linux/kernel/sched/core.c
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   1/*
   2 *  kernel/sched/core.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/sysctl.h>
  60#include <linux/syscalls.h>
  61#include <linux/times.h>
  62#include <linux/tsacct_kern.h>
  63#include <linux/kprobes.h>
  64#include <linux/delayacct.h>
  65#include <linux/unistd.h>
  66#include <linux/pagemap.h>
  67#include <linux/hrtimer.h>
  68#include <linux/tick.h>
  69#include <linux/debugfs.h>
  70#include <linux/ctype.h>
  71#include <linux/ftrace.h>
  72#include <linux/slab.h>
  73#include <linux/init_task.h>
  74#include <linux/binfmts.h>
  75
  76#include <asm/switch_to.h>
  77#include <asm/tlb.h>
  78#include <asm/irq_regs.h>
  79#include <asm/mutex.h>
  80#ifdef CONFIG_PARAVIRT
  81#include <asm/paravirt.h>
  82#endif
  83
  84#include "sched.h"
  85#include "../workqueue_sched.h"
  86#include "../smpboot.h"
  87
  88#define CREATE_TRACE_POINTS
  89#include <trace/events/sched.h>
  90
  91void start_bandwidth_timer(struct hrtimer *period_timer, ktime_t period)
  92{
  93        unsigned long delta;
  94        ktime_t soft, hard, now;
  95
  96        for (;;) {
  97                if (hrtimer_active(period_timer))
  98                        break;
  99
 100                now = hrtimer_cb_get_time(period_timer);
 101                hrtimer_forward(period_timer, now, period);
 102
 103                soft = hrtimer_get_softexpires(period_timer);
 104                hard = hrtimer_get_expires(period_timer);
 105                delta = ktime_to_ns(ktime_sub(hard, soft));
 106                __hrtimer_start_range_ns(period_timer, soft, delta,
 107                                         HRTIMER_MODE_ABS_PINNED, 0);
 108        }
 109}
 110
 111DEFINE_MUTEX(sched_domains_mutex);
 112DEFINE_PER_CPU_SHARED_ALIGNED(struct rq, runqueues);
 113
 114static void update_rq_clock_task(struct rq *rq, s64 delta);
 115
 116void update_rq_clock(struct rq *rq)
 117{
 118        s64 delta;
 119
 120        if (rq->skip_clock_update > 0)
 121                return;
 122
 123        delta = sched_clock_cpu(cpu_of(rq)) - rq->clock;
 124        rq->clock += delta;
 125        update_rq_clock_task(rq, delta);
 126}
 127
 128/*
 129 * Debugging: various feature bits
 130 */
 131
 132#define SCHED_FEAT(name, enabled)       \
 133        (1UL << __SCHED_FEAT_##name) * enabled |
 134
 135const_debug unsigned int sysctl_sched_features =
 136#include "features.h"
 137        0;
 138
 139#undef SCHED_FEAT
 140
 141#ifdef CONFIG_SCHED_DEBUG
 142#define SCHED_FEAT(name, enabled)       \
 143        #name ,
 144
 145static const char * const sched_feat_names[] = {
 146#include "features.h"
 147};
 148
 149#undef SCHED_FEAT
 150
 151static int sched_feat_show(struct seq_file *m, void *v)
 152{
 153        int i;
 154
 155        for (i = 0; i < __SCHED_FEAT_NR; i++) {
 156                if (!(sysctl_sched_features & (1UL << i)))
 157                        seq_puts(m, "NO_");
 158                seq_printf(m, "%s ", sched_feat_names[i]);
 159        }
 160        seq_puts(m, "\n");
 161
 162        return 0;
 163}
 164
 165#ifdef HAVE_JUMP_LABEL
 166
 167#define jump_label_key__true  STATIC_KEY_INIT_TRUE
 168#define jump_label_key__false STATIC_KEY_INIT_FALSE
 169
 170#define SCHED_FEAT(name, enabled)       \
 171        jump_label_key__##enabled ,
 172
 173struct static_key sched_feat_keys[__SCHED_FEAT_NR] = {
 174#include "features.h"
 175};
 176
 177#undef SCHED_FEAT
 178
 179static void sched_feat_disable(int i)
 180{
 181        if (static_key_enabled(&sched_feat_keys[i]))
 182                static_key_slow_dec(&sched_feat_keys[i]);
 183}
 184
 185static void sched_feat_enable(int i)
 186{
 187        if (!static_key_enabled(&sched_feat_keys[i]))
 188                static_key_slow_inc(&sched_feat_keys[i]);
 189}
 190#else
 191static void sched_feat_disable(int i) { };
 192static void sched_feat_enable(int i) { };
 193#endif /* HAVE_JUMP_LABEL */
 194
 195static ssize_t
 196sched_feat_write(struct file *filp, const char __user *ubuf,
 197                size_t cnt, loff_t *ppos)
 198{
 199        char buf[64];
 200        char *cmp;
 201        int neg = 0;
 202        int i;
 203
 204        if (cnt > 63)
 205                cnt = 63;
 206
 207        if (copy_from_user(&buf, ubuf, cnt))
 208                return -EFAULT;
 209
 210        buf[cnt] = 0;
 211        cmp = strstrip(buf);
 212
 213        if (strncmp(cmp, "NO_", 3) == 0) {
 214                neg = 1;
 215                cmp += 3;
 216        }
 217
 218        for (i = 0; i < __SCHED_FEAT_NR; i++) {
 219                if (strcmp(cmp, sched_feat_names[i]) == 0) {
 220                        if (neg) {
 221                                sysctl_sched_features &= ~(1UL << i);
 222                                sched_feat_disable(i);
 223                        } else {
 224                                sysctl_sched_features |= (1UL << i);
 225                                sched_feat_enable(i);
 226                        }
 227                        break;
 228                }
 229        }
 230
 231        if (i == __SCHED_FEAT_NR)
 232                return -EINVAL;
 233
 234        *ppos += cnt;
 235
 236        return cnt;
 237}
 238
 239static int sched_feat_open(struct inode *inode, struct file *filp)
 240{
 241        return single_open(filp, sched_feat_show, NULL);
 242}
 243
 244static const struct file_operations sched_feat_fops = {
 245        .open           = sched_feat_open,
 246        .write          = sched_feat_write,
 247        .read           = seq_read,
 248        .llseek         = seq_lseek,
 249        .release        = single_release,
 250};
 251
 252static __init int sched_init_debug(void)
 253{
 254        debugfs_create_file("sched_features", 0644, NULL, NULL,
 255                        &sched_feat_fops);
 256
 257        return 0;
 258}
 259late_initcall(sched_init_debug);
 260#endif /* CONFIG_SCHED_DEBUG */
 261
 262/*
 263 * Number of tasks to iterate in a single balance run.
 264 * Limited because this is done with IRQs disabled.
 265 */
 266const_debug unsigned int sysctl_sched_nr_migrate = 32;
 267
 268/*
 269 * period over which we average the RT time consumption, measured
 270 * in ms.
 271 *
 272 * default: 1s
 273 */
 274const_debug unsigned int sysctl_sched_time_avg = MSEC_PER_SEC;
 275
 276/*
 277 * period over which we measure -rt task cpu usage in us.
 278 * default: 1s
 279 */
 280unsigned int sysctl_sched_rt_period = 1000000;
 281
 282__read_mostly int scheduler_running;
 283
 284/*
 285 * part of the period that we allow rt tasks to run in us.
 286 * default: 0.95s
 287 */
 288int sysctl_sched_rt_runtime = 950000;
 289
 290
 291
 292/*
 293 * __task_rq_lock - lock the rq @p resides on.
 294 */
 295static inline struct rq *__task_rq_lock(struct task_struct *p)
 296        __acquires(rq->lock)
 297{
 298        struct rq *rq;
 299
 300        lockdep_assert_held(&p->pi_lock);
 301
 302        for (;;) {
 303                rq = task_rq(p);
 304                raw_spin_lock(&rq->lock);
 305                if (likely(rq == task_rq(p)))
 306                        return rq;
 307                raw_spin_unlock(&rq->lock);
 308        }
 309}
 310
 311/*
 312 * task_rq_lock - lock p->pi_lock and lock the rq @p resides on.
 313 */
 314static struct rq *task_rq_lock(struct task_struct *p, unsigned long *flags)
 315        __acquires(p->pi_lock)
 316        __acquires(rq->lock)
 317{
 318        struct rq *rq;
 319
 320        for (;;) {
 321                raw_spin_lock_irqsave(&p->pi_lock, *flags);
 322                rq = task_rq(p);
 323                raw_spin_lock(&rq->lock);
 324                if (likely(rq == task_rq(p)))
 325                        return rq;
 326                raw_spin_unlock(&rq->lock);
 327                raw_spin_unlock_irqrestore(&p->pi_lock, *flags);
 328        }
 329}
 330
 331static void __task_rq_unlock(struct rq *rq)
 332        __releases(rq->lock)
 333{
 334        raw_spin_unlock(&rq->lock);
 335}
 336
 337static inline void
 338task_rq_unlock(struct rq *rq, struct task_struct *p, unsigned long *flags)
 339        __releases(rq->lock)
 340        __releases(p->pi_lock)
 341{
 342        raw_spin_unlock(&rq->lock);
 343        raw_spin_unlock_irqrestore(&p->pi_lock, *flags);
 344}
 345
 346/*
 347 * this_rq_lock - lock this runqueue and disable interrupts.
 348 */
 349static struct rq *this_rq_lock(void)
 350        __acquires(rq->lock)
 351{
 352        struct rq *rq;
 353
 354        local_irq_disable();
 355        rq = this_rq();
 356        raw_spin_lock(&rq->lock);
 357
 358        return rq;
 359}
 360
 361#ifdef CONFIG_SCHED_HRTICK
 362/*
 363 * Use HR-timers to deliver accurate preemption points.
 364 *
 365 * Its all a bit involved since we cannot program an hrt while holding the
 366 * rq->lock. So what we do is store a state in in rq->hrtick_* and ask for a
 367 * reschedule event.
 368 *
 369 * When we get rescheduled we reprogram the hrtick_timer outside of the
 370 * rq->lock.
 371 */
 372
 373static void hrtick_clear(struct rq *rq)
 374{
 375        if (hrtimer_active(&rq->hrtick_timer))
 376                hrtimer_cancel(&rq->hrtick_timer);
 377}
 378
 379/*
 380 * High-resolution timer tick.
 381 * Runs from hardirq context with interrupts disabled.
 382 */
 383static enum hrtimer_restart hrtick(struct hrtimer *timer)
 384{
 385        struct rq *rq = container_of(timer, struct rq, hrtick_timer);
 386
 387        WARN_ON_ONCE(cpu_of(rq) != smp_processor_id());
 388
 389        raw_spin_lock(&rq->lock);
 390        update_rq_clock(rq);
 391        rq->curr->sched_class->task_tick(rq, rq->curr, 1);
 392        raw_spin_unlock(&rq->lock);
 393
 394        return HRTIMER_NORESTART;
 395}
 396
 397#ifdef CONFIG_SMP
 398/*
 399 * called from hardirq (IPI) context
 400 */
 401static void __hrtick_start(void *arg)
 402{
 403        struct rq *rq = arg;
 404
 405        raw_spin_lock(&rq->lock);
 406        hrtimer_restart(&rq->hrtick_timer);
 407        rq->hrtick_csd_pending = 0;
 408        raw_spin_unlock(&rq->lock);
 409}
 410
 411/*
 412 * Called to set the hrtick timer state.
 413 *
 414 * called with rq->lock held and irqs disabled
 415 */
 416void hrtick_start(struct rq *rq, u64 delay)
 417{
 418        struct hrtimer *timer = &rq->hrtick_timer;
 419        ktime_t time = ktime_add_ns(timer->base->get_time(), delay);
 420
 421        hrtimer_set_expires(timer, time);
 422
 423        if (rq == this_rq()) {
 424                hrtimer_restart(timer);
 425        } else if (!rq->hrtick_csd_pending) {
 426                __smp_call_function_single(cpu_of(rq), &rq->hrtick_csd, 0);
 427                rq->hrtick_csd_pending = 1;
 428        }
 429}
 430
 431static int
 432hotplug_hrtick(struct notifier_block *nfb, unsigned long action, void *hcpu)
 433{
 434        int cpu = (int)(long)hcpu;
 435
 436        switch (action) {
 437        case CPU_UP_CANCELED:
 438        case CPU_UP_CANCELED_FROZEN:
 439        case CPU_DOWN_PREPARE:
 440        case CPU_DOWN_PREPARE_FROZEN:
 441        case CPU_DEAD:
 442        case CPU_DEAD_FROZEN:
 443                hrtick_clear(cpu_rq(cpu));
 444                return NOTIFY_OK;
 445        }
 446
 447        return NOTIFY_DONE;
 448}
 449
 450static __init void init_hrtick(void)
 451{
 452        hotcpu_notifier(hotplug_hrtick, 0);
 453}
 454#else
 455/*
 456 * Called to set the hrtick timer state.
 457 *
 458 * called with rq->lock held and irqs disabled
 459 */
 460void hrtick_start(struct rq *rq, u64 delay)
 461{
 462        __hrtimer_start_range_ns(&rq->hrtick_timer, ns_to_ktime(delay), 0,
 463                        HRTIMER_MODE_REL_PINNED, 0);
 464}
 465
 466static inline void init_hrtick(void)
 467{
 468}
 469#endif /* CONFIG_SMP */
 470
 471static void init_rq_hrtick(struct rq *rq)
 472{
 473#ifdef CONFIG_SMP
 474        rq->hrtick_csd_pending = 0;
 475
 476        rq->hrtick_csd.flags = 0;
 477        rq->hrtick_csd.func = __hrtick_start;
 478        rq->hrtick_csd.info = rq;
 479#endif
 480
 481        hrtimer_init(&rq->hrtick_timer, CLOCK_MONOTONIC, HRTIMER_MODE_REL);
 482        rq->hrtick_timer.function = hrtick;
 483}
 484#else   /* CONFIG_SCHED_HRTICK */
 485static inline void hrtick_clear(struct rq *rq)
 486{
 487}
 488
 489static inline void init_rq_hrtick(struct rq *rq)
 490{
 491}
 492
 493static inline void init_hrtick(void)
 494{
 495}
 496#endif  /* CONFIG_SCHED_HRTICK */
 497
 498/*
 499 * resched_task - mark a task 'to be rescheduled now'.
 500 *
 501 * On UP this means the setting of the need_resched flag, on SMP it
 502 * might also involve a cross-CPU call to trigger the scheduler on
 503 * the target CPU.
 504 */
 505#ifdef CONFIG_SMP
 506
 507#ifndef tsk_is_polling
 508#define tsk_is_polling(t) 0
 509#endif
 510
 511void resched_task(struct task_struct *p)
 512{
 513        int cpu;
 514
 515        assert_raw_spin_locked(&task_rq(p)->lock);
 516
 517        if (test_tsk_need_resched(p))
 518                return;
 519
 520        set_tsk_need_resched(p);
 521
 522        cpu = task_cpu(p);
 523        if (cpu == smp_processor_id())
 524                return;
 525
 526        /* NEED_RESCHED must be visible before we test polling */
 527        smp_mb();
 528        if (!tsk_is_polling(p))
 529                smp_send_reschedule(cpu);
 530}
 531
 532void resched_cpu(int cpu)
 533{
 534        struct rq *rq = cpu_rq(cpu);
 535        unsigned long flags;
 536
 537        if (!raw_spin_trylock_irqsave(&rq->lock, flags))
 538                return;
 539        resched_task(cpu_curr(cpu));
 540        raw_spin_unlock_irqrestore(&rq->lock, flags);
 541}
 542
 543#ifdef CONFIG_NO_HZ
 544/*
 545 * In the semi idle case, use the nearest busy cpu for migrating timers
 546 * from an idle cpu.  This is good for power-savings.
 547 *
 548 * We don't do similar optimization for completely idle system, as
 549 * selecting an idle cpu will add more delays to the timers than intended
 550 * (as that cpu's timer base may not be uptodate wrt jiffies etc).
 551 */
 552int get_nohz_timer_target(void)
 553{
 554        int cpu = smp_processor_id();
 555        int i;
 556        struct sched_domain *sd;
 557
 558        rcu_read_lock();
 559        for_each_domain(cpu, sd) {
 560                for_each_cpu(i, sched_domain_span(sd)) {
 561                        if (!idle_cpu(i)) {
 562                                cpu = i;
 563                                goto unlock;
 564                        }
 565                }
 566        }
 567unlock:
 568        rcu_read_unlock();
 569        return cpu;
 570}
 571/*
 572 * When add_timer_on() enqueues a timer into the timer wheel of an
 573 * idle CPU then this timer might expire before the next timer event
 574 * which is scheduled to wake up that CPU. In case of a completely
 575 * idle system the next event might even be infinite time into the
 576 * future. wake_up_idle_cpu() ensures that the CPU is woken up and
 577 * leaves the inner idle loop so the newly added timer is taken into
 578 * account when the CPU goes back to idle and evaluates the timer
 579 * wheel for the next timer event.
 580 */
 581void wake_up_idle_cpu(int cpu)
 582{
 583        struct rq *rq = cpu_rq(cpu);
 584
 585        if (cpu == smp_processor_id())
 586                return;
 587
 588        /*
 589         * This is safe, as this function is called with the timer
 590         * wheel base lock of (cpu) held. When the CPU is on the way
 591         * to idle and has not yet set rq->curr to idle then it will
 592         * be serialized on the timer wheel base lock and take the new
 593         * timer into account automatically.
 594         */
 595        if (rq->curr != rq->idle)
 596                return;
 597
 598        /*
 599         * We can set TIF_RESCHED on the idle task of the other CPU
 600         * lockless. The worst case is that the other CPU runs the
 601         * idle task through an additional NOOP schedule()
 602         */
 603        set_tsk_need_resched(rq->idle);
 604
 605        /* NEED_RESCHED must be visible before we test polling */
 606        smp_mb();
 607        if (!tsk_is_polling(rq->idle))
 608                smp_send_reschedule(cpu);
 609}
 610
 611static inline bool got_nohz_idle_kick(void)
 612{
 613        int cpu = smp_processor_id();
 614        return idle_cpu(cpu) && test_bit(NOHZ_BALANCE_KICK, nohz_flags(cpu));
 615}
 616
 617#else /* CONFIG_NO_HZ */
 618
 619static inline bool got_nohz_idle_kick(void)
 620{
 621        return false;
 622}
 623
 624#endif /* CONFIG_NO_HZ */
 625
 626void sched_avg_update(struct rq *rq)
 627{
 628        s64 period = sched_avg_period();
 629
 630        while ((s64)(rq->clock - rq->age_stamp) > period) {
 631                /*
 632                 * Inline assembly required to prevent the compiler
 633                 * optimising this loop into a divmod call.
