SCHED_IDLE:
5786                ret = 0;
5787        }
5788        return ret;
5789}
5790
5791/**
5792 * sys_sched_rr_get_interval - return the default timeslice of a process.
5793 * @pid: pid of the process.
5794 * @interval: userspace pointer to the timeslice value.
5795 *
5796 * this syscall writes the default timeslice value of a given process
5797 * into the user-space timespec buffer. A value of '0' means infinity.
5798 */
5799SYSCALL_DEFINE2(sched_rr_get_interval, pid_t, pid,
5800                struct timespec __user *, interval)
5801{
5802        struct task_struct *p;
5803        unsigned int time_slice;
5804        unsigned long flags;
5805        struct rq *rq;
5806        int retval;
5807        struct timespec t;
5808
5809        if (pid < 0)
5810                return -EINVAL;
5811
5812        retval = -ESRCH;
5813        rcu_read_lock();
5814        p = find_process_by_pid(pid);
5815        if (!p)
5816                goto out_unlock;
5817
5818        retval = security_task_getscheduler(p);
5819        if (retval)
5820                goto out_unlock;
5821
5822        rq = task_rq_lock(p, &flags);
5823        time_slice = p->sched_class->get_rr_interval(rq, p);
5824        task_rq_unlock(rq, p, &flags);
5825
5826        rcu_read_unlock();
5827        jiffies_to_timespec(time_slice, &t);
5828        retval = copy_to_user(interval, &t, sizeof(t)) ? -EFAULT : 0;
5829        return retval;
5830
5831out_unlock:
5832        rcu_read_unlock();
5833        return retval;
5834}
5835
5836static const char stat_nam[] = TASK_STATE_TO_CHAR_STR;
5837
5838void sched_show_task(struct task_struct *p)
5839{
5840        unsigned long free = 0;
5841        unsigned state;
5842
5843        state = p->state ? __ffs(p->state) + 1 : 0;
5844        printk(KERN_INFO "%-15.15s %c", p->comm,
5845                state < sizeof(stat_nam) - 1 ? stat_nam[state] : '?');
5846#if BITS_PER_LONG == 32
5847        if (state == TASK_RUNNING)
5848                printk(KERN_CONT " running  ");
5849        else
5850                printk(KERN_CONT " %08lx ", thread_saved_pc(p));
5851#else
5852        if (state == TASK_RUNNING)
5853                printk(KERN_CONT "  running task    ");
5854        else
5855                printk(KERN_CONT " %016lx ", thread_saved_pc(p));
5856#endif
5857#ifdef CONFIG_DEBUG_STACK_USAGE
5858        free = stack_not_used(p);
5859#endif
5860        printk(KERN_CONT "%5lu %5d %6d 0x%08lx\n", free,
5861                task_pid_nr(p), task_pid_nr(p->real_parent),
5862                (unsigned long)task_thread_info(p)->flags);
5863
5864        show_stack(p, NULL);
5865}
5866
5867void show_state_filter(unsigned long state_filter)
5868{
5869        struct task_struct *g, *p;
5870
5871#if BITS_PER_LONG == 32
5872        printk(KERN_INFO
5873                "  task                PC stack   pid father\n");
5874#else
5875        printk(KERN_INFO
5876                "  task                        PC stack   pid father\n");
5877#endif
5878        read_lock(&tasklist_lock);
5879        do_each_thread(g, p) {
5880                /*
5881                 * reset the NMI-timeout, listing all files on a slow
5882                 * console might take a lot of time:
5883                 */
5884                touch_nmi_watchdog();
5885                if (!state_filter || (p->state & state_filter))
5886                        sched_show_task(p);
5887        } while_each_thread(g, p);
5888
5889        touch_all_softlockup_watchdogs();
5890
5891#ifdef CONFIG_SCHED_DEBUG
5892        sysrq_sched_debug_show();
5893#endif
5894        read_unlock(&tasklist_lock);
5895        /*
5896         * Only show locks if all tasks are dumped:
5897         */
5898        if (!state_filter)
5899                debug_show_all_locks();
5900}
5901
5902void __cpuinit init_idle_bootup_task(struct task_struct *idle)
5903{
5904        idle->sched_class = &idle_sched_class;
5905}
5906
5907/**
5908 * init_idle - set up an idle thread for a given CPU
5909 * @idle: task in question
5910 * @cpu: cpu the idle task belongs to
5911 *
5912 * NOTE: this function does not set the idle thread's NEED_RESCHED
5913 * flag, to make booting more robust.