 634                 * See __iter_div_u64_rem() for another example of this.
 635                 */
 636                asm("" : "+rm" (rq->age_stamp));
 637                rq->age_stamp += period;
 638                rq->rt_avg /= 2;
 639        }
 640}
 641
 642#else /* !CONFIG_SMP */
 643void resched_task(struct task_struct *p)
 644{
 645        assert_raw_spin_locked(&task_rq(p)->lock);
 646        set_tsk_need_resched(p);
 647}
 648#endif /* CONFIG_SMP */
 649
 650#if defined(CONFIG_RT_GROUP_SCHED) || (defined(CONFIG_FAIR_GROUP_SCHED) && \
 651                        (defined(CONFIG_SMP) || defined(CONFIG_CFS_BANDWIDTH)))
 652/*
 653 * Iterate task_group tree rooted at *from, calling @down when first entering a
 654 * node and @up when leaving it for the final time.
 655 *
 656 * Caller must hold rcu_lock or sufficient equivalent.
 657 */
 658int walk_tg_tree_from(struct task_group *from,
 659                             tg_visitor down, tg_visitor up, void *data)
 660{
 661        struct task_group *parent, *child;
 662        int ret;
 663
 664        parent = from;
 665
 666down:
 667        ret = (*down)(parent, data);
 668        if (ret)
 669                goto out;
 670        list_for_each_entry_rcu(child, &parent->children, siblings) {
 671                parent = child;
 672                goto down;
 673
 674up:
 675                continue;
 676        }
 677        ret = (*up)(parent, data);
 678        if (ret || parent == from)
 679                goto out;
 680
 681        child = parent;
 682        parent = parent->parent;
 683        if (parent)
 684                goto up;
 685out:
 686        return ret;
 687}
 688
 689int tg_nop(struct task_group *tg, void *data)
 690{
 691        return 0;
 692}
 693#endif
 694
 695static void set_load_weight(struct task_struct *p)
 696{
 697        int prio = p->static_prio - MAX_RT_PRIO;
 698        struct load_weight *load = &p->se.load;
 699
 700        /*
 701         * SCHED_IDLE tasks get minimal weight:
 702         */
 703        if (p->policy == SCHED_IDLE) {
 704                load->weight = scale_load(WEIGHT_IDLEPRIO);
 705                load->inv_weight = WMULT_IDLEPRIO;
 706                return;
 707        }
 708
 709        load->weight = scale_load(prio_to_weight[prio]);
 710        load->inv_weight = prio_to_wmult[prio];
 711}
 712
 713static void enqueue_task(struct rq *rq, struct task_struct *p, int flags)
 714{
 715        update_rq_clock(rq);
 716        sched_info_queued(p);
 717        p->sched_class->enqueue_task(rq, p, flags);
 718}
 719
 720static void dequeue_task(struct rq *rq, struct task_struct *p, int flags)
 721{
 722        update_rq_clock(rq);
 723        sched_info_dequeued(p);
 724        p->sched_class->dequeue_task(rq, p, flags);
 725}
 726
 727void activate_task(struct rq *rq, struct task_struct *p, int flags)
 728{
 729        if (task_contributes_to_load(p))
 730                rq->nr_uninterruptible--;
 731
 732        enqueue_task(rq, p, flags);
 733}
 734
 735void deactivate_task(struct rq *rq, struct task_struct *p, int flags)
 736{
 737        if (task_contributes_to_load(p))
 738                rq->nr_uninterruptible++;
 739
 740        dequeue_task(rq, p, flags);
 741}
 742
 743static void update_rq_clock_task(struct rq *rq, s64 delta)
 744{
 745/*
 746 * In theory, the compile should just see 0 here, and optimize out the call
 747 * to sched_rt_avg_update. But I don't trust it...
 748 */
 749#if defined(CONFIG_IRQ_TIME_ACCOUNTING) || defined(CONFIG_PARAVIRT_TIME_ACCOUNTING)
 750        s64 steal = 0, irq_delta = 0;
 751#endif
 752#ifdef CONFIG_IRQ_TIME_ACCOUNTING
 753        irq_delta = irq_time_read(cpu_of(rq)) - rq->prev_irq_time;
 754
 755        /*
 756         * Since irq_time is only updated on {soft,}irq_exit, we might run into
 757         * this case when a previous update_rq_clock() happened inside a
 758         * {soft,}irq region.
 759         *
 760         * When this happens, we stop ->clock_task and only update the
 761         * prev_irq_time stamp to account for the part that fit, so that a next
 762         * update will consume the rest. This ensures ->clock_task is
 763         * monotonic.
 764         *
 765         * It does however cause some slight miss-attribution of {soft,}irq
 766         * time, a more accurate solution would be to update the irq_time using
 767         * the current rq->clock timestamp, except that would require using
 768         * atomic ops.
 769         */
 770        if (irq_delta > delta)
 771                irq_delta = delta;
 772
 773        rq->prev_irq_time += irq_delta;
 774        delta -= irq_delta;
 775#endif
 776#ifdef CONFIG_PARAVIRT_TIME_ACCOUNTING
 777        if (static_key_false((&paravirt_steal_rq_enabled))) {
 778                u64 st;
 779
 780                steal = paravirt_steal_clock(cpu_of(rq));
 781                steal -= rq->prev_steal_time_rq;
 782
 783                if (unlikely(steal > delta))
 784                        steal = delta;
 785
 786                st = steal_ticks(steal);
 787                steal = st * TICK_NSEC;
 788
 789                rq->prev_steal_time_rq += steal;
 790
 791                delta -= steal;
 792        }
 793#endif
 794
 795        rq->clock_task += delta;
 796
 797#if defined(CONFIG_IRQ_TIME_ACCOUNTING) || defined(CONFIG_PARAVIRT_TIME_ACCOUNTING)
 798        if ((irq_delta + steal) && sched_feat(NONTASK_POWER))
 799                sched_rt_avg_update(rq, irq_delta + steal);
 800#endif
 801}
 802
 803void sched_set_stop_task(int cpu, struct task_struct *stop)
 804{
 805        struct sched_param param = { .sched_priority = MAX_RT_PRIO - 1 };
 806        struct task_struct *old_stop = cpu_rq(cpu)->stop;
 807
 808        if (stop) {
 809                /*
 810                 * Make it appear like a SCHED_FIFO task, its something
 811                 * userspace knows about and won't get confused about.
 812                 *
 813                 * Also, it will make PI more or less work without too
 814                 * much confusion -- but then, stop work should not
 815                 * rely on PI working anyway.
 816                 */
 817                sched_setscheduler_nocheck(stop, SCHED_FIFO, &param);
 818
 819                stop->sched_class = &stop_sched_class;
 820        }
 821
 822        cpu_rq(cpu)->stop = stop;
 823
 824        if (old_stop) {
 825                /*
 826                 * Reset it back to a normal scheduling class so that
 827                 * it can die in pieces.
 828                 */
 829                old_stop->sched_class = &rt_sched_class;
 830        }
 831}
 832
 833/*
 834 * __normal_prio - return the priority that is based on the static prio
 835 */
 836static inline int __normal_prio(struct task_struct *p)
 837{
 838        return p->static_prio;
 839}
 840
 841/*
 842 * Calculate the expected normal priority: i.e. priority
 843 * without taking RT-inheritance into account. Might be
 844 * boosted by interactivity modifiers. Changes upon fork,
 845 * setprio syscalls, and whenever the interactivity
 846 * estimator recalculates.
 847 */
 848static inline int normal_prio(struct task_struct *p)
 849{
 850        int prio;
 851
 852        if (task_has_rt_policy(p))
 853                prio = MAX_RT_PRIO-1 - p->rt_priority;
 854        else
 855                prio = __normal_prio(p);
 856        return prio;
 857}
 858
 859/*
 860 * Calculate the current priority, i.e. the priority
 861 * taken into account by the scheduler. This value might
 862 * be boosted by RT tasks, or might be boosted by
 863 * interactivity modifiers. Will be RT if the task got
 864 * RT-boosted. If not then it returns p->normal_prio.
 865 */
 866static int effective_prio(struct task_struct *p)
 867{
 868        p->normal_prio = normal_prio(p);
 869        /*
 870         * If we are RT tasks or we were boosted to RT priority,
 871         * keep the priority unchanged. Otherwise, update priority
 872         * to the normal priority:
 873         */
 874        if (!rt_prio(p->prio))
 875                return p->normal_prio;
 876        return p->prio;
 877}
 878
 879/**
 880 * task_curr - is this task currently executing on a CPU?
 881 * @p: the task in question.
 882 */
 883inline int task_curr(const struct task_struct *p)
 884{
 885        return cpu_curr(task_cpu(p)) == p;
 886}
 887
 888static inline void check_class_changed(struct rq *rq, struct task_struct *p,
 889                                       const struct sched_class *prev_class,
 890                                       int oldprio)
 891{
 892        if (prev_class != p->sched_class) {
 893                if (prev_class->switched_from)
 894                        prev_class->switched_from(rq, p);
 895                p->sched_class->switched_to(rq, p);
 896        } else if (oldprio != p->prio)
 897                p->sched_class->prio_changed(rq, p, oldprio);
 898}
 899
 900void check_preempt_curr(struct rq *rq, struct task_struct *p, int flags)
 901{
 902        const struct sched_class *class;
 903
 904        if (p->sched_class == rq->curr->sched_class) {
 905                rq->curr->sched_class->check_preempt_curr(rq, p, flags);
 906        } else {
 907                for_each_class(class) {
 908                        if (class == rq->curr->sched_class)
 909                                break;
 910                        if (class == p->sched_class) {
 911                                resched_task(rq->curr);
 912                                break;
 913                        }
 914                }
 915        }
 916
 917        /*
 918         * A queue event has occurred, and we're going to schedule.  In
 919         * this case, we can save a useless back to back clock update.
 920         */
 921        if (rq->curr->on_rq && test_tsk_need_resched(rq->curr))
 922                rq->skip_clock_update = 1;
 923}
 924
 925#ifdef CONFIG_SMP
 926void set_task_cpu(struct task_struct *p, unsigned int new_cpu)
 927{
 928#ifdef CONFIG_SCHED_DEBUG
 929        /*
 930         * We should never call set_task_cpu() on a blocked task,
 931         * ttwu() will sort out the placement.
 932         */
 933        WARN_ON_ONCE(p->state != TASK_RUNNING && p->state != TASK_WAKING &&
 934                        !(task_thread_info(p)->preempt_count & PREEMPT_ACTIVE));
 935
 936#ifdef CONFIG_LOCKDEP
 937        /*
 938         * The caller should hold either p->pi_lock or rq->lock, when changing
 939         * a task's CPU. ->pi_lock for waking tasks, rq->lock for runnable tasks.
 940         *
 941         * sched_move_task() holds both and thus holding either pins the cgroup,
 942         * see task_group().
 943         *
 944         * Furthermore, all task_rq users should acquire both locks, see
 945         * task_rq_lock().
 946         */
 947        WARN_ON_ONCE(debug_locks && !(lockdep_is_held(&p->pi_lock) ||
 948                                      lockdep_is_held(&task_rq(p)->lock)));
 949#endif
 950#endif
 951
 952        trace_sched_migrate_task(p, new_cpu);
 953
 954        if (task_cpu(p) != new_cpu) {
 955                p->se.nr_migrations++;
 956                perf_sw_event(PERF_COUNT_SW_CPU_MIGRATIONS, 1, NULL, 0);
 957        }
 958
 959        __set_task_cpu(p, new_cpu);
 960}
 961
 962struct migration_arg {
 963        struct task_struct *task;
 964        int dest_cpu;
 965};
 966
 967static int migration_cpu_stop(void *data);
 968
 969/*
 970 * wait_task_inactive - wait for a thread to unschedule.
 971 *
 972 * If @match_state is nonzero, it's the @p->state value just checked and
 973 * not expected to change.  If it changes, i.e. @p might have woken up,
 974 * then return zero.  When we succeed in waiting for @p to be off its CPU,
 975 * we return a positive number (its total switch count).  If a second call
 976 * a short while later returns the same number, the caller can be sure that
 977 * @p has remained unscheduled the whole time.
 978 *
 979 * The caller must ensure that the task *will* unschedule sometime soon,
 980 * else this function might spin for a *long* time. This function can't
 981 * be called with interrupts off, or it may introduce deadlock with
 982 * smp_call_function() if an IPI is sent by the same process we are
 983 * waiting to become inactive.
 984 */
 985unsigned long wait_task_inactive(struct task_struct *p, long match_state)
 986{
 987        unsigned long flags;
 988        int running, on_rq;
 989        unsigned long ncsw;
 990        struct rq *rq;
 991
 992        for (;;) {
 993                /*
 994                 * We do the initial early heuristics without holding
 995                 * any task-queue locks at all. We'll only try to get
 996                 * the runqueue lock when things look like they will
 997                 * work out!
 998                 */
 999                rq = task_rq(p);
1000
1001                /*
1002                 * If the task is actively running on another CPU
1003                 * still, just relax and busy-wait without holding
1004                 * any locks.
1005                 *
1006                 * NOTE! Since we don't hold any locks, it's not
1007                 * even sure that "rq" stays as the right runqueue!
1008                 * But we don't care, since "task_running()" will
1009                 * return false if the runqueue has changed and p
1010                 * is actually now running somewhere else!
1011                 */
1012                while (task_running(rq, p)) {
1013                        if (match_state && unlikely(p->state != match_state))
1014                                return 0;
1015                        cpu_relax();
1016                }
1017
1018                /*
1019                 * Ok, time to look more closely! We need the rq
1020                 * lock now, to be *sure*. If we're wrong, we'll
1021                 * just go back and repeat.
1022                 */
1023                rq = task_rq_lock(p, &flags);
1024                trace_sched_wait_task(p);
1025                running = task_running(rq, p);
1026                on_rq = p->on_rq;
1027                ncsw = 0;
1028                if (!match_state || p->state == match_state)
1029                        ncsw = p->nvcsw | LONG_MIN; /* sets MSB */
1030                task_rq_unlock(rq, p, &flags);
1031
1032                /*
1033                 * If it changed from the expected state, bail out now.
1034                 */
1035                if (unlikely(!ncsw))
1036                        break;
1037
1038                /*
1039                 * Was it really running after all now that we
1040                 * checked with the proper locks actually held?
1041                 *
1042                 * Oops. Go back and try again..
1043                 */
1044                if (unlikely(running)) {
1045                        cpu_relax();
1046                        continue;
1047                }
1048
1049                /*
1050                 * It's not enough that it's not actively running,
1051                 * it must be off the runqueue _entirely_, and not
1052                 * preempted!
1053                 *
1054                 * So if it was still runnable (but just not actively
1055                 * running right now), it's preempted, and we should
1056                 * yield - it could be a while.
1057                 */
1058                if (unlikely(on_rq)) {
1059                        ktime_t to = ktime_set(0, NSEC_PER_SEC/HZ);
1060
1061                        set_current_state(TASK_UNINTERRUPTIBLE);
1062                        schedule_hrtimeout(&to, HRTIMER_MODE_REL);
1063                        continue;
1064                }
1065
1066                /*
1067                 * Ahh, all good. It wasn't running, and it wasn't
1068                 * runnable, which means that it will never become
1069                 * running in the future either. We're all done!
1070                 */
1071                break;
1072        }
1073
1074        return ncsw;
1075}
1076
1077/***
1078 * kick_process - kick a running thread to enter/exit the kernel
1079 * @p: the to-be-kicked thread
1080 *
1081 * Cause a process which is running on another CPU to enter
1082 * kernel-mode, without any delay. (to get signals handled.)
1083 *
1084 * NOTE: this function doesn't have to take the runqueue lock,
1085 * because all it wants to ensure is that the remote task enters
1086 * the kernel. If the IPI races and the task has been migrated
1087 * to another CPU then no harm is done and the purpose has been
1088 * achieved as well.
1089 */
1090void kick_process(struct task_struct *p)
1091{
1092        int cpu;
1093
1094        preempt_disable();
1095        cpu = task_cpu(p);
1096        if ((cpu != smp_processor_id()) && task_curr(p))
1097                smp_send_reschedule(cpu);
1098        preempt_enable();
1099}
1100EXPORT_SYMBOL_GPL(kick_process);
1101#endif /* CONFIG_SMP */
1102
1103#ifdef CONFIG_SMP
1104/*
1105 * ->cpus_allowed is protected by both rq->lock and p->pi_lock
1106 */
1107static int select_fallback_rq(int cpu, struct task_struct *p)
1108{
1109        const struct cpumask *nodemask = cpumask_of_node(cpu_to_node(cpu));
1110        enum { cpuset, possible, fail } state = cpuset;
1111        int dest_cpu;
1112
1113        /* Look for allowed, online CPU in same node. */
1114        for_each_cpu(dest_cpu, nodemask) {
1115                if (!cpu_online(dest_cpu))
1116                        continue;
1117                if (!cpu_active(dest_cpu))
1118                        continue;
1119                if (cpumask_test_cpu(dest_cpu, tsk_cpus_allowed(p)))
1120                        return dest_cpu;
1121        }
1122
1123        for (;;) {
1124                /* Any allowed, online CPU? */
1125                for_each_cpu(dest_cpu, tsk_cpus_allowed(p)) {
1126                        if (!cpu_online(dest_cpu))
1127                                continue;
1128                        if (!cpu_active(dest_cpu))
1129                                continue;
1130                        goto out;
1131                }
1132
1133                switch (state) {
1134                case cpuset:
1135                        /* No more Mr. Nice Guy. */
1136                        cpuset_cpus_allowed_fallback(p);
1137                        state = possible;
1138                        break;
1139
1140                case possible:
1141                        do_set_cpus_allowed(p, cpu_possible_mask);
1142                        state = fail;
1143                        break;
1144
1145                case fail:
1146                        BUG();
1147                        break;
1148                }
1149        }
1150
1151out:
1152        if (state != cpuset) {
1153                /*
1154                 * Don't tell them about moving exiting tasks or
1155                 * kernel threads (both mm NULL), since they never
1156                 * leave kernel.
1157                 */
1158                if (p->mm && printk_ratelimit()) {
1159                        printk_sched("process %d (%s) no longer affine to cpu%d\n",
1160                                        task_pid_nr(p), p->comm, cpu);
1161                }
1162        }
1163
1164        return dest_cpu;
1165}
1166
1167/*
1168 * The caller (fork, wakeup) owns p->pi_lock, ->cpus_allowed is stable.
1169 */
1170static inline
1171int select_task_rq(struct task_struct *p, int sd_flags, int wake_flags)
1172{
1173        int cpu = p->sched_class->select_task_rq(p, sd_flags, wake_flags);
1174
1175        /*
1176         * In order not to call set_task_cpu() on a blocking task we need
1177         * to rely on ttwu() to place the task on a valid ->cpus_allowed
1178         * cpu.
1179         *
1180         * Since this is common to all placement strategies, this lives here.
1181         *
1182         * [ this allows ->select_task() to simply return task_cpu(p) and
1183         *   not worry about this generic constraint ]
1184         */
1185        if (unlikely(!cpumask_test_cpu(cpu, tsk_cpus_allowed(p)) ||
1186                     !cpu_online(cpu)))
1187                cpu = select_fallback_rq(task_cpu(p), p);
1188
1189        return cpu;
1190}
1191
1192static void update_avg(u64 *avg, u64 sample)
1193{
1194        s64 diff = sample - *avg;
1195        *avg += diff >> 3;
1196}
1197#endif
1198
1199static void
1200ttwu_stat(struct task_struct *p, int cpu, int wake_flags)
1201{
1202#ifdef CONFIG_SCHEDSTATS
1203        struct rq *rq = this_rq();
1204
1205#ifdef CONFIG_SMP
1206        int this_cpu = smp_processor_id();
1207
1208        if (cpu == this_cpu) {
1209                schedstat_inc(rq, ttwu_local);
1210                schedstat_inc(p, se.statistics.nr_wakeups_local);
1211        } else {
1212                struct sched_domain *sd;
1213
1214                schedstat_inc(p, se.statistics.nr_wakeups_remote);
1215                rcu_read_lock();
1216                for_each_domain(this_cpu, sd) {
1217                        if (cpumask_test_cpu(cpu, sched_domain_span(sd))) {
1218                                schedstat_inc(sd, ttwu_wake_remote);
1219                                break;
1220                        }
1221                }
1222                rcu_read_unlock();
1223        }
1224
1225        if (wake_flags & WF_MIGRATED)
1226                schedstat_inc(p, se.statistics.nr_wakeups_migrate);
1227
1228#endif /* CONFIG_SMP */
1229
1230        schedstat_inc(rq, ttwu_count);
1231        schedstat_inc(p, se.statistics.nr_wakeups);
1232
1233        if (wake_flags & WF_SYNC)
1234                schedstat_inc(p, se.statistics.nr_wakeups_sync);
1235
1236#endif /* CONFIG_SCHEDSTATS */
1237}
1238
1239static void ttwu_activate(struct rq *rq, struct task_struct *p, int en_flags)
1240{
1241        activate_task(rq, p, en_flags);
1242        p->on_rq = 1;
1243
1244        /* if a worker is waking up, notify workqueue */
1245        if (p->flags & PF_WQ_WORKER)
1246                wq_worker_waking_up(p, cpu_of(rq));
1247}
1248
1249/*
1250 * Mark the task runnable and perform wakeup-preemption.
1251 */
1252static void
1253ttwu_do_wakeup(struct rq *rq, struct task_struct *p, int wake_flags)
1254{
1255        trace_sched_wakeup(p, true);
1256        check_preempt_curr(rq, p, wake_flags);
1257
1258        p->state = TASK_RUNNING;
1259#ifdef CONFIG_SMP
1260        if (p->sched_class->task_woken)
1261                p->sched_class->task_woken(rq, p);
1262
1263        if (rq->idle_stamp) {
1264                u64 delta = rq->clock - rq->idle_stamp;
1265                u64 max = 2*sysctl_sched_migration_cost;
1266
1267                if (delta > max)
1268                        rq->avg_idle = max;
1269                else
1270                        update_avg(&rq->avg_idle, delta);
1271                rq->idle_stamp = 0;
1272        }
1273#endif
1274}
1275
1276static void
1277ttwu_do_activate(struct rq *rq, struct task_struct *p, int wake_flags)
1278{
1279#ifdef CONFIG_SMP
1280        if (p->sched_contributes_to_load)
1281                rq->nr_uninterruptible--;
1282#endif
1283
1284        ttwu_activate(rq, p, ENQUEUE_WAKEUP | ENQUEUE_WAKING);
1285        ttwu_do_wakeup(rq, p, wake_flags);
1286}
1287
1288/*
1289 * Called in case the task @p isn't fully descheduled from its runqueue,
1290 * in this case we must do a remote wakeup. Its a 'light' wakeup though,
1291 * since all we need to do is flip p->state to TASK_RUNNING, since
1292 * the task is still ->on_rq.
1293 */
1294static int ttwu_remote(struct task_struct *p, int wake_flags)
1295{
1296        struct rq *rq;
1297        int ret = 0;
1298
1299        rq = __task_rq_lock(p);
1300        if (p->on_rq) {
1301                ttwu_do_wakeup(rq, p, wake_flags);
1302                ret = 1;
1303        }
1304        __task_rq_unlock(rq);
1305
1306        return ret;
1307}
1308
1309#ifdef CONFIG_SMP
1310static void sched_ttwu_pending(void)
1311{
1312        struct rq *rq = this_rq();
1313        struct llist_node *llist = llist_del_all(&rq->wake_list);
1314        struct task_struct *p;
1315
1316        raw_spin_lock(&rq->lock);
1317
1318        while (llist) {
1319                p = llist_entry(llist, struct task_struct, wake_entry);
1320                llist = llist_next(llist);
1321                ttwu_do_activate(rq, p, 0);
1322        }
1323
1324        raw_spin_unlock(&rq->lock);
1325}
1326
1327void scheduler_ipi(void)
1328{
1329        if (llist_empty(&this_rq()->wake_list) && !got_nohz_idle_kick())
1330                return;
1331
1332        /*
1333         * Not all reschedule IPI handlers call irq_enter/irq_exit, since
1334         * traditionally all their work was done from the interrupt return
1335         * path. Now that we actually do some work, we need to make sure
1336         * we do call them.
1337         *
1338         * Some archs already do call them, luckily irq_enter/exit nest
1339         * properly.
1340         *
1341         * Arguably we should visit all archs and update all handlers,
1342         * however a fair share of IPIs are still resched only so this would
1343         * somewhat pessimize the simple resched case.
1344         */
1345        irq_enter();
1346        sched_ttwu_pending();
1347
1348        /*
1349         * Check if someone kicked us for doing the nohz idle load balance.
1350         */
1351        if (unlikely(got_nohz_idle_kick() && !need_resched())) {
1352                this_rq()->idle_balance = 1;
1353                raise_softirq_irqoff(SCHED_SOFTIRQ);
1354        }
1355        irq_exit();
1356}
1357
1358static void ttwu_queue_remote(struct task_struct *p, int cpu)
1359{
1360        if (llist_add(&p->wake_entry, &cpu_rq(cpu)->wake_list))
1361                smp_send_reschedule(cpu);
1362}
1363
1364bool cpus_share_cache(int this_cpu, int that_cpu)
1365{
1366        return per_cpu(sd_llc_id, this_cpu) == per_cpu(sd_llc_id, that_cpu);
1367}
1368#endif /* CONFIG_SMP */
1369
1370static void ttwu_queue(struct task_struct *p, int cpu)
1371{
1372        struct rq *rq = cpu_rq(cpu);
1373
1374#if defined(CONFIG_SMP)
1375        if (sched_feat(TTWU_QUEUE) && !cpus_share_cache(smp_processor_id(), cpu)) {
1376                sched_clock_cpu(cpu); /* sync clocks x-cpu */
1377                ttwu_queue_remote(p, cpu);
1378                return;
1379        }
1380#endif
1381
1382        raw_spin_lock(&rq->lock);
1383        ttwu_do_activate(rq, p, 0);
1384        raw_spin_unlock(&rq->lock);
1385}
1386
1387/**
1388 * try_to_wake_up - wake up a thread
1389 * @p: the thread to be awakened
1390 * @state: the mask of task states that can be woken
1391 * @wake_flags: wake modifier flags (WF_*)
1392 *
1393 * Put it on the run-queue if it's not already there. The "current"
1394 * thread is always on the run-queue (except when the actual
1395 * re-schedule is in progress), and as such you're allowed to do
1396 * the simpler "current->state = TASK_RUNNING" to mark yourself
1397 * runnable without the overhead of this.
1398 *
1399 * Returns %true if @p was woken up, %false if it was already running
1400 * or @state didn't match @p's state.
1401 */
1402static int
1403try_to_wake_up(struct task_struct *p, unsigned int state, int wake_flags)
1404{
1405        unsigned long flags;
1406        int cpu, success = 0;
1407
1408        smp_wmb();
1409        raw_spin_lock_irqsave(&p->pi_lock, flags);
1410        if (!(p->state & state))
1411                goto out;
1412
1413        success = 1; /* we're going to change ->state */
1414        cpu = task_cpu(p);
1415
1416        if (p->on_rq && ttwu_remote(p, wake_flags))
1417                goto stat;
1418
1419#ifdef CONFIG_SMP
1420        /*
1421         * If the owning (remote) cpu is still in the middle of schedule() with
1422         * this task as prev, wait until its done referencing the task.
1423         */
1424        while (p->on_cpu)
1425                cpu_relax();
1426        /*
1427         * Pairs with the smp_wmb() in finish_lock_switch().
1428         */
1429        smp_rmb();
1430
1431        p->sched_contributes_to_load = !!task_contributes_to_load(p);
1432        p->state = TASK_WAKING;
1433
1434        if (p->sched_class->task_waking)
1435                p->sched_class->task_waking(p);
1436
1437        cpu = select_task_rq(p, SD_BALANCE_WAKE, wake_flags);
1438        if (task_cpu(p) != cpu) {
1439                wake_flags |= WF_MIGRATED;
1440                set_task_cpu(p, cpu);
1441        }
1442#endif /* CONFIG_SMP */
1443
1444        ttwu_queue(p, cpu);
1445stat:
1446        ttwu_stat(p, cpu, wake_flags);
1447out:
1448        raw_spin_unlock_irqrestore(&p->pi_lock, flags);
1449
1450        return success;
1451}
1452
1453/**
1454 * try_to_wake_up_local - try to wake up a local task with rq lock held
1455 * @p: the thread to be awakened
1456 *
1457 * Put @p on the run-queue if it's not already there. The caller must
1458 * ensure that this_rq() is locked, @p is bound to this_rq() and not
1459 * the current task.
1460 */
1461static void try_to_wake_up_local(struct task_struct *p)
1462{
1463        struct rq *rq = task_rq(p);
1464
1465        BUG_ON(rq != this_rq());
1466        BUG_ON(p == current);
1467        lockdep_assert_held(&rq->lock);
1468
1469        if (!raw_spin_trylock(&p->pi_lock)) {
1470                raw_spin_unlock(&rq->lock);
1471                raw_spin_lock(&p->pi_lock);
1472                raw_spin_lock(&rq->lock);
1473        }
1474
1475        if (!(p->state & TASK_NORMAL))
1476                goto out;
1477
1478        if (!p->on_rq)
1479                ttwu_activate(rq, p, ENQUEUE_WAKEUP);
1480
1481        ttwu_do_wakeup(rq, p, 0);
1482        ttwu_stat(p, smp_processor_id(), 0);
1483out:
1484        raw_spin_unlock(&p->pi_lock);
1485}
1486
1487/**
1488 * wake_up_process - Wake up a specific process
1489 * @p: The process to be woken up.
1490 *
1491 * Attempt to wake up the nominated process and move it to the set of runnable
1492 * processes.  Returns 1 if the process was woken up, 0 if it was already
1493 * running.
1494 *
1495 * It may be assumed that this function implies a write memory barrier before
1496 * changing the task state if and only if any tasks are woken up.
1497 */
1498int wake_up_process(struct task_struct *p)
1499{
1500        return try_to_wake_up(p, TASK_ALL, 0);
1501}
1502EXPORT_SYMBOL(wake_up_process);
1503
1504int wake_up_state(struct task_struct *p, unsigned int state)
1505{
1506        return try_to_wake_up(p, state, 0);
1507}
1508
1509/*
1510 * Perform scheduler related setup for a newly forked process p.
1511 * p is forked by current.
1512 *
1513 * __sched_fork() is basic setup used by init_idle() too:
1514 */
1515static void __sched_fork(struct task_struct *p)
1516{
1517        p->on_rq                        = 0;
1518
1519        p->se.on_rq                     = 0;
1520        p->se.exec_start                = 0;
1521        p->se.sum_exec_runtime          = 0;
1522        p->se.prev_sum_exec_runtime     = 0;
1523        p->se.nr_migrations             = 0;
1524        p->se.vruntime                  = 0;
1525        INIT_LIST_HEAD(&p->se.group_node);
1526
1527#ifdef CONFIG_SCHEDSTATS
1528        memset(&p->se.statistics, 0, sizeof(p->se.statistics));
1529#endif
1530
1531        INIT_LIST_HEAD(&p->rt.run_list);
1532
1533#ifdef CONFIG_PREEMPT_NOTIFIERS
1534        INIT_HLIST_HEAD(&p->preempt_notifiers);
1535#endif
1536}
1537
1538/*
1539 * fork()/clone()-time setup:
1540 */
1541void sched_fork(struct task_struct *p)
1542{
1543        unsigned long flags;
1544        int cpu = get_cpu();
1545
1546        __sched_fork(p);
1547        /*
1548         * We mark the process as running here. This guarantees that
1549         * nobody will actually run it, and a signal or other external
1550         * event cannot wake it up and insert it on the runqueue either.
1551         */
1552        p->state = TASK_RUNNING;
1553
1554        /*
1555         * Make sure we do not leak PI boosting priority to the child.
1556         */
1557        p->prio = current->normal_prio;
1558
1559        /*
1560         * Revert to default priority/policy on fork if requested.
1561         */
1562        if (unlikely(p->sched_reset_on_fork)) {
1563                if (task_has_rt_policy(p)) {
1564                        p->policy = SCHED_NORMAL;
1565                        p->static_prio = NICE_TO_PRIO(0);
1566                        p->rt_priority = 0;
1567                } else if (PRIO_TO_NICE(p->static_prio) < 0)
1568                        p->static_prio = NICE_TO_PRIO(0);
1569
1570                p->prio = p->normal_prio = __normal_prio(p);
1571                set_load_weight(p);
1572
1573                /*
1574                 * We don't need the reset flag anymore after the fork. It has
1575                 * fulfilled its duty:
1576                 */
1577                p->sched_reset_on_fork = 0;
1578        }
1579
1580        if (!rt_prio(p->prio))
1581                p->sched_class = &fair_sched_class;
1582
1583        if (p->sched_class->task_fork)
1584                p->sched_class->task_fork(p);
1585
1586        /*
1587         * The child is not yet in the pid-hash so no cgroup attach races,
1588         * and the cgroup is pinned to this child due to cgroup_fork()
1589         * is ran before sched_fork().
1590         *
1591         * Silence PROVE_RCU.
1592         */
1593        raw_spin_lock_irqsave(&p->pi_lock, flags);
1594        set_task_cpu(p, cpu);
1595        raw_spin_unlock_irqrestore(&p->pi_lock, flags);
1596
1597#if defined(CONFIG_SCHEDSTATS) || defined(CONFIG_TASK_DELAY_ACCT)
1598        if (likely(sched_info_on()))
1599                memset(&p->sched_info, 0, sizeof(p->sched_info));
1600#endif
1601#if defined(CONFIG_SMP)
1602        p->on_cpu = 0;
1603#endif
1604#ifdef CONFIG_PREEMPT_COUNT
1605        /* Want to start with kernel preemption disabled. */
1606        task_thread_info(p)->preempt_count = 1;
1607#endif
1608#ifdef CONFIG_SMP
1609        plist_node_init(&p->pushable_tasks, MAX_PRIO);
1610#endif
1611
1612        put_cpu();
1613}
1614
1615/*
1616 * wake_up_new_task - wake up a newly created task for the first time.
1617 *
1618 * This function will do some initial scheduler statistics housekeeping
1619 * that must be done for every newly created context, then puts the task
1620 * on the runqueue and wakes it.
1621 */
1622void wake_up_new_task(struct task_struct *p)
1623{
1624        unsigned long flags;
1625        struct rq *rq;
1626
1627        raw_spin_lock_irqsave(&p->pi_lock, flags);
1628#ifdef CONFIG_SMP
1629        /*
1630         * Fork balancing, do it here and not earlier because:
1631         *  - cpus_allowed can change in the fork path
1632         *  - any previously selected cpu might disappear through hotplug
1633         */
1634        set_task_cpu(p, select_task_rq(p, SD_BALANCE_FORK, 0));
1635#endif
1636
1637        rq = __task_rq_lock(p);
1638        activate_task(rq, p, 0);
1639        p->on_rq = 1;
1640        trace_sched_wakeup_new(p, true);
1641        check_preempt_curr(rq, p, WF_FORK);
1642#ifdef CONFIG_SMP
1643        if (p->sched_class->task_woken)
1644                p->sched_class->task_woken(rq, p);
1645#endif
1646        task_rq_unlock(rq, p, &flags);
1647}
1648
1649#ifdef CONFIG_PREEMPT_NOTIFIERS
1650
1651/**
1652 * preempt_notifier_register - tell me when current is being preempted & rescheduled
1653 * @notifier: notifier struct to register
1654 */
1655void preempt_notifier_register(struct preempt_notifier *notifier)
1656{
1657        hlist_add_head(&notifier->link, &current->preempt_notifiers);
1658}
1659EXPORT_SYMBOL_GPL(preempt_notifier_register);
1660
1661/**
1662 * preempt_notifier_unregister - no longer interested in preemption notifications
1663 * @notifier: notifier struct to unregister
1664 *
1665 * This is safe to call from within a preemption notifier.