5914 */
5915void __cpuinit init_idle(struct task_struct *idle, int cpu)
5916{
5917        struct rq *rq = cpu_rq(cpu);
5918        unsigned long flags;
5919
5920        raw_spin_lock_irqsave(&rq->lock, flags);
5921
5922        __sched_fork(idle);
5923        idle->state = TASK_RUNNING;
5924        idle->se.exec_start = sched_clock();
5925
5926        do_set_cpus_allowed(idle, cpumask_of(cpu));
5927        /*
5928         * We're having a chicken and egg problem, even though we are
5929         * holding rq->lock, the cpu isn't yet set to this cpu so the
5930         * lockdep check in task_group() will fail.
5931         *
5932         * Similar case to sched_fork(). / Alternatively we could
5933         * use task_rq_lock() here and obtain the other rq->lock.
5934         *
5935         * Silence PROVE_RCU
5936         */
5937        rcu_read_lock();
5938        __set_task_cpu(idle, cpu);
5939        rcu_read_unlock();
5940
5941        rq->curr = rq->idle = idle;
5942#if defined(CONFIG_SMP)
5943        idle->on_cpu = 1;
5944#endif
5945        raw_spin_unlock_irqrestore(&rq->lock, flags);
5946
5947        /* Set the preempt count _outside_ the spinlocks! */
5948        task_thread_info(idle)->preempt_count = 0;
5949
5950        /*
5951         * The idle tasks have their own, simple scheduling class:
5952         */
5953        idle->sched_class = &idle_sched_class;
5954        ftrace_graph_init_idle_task(idle, cpu);
5955}
5956
5957/*
5958 * In a system that switches off the HZ timer nohz_cpu_mask
5959 * indicates which cpus entered this state. This is used
5960 * in the rcu update to wait only for active cpus. For system
5961 * which do not switch off the HZ timer nohz_cpu_mask should
5962 * always be CPU_BITS_NONE.
5963 */
5964cpumask_var_t nohz_cpu_mask;
5965
5966/*
5967 * Increase the granularity value when there are more CPUs,
5968 * because with more CPUs the 'effective latency' as visible
5969 * to users decreases. But the relationship is not linear,
5970 * so pick a second-best guess by going with the log2 of the
5971 * number of CPUs.
5972 *
5973 * This idea comes from the SD scheduler of Con Kolivas:
5974 */
5975static int get_update_sysctl_factor(void)
5976{
5977        unsigned int cpus = min_t(int, num_online_cpus(), 8);
5978        unsigned int factor;
5979
5980        switch (sysctl_sched_tunable_scaling) {
5981        case SCHED_TUNABLESCALING_NONE:
5982                factor = 1;
5983                break;
5984        case SCHED_TUNABLESCALING_LINEAR:
5985                factor = cpus;
5986                break;
5987        case SCHED_TUNABLESCALING_LOG:
5988        default:
5989                factor = 1 + ilog2(cpus);
5990                break;
5991        }
5992
5993        return factor;
5994}
5995
5996static void update_sysctl(void)
5997{
5998        unsigned int factor = get_update_sysctl_factor();
5999
6000#define SET_SYSCTL(name) \
6001        (sysctl_##name = (factor) * normalized_sysctl_##name)
6002        SET_SYSCTL(sched_min_granularity);
6003        SET_SYSCTL(sched_latency);
6004        SET_SYSCTL(sched_wakeup_granularity);
6005#undef SET_SYSCTL
6006}
6007
6008static inline void sched_init_granularity(void)
6009{
6010        update_sysctl();
6011}
6012
6013#ifdef CONFIG_SMP
6014void do_set_cpus_allowed(struct task_struct *p, const struct cpumask *new_mask)
6015{
6016        if (p->sched_class && p->sched_class->set_cpus_allowed)
6017                p->sched_class->set_cpus_allowed(p, new_mask);
6018        else {
6019                cpumask_copy(&p->cpus_allowed, new_mask);
6020                p->rt.nr_cpus_allowed = cpumask_weight(new_mask);
6021        }
6022}
6023
6024/*
6025 * This is how migration works:
6026 *
6027 * 1) we invoke migration_cpu_stop() on the target CPU using
6028 *    stop_one_cpu().