1666 */
1667void preempt_notifier_unregister(struct preempt_notifier *notifier)
1668{
1669        hlist_del(&notifier->link);
1670}
1671EXPORT_SYMBOL_GPL(preempt_notifier_unregister);
1672
1673static void fire_sched_in_preempt_notifiers(struct task_struct *curr)
1674{
1675        struct preempt_notifier *notifier;
1676        struct hlist_node *node;
1677
1678        hlist_for_each_entry(notifier, node, &curr->preempt_notifiers, link)
1679                notifier->ops->sched_in(notifier, raw_smp_processor_id());
1680}
1681
1682static void
1683fire_sched_out_preempt_notifiers(struct task_struct *curr,
1684                                 struct task_struct *next)
1685{
1686        struct preempt_notifier *notifier;
1687        struct hlist_node *node;
1688
1689        hlist_for_each_entry(notifier, node, &curr->preempt_notifiers, link)
1690                notifier->ops->sched_out(notifier, next);
1691}
1692
1693#else /* !CONFIG_PREEMPT_NOTIFIERS */
1694
1695static void fire_sched_in_preempt_notifiers(struct task_struct *curr)
1696{
1697}
1698
1699static void
1700fire_sched_out_preempt_notifiers(struct task_struct *curr,
1701                                 struct task_struct *next)
1702{
1703}
1704
1705#endif /* CONFIG_PREEMPT_NOTIFIERS */
1706
1707/**
1708 * prepare_task_switch - prepare to switch tasks
1709 * @rq: the runqueue preparing to switch
1710 * @prev: the current task that is being switched out
1711 * @next: the task we are going to switch to.
1712 *
1713 * This is called with the rq lock held and interrupts off. It must
1714 * be paired with a subsequent finish_task_switch after the context
1715 * switch.
1716 *
1717 * prepare_task_switch sets up locking and calls architecture specific
1718 * hooks.
1719 */
1720static inline void
1721prepare_task_switch(struct rq *rq, struct task_struct *prev,
1722                    struct task_struct *next)
1723{
1724        trace_sched_switch(prev, next);
1725        sched_info_switch(prev, next);
1726        perf_event_task_sched_out(prev, next);
1727        fire_sched_out_preempt_notifiers(prev, next);
1728        prepare_lock_switch(rq, next);
1729        prepare_arch_switch(next);
1730}
1731
1732/**
1733 * finish_task_switch - clean up after a task-switch
1734 * @rq: runqueue associated with task-switch
1735 * @prev: the thread we just switched away from.
1736 *
1737 * finish_task_switch must be called after the context switch, paired
1738 * with a prepare_task_switch call before the context switch.
1739 * finish_task_switch will reconcile locking set up by prepare_task_switch,
1740 * and do any other architecture-specific cleanup actions.
1741 *
1742 * Note that we may have delayed dropping an mm in context_switch(). If
1743 * so, we finish that here outside of the runqueue lock. (Doing it
1744 * with the lock held can cause deadlocks; see schedule() for
1745 * details.)
1746 */
1747static void finish_task_switch(struct rq *rq, struct task_struct *prev)
1748        __releases(rq->lock)
1749{
1750        struct mm_struct *mm = rq->prev_mm;
1751        long prev_state;
1752
1753        rq->prev_mm = NULL;
1754
1755        /*
1756         * A task struct has one reference for the use as "current".
1757         * If a task dies, then it sets TASK_DEAD in tsk->state and calls
1758         * schedule one last time. The schedule call will never return, and
1759         * the scheduled task must drop that reference.
1760         * The test for TASK_DEAD must occur while the runqueue locks are
1761         * still held, otherwise prev could be scheduled on another cpu, die
1762         * there before we look at prev->state, and then the reference would
1763         * be dropped twice.
1764         *              Manfred Spraul <manfred@colorfullife.com>
1765         */
1766        prev_state = prev->state;
1767        vtime_task_switch(prev);
1768        finish_arch_switch(prev);
1769        perf_event_task_sched_in(prev, current);
1770        finish_lock_switch(rq, prev);
1771        finish_arch_post_lock_switch();
1772
1773        fire_sched_in_preempt_notifiers(current);
1774        if (mm)
1775                mmdrop(mm);
1776        if (unlikely(prev_state == TASK_DEAD)) {
1777                /*
1778                 * Remove function-return probe instances associated with this
1779                 * task and put them back on the free list.
1780                 */
1781                kprobe_flush_task(prev);
1782                put_task_struct(prev);
1783        }
1784}
1785
1786#ifdef CONFIG_SMP
1787
1788/* assumes rq->lock is held */
1789static inline void pre_schedule(struct rq *rq, struct task_struct *prev)
1790{
1791        if (prev->sched_class->pre_schedule)
1792                prev->sched_class->pre_schedule(rq, prev);
1793}
1794
1795/* rq->lock is NOT held, but preemption is disabled */
1796static inline void post_schedule(struct rq *rq)
1797{
1798        if (rq->post_schedule) {
1799                unsigned long flags;
1800
1801                raw_spin_lock_irqsave(&rq->lock, flags);
1802                if (rq->curr->sched_class->post_schedule)
1803                        rq->curr->sched_class->post_schedule(rq);
1804                raw_spin_unlock_irqrestore(&rq->lock, flags);
1805
1806                rq->post_schedule = 0;
1807        }
1808}
1809
1810#else
1811
1812static inline void pre_schedule(struct rq *rq, struct task_struct *p)
1813{
1814}
1815
1816static inline void post_schedule(struct rq *rq)
1817{
1818}
1819
1820#endif
1821
1822/**
1823 * schedule_tail - first thing a freshly forked thread must call.
1824 * @prev: the thread we just switched away from.
1825 */
1826asmlinkage void schedule_tail(struct task_struct *prev)
1827        __releases(rq->lock)
1828{
1829        struct rq *rq = this_rq();
1830
1831        finish_task_switch(rq, prev);
1832
1833        /*
1834         * FIXME: do we need to worry about rq being invalidated by the
1835         * task_switch?
1836         */
1837        post_schedule(rq);
1838
1839#ifdef __ARCH_WANT_UNLOCKED_CTXSW
1840        /* In this case, finish_task_switch does not reenable preemption */
1841        preempt_enable();
1842#endif
1843        if (current->set_child_tid)
1844                put_user(task_pid_vnr(current), current->set_child_tid);
1845}
1846
1847/*
1848 * context_switch - switch to the new MM and the new
1849 * thread's register state.
1850 */
1851static inline void
1852context_switch(struct rq *rq, struct task_struct *prev,
1853               struct task_struct *next)
1854{
1855        struct mm_struct *mm, *oldmm;
1856
1857        prepare_task_switch(rq, prev, next);
1858
1859        mm = next->mm;
1860        oldmm = prev->active_mm;
1861        /*
1862         * For paravirt, this is coupled with an exit in switch_to to
1863         * combine the page table reload and the switch backend into
1864         * one hypercall.
1865         */
1866        arch_start_context_switch(prev);
1867
1868        if (!mm) {
1869                next->active_mm = oldmm;
1870                atomic_inc(&oldmm->mm_count);
1871                enter_lazy_tlb(oldmm, next);
1872        } else
1873                switch_mm(oldmm, mm, next);
1874
1875        if (!prev->mm) {
1876                prev->active_mm = NULL;
1877                rq->prev_mm = oldmm;
1878        }
1879        /*
1880         * Since the runqueue lock will be released by the next
1881         * task (which is an invalid locking op but in the case
1882         * of the scheduler it's an obvious special-case), so we
1883         * do an early lockdep release here:
1884         */
1885#ifndef __ARCH_WANT_UNLOCKED_CTXSW
1886        spin_release(&rq->lock.dep_map, 1, _THIS_IP_);
1887#endif
1888
1889        /* Here we just switch the register state and the stack. */
1890        rcu_switch(prev, next);
1891        switch_to(prev, next, prev);
1892
1893        barrier();
1894        /*
1895         * this_rq must be evaluated again because prev may have moved
1896         * CPUs since it called schedule(), thus the 'rq' on its stack
1897         * frame will be invalid.
1898         */
1899        finish_task_switch(this_rq(), prev);
1900}
1901
1902/*
1903 * nr_running, nr_uninterruptible and nr_context_switches:
1904 *
1905 * externally visible scheduler statistics: current number of runnable
1906 * threads, current number of uninterruptible-sleeping threads, total
1907 * number of context switches performed since bootup.
1908 */
1909unsigned long nr_running(void)
1910{
1911        unsigned long i, sum = 0;
1912
1913        for_each_online_cpu(i)
1914                sum += cpu_rq(i)->nr_running;
1915
1916        return sum;
1917}
1918
1919unsigned long nr_uninterruptible(void)
1920{
1921        unsigned long i, sum = 0;
1922
1923        for_each_possible_cpu(i)
1924                sum += cpu_rq(i)->nr_uninterruptible;
1925
1926        /*
1927         * Since we read the counters lockless, it might be slightly
1928         * inaccurate. Do not allow it to go below zero though:
1929         */
1930        if (unlikely((long)sum < 0))
1931                sum = 0;
1932
1933        return sum;
1934}
1935
1936unsigned long long nr_context_switches(void)
1937{
1938        int i;
1939        unsigned long long sum = 0;
1940
1941        for_each_possible_cpu(i)
1942                sum += cpu_rq(i)->nr_switches;
1943
1944        return sum;
1945}
1946
1947unsigned long nr_iowait(void)
1948{
1949        unsigned long i, sum = 0;
1950
1951        for_each_possible_cpu(i)
1952                sum += atomic_read(&cpu_rq(i)->nr_iowait);
1953
1954        return sum;
1955}
1956
1957unsigned long nr_iowait_cpu(int cpu)
1958{
1959        struct rq *this = cpu_rq(cpu);
1960        return atomic_read(&this->nr_iowait);
1961}
1962
1963unsigned long this_cpu_load(void)
1964{
1965        struct rq *this = this_rq();
1966        return this->cpu_load[0];
1967}
1968
1969
1970/*
1971 * Global load-average calculations
1972 *
1973 * We take a distributed and async approach to calculating the global load-avg
1974 * in order to minimize overhead.
1975 *
1976 * The global load average is an exponentially decaying average of nr_running +
1977 * nr_uninterruptible.
1978 *
1979 * Once every LOAD_FREQ:
1980 *
1981 *   nr_active = 0;
1982 *   for_each_possible_cpu(cpu)
1983 *      nr_active += cpu_of(cpu)->nr_running + cpu_of(cpu)->nr_uninterruptible;
1984 *
1985 *   avenrun[n] = avenrun[0] * exp_n + nr_active * (1 - exp_n)
1986 *
1987 * Due to a number of reasons the above turns in the mess below:
1988 *
1989 *  - for_each_possible_cpu() is prohibitively expensive on machines with
1990 *    serious number of cpus, therefore we need to take a distributed approach
1991 *    to calculating nr_active.
1992 *
1993 *        \Sum_i x_i(t) = \Sum_i x_i(t) - x_i(t_0) | x_i(t_0) := 0
1994 *                      = \Sum_i { \Sum_j=1 x_i(t_j) - x_i(t_j-1) }
1995 *
1996 *    So assuming nr_active := 0 when we start out -- true per definition, we
1997 *    can simply take per-cpu deltas and fold those into a global accumulate
1998 *    to obtain the same result. See calc_load_fold_active().
1999 *
2000 *    Furthermore, in order to avoid synchronizing all per-cpu delta folding
2001 *    across the machine, we assume 10 ticks is sufficient time for every
2002 *    cpu to have completed this task.
2003 *
2004 *    This places an upper-bound on the IRQ-off latency of the machine. Then
2005 *    again, being late doesn't loose the delta, just wrecks the sample.
2006 *
2007 *  - cpu_rq()->nr_uninterruptible isn't accurately tracked per-cpu because
2008 *    this would add another cross-cpu cacheline miss and atomic operation
2009 *    to the wakeup path. Instead we increment on whatever cpu the task ran
2010 *    when it went into uninterruptible state and decrement on whatever cpu
2011 *    did the wakeup. This means that only the sum of nr_uninterruptible over
2012 *    all cpus yields the correct result.
2013 *
2014 *  This covers the NO_HZ=n code, for extra head-aches, see the comment below.
2015 */
2016
2017/* Variables and functions for calc_load */
2018static atomic_long_t calc_load_tasks;
2019static unsigned long calc_load_update;
2020unsigned long avenrun[3];
2021EXPORT_SYMBOL(avenrun); /* should be removed */
2022
2023/**
2024 * get_avenrun - get the load average array
2025 * @loads:      pointer to dest load array
2026 * @offset:     offset to add
2027 * @shift:      shift count to shift the result left
2028 *
2029 * These values are estimates at best, so no need for locking.
2030 */
2031void get_avenrun(unsigned long *loads, unsigned long offset, int shift)
2032{
2033        loads[0] = (avenrun[0] + offset) << shift;
2034        loads[1] = (avenrun[1] + offset) << shift;
2035        loads[2] = (avenrun[2] + offset) << shift;
2036}
2037
2038static long calc_load_fold_active(struct rq *this_rq)
2039{
2040        long nr_active, delta = 0;
2041
2042        nr_active = this_rq->nr_running;
2043        nr_active += (long) this_rq->nr_uninterruptible;
2044
2045        if (nr_active != this_rq->calc_load_active) {
2046                delta = nr_active - this_rq->calc_load_active;
2047                this_rq->calc_load_active = nr_active;
2048        }
2049
2050        return delta;
2051}
2052
2053/*
2054 * a1 = a0 * e + a * (1 - e)
2055 */
2056static unsigned long
2057calc_load(unsigned long load, unsigned long exp, unsigned long active)
2058{
2059        load *= exp;
2060        load += active * (FIXED_1 - exp);
2061        load += 1UL << (FSHIFT - 1);
2062        return load >> FSHIFT;
2063}
2064
2065#ifdef CONFIG_NO_HZ
2066/*
2067 * Handle NO_HZ for the global load-average.
2068 *
2069 * Since the above described distributed algorithm to compute the global
2070 * load-average relies on per-cpu sampling from the tick, it is affected by
2071 * NO_HZ.
2072 *
2073 * The basic idea is to fold the nr_active delta into a global idle-delta upon
2074 * entering NO_HZ state such that we can include this as an 'extra' cpu delta
2075 * when we read the global state.
2076 *
2077 * Obviously reality has to ruin such a delightfully simple scheme:
2078 *
2079 *  - When we go NO_HZ idle during the window, we can negate our sample
2080 *    contribution, causing under-accounting.
2081 *
2082 *    We avoid this by keeping two idle-delta counters and flipping them
2083 *    when the window starts, thus separating old and new NO_HZ load.
2084 *
2085 *    The only trick is the slight shift in index flip for read vs write.
2086 *
2087 *        0s            5s            10s           15s
2088 *          +10           +10           +10           +10
2089 *        |-|-----------|-|-----------|-|-----------|-|
2090 *    r:0 0 1           1 0           0 1           1 0
2091 *    w:0 1 1           0 0           1 1           0 0
2092 *
2093 *    This ensures we'll fold the old idle contribution in this window while
2094 *    accumlating the new one.
2095 *
2096 *  - When we wake up from NO_HZ idle during the window, we push up our
2097 *    contribution, since we effectively move our sample point to a known
2098 *    busy state.
2099 *
2100 *    This is solved by pushing the window forward, and thus skipping the
2101 *    sample, for this cpu (effectively using the idle-delta for this cpu which
2102 *    was in effect at the time the window opened). This also solves the issue
2103 *    of having to deal with a cpu having been in NOHZ idle for multiple
2104 *    LOAD_FREQ intervals.
2105 *
2106 * When making the ILB scale, we should try to pull this in as well.
2107 */
2108static atomic_long_t calc_load_idle[2];
2109static int calc_load_idx;
2110
2111static inline int calc_load_write_idx(void)
2112{
2113        int idx = calc_load_idx;
2114
2115        /*
2116         * See calc_global_nohz(), if we observe the new index, we also
2117         * need to observe the new update time.
2118         */
2119        smp_rmb();
2120
2121        /*
2122         * If the folding window started, make sure we start writing in the
2123         * next idle-delta.
2124         */
2125        if (!time_before(jiffies, calc_load_update))
2126                idx++;
2127
2128        return idx & 1;
2129}
2130
2131static inline int calc_load_read_idx(void)
2132{
2133        return calc_load_idx & 1;
2134}
2135
2136void calc_load_enter_idle(void)
2137{
2138        struct rq *this_rq = this_rq();
2139        long delta;
2140
2141        /*
2142         * We're going into NOHZ mode, if there's any pending delta, fold it
2143         * into the pending idle delta.
2144         */
2145        delta = calc_load_fold_active(this_rq);
2146        if (delta) {
2147                int idx = calc_load_write_idx();
2148                atomic_long_add(delta, &calc_load_idle[idx]);
2149        }
2150}
2151
2152void calc_load_exit_idle(void)
2153{
2154        struct rq *this_rq = this_rq();
2155
2156        /*
2157         * If we're still before the sample window, we're done.
2158         */
2159        if (time_before(jiffies, this_rq->calc_load_update))
2160                return;
2161
2162        /*
2163         * We woke inside or after the sample window, this means we're already
2164         * accounted through the nohz accounting, so skip the entire deal and
2165         * sync up for the next window.
2166         */
2167        this_rq->calc_load_update = calc_load_update;
2168        if (time_before(jiffies, this_rq->calc_load_update + 10))
2169                this_rq->calc_load_update += LOAD_FREQ;
2170}
2171
2172static long calc_load_fold_idle(void)
2173{
2174        int idx = calc_load_read_idx();
2175        long delta = 0;
2176
2177        if (atomic_long_read(&calc_load_idle[idx]))
2178                delta = atomic_long_xchg(&calc_load_idle[idx], 0);
2179
2180        return delta;
2181}
2182
2183/**
2184 * fixed_power_int - compute: x^n, in O(log n) time
2185 *
2186 * @x:         base of the power
2187 * @frac_bits: fractional bits of @x
2188 * @n:         power to raise @x to.
2189 *
2190 * By exploiting the relation between the definition of the natural power
2191 * function: x^n := x*x*...*x (x multiplied by itself for n times), and
2192 * the binary encoding of numbers used by computers: n := \Sum n_i * 2^i,
2193 * (where: n_i \elem {0, 1}, the binary vector representing n),
2194 * we find: x^n := x^(\Sum n_i * 2^i) := \Prod x^(n_i * 2^i), which is
2195 * of course trivially computable in O(log_2 n), the length of our binary
2196 * vector.
2197 */
2198static unsigned long
2199fixed_power_int(unsigned long x, unsigned int frac_bits, unsigned int n)
2200{
2201        unsigned long result = 1UL << frac_bits;
2202
2203        if (n) for (;;) {
2204                if (n & 1) {
2205                        result *= x;
2206                        result += 1UL << (frac_bits - 1);
2207                        result >>= frac_bits;
2208                }
2209                n >>= 1;
2210                if (!n)
2211                        break;
2212                x *= x;
2213                x += 1UL << (frac_bits - 1);
2214                x >>= frac_bits;
2215        }
2216
2217        return result;
2218}
2219
2220/*
2221 * a1 = a0 * e + a * (1 - e)
2222 *
2223 * a2 = a1 * e + a * (1 - e)
2224 *    = (a0 * e + a * (1 - e)) * e + a * (1 - e)
2225 *    = a0 * e^2 + a * (1 - e) * (1 + e)
2226 *
2227 * a3 = a2 * e + a * (1 - e)
2228 *    = (a0 * e^2 + a * (1 - e) * (1 + e)) * e + a * (1 - e)
2229 *    = a0 * e^3 + a * (1 - e) * (1 + e + e^2)
2230 *
2231 *  ...
2232 *
2233 * an = a0 * e^n + a * (1 - e) * (1 + e + ... + e^n-1) [1]
2234 *    = a0 * e^n + a * (1 - e) * (1 - e^n)/(1 - e)
2235 *    = a0 * e^n + a * (1 - e^n)
2236 *
2237 * [1] application of the geometric series:
2238 *
2239 *              n         1 - x^(n+1)
2240 *     S_n := \Sum x^i = -------------
2241 *             i=0          1 - x
2242 */
2243static unsigned long
2244calc_load_n(unsigned long load, unsigned long exp,
2245            unsigned long active, unsigned int n)
2246{
2247
2248        return calc_load(load, fixed_power_int(exp, FSHIFT, n), active);
2249}
2250
2251/*
2252 * NO_HZ can leave us missing all per-cpu ticks calling
2253 * calc_load_account_active(), but since an idle CPU folds its delta into
2254 * calc_load_tasks_idle per calc_load_account_idle(), all we need to do is fold
2255 * in the pending idle delta if our idle period crossed a load cycle boundary.
2256 *
2257 * Once we've updated the global active value, we need to apply the exponential
2258 * weights adjusted to the number of cycles missed.
2259 */
2260static void calc_global_nohz(void)
2261{
2262        long delta, active, n;
2263
2264        if (!time_before(jiffies, calc_load_update + 10)) {
2265                /*
2266                 * Catch-up, fold however many we are behind still
2267                 */
2268                delta = jiffies - calc_load_update - 10;
2269                n = 1 + (delta / LOAD_FREQ);
2270
2271                active = atomic_long_read(&calc_load_tasks);
2272                active = active > 0 ? active * FIXED_1 : 0;
2273
2274                avenrun[0] = calc_load_n(avenrun[0], EXP_1, active, n);
2275                avenrun[1] = calc_load_n(avenrun[1], EXP_5, active, n);
2276                avenrun[2] = calc_load_n(avenrun[2], EXP_15, active, n);
2277
2278                calc_load_update += n * LOAD_FREQ;
2279        }
2280
2281        /*
2282         * Flip the idle index...
2283         *
2284         * Make sure we first write the new time then flip the index, so that
2285         * calc_load_write_idx() will see the new time when it reads the new
2286         * index, this avoids a double flip messing things up.
2287         */
2288        smp_wmb();
2289        calc_load_idx++;
2290}
2291#else /* !CONFIG_NO_HZ */
2292
2293static inline long calc_load_fold_idle(void) { return 0; }
2294static inline void calc_global_nohz(void) { }
2295
2296#endif /* CONFIG_NO_HZ */
2297
2298/*
2299 * calc_load - update the avenrun load estimates 10 ticks after the
2300 * CPUs have updated calc_load_tasks.
2301 */
2302void calc_global_load(unsigned long ticks)
2303{
2304        long active, delta;
2305
2306        if (time_before(jiffies, calc_load_update + 10))
2307                return;
2308
2309        /*
2310         * Fold the 'old' idle-delta to include all NO_HZ cpus.
2311         */
2312        delta = calc_load_fold_idle();
2313        if (delta)
2314                atomic_long_add(delta, &calc_load_tasks);
2315
2316        active = atomic_long_read(&calc_load_tasks);
2317        active = active > 0 ? active * FIXED_1 : 0;
2318
2319        avenrun[0] = calc_load(avenrun[0], EXP_1, active);
2320        avenrun[1] = calc_load(avenrun[1], EXP_5, active);
2321        avenrun[2] = calc_load(avenrun[2], EXP_15, active);
2322
2323        calc_load_update += LOAD_FREQ;
2324
2325        /*
2326         * In case we idled for multiple LOAD_FREQ intervals, catch up in bulk.
2327         */
2328        calc_global_nohz();
2329}
2330
2331/*
2332 * Called from update_cpu_load() to periodically update this CPU's
2333 * active count.
2334 */
2335static void calc_load_account_active(struct rq *this_rq)
2336{
2337        long delta;
2338
2339        if (time_before(jiffies, this_rq->calc_load_update))
2340                return;
2341
2342        delta  = calc_load_fold_active(this_rq);
2343        if (delta)
2344                atomic_long_add(delta, &calc_load_tasks);
2345
2346        this_rq->calc_load_update += LOAD_FREQ;
2347}
2348
2349/*
2350 * End of global load-average stuff
2351 */
2352
2353/*
2354 * The exact cpuload at various idx values, calculated at every tick would be
2355 * load = (2^idx - 1) / 2^idx * load + 1 / 2^idx * cur_load
2356 *
2357 * If a cpu misses updates for n-1 ticks (as it was idle) and update gets called
2358 * on nth tick when cpu may be busy, then we have:
2359 * load = ((2^idx - 1) / 2^idx)^(n-1) * load
2360 * load = (2^idx - 1) / 2^idx) * load + 1 / 2^idx * cur_load
2361 *
2362 * decay_load_missed() below does efficient calculation of
2363 * load = ((2^idx - 1) / 2^idx)^(n-1) * load
2364 * avoiding 0..n-1 loop doing load = ((2^idx - 1) / 2^idx) * load
2365 *
2366 * The calculation is approximated on a 128 point scale.
2367 * degrade_zero_ticks is the number of ticks after which load at any
2368 * particular idx is approximated to be zero.
2369 * degrade_factor is a precomputed table, a row for each load idx.
2370 * Each column corresponds to degradation factor for a power of two ticks,
2371 * based on 128 point scale.
2372 * Example:
2373 * row 2, col 3 (=12) says that the degradation at load idx 2 after
2374 * 8 ticks is 12/128 (which is an approximation of exact factor 3^8/4^8).
2375 *
2376 * With this power of 2 load factors, we can degrade the load n times
2377 * by looking at 1 bits in n and doing as many mult/shift instead of
2378 * n mult/shifts needed by the exact degradation.
2379 */
2380#define DEGRADE_SHIFT           7
2381static const unsigned char
2382                degrade_zero_ticks[CPU_LOAD_IDX_MAX] = {0, 8, 32, 64, 128};
2383static const unsigned char
2384                degrade_factor[CPU_LOAD_IDX_MAX][DEGRADE_SHIFT + 1] = {
2385                                        {0, 0, 0, 0, 0, 0, 0, 0},
2386                                        {64, 32, 8, 0, 0, 0, 0, 0},
2387                                        {96, 72, 40, 12, 1, 0, 0},
2388                                        {112, 98, 75, 43, 15, 1, 0},
2389                                        {120, 112, 98, 76, 45, 16, 2} };
2390
2391/*
2392 * Update cpu_load for any missed ticks, due to tickless idle. The backlog
2393 * would be when CPU is idle and so we just decay the old load without
2394 * adding any new load.
2395 */
2396static unsigned long
2397decay_load_missed(unsigned long load, unsigned long missed_updates, int idx)
2398{
2399        int j = 0;
2400
2401        if (!missed_updates)
2402                return load;
2403
2404        if (missed_updates >= degrade_zero_ticks[idx])
2405                return 0;
2406
2407        if (idx == 1)
2408                return load >> missed_updates;
2409
2410        while (missed_updates) {
2411                if (missed_updates % 2)
2412                        load = (load * degrade_factor[idx][j]) >> DEGRADE_SHIFT;
2413
2414                missed_updates >>= 1;
2415                j++;
2416        }
2417        return load;
2418}
2419
2420/*
2421 * Update rq->cpu_load[] statistics. This function is usually called every
2422 * scheduler tick (TICK_NSEC). With tickless idle this will not be called
2423 * every tick. We fix it up based on jiffies.
2424 */
2425static void __update_cpu_load(struct rq *this_rq, unsigned long this_load,
2426                              unsigned long pending_updates)
2427{
2428        int i, scale;
2429
2430        this_rq->nr_load_updates++;
2431
2432        /* Update our load: */
2433        this_rq->cpu_load[0] = this_load; /* Fasttrack for idx 0 */
2434        for (i = 1, scale = 2; i < CPU_LOAD_IDX_MAX; i++, scale += scale) {
2435                unsigned long old_load, new_load;
2436
2437                /* scale is effectively 1 << i now, and >> i divides by scale */
2438
2439                old_load = this_rq->cpu_load[i];
2440                old_load = decay_load_missed(old_load, pending_updates - 1, i);
2441                new_load = this_load;
2442                /*
2443                 * Round up the averaging division if load is increasing. This
2444                 * prevents us from getting stuck on 9 if the load is 10, for
2445                 * example.
2446                 */
2447                if (new_load > old_load)
2448                        new_load += scale - 1;
2449
2450                this_rq->cpu_load[i] = (old_load * (scale - 1) + new_load) >> i;
2451        }
2452
2453        sched_avg_update(this_rq);
2454}
2455
2456#ifdef CONFIG_NO_HZ
2457/*
2458 * There is no sane way to deal with nohz on smp when using jiffies because the
2459 * cpu doing the jiffies update might drift wrt the cpu doing the jiffy reading
2460 * causing off-by-one errors in observed deltas; {0,2} instead of {1,1}.
2461 *
2462 * Therefore we cannot use the delta approach from the regular tick since that
2463 * would seriously skew the load calculation. However we'll make do for those
2464 * updates happening while idle (nohz_idle_balance) or coming out of idle
2465 * (tick_nohz_idle_exit).
2466 *
2467 * This means we might still be one tick off for nohz periods.
2468 */
2469
2470/*
2471 * Called from nohz_idle_balance() to update the load ratings before doing the
2472 * idle balance.
2473 */
2474void update_idle_cpu_load(struct rq *this_rq)
2475{
2476        unsigned long curr_jiffies = ACCESS_ONCE(jiffies);
2477        unsigned long load = this_rq->load.weight;
2478        unsigned long pending_updates;
2479
2480        /*
2481         * bail if there's load or we're actually up-to-date.
2482         */
2483        if (load || curr_jiffies == this_rq->last_load_update_tick)
2484                return;
2485
2486        pending_updates = curr_jiffies - this_rq->last_load_update_tick;
2487        this_rq->last_load_update_tick = curr_jiffies;
2488
2489        __update_cpu_load(this_rq, load, pending_updates);
2490}
2491
2492/*
2493 * Called from tick_nohz_idle_exit() -- try and fix up the ticks we missed.
2494 */
2495void update_cpu_load_nohz(void)
2496{
2497        struct rq *this_rq = this_rq();
2498        unsigned long curr_jiffies = ACCESS_ONCE(jiffies);
2499        unsigned long pending_updates;
2500
2501        if (curr_jiffies == this_rq->last_load_update_tick)
2502                return;
2503
2504        raw_spin_lock(&this_rq->lock);
2505        pending_updates = curr_jiffies - this_rq->last_load_update_tick;
2506        if (pending_updates) {
2507                this_rq->last_load_update_tick = curr_jiffies;
2508                /*
2509                 * We were idle, this means load 0, the current load might be
2510                 * !0 due to remote wakeups and the sort.
2511                 */
2512                __update_cpu_load(this_rq, 0, pending_updates);
2513        }
2514        raw_spin_unlock(&this_rq->lock);
2515}
2516#endif /* CONFIG_NO_HZ */
2517
2518/*
2519 * Called from scheduler_tick()
2520 */
2521static void update_cpu_load_active(struct rq *this_rq)
2522{
2523        /*
2524         * See the mess around update_idle_cpu_load() / update_cpu_load_nohz().
2525         */
2526        this_rq->last_load_update_tick = jiffies;
2527        __update_cpu_load(this_rq, this_rq->load.weight, 1);
2528
2529        calc_load_account_active(this_rq);
2530}
2531
2532#ifdef CONFIG_SMP
2533
2534/*
2535 * sched_exec - execve() is a valuable balancing opportunity, because at
2536 * this point the task has the smallest effective memory and cache footprint.
2537 */
2538void sched_exec(void)
2539{
2540        struct task_struct *p = current;
2541        unsigned long flags;
2542        int dest_cpu;
2543
2544        raw_spin_lock_irqsave(&p->pi_lock, flags);
2545        dest_cpu = p->sched_class->select_task_rq(p, SD_BALANCE_EXEC, 0);
2546        if (dest_cpu == smp_processor_id())
2547                goto unlock;
2548
2549        if (likely(cpu_active(dest_cpu))) {
2550                struct migration_arg arg = { p, dest_cpu };
2551
2552                raw_spin_unlock_irqrestore(&p->pi_lock, flags);
2553                stop_one_cpu(task_cpu(p), migration_cpu_stop, &arg);
2554                return;
2555        }
2556unlock:
2557        raw_spin_unlock_irqrestore(&p->pi_lock, flags);
2558}
2559
2560#endif
2561
2562DEFINE_PER_CPU(struct kernel_stat, kstat);
2563DEFINE_PER_CPU(struct kernel_cpustat, kernel_cpustat);
2564
2565EXPORT_PER_CPU_SYMBOL(kstat);
2566EXPORT_PER_CPU_SYMBOL(kernel_cpustat);
2567
2568/*
2569 * Return any ns on the sched_clock that have not yet been accounted in
2570 * @p in case that task is currently running.
2571 *
2572 * Called with task_rq_lock() held on @rq.
2573 */
2574static u64 do_task_delta_exec(struct task_struct *p, struct rq *rq)
2575{
2576        u64 ns = 0;
2577
2578        if (task_current(rq, p)) {
2579                update_rq_clock(rq);
2580                ns = rq->clock_task - p->se.exec_start;
2581                if ((s64)ns < 0)
2582                        ns = 0;
2583        }
2584
2585        return ns;
2586}
2587
2588unsigned long long task_delta_exec(struct task_struct *p)
2589{
2590        unsigned long flags;
2591        struct rq *rq;
2592        u64 ns = 0;
2593
2594        rq = task_rq_lock(p, &flags);
2595        ns = do_task_delta_exec(p, rq);
2596        task_rq_unlock(rq, p, &flags);
2597
2598        return ns;
2599}
2600
2601/*
2602 * Return accounted runtime for the task.
2603 * In case the task is currently running, return the runtime plus current's
2604 * pending runtime that have not been accounted yet.
2605 */
2606unsigned long long task_sched_runtime(struct task_struct *p)
2607{
2608        unsigned long flags;
2609        struct rq *rq;
2610        u64 ns = 0;
2611
2612        rq = task_rq_lock(p, &flags);
2613        ns = p->se.sum_exec_runtime + do_task_delta_exec(p, rq);
2614        task_rq_unlock(rq, p, &flags);
2615
2616        return ns;
2617}
2618
2619/*
2620 * This function gets called by the timer code, with HZ frequency.
2621 * We call it with interrupts disabled.
2622 */
2623void scheduler_tick(void)
2624{
2625        int cpu = smp_processor_id();
2626        struct rq *rq = cpu_rq(cpu);
2627        struct task_struct *curr = rq->curr;
2628
2629        sched_clock_tick();
2630
2631        raw_spin_lock(&rq->lock);
2632        update_rq_clock(rq);
2633        update_cpu_load_active(rq);
2634        curr->sched_class->task_tick(rq, curr, 0);
2635        raw_spin_unlock(&rq->lock);
2636
2637        perf_event_task_tick();
2638
2639#ifdef CONFIG_SMP
2640        rq->idle_balance = idle_cpu(cpu);
2641        trigger_load_balance(rq, cpu);
2642#endif
2643}
2644
2645notrace unsigned long get_parent_ip(unsigned long addr)
2646{
2647        if (in_lock_functions(addr)) {
2648                addr = CALLER_ADDR2;
2649                if (in_lock_functions(addr))
2650                        addr = CALLER_ADDR3;
2651        }
2652        return addr;
2653}
2654
2655#if defined(CONFIG_PREEMPT) && (defined(CONFIG_DEBUG_PREEMPT) || \
2656                                defined(CONFIG_PREEMPT_TRACER))
2657
2658void __kprobes add_preempt_count(int val)
2659{
2660#ifdef CONFIG_DEBUG_PREEMPT
2661        /*
2662         * Underflow?
2663         */
2664        if (DEBUG_LOCKS_WARN_ON((preempt_count() < 0)))
2665                return;
2666#endif
2667        preempt_count() += val;
2668#ifdef CONFIG_DEBUG_PREEMPT
2669        /*
2670         * Spinlock count overflowing soon?
2671         */
2672        DEBUG_LOCKS_WARN_ON((preempt_count() & PREEMPT_MASK) >=
2673                                PREEMPT_MASK - 10);
2674#endif
2675        if (preempt_count() == val)
2676                trace_preempt_off(CALLER_ADDR0, get_parent_ip(CALLER_ADDR1));
2677}
2678EXPORT_SYMBOL(add_preempt_count);
2679
2680void __kprobes sub_preempt_count(int val)
2681{
2682#ifdef CONFIG_DEBUG_PREEMPT
2683        /*
2684         * Underflow?
2685         */
2686        if (DEBUG_LOCKS_WARN_ON(val > preempt_count()))
2687                return;
2688        /*
2689         * Is the spinlock portion underflowing?