6029 * 2) stopper starts to run (implicitly forcing the migrated thread
6030 *    off the CPU)
6031 * 3) it checks whether the migrated task is still in the wrong runqueue.
6032 * 4) if it's in the wrong runqueue then the migration thread removes
6033 *    it and puts it into the right queue.
6034 * 5) stopper completes and stop_one_cpu() returns and the migration
6035 *    is done.
6036 */
6037
6038/*
6039 * Change a given task's CPU affinity. Migrate the thread to a
6040 * proper CPU and schedule it away if the CPU it's executing on
6041 * is removed from the allowed bitmask.
6042 *
6043 * NOTE: the caller must have a valid reference to the task, the
6044 * task must not exit() & deallocate itself prematurely. The
6045 * call is not atomic; no spinlocks may be held.
6046 */
6047int set_cpus_allowed_ptr(struct task_struct *p, const struct cpumask *new_mask)
6048{
6049        unsigned long flags;
6050        struct rq *rq;
6051        unsigned int dest_cpu;
6052        int ret = 0;
6053
6054        rq = task_rq_lock(p, &flags);
6055
6056        if (cpumask_equal(&p->cpus_allowed, new_mask))
6057                goto out;
6058
6059        if (!cpumask_intersects(new_mask, cpu_active_mask)) {
6060                ret = -EINVAL;
6061                goto out;
6062        }
6063
6064        if (unlikely((p->flags & PF_THREAD_BOUND) && p != current)) {
6065                ret = -EINVAL;
6066                goto out;
6067        }
6068
6069        do_set_cpus_allowed(p, new_mask);
6070
6071        /* Can the task run on the task's current CPU? If so, we're done */
6072        if (cpumask_test_cpu(task_cpu(p), new_mask))
6073                goto out;
6074
6075        dest_cpu = cpumask_any_and(cpu_active_mask, new_mask);
6076        if (p->on_rq) {
6077                struct migration_arg arg = { p, dest_cpu };
6078                /* Need help from migration thread: drop lock and wait. */
6079                task_rq_unlock(rq, p, &flags);
6080                stop_one_cpu(cpu_of(rq), migration_cpu_stop, &arg);
6081                tlb_migrate_finish(p->mm);
6082                return 0;
6083        }
6084out:
6085        task_rq_unlock(rq, p, &flags);
6086
6087        return ret;
6088}
6089EXPORT_SYMBOL_GPL(set_cpus_allowed_ptr);
6090
6091/*
6092 * Move (not current) task off this cpu, onto dest cpu. We're doing
6093 * this because either it can't run here any more (set_cpus_allowed()
6094 * away from this CPU, or CPU going down), or because we're
6095 * attempting to rebalance this task on exec (sched_exec).
6096 *
6097 * So we race with normal scheduler movements, but that's OK, as long
6098 * as the task is no longer on this CPU.
6099 *
6100 * Returns non-zero if task was successfully migrated.
6101 */
6102static int __migrate_task(struct task_struct *p, int src_cpu, int dest_cpu)
6103{
6104        struct rq *rq_dest, *rq_src;
6105        int ret = 0;
6106
6107        if (unlikely(!cpu_active(dest_cpu)))
6108                return ret;
6109
6110        rq_src = cpu_rq(src_cpu);
6111        rq_dest = cpu_rq(dest_cpu);
6112
6113        raw_spin_lock(&p->pi_lock);
6114        double_rq_lock(rq_src, rq_dest);
6115        /* Already moved. */
6116        if (task_cpu(p) != src_cpu)
6117                goto done;
6118        /* Affinity changed (again). */
6119        if (!cpumask_test_cpu(dest_cpu, &p->cpus_allowed))
6120                goto fail;
6121
6122        /*
6123         * If we're not on a rq, the next wake-up will ensure we're
6124         * placed properly.
6125         */
6126        if (p->on_rq) {
6127                deactivate_task(rq_src, p, 0);
6128                set_task_cpu(p, dest_cpu);
6129                activate_task(rq_dest, p, 0);
6130                check_preempt_curr(rq_dest, p, 0);
6131        }
6132done:
6133        ret = 1;
6134fail:
6135        double_rq_unlock(rq_src, rq_dest);