2690         */
2691        if (DEBUG_LOCKS_WARN_ON((val < PREEMPT_MASK) &&
2692                        !(preempt_count() & PREEMPT_MASK)))
2693                return;
2694#endif
2695
2696        if (preempt_count() == val)
2697                trace_preempt_on(CALLER_ADDR0, get_parent_ip(CALLER_ADDR1));
2698        preempt_count() -= val;
2699}
2700EXPORT_SYMBOL(sub_preempt_count);
2701
2702#endif
2703
2704/*
2705 * Print scheduling while atomic bug:
2706 */
2707static noinline void __schedule_bug(struct task_struct *prev)
2708{
2709        if (oops_in_progress)
2710                return;
2711
2712        printk(KERN_ERR "BUG: scheduling while atomic: %s/%d/0x%08x\n",
2713                prev->comm, prev->pid, preempt_count());
2714
2715        debug_show_held_locks(prev);
2716        print_modules();
2717        if (irqs_disabled())
2718                print_irqtrace_events(prev);
2719        dump_stack();
2720        add_taint(TAINT_WARN);
2721}
2722
2723/*
2724 * Various schedule()-time debugging checks and statistics:
2725 */
2726static inline void schedule_debug(struct task_struct *prev)
2727{
2728        /*
2729         * Test if we are atomic. Since do_exit() needs to call into
2730         * schedule() atomically, we ignore that path for now.
2731         * Otherwise, whine if we are scheduling when we should not be.
2732         */
2733        if (unlikely(in_atomic_preempt_off() && !prev->exit_state))
2734                __schedule_bug(prev);
2735        rcu_sleep_check();
2736
2737        profile_hit(SCHED_PROFILING, __builtin_return_address(0));
2738
2739        schedstat_inc(this_rq(), sched_count);
2740}
2741
2742static void put_prev_task(struct rq *rq, struct task_struct *prev)
2743{
2744        if (prev->on_rq || rq->skip_clock_update < 0)
2745                update_rq_clock(rq);
2746        prev->sched_class->put_prev_task(rq, prev);
2747}
2748
2749/*
2750 * Pick up the highest-prio task:
2751 */
2752static inline struct task_struct *
2753pick_next_task(struct rq *rq)
2754{
2755        const struct sched_class *class;
2756        struct task_struct *p;
2757
2758        /*
2759         * Optimization: we know that if all tasks are in
2760         * the fair class we can call that function directly:
2761         */
2762        if (likely(rq->nr_running == rq->cfs.h_nr_running)) {
2763                p = fair_sched_class.pick_next_task(rq);
2764                if (likely(p))
2765                        return p;
2766        }
2767
2768        for_each_class(class) {
2769                p = class->pick_next_task(rq);
2770                if (p)
2771                        return p;
2772        }
2773
2774        BUG(); /* the idle class will always have a runnable task */
2775}
2776
2777/*
2778 * __schedule() is the main scheduler function.
2779 *
2780 * The main means of driving the scheduler and thus entering this function are:
2781 *
2782 *   1. Explicit blocking: mutex, semaphore, waitqueue, etc.
2783 *
2784 *   2. TIF_NEED_RESCHED flag is checked on interrupt and userspace return
2785 *      paths. For example, see arch/x86/entry_64.S.
2786 *
2787 *      To drive preemption between tasks, the scheduler sets the flag in timer
2788 *      interrupt handler scheduler_tick().
2789 *
2790 *   3. Wakeups don't really cause entry into schedule(). They add a
2791 *      task to the run-queue and that's it.
2792 *
2793 *      Now, if the new task added to the run-queue preempts the current
2794 *      task, then the wakeup sets TIF_NEED_RESCHED and schedule() gets
2795 *      called on the nearest possible occasion:
2796 *
2797 *       - If the kernel is preemptible (CONFIG_PREEMPT=y):
2798 *
2799 *         - in syscall or exception context, at the next outmost
2800 *           preempt_enable(). (this might be as soon as the wake_up()'s
2801 *           spin_unlock()!)
2802 *
2803 *         - in IRQ context, return from interrupt-handler to
2804 *           preemptible context
2805 *
2806 *       - If the kernel is not preemptible (CONFIG_PREEMPT is not set)
2807 *         then at the next:
2808 *
2809 *          - cond_resched() call
2810 *          - explicit schedule() call
2811 *          - return from syscall or exception to user-space
2812 *          - return from interrupt-handler to user-space
2813 */
2814static void __sched __schedule(void)
2815{
2816        struct task_struct *prev, *next;
2817        unsigned long *switch_count;
2818        struct rq *rq;
2819        int cpu;
2820
2821need_resched:
2822        preempt_disable();
2823        cpu = smp_processor_id();
2824        rq = cpu_rq(cpu);
2825        rcu_note_context_switch(cpu);
2826        prev = rq->curr;
2827
2828        schedule_debug(prev);
2829
2830        if (sched_feat(HRTICK))
2831                hrtick_clear(rq);
2832
2833        raw_spin_lock_irq(&rq->lock);
2834
2835        switch_count = &prev->nivcsw;
2836        if (prev->state && !(preempt_count() & PREEMPT_ACTIVE)) {
2837                if (unlikely(signal_pending_state(prev->state, prev))) {
2838                        prev->state = TASK_RUNNING;
2839                } else {
2840                        deactivate_task(rq, prev, DEQUEUE_SLEEP);
2841                        prev->on_rq = 0;
2842
2843                        /*
2844                         * If a worker went to sleep, notify and ask workqueue
2845                         * whether it wants to wake up a task to maintain
2846                         * concurrency.
2847                         */
2848                        if (prev->flags & PF_WQ_WORKER) {
2849                                struct task_struct *to_wakeup;
2850
2851                                to_wakeup = wq_worker_sleeping(prev, cpu);
2852                                if (to_wakeup)
2853                                        try_to_wake_up_local(to_wakeup);
2854                        }
2855                }
2856                switch_count = &prev->nvcsw;
2857        }
2858
2859        pre_schedule(rq, prev);
2860
2861        if (unlikely(!rq->nr_running))
2862                idle_balance(cpu, rq);
2863
2864        put_prev_task(rq, prev);
2865        next = pick_next_task(rq);
2866        clear_tsk_need_resched(prev);
2867        rq->skip_clock_update = 0;
2868
2869        if (likely(prev != next)) {
2870                rq->nr_switches++;
2871                rq->curr = next;
2872                ++*switch_count;
2873
2874                context_switch(rq, prev, next); /* unlocks the rq */
2875                /*
2876                 * The context switch have flipped the stack from under us
2877                 * and restored the local variables which were saved when
2878                 * this task called schedule() in the past. prev == current
2879                 * is still correct, but it can be moved to another cpu/rq.
2880                 */
2881                cpu = smp_processor_id();
2882                rq = cpu_rq(cpu);
2883        } else
2884                raw_spin_unlock_irq(&rq->lock);
2885
2886        post_schedule(rq);
2887
2888        sched_preempt_enable_no_resched();
2889        if (need_resched())
2890                goto need_resched;
2891}
2892
2893static inline void sched_submit_work(struct task_struct *tsk)
2894{
2895        if (!tsk->state || tsk_is_pi_blocked(tsk))
2896                return;
2897        /*
2898         * If we are going to sleep and we have plugged IO queued,
2899         * make sure to submit it to avoid deadlocks.
2900         */
2901        if (blk_needs_flush_plug(tsk))
2902                blk_schedule_flush_plug(tsk);
2903}
2904
2905asmlinkage void __sched schedule(void)
2906{
2907        struct task_struct *tsk = current;
2908
2909        sched_submit_work(tsk);
2910        __schedule();
2911}
2912EXPORT_SYMBOL(schedule);
2913
2914#ifdef CONFIG_RCU_USER_QS
2915asmlinkage void __sched schedule_user(void)
2916{
2917        /*
2918         * If we come here after a random call to set_need_resched(),
2919         * or we have been woken up remotely but the IPI has not yet arrived,
2920         * we haven't yet exited the RCU idle mode. Do it here manually until
2921         * we find a better solution.
2922         */
2923        rcu_user_exit();
2924        schedule();
2925        rcu_user_enter();
2926}
2927#endif
2928
2929/**
2930 * schedule_preempt_disabled - called with preemption disabled
2931 *
2932 * Returns with preemption disabled. Note: preempt_count must be 1
2933 */
2934void __sched schedule_preempt_disabled(void)
2935{
2936        sched_preempt_enable_no_resched();
2937        schedule();
2938        preempt_disable();
2939}
2940
2941#ifdef CONFIG_MUTEX_SPIN_ON_OWNER
2942
2943static inline bool owner_running(struct mutex *lock, struct task_struct *owner)
2944{
2945        if (lock->owner != owner)
2946                return false;
2947
2948        /*
2949         * Ensure we emit the owner->on_cpu, dereference _after_ checking
2950         * lock->owner still matches owner, if that fails, owner might
2951         * point to free()d memory, if it still matches, the rcu_read_lock()
2952         * ensures the memory stays valid.
2953         */
2954        barrier();
2955
2956        return owner->on_cpu;
2957}
2958
2959/*
2960 * Look out! "owner" is an entirely speculative pointer
2961 * access and not reliable.
2962 */
2963int mutex_spin_on_owner(struct mutex *lock, struct task_struct *owner)
2964{
2965        if (!sched_feat(OWNER_SPIN))
2966                return 0;
2967
2968        rcu_read_lock();
2969        while (owner_running(lock, owner)) {
2970                if (need_resched())
2971                        break;
2972
2973                arch_mutex_cpu_relax();
2974        }
2975        rcu_read_unlock();
2976
2977        /*
2978         * We break out the loop above on need_resched() and when the
2979         * owner changed, which is a sign for heavy contention. Return
2980         * success only when lock->owner is NULL.
2981         */
2982        return lock->owner == NULL;
2983}
2984#endif
2985
2986#ifdef CONFIG_PREEMPT
2987/*
2988 * this is the entry point to schedule() from in-kernel preemption
2989 * off of preempt_enable. Kernel preemptions off return from interrupt
2990 * occur there and call schedule directly.
2991 */
2992asmlinkage void __sched notrace preempt_schedule(void)
2993{
2994        struct thread_info *ti = current_thread_info();
2995
2996        /*
2997         * If there is a non-zero preempt_count or interrupts are disabled,
2998         * we do not want to preempt the current task. Just return..
2999         */
3000        if (likely(ti->preempt_count || irqs_disabled()))
3001                return;
3002
3003        do {
3004                add_preempt_count_notrace(PREEMPT_ACTIVE);
3005                __schedule();
3006                sub_preempt_count_notrace(PREEMPT_ACTIVE);
3007
3008                /*
3009                 * Check again in case we missed a preemption opportunity
3010                 * between schedule and now.
3011                 */
3012                barrier();
3013        } while (need_resched());
3014}
3015EXPORT_SYMBOL(preempt_schedule);
3016
3017/*
3018 * this is the entry point to schedule() from kernel preemption
3019 * off of irq context.
3020 * Note, that this is called and return with irqs disabled. This will
3021 * protect us against recursive calling from irq.
3022 */
3023asmlinkage void __sched preempt_schedule_irq(void)
3024{
3025        struct thread_info *ti = current_thread_info();
3026
3027        /* Catch callers which need to be fixed */
3028        BUG_ON(ti->preempt_count || !irqs_disabled());
3029
3030        rcu_user_exit();
3031        do {
3032                add_preempt_count(PREEMPT_ACTIVE);
3033                local_irq_enable();
3034                __schedule();
3035                local_irq_disable();
3036                sub_preempt_count(PREEMPT_ACTIVE);
3037
3038                /*
3039                 * Check again in case we missed a preemption opportunity
3040                 * between schedule and now.
3041                 */
3042                barrier();
3043        } while (need_resched());
3044}
3045
3046#endif /* CONFIG_PREEMPT */
3047
3048int default_wake_function(wait_queue_t *curr, unsigned mode, int wake_flags,
3049                          void *key)
3050{
3051        return try_to_wake_up(curr->private, mode, wake_flags);
3052}
3053EXPORT_SYMBOL(default_wake_function);
3054
3055/*
3056 * The core wakeup function. Non-exclusive wakeups (nr_exclusive == 0) just
3057 * wake everything up. If it's an exclusive wakeup (nr_exclusive == small +ve
3058 * number) then we wake all the non-exclusive tasks and one exclusive task.
3059 *
3060 * There are circumstances in which we can try to wake a task which has already
3061 * started to run but is not in state TASK_RUNNING. try_to_wake_up() returns
3062 * zero in this (rare) case, and we handle it by continuing to scan the queue.
3063 */
3064static void __wake_up_common(wait_queue_head_t *q, unsigned int mode,
3065                        int nr_exclusive, int wake_flags, void *key)
3066{
3067        wait_queue_t *curr, *next;
3068
3069        list_for_each_entry_safe(curr, next, &q->task_list, task_list) {
3070                unsigned flags = curr->flags;
3071
3072                if (curr->func(curr, mode, wake_flags, key) &&
3073                                (flags & WQ_FLAG_EXCLUSIVE) && !--nr_exclusive)
3074                        break;
3075        }
3076}
3077
3078/**
3079 * __wake_up - wake up threads blocked on a waitqueue.
3080 * @q: the waitqueue
3081 * @mode: which threads
3082 * @nr_exclusive: how many wake-one or wake-many threads to wake up
3083 * @key: is directly passed to the wakeup function
3084 *
3085 * It may be assumed that this function implies a write memory barrier before
3086 * changing the task state if and only if any tasks are woken up.
3087 */
3088void __wake_up(wait_queue_head_t *q, unsigned int mode,
3089                        int nr_exclusive, void *key)
3090{
3091        unsigned long flags;
3092
3093        spin_lock_irqsave(&q->lock, flags);
3094        __wake_up_common(q, mode, nr_exclusive, 0, key);
3095        spin_unlock_irqrestore(&q->lock, flags);
3096}
3097EXPORT_SYMBOL(__wake_up);
3098
3099/*
3100 * Same as __wake_up but called with the spinlock in wait_queue_head_t held.
3101 */
3102void __wake_up_locked(wait_queue_head_t *q, unsigned int mode, int nr)
3103{
3104        __wake_up_common(q, mode, nr, 0, NULL);
3105}
3106EXPORT_SYMBOL_GPL(__wake_up_locked);
3107
3108void __wake_up_locked_key(wait_queue_head_t *q, unsigned int mode, void *key)
3109{
3110        __wake_up_common(q, mode, 1, 0, key);
3111}
3112EXPORT_SYMBOL_GPL(__wake_up_locked_key);
3113
3114/**
3115 * __wake_up_sync_key - wake up threads blocked on a waitqueue.
3116 * @q: the waitqueue
3117 * @mode: which threads
3118 * @nr_exclusive: how many wake-one or wake-many threads to wake up
3119 * @key: opaque value to be passed to wakeup targets
3120 *
3121 * The sync wakeup differs that the waker knows that it will schedule
3122 * away soon, so while the target thread will be woken up, it will not
3123 * be migrated to another CPU - ie. the two threads are 'synchronized'
3124 * with each other. This can prevent needless bouncing between CPUs.
3125 *
3126 * On UP it can prevent extra preemption.
3127 *
3128 * It may be assumed that this function implies a write memory barrier before
3129 * changing the task state if and only if any tasks are woken up.
3130 */
3131void __wake_up_sync_key(wait_queue_head_t *q, unsigned int mode,
3132                        int nr_exclusive, void *key)
3133{
3134        unsigned long flags;
3135        int wake_flags = WF_SYNC;
3136
3137        if (unlikely(!q))
3138                return;
3139
3140        if (unlikely(!nr_exclusive))
3141                wake_flags = 0;
3142
3143        spin_lock_irqsave(&q->lock, flags);
3144        __wake_up_common(q, mode, nr_exclusive, wake_flags, key);
3145        spin_unlock_irqrestore(&q->lock, flags);
3146}
3147EXPORT_SYMBOL_GPL(__wake_up_sync_key);
3148
3149/*
3150 * __wake_up_sync - see __wake_up_sync_key()
3151 */
3152void __wake_up_sync(wait_queue_head_t *q, unsigned int mode, int nr_exclusive)
3153{
3154        __wake_up_sync_key(q, mode, nr_exclusive, NULL);
3155}
3156EXPORT_SYMBOL_GPL(__wake_up_sync);      /* For internal use only */
3157
3158/**
3159 * complete: - signals a single thread waiting on this completion
3160 * @x:  holds the state of this particular completion
3161 *
3162 * This will wake up a single thread waiting on this completion. Threads will be
3163 * awakened in the same order in which they were queued.
3164 *
3165 * See also complete_all(), wait_for_completion() and related routines.
3166 *
3167 * It may be assumed that this function implies a write memory barrier before
3168 * changing the task state if and only if any tasks are woken up.
3169 */
3170void complete(struct completion *x)
3171{
3172        unsigned long flags;
3173
3174        spin_lock_irqsave(&x->wait.lock, flags);
3175        x->done++;
3176        __wake_up_common(&x->wait, TASK_NORMAL, 1, 0, NULL);
3177        spin_unlock_irqrestore(&x->wait.lock, flags);
3178}
3179EXPORT_SYMBOL(complete);
3180
3181/**
3182 * complete_all: - signals all threads waiting on this completion
3183 * @x:  holds the state of this particular completion
3184 *
3185 * This will wake up all threads waiting on this particular completion event.
3186 *
3187 * It may be assumed that this function implies a write memory barrier before
3188 * changing the task state if and only if any tasks are woken up.
3189 */
3190void complete_all(struct completion *x)
3191{
3192        unsigned long flags;
3193
3194        spin_lock_irqsave(&x->wait.lock, flags);
3195        x->done += UINT_MAX/2;
3196        __wake_up_common(&x->wait, TASK_NORMAL, 0, 0, NULL);
3197        spin_unlock_irqrestore(&x->wait.lock, flags);
3198}
3199EXPORT_SYMBOL(complete_all);
3200
3201static inline long __sched
3202do_wait_for_common(struct completion *x, long timeout, int state)
3203{
3204        if (!x->done) {
3205                DECLARE_WAITQUEUE(wait, current);
3206
3207                __add_wait_queue_tail_exclusive(&x->wait, &wait);
3208                do {
3209                        if (signal_pending_state(state, current)) {
3210                                timeout = -ERESTARTSYS;
3211                                break;
3212                        }
3213                        __set_current_state(state);
3214                        spin_unlock_irq(&x->wait.lock);
3215                        timeout = schedule_timeout(timeout);
3216                        spin_lock_irq(&x->wait.lock);
3217                } while (!x->done && timeout);
3218                __remove_wait_queue(&x->wait, &wait);
3219                if (!x->done)
3220                        return timeout;
3221        }
3222        x->done--;
3223        return timeout ?: 1;
3224}
3225
3226static long __sched
3227wait_for_common(struct completion *x, long timeout, int state)
3228{
3229        might_sleep();
3230
3231        spin_lock_irq(&x->wait.lock);
3232        timeout = do_wait_for_common(x, timeout, state);
3233        spin_unlock_irq(&x->wait.lock);
3234        return timeout;
3235}
3236
3237/**
3238 * wait_for_completion: - waits for completion of a task
3239 * @x:  holds the state of this particular completion
3240 *
3241 * This waits to be signaled for completion of a specific task. It is NOT
3242 * interruptible and there is no timeout.
3243 *
3244 * See also similar routines (i.e. wait_for_completion_timeout()) with timeout
3245 * and interrupt capability. Also see complete().
3246 */
3247void __sched wait_for_completion(struct completion *x)
3248{
3249        wait_for_common(x, MAX_SCHEDULE_TIMEOUT, TASK_UNINTERRUPTIBLE);
3250}
3251EXPORT_SYMBOL(wait_for_completion);
3252
3253/**
3254 * wait_for_completion_timeout: - waits for completion of a task (w/timeout)
3255 * @x:  holds the state of this particular completion
3256 * @timeout:  timeout value in jiffies
3257 *
3258 * This waits for either a completion of a specific task to be signaled or for a
3259 * specified timeout to expire. The timeout is in jiffies. It is not
3260 * interruptible.
3261 *
3262 * The return value is 0 if timed out, and positive (at least 1, or number of
3263 * jiffies left till timeout) if completed.
3264 */
3265unsigned long __sched
3266wait_for_completion_timeout(struct completion *x, unsigned long timeout)
3267{
3268        return wait_for_common(x, timeout, TASK_UNINTERRUPTIBLE);
3269}
3270EXPORT_SYMBOL(wait_for_completion_timeout);
3271
3272/**
3273 * wait_for_completion_interruptible: - waits for completion of a task (w/intr)
3274 * @x:  holds the state of this particular completion
3275 *
3276 * This waits for completion of a specific task to be signaled. It is
3277 * interruptible.
3278 *
3279 * The return value is -ERESTARTSYS if interrupted, 0 if completed.
3280 */
3281int __sched wait_for_completion_interruptible(struct completion *x)
3282{
3283        long t = wait_for_common(x, MAX_SCHEDULE_TIMEOUT, TASK_INTERRUPTIBLE);
3284        if (t == -ERESTARTSYS)
3285                return t;
3286        return 0;
3287}
3288EXPORT_SYMBOL(wait_for_completion_interruptible);
3289
3290/**
3291 * wait_for_completion_interruptible_timeout: - waits for completion (w/(to,intr))
3292 * @x:  holds the state of this particular completion
3293 * @timeout:  timeout value in jiffies
3294 *
3295 * This waits for either a completion of a specific task to be signaled or for a
3296 * specified timeout to expire. It is interruptible. The timeout is in jiffies.
3297 *
3298 * The return value is -ERESTARTSYS if interrupted, 0 if timed out,
3299 * positive (at least 1, or number of jiffies left till timeout) if completed.
3300 */
3301long __sched
3302wait_for_completion_interruptible_timeout(struct completion *x,
3303                                          unsigned long timeout)
3304{
3305        return wait_for_common(x, timeout, TASK_INTERRUPTIBLE);
3306}
3307EXPORT_SYMBOL(wait_for_completion_interruptible_timeout);
3308
3309/**
3310 * wait_for_completion_killable: - waits for completion of a task (killable)
3311 * @x:  holds the state of this particular completion
3312 *
3313 * This waits to be signaled for completion of a specific task. It can be
3314 * interrupted by a kill signal.
3315 *
3316 * The return value is -ERESTARTSYS if interrupted, 0 if completed.
3317 */
3318int __sched wait_for_completion_killable(struct completion *x)
3319{
3320        long t = wait_for_common(x, MAX_SCHEDULE_TIMEOUT, TASK_KILLABLE);
3321        if (t == -ERESTARTSYS)
3322                return t;
3323        return 0;
3324}
3325EXPORT_SYMBOL(wait_for_completion_killable);
3326
3327/**
3328 * wait_for_completion_killable_timeout: - waits for completion of a task (w/(to,killable))
3329 * @x:  holds the state of this particular completion
3330 * @timeout:  timeout value in jiffies
3331 *
3332 * This waits for either a completion of a specific task to be
3333 * signaled or for a specified timeout to expire. It can be
3334 * interrupted by a kill signal. The timeout is in jiffies.
3335 *
3336 * The return value is -ERESTARTSYS if interrupted, 0 if timed out,
3337 * positive (at least 1, or number of jiffies left till timeout) if completed.
3338 */
3339long __sched
3340wait_for_completion_killable_timeout(struct completion *x,
3341                                     unsigned long timeout)
3342{
3343        return wait_for_common(x, timeout, TASK_KILLABLE);
3344}
3345EXPORT_SYMBOL(wait_for_completion_killable_timeout);
3346
3347/**
3348 *      try_wait_for_completion - try to decrement a completion without blocking
3349 *      @x:     completion structure
3350 *
3351 *      Returns: 0 if a decrement cannot be done without blocking
3352 *               1 if a decrement succeeded.
3353 *
3354 *      If a completion is being used as a counting completion,
3355 *      attempt to decrement the counter without blocking. This
3356 *      enables us to avoid waiting if the resource the completion
3357 *      is protecting is not available.
3358 */
3359bool try_wait_for_completion(struct completion *x)
3360{
3361        unsigned long flags;
3362        int ret = 1;
3363
3364        spin_lock_irqsave(&x->wait.lock, flags);
3365        if (!x->done)
3366                ret = 0;
3367        else
3368                x->done--;
3369        spin_unlock_irqrestore(&x->wait.lock, flags);
3370        return ret;
3371}
3372EXPORT_SYMBOL(try_wait_for_completion);
3373
3374/**
3375 *      completion_done - Test to see if a completion has any waiters
3376 *      @x:     completion structure
3377 *
3378 *      Returns: 0 if there are waiters (wait_for_completion() in progress)
3379 *               1 if there are no waiters.
3380 *
3381 */
3382bool completion_done(struct completion *x)
3383{
3384        unsigned long flags;
3385        int ret = 1;
3386
3387        spin_lock_irqsave(&x->wait.lock, flags);
3388        if (!x->done)
3389                ret = 0;
3390        spin_unlock_irqrestore(&x->wait.lock, flags);
3391        return ret;
3392}
3393EXPORT_SYMBOL(completion_done);
3394
3395static long __sched
3396sleep_on_common(wait_queue_head_t *q, int state, long timeout)
3397{
3398        unsigned long flags;
3399        wait_queue_t wait;
3400
3401        init_waitqueue_entry(&wait, current);
3402
3403        __set_current_state(state);
3404
3405        spin_lock_irqsave(&q->lock, flags);
3406        __add_wait_queue(q, &wait);
3407        spin_unlock(&q->lock);
3408        timeout = schedule_timeout(timeout);
3409        spin_lock_irq(&q->lock);
3410        __remove_wait_queue(q, &wait);
3411        spin_unlock_irqrestore(&q->lock, flags);
3412
3413        return timeout;
3414}
3415
3416void __sched interruptible_sleep_on(wait_queue_head_t *q)
3417{
3418        sleep_on_common(q, TASK_INTERRUPTIBLE, MAX_SCHEDULE_TIMEOUT);
3419}
3420EXPORT_SYMBOL(interruptible_sleep_on);
3421
3422long __sched
3423interruptible_sleep_on_timeout(wait_queue_head_t *q, long timeout)
3424{
3425        return sleep_on_common(q, TASK_INTERRUPTIBLE, timeout);
3426}
3427EXPORT_SYMBOL(interruptible_sleep_on_timeout);
3428
3429void __sched sleep_on(wait_queue_head_t *q)
3430{
3431        sleep_on_common(q, TASK_UNINTERRUPTIBLE, MAX_SCHEDULE_TIMEOUT);
3432}
3433EXPORT_SYMBOL(sleep_on);
3434
3435long __sched sleep_on_timeout(wait_queue_head_t *q, long timeout)
3436{
3437        return sleep_on_common(q, TASK_UNINTERRUPTIBLE, timeout);
3438}
3439EXPORT_SYMBOL(sleep_on_timeout);
3440
3441#ifdef CONFIG_RT_MUTEXES
3442
3443/*
3444 * rt_mutex_setprio - set the current priority of a task
3445 * @p: task
3446 * @prio: prio value (kernel-internal form)
3447 *
3448 * This function changes the 'effective' priority of a task. It does
3449 * not touch ->normal_prio like __setscheduler().
3450 *
3451 * Used by the rt_mutex code to implement priority inheritance logic.
3452 */
3453void rt_mutex_setprio(struct task_struct *p, int prio)
3454{
3455        int oldprio, on_rq, running;
3456        struct rq *rq;
3457        const struct sched_class *prev_class;
3458
3459        BUG_ON(prio < 0 || prio > MAX_PRIO);
3460
3461        rq = __task_rq_lock(p);
3462
3463        /*
3464         * Idle task boosting is a nono in general. There is one
3465         * exception, when PREEMPT_RT and NOHZ is active:
3466         *
3467         * The idle task calls get_next_timer_interrupt() and holds
3468         * the timer wheel base->lock on the CPU and another CPU wants
3469         * to access the timer (probably to cancel it). We can safely
3470         * ignore the boosting request, as the idle CPU runs this code
3471         * with interrupts disabled and will complete the lock
3472         * protected section without being interrupted. So there is no
3473         * real need to boost.
3474         */
3475        if (unlikely(p == rq->idle)) {
3476                WARN_ON(p != rq->curr);
3477                WARN_ON(p->pi_blocked_on);
3478                goto out_unlock;
3479        }
3480
3481        trace_sched_pi_setprio(p, prio);
3482        oldprio = p->prio;
3483        prev_class = p->sched_class;
3484        on_rq = p->on_rq;
3485        running = task_current(rq, p);
3486        if (on_rq)
3487                dequeue_task(rq, p, 0);
3488        if (running)
3489                p->sched_class->put_prev_task(rq, p);
3490
3491        if (rt_prio(prio))
3492                p->sched_class = &rt_sched_class;
3493        else
3494                p->sched_class = &fair_sched_class;
3495
3496        p->prio = prio;
3497
3498        if (running)
3499                p->sched_class->set_curr_task(rq);
3500        if (on_rq)
3501                enqueue_task(rq, p, oldprio < prio ? ENQUEUE_HEAD : 0);
3502
3503        check_class_changed(rq, p, prev_class, oldprio);
3504out_unlock:
3505        __task_rq_unlock(rq);
3506}
3507#endif
3508void set_user_nice(struct task_struct *p, long nice)
3509{
3510        int old_prio, delta, on_rq;
3511        unsigned long flags;
3512        struct rq *rq;
3513
3514        if (TASK_NICE(p) == nice || nice < -20 || nice > 19)
3515                return;
3516        /*
3517         * We have to be careful, if called from sys_setpriority(),
3518         * the task might be in the middle of scheduling on another CPU.
3519         */
3520        rq = task_rq_lock(p, &flags);
3521        /*
3522         * The RT priorities are set via sched_setscheduler(), but we still
3523         * allow the 'normal' nice value to be set - but as expected
3524         * it wont have any effect on scheduling until the task is
3525         * SCHED_FIFO/SCHED_RR:
3526         */
3527        if (task_has_rt_policy(p)) {
3528                p->static_prio = NICE_TO_PRIO(nice);
3529                goto out_unlock;
3530        }
3531        on_rq = p->on_rq;
3532        if (on_rq)
3533                dequeue_task(rq, p, 0);
3534
3535        p->static_prio = NICE_TO_PRIO(nice);
3536        set_load_weight(p);
3537        old_prio = p->prio;
3538        p->prio = effective_prio(p);
3539        delta = p->prio - old_prio;
3540
3541        if (on_rq) {
3542                enqueue_task(rq, p, 0);
3543                /*
3544                 * If the task increased its priority or is running and
3545                 * lowered its priority, then reschedule its CPU:
3546                 */
3547                if (delta < 0 || (delta > 0 && task_running(rq, p)))
3548                        resched_task(rq->curr);
3549        }
3550out_unlock:
3551        task_rq_unlock(rq, p, &flags);
3552}
3553EXPORT_SYMBOL(set_user_nice);
3554
3555/*
3556 * can_nice - check if a task can reduce its nice value
3557 * @p: task
3558 * @nice: nice value
3559 */
3560int can_nice(const struct task_struct *p, const int nice)
3561{
3562        /* convert nice value [19,-20] to rlimit style value [1,40] */
3563        int nice_rlim = 20 - nice;
3564
3565        return (nice_rlim <= task_rlimit(p, RLIMIT_NICE) ||
3566                capable(CAP_SYS_NICE));
3567}
3568
3569#ifdef __ARCH_WANT_SYS_NICE
3570
3571/*
3572 * sys_nice - change the priority of the current process.
3573 * @increment: priority increment
3574 *
3575 * sys_setpriority is a more generic, but much slower function that
3576 * does similar things.
3577 */
3578SYSCALL_DEFINE1(nice, int, increment)
3579{
3580        long nice, retval;
3581
3582        /*
3583         * Setpriority might change our priority at the same moment.
3584         * We don't have to worry. Conceptually one call occurs first
3585         * and we have a single winner.
3586         */
3587        if (increment < -40)
3588                increment = -40;
3589        if (increment > 40)
3590                increment = 40;
3591
3592        nice = TASK_NICE(current) + increment;
3593        if (nice < -20)
3594                nice = -20;
3595        if (nice > 19)
3596                nice = 19;
3597
3598        if (increment < 0 && !can_nice(current, nice))
3599                return -EPERM;
3600
3601        retval = security_task_setnice(current, nice);
3602        if (retval)
3603                return retval;
3604
3605        set_user_nice(current, nice);
3606        return 0;
3607}
3608
3609#endif
3610
3611/**
3612 * task_prio - return the priority value of a given task.
3613 * @p: the task in question.
3614 *
3615 * This is the priority value as seen by users in /proc.
3616 * RT tasks are offset by -200. Normal tasks are centered
3617 * around 0, value goes from -16 to +15.
3618 */
3619int task_prio(const struct task_struct *p)
3620{
3621        return p->prio - MAX_RT_PRIO;
3622}
3623
3624/**
3625 * task_nice - return the nice value of a given task.
3626 * @p: the task in question.
3627 */
3628int task_nice(const struct task_struct *p)
3629{
3630        return TASK_NICE(p);
3631}
3632EXPORT_SYMBOL(task_nice);
3633
3634/**
3635 * idle_cpu - is a given cpu idle currently?
3636 * @cpu: the processor in question.
3637 */
3638int idle_cpu(int cpu)
3639{
3640        struct rq *rq = cpu_rq(cpu);
3641
3642        if (rq->curr != rq->idle)
3643                return 0;
3644
3645        if (rq->nr_running)
3646                return 0;
3647
3648#ifdef CONFIG_SMP
3649        if (!llist_empty(&rq->wake_list))
3650                return 0;
3651#endif
3652
3653        return 1;
3654}
3655
3656/**
3657 * idle_task - return the idle task for a given cpu.
3658 * @cpu: the processor in question.
3659 */
3660struct task_struct *idle_task(int cpu)
3661{
3662        return cpu_rq(cpu)->idle;
3663}
3664
3665/**
3666 * find_process_by_pid - find a process with a matching PID value.
3667 * @pid: the pid in question.
3668 */
3669static struct task_struct *find_process_by_pid(pid_t pid)
3670{
3671        return pid ? find_task_by_vpid(pid) : current;
3672}
3673
3674/* Actually do priority change: must hold rq lock. */
3675static void
3676__setscheduler(struct rq *rq, struct task_struct *p, int policy, int prio)
3677{
3678        p->policy = policy;
3679        p->rt_priority = prio;
3680        p->normal_prio = normal_prio(p);
3681        /* we are holding p->pi_lock already */
3682        p->prio = rt_mutex_getprio(p);
3683        if (rt_prio(p->prio))
3684                p->sched_class = &rt_sched_class;
3685        else
3686                p->sched_class = &fair_sched_class;
3687        set_load_weight(p);
3688}
3689
3690/*
3691 * check the target process has a UID that matches the current process's
3692 */
3693static bool check_same_owner(struct task_struct *p)
3694{
3695        const struct cred *cred = current_cred(), *pcred;
3696        bool match;
3697
3698        rcu_read_lock();
3699        pcred = __task_cred(p);
3700        match = (uid_eq(cred->euid, pcred->euid) ||
3701                 uid_eq(cred->euid, pcred->uid));
3702        rcu_read_unlock();
3703        return match;
3704}
3705
3706static int __sched_setscheduler(struct task_struct *p, int policy,
3707                                const struct sched_param *param, bool user)
3708{
3709        int retval, oldprio, oldpolicy = -1, on_rq, running;
3710        unsigned long flags;
3711        const struct sched_class *prev_class;
3712        struct rq *rq;
3713        int reset_on_fork;
3714
3715        /* may grab non-irq protected spin_locks */
3716        BUG_ON(in_interrupt());
3717recheck:
3718        /* double check policy once rq lock held */
3719        if (policy < 0) {
3720                reset_on_fork = p->sched_reset_on_fork;
3721                policy = oldpolicy = p->policy;
3722        } else {
3723                reset_on_fork = !!(policy & SCHED_RESET_ON_FORK);
3724                policy &= ~SCHED_RESET_ON_FORK;
3725
3726                if (policy != SCHED_FIFO && policy != SCHED_RR &&
3727                                policy != SCHED_NORMAL && policy != SCHED_BATCH &&
3728                                policy != SCHED_IDLE)
3729                        return -EINVAL;
3730        }
3731
3732        /*
3733         * Valid priorities for SCHED_FIFO and SCHED_RR are
3734         * 1..MAX_USER_RT_PRIO-1, valid priority for SCHED_NORMAL,
3735         * SCHED_BATCH and SCHED_IDLE is 0.
3736         */
3737        if (param->sched_priority < 0 ||
3738            (p->mm && param->sched_priority > MAX_USER_RT_PRIO-1) ||
3739            (!p->mm && param->sched_priority > MAX_RT_PRIO-1))
3740                return -EINVAL;
3741        if (rt_policy(policy) != (param->sched_priority != 0))
3742                return -EINVAL;
3743
3744        /*
3745         * Allow unprivileged RT tasks to decrease priority:
3746         */
3747        if (user && !capable(CAP_SYS_NICE)) {
3748                if (rt_policy(policy)) {
3749                        unsigned long rlim_rtprio =
3750                                        task_rlimit(p, RLIMIT_RTPRIO);
3751
3752                        /* can't set/change the rt policy */
3753                        if (policy != p->policy && !rlim_rtprio)
3754                                return -EPERM;
3755
3756                        /* can't increase priority */
3757                        if (param->sched_priority > p->rt_priority &&
3758                            param->sched_priority > rlim_rtprio)
3759                                return -EPERM;
3760                }
3761
3762                /*
3763                 * Treat SCHED_IDLE as nice 20. Only allow a switch to
3764                 * SCHED_NORMAL if the RLIMIT_NICE would normally permit it.
3765                 */
3766                if (p->policy == SCHED_IDLE && policy != SCHED_IDLE) {
3767                        if (!can_nice(p, TASK_NICE(p)))
3768                                return -EPERM;
3769                }
3770
3771                /* can't change other user's priorities */
3772                if (!check_same_owner(p))
3773                        return -EPERM;
3774
3775                /* Normal users shall not reset the sched_reset_on_fork flag */
3776                if (p->sched_reset_on_fork && !reset_on_fork)
3777                        return -EPERM;
3778        }
3779
3780        if (user) {
3781                retval = security_task_setscheduler(p);
3782                if (retval)
3783                        return retval;
3784        }
3785
3786        /*
3787         * make sure no PI-waiters arrive (or leave) while we are
3788         * changing the priority of the task:
3789         *
3790         * To be able to change p->policy safely, the appropriate
3791         * runqueue lock must be held.
3792         */
3793        rq = task_rq_lock(p, &flags);
3794
3795        /*
3796         * Changing the policy of the stop threads its a very bad idea
3797         */
3798        if (p == rq->stop) {
3799                task_rq_unlock(rq, p, &flags);
3800                return -EINVAL;
3801        }
3802
3803        /*
3804         * If not changing anything there's no need to proceed further:
3805         */
3806        if (unlikely(policy == p->policy && (!rt_policy(policy) ||
3807                        param->sched_priority == p->rt_priority))) {
3808                task_rq_unlock(rq, p, &flags);
3809                return 0;
3810        }
3811
3812#ifdef CONFIG_RT_GROUP_SCHED
3813        if (user) {
3814                /*
3815                 * Do not allow realtime tasks into groups that have no runtime
3816                 * assigned.
3817                 */
3818                if (rt_bandwidth_enabled() && rt_policy(policy) &&
3819                                task_group(p)->rt_bandwidth.rt_runtime == 0 &&
3820                                !task_group_is_autogroup(task_group(p))) {
3821                        task_rq_unlock(rq, p, &flags);
3822                        return -EPERM;
3823                }
3824        }
3825#endif
3826
3827        /* recheck policy now with rq lock held */
3828        if (unlikely(oldpolicy != -1 && oldpolicy != p->policy)) {
3829                policy = oldpolicy = -1;
3830                task_rq_unlock(rq, p, &flags);
3831                goto recheck;
3832        }
3833        on_rq = p->on_rq;
3834        running = task_current(rq, p);
3835        if (on_rq)
3836                dequeue_task(rq, p, 0);
3837        if (running)
3838                p->sched_class->put_prev_task(rq, p);
3839
3840        p->sched_reset_on_fork = reset_on_fork;
3841
3842        oldprio = p->prio;
3843        prev_class = p->sched_class;
3844        __setscheduler(rq, p, policy, param->sched_priority);
3845
3846        if (running)
3847                p->sched_class->set_curr_task(rq);
3848        if (on_rq)
3849                enqueue_task(rq, p, 0);
3850
3851        check_class_changed(rq, p, prev_class, oldprio);
3852        task_rq_unlock(rq, p, &flags);
3853
3854        rt_mutex_adjust_pi(p);
3855
3856        return 0;
3857}
3858
3859/**
3860 * sched_setscheduler - change the scheduling policy and/or RT priority of a thread.
3861 * @p: the task in question.
3862 * @policy: new policy.
3863 * @param: structure containing the new RT priority.
3864 *
3865 * NOTE that the task may be already dead.
3866 */
3867int sched_setscheduler(struct task_struct *p, int policy,
3868                       const struct sched_param *param)
3869{
3870        return __sched_setscheduler(p, policy, param, true);
3871}
3872EXPORT_SYMBOL_GPL(sched_setscheduler);
3873
3874/**
3875 * sched_setscheduler_nocheck - change the scheduling policy and/or RT priority of a thread from kernelspace.
3876 * @p: the task in question.
3877 * @policy: new policy.
3878 * @param: structure containing the new RT priority.
3879 *
3880 * Just like sched_setscheduler, only don't bother checking if the
3881 * current context has permission.  For example, this is needed in
3882 * stop_machine(): we create temporary high priority worker threads,
3883 * but our caller might not have that capability.
3884 */
3885int sched_setscheduler_nocheck(struct task_struct *p, int policy,
3886                               const struct sched_param *param)
3887{
3888        return __sched_setscheduler(p, policy, param, false);
3889}
3890
3891static int
3892do_sched_setscheduler(pid_t pid, int policy, struct sched_param __user *param)
3893{
3894        struct sched_param lparam;
3895        struct task_struct *p;
3896        int retval;
3897
3898        if (!param || pid < 0)
3899                return -EINVAL;
3900        if (copy_from_user(&lparam, param, sizeof(struct sched_param)))
3901                return -EFAULT;
3902
3903        rcu_read_lock();
3904        retval = -ESRCH;
3905        p = find_process_by_pid(pid);
3906        if (p != NULL)
3907                retval = sched_setscheduler(p, policy, &lparam);
3908        rcu_read_unlock();
3909
3910        return retval;
3911}
3912
3913/**
3914 * sys_sched_setscheduler - set/change the scheduler policy and RT priority
3915 * @pid: the pid in question.
3916 * @policy: new policy.
3917 * @param: structure containing the new RT priority.
3918 */
3919SYSCALL_DEFINE3(sched_setscheduler, pid_t, pid, int, policy,
3920                struct sched_param __user *, param)
3921{
3922        /* negative values for policy are not valid */
3923        if (policy < 0)
3924                return -EINVAL;
3925
3926        return do_sched_setscheduler(pid, policy, param);
3927}
3928
3929/**
3930 * sys_sched_setparam - set/change the RT priority of a thread
3931 * @pid: the pid in question.
3932 * @param: structure containing the new RT priority.
3933 */
3934SYSCALL_DEFINE2(sched_setparam, pid_t, pid, struct sched_param __user *, param)
3935{
3936        return do_sched_setscheduler(pid, -1, param);
3937}
3938
3939/**
3940 * sys_sched_getscheduler - get the policy (scheduling class) of a thread
3941 * @pid: the pid in question.
3942 */
3943SYSCALL_DEFINE1(sched_getscheduler, pid_t, pid)
3944{
3945        struct task_struct *p;
3946        int retval;
3947
3948        if (pid < 0)
3949                return -EINVAL;
3950
3951        retval = -ESRCH;
3952        rcu_read_lock();
3953        p = find_process_by_pid(pid);
3954        if (p) {
3955                retval = security_task_getscheduler(p);
3956                if (!retval)
3957                        retval = p->policy
3958                                | (p->sched_reset_on_fork ? SCHED_RESET_ON_FORK : 0);
3959        }
3960        rcu_read_unlock();
3961        return retval;
3962}
3963
3964/**
3965 * sys_sched_getparam - get the RT priority of a thread
3966 * @pid: the pid in question.
3967 * @param: structure containing the RT priority.
3968 */
3969SYSCALL_DEFINE2(sched_getparam, pid_t, pid, struct sched_param __user *, param)
3970{
3971        struct sched_param lp;
3972        struct task_struct *p;
3973        int retval;
3974
3975        if (!param || pid < 0)
3976                return -EINVAL;
3977
3978        rcu_read_lock();
3979        p = find_process_by_pid(pid);
3980        retval = -ESRCH;
3981        if (!p)
3982                goto out_unlock;
3983
3984        retval = security_task_getscheduler(p);
3985        if (retval)
3986                goto out_unlock;
3987
3988        lp.sched_priority = p->rt_priority;
3989        rcu_read_unlock();
3990
3991        /*
3992         * This one might sleep, we cannot do it with a spinlock held ...
3993         */
3994        retval = copy_to_user(param, &lp, sizeof(*param)) ? -EFAULT : 0;
3995
3996        return retval;
3997
3998out_unlock:
3999        rcu_read_unlock();
4000        return retval;
4001}
4002
4003long sched_setaffinity(pid_t pid, const struct cpumask *in_mask)
4004{
4005        cpumask_var_t cpus_allowed, new_mask;
4006        struct task_struct *p;
4007        int retval;
4008
4009        get_online_cpus();
4010        rcu_read_lock();
4011
4012        p = find_process_by_pid(pid);
4013        if (!p) {
4014                rcu_read_unlock();
4015                put_online_cpus();
4016                return -ESRCH;
4017        }
4018
4019        /* Prevent p going away */
4020        get_task_struct(p);
4021        rcu_read_unlock();
4022
4023        if (!alloc_cpumask_var(&cpus_allowed, GFP_KERNEL)) {
4024                retval = -ENOMEM;
4025                goto out_put_task;
4026        }
4027        if (!alloc_cpumask_var(&new_mask, GFP_KERNEL)) {
4028                retval = -ENOMEM;
4029                goto out_free_cpus_allowed;
4030        }
4031        retval = -EPERM;
4032        if (!check_same_owner(p) && !ns_capable(task_user_ns(p), CAP_SYS_NICE))
4033                goto out_unlock;
4034
4035        retval = security_task_setscheduler(p);
4036        if (retval)
4037                goto out_unlock;
4038
4039        cpuset_cpus_allowed(p, cpus_allowed);
4040        cpumask_and(new_mask, in_mask, cpus_allowed);
4041again:
4042        retval = set_cpus_allowed_ptr(p, new_mask);
4043
4044        if (!retval) {
4045                cpuset_cpus_allowed(p, cpus_allowed);
4046                if (!cpumask_subset(new_mask, cpus_allowed)) {
4047                        /*
4048                         * We must have raced with a concurrent cpuset
4049                         * update. Just reset the cpus_allowed to the
4050                         * cpuset's cpus_allowed
4051                         */
4052                        cpumask_copy(new_mask, cpus_allowed);
4053                        goto again;
4054                }
4055        }
4056out_unlock:
4057        free_cpumask_var(new_mask);
4058out_free_cpus_allowed:
4059        free_cpumask_var(cpus_allowed);
4060out_put_task:
4061        put_task_struct(p);
4062        put_online_cpus();
4063        return retval;
4064}
4065
4066static int get_user_cpu_mask(unsigned long __user *user_mask_ptr, unsigned len,
4067                             struct cpumask *new_mask)
4068{
4069        if (len < cpumask_size())
4070                cpumask_clear(new_mask);
4071        else if (len > cpumask_size())
4072                len = cpumask_size();
4073
4074        return copy_from_user(new_mask, user_mask_ptr, len) ? -EFAULT : 0;
4075}
4076
4077/**
4078 * sys_sched_setaffinity - set the cpu affinity of a process
4079 * @pid: pid of the process
4080 * @len: length in bytes of the bitmask pointed to by user_mask_ptr
4081 * @user_mask_ptr: user-space pointer to the new cpu mask
4082 */
4083SYSCALL_DEFINE3(sched_setaffinity, pid_t, pid, unsigned int, len,
4084                unsigned long __user *, user_mask_ptr)
4085{
4086        cpumask_var_t new_mask;
4087        int retval;
4088
4089        if (!alloc_cpumask_var(&new_mask, GFP_KERNEL))
4090                return -ENOMEM;
4091
4092        retval = get_user_cpu_mask(user_mask_ptr, len, new_mask);
4093        if (retval == 0)
4094                retval = sched_setaffinity(pid, new_mask);
4095        free_cpumask_var(new_mask);
4096        return retval;
4097}
4098
4099long sched_getaffinity(pid_t pid, struct cpumask *mask)
4100{
4101        struct task_struct *p;
4102        unsigned long flags;
4103        int retval;
4104
4105        get_online_cpus();
4106        rcu_read_lock();
4107
4108        retval = -ESRCH;
4109        p = find_process_by_pid(pid);
4110        if (!p)
4111                goto out_unlock;
4112
4113        retval = security_task_getscheduler(p);
4114        if (retval)
4115                goto out_unlock;
4116
4117        raw_spin_lock_irqsave(&p->pi_lock, flags);
4118        cpumask_and(mask, &p->cpus_allowed, cpu_online_mask);
4119        raw_spin_unlock_irqrestore(&p->pi_lock, flags);
4120
4121out_unlock:
4122        rcu_read_unlock();
4123        put_online_cpus();
4124
4125        return retval;
4126}
4127
4128/**
4129 * sys_sched_getaffinity - get the cpu affinity of a process
4130 * @pid: pid of the process
4131 * @len: length in bytes of the bitmask pointed to by user_mask_ptr
4132 * @user_mask_ptr: user-space pointer to hold the current cpu mask
4133 */
4134SYSCALL_DEFINE3(sched_getaffinity, pid_t, pid, unsigned int, len,
4135                unsigned long __user *, user_mask_ptr)
4136{
4137        int ret;
4138        cpumask_var_t mask;
4139
4140        if ((len * BITS_PER_BYTE) < nr_cpu_ids)
4141                return -EINVAL;
4142        if (len & (sizeof(unsigned long)-1))
4143                return -EINVAL;
4144
4145        if (!alloc_cpumask_var(&mask, GFP_KERNEL))
4146                return -ENOMEM;
4147
4148        ret = sched_getaffinity(pid, mask);
4149        if (ret == 0) {
4150                size_t retlen = min_t(size_t, len, cpumask_size());
4151
4152                if (copy_to_user(user_mask_ptr, mask, retlen))
4153                        ret = -EFAULT;
4154                else
4155                        ret = retlen;
4156        }
4157        free_cpumask_var(mask);
4158
4159        return ret;
4160}
4161
4162/**
4163 * sys_sched_yield - yield the current processor to other threads.
4164 *
4165 * This function yields the current CPU to other tasks. If there are no
4166 * other threads running on this CPU then this function will return.
4167 */
4168SYSCALL_DEFINE0(sched_yield)
4169{
4170        struct rq *rq = this_rq_lock();
4171
4172        schedstat_inc(rq, yld_count);
4173        current->sched_class->yield_task(rq);
4174
4175        /*
4176         * Since we are going to call schedule() anyway, there's
4177         * no need to preempt or enable interrupts:
4178         */
4179        __release(rq->lock);
4180        spin_release(&rq->lock.dep_map, 1, _THIS_IP_);
4181        do_raw_spin_unlock(&rq->lock);
4182        sched_preempt_enable_no_resched();
4183
4184        schedule();
4185
4186        return 0;
4187}
4188
4189static inline int should_resched(void)
4190{
4191        return need_resched() && !(preempt_count() & PREEMPT_ACTIVE);
4192}
4193
4194static void __cond_resched(void)
4195{
4196        add_preempt_count(PREEMPT_ACTIVE);
4197        __schedule();
4198        sub_preempt_count(PREEMPT_ACTIVE);
4199}
4200
4201int __sched _cond_resched(void)
4202{
4203        if (should_resched()) {
4204                __cond_resched();
4205                return 1;
4206        }
4207        return 0;
4208}
4209EXPORT_SYMBOL(_cond_resched);
4210
4211/*
4212 * __cond_resched_lock() - if a reschedule is pending, drop the given lock,
4213 * call schedule, and on return reacquire the lock.
4214 *
4215 * This works OK both with and without CONFIG_PREEMPT. We do strange low-level
4216 * operations here to prevent schedule() from being called twice (once via
4217 * spin_unlock(), once by hand).
4218 */
4219int __cond_resched_lock(spinlock_t *lock)
4220{
4221        int resched = should_resched();
4222        int ret = 0;
4223
4224        lockdep_assert_held(lock);
4225
4226        if (spin_needbreak(lock) || resched) {
4227                spin_unlock(lock);
4228                if (resched)
4229                        __cond_resched();
4230                else
4231                        cpu_relax();
4232                ret = 1;
4233                spin_lock(lock);
4234        }
4235        return ret;
4236}
4237EXPORT_SYMBOL(__cond_resched_lock);
4238
4239int __sched __cond_resched_softirq(void)
4240{
4241        BUG_ON(!in_softirq());
4242
4243        if (should_resched()) {
4244                local_bh_enable();
4245                __cond_resched();
4246                local_bh_disable();
4247                return 1;
4248        }
4249        return 0;
4250}
4251EXPORT_SYMBOL(__cond_resched_softirq);
4252
4253/**
4254 * yield - yield the current processor to other threads.
4255 *
4256 * Do not ever use this function, there's a 99% chance you're doing it wrong.
4257 *
4258 * The scheduler is at all times free to pick the calling task as the most
4259 * eligible task to run, if removing the yield() call from your code breaks
4260 * it, its already broken.
4261 *
4262 * Typical broken usage is:
4263 *
4264 * while (!event)
4265 *      yield();
4266 *
4267 * where one assumes that yield() will let 'the other' process run that will
4268 * make event true. If the current task is a SCHED_FIFO task that will never
4269 * happen. Never use yield() as a progress guarantee!!
4270 *
4271 * If you want to use yield() to wait for something, use wait_event().
4272 * If you want to use yield() to be 'nice' for others, use cond_resched().
4273 * If you still want to use yield(), do not!
4274 */
4275void __sched yield(void)
4276{
4277        set_current_state(TASK_RUNNING);
4278        sys_sched_yield();
4279}
4280EXPORT_SYMBOL(yield);
4281
4282/**
4283 * yield_to - yield the current processor to another thread in
4284 * your thread group, or accelerate that thread toward the
4285 * processor it's on.
4286 * @p: target task
4287 * @preempt: whether task preemption is allowed or not
4288 *
4289 * It's the caller's job to ensure that the target task struct
4290 * can't go away on us before we can do any checks.
4291 *
4292 * Returns true if we indeed boosted the target task.
4293 */
4294bool __sched yield_to(struct task_struct *p, bool preempt)
4295{
4296        struct task_struct *curr = current;
4297        struct rq *rq, *p_rq;
4298        unsigned long flags;
4299        bool yielded = 0;
4300
4301        local_irq_save(flags);
4302        rq = this_rq();
4303
4304again:
4305        p_rq = task_rq(p);
4306        double_rq_lock(rq, p_rq);
4307        while (task_rq(p) != p_rq) {
4308                double_rq_unlock(rq, p_rq);
4309                goto again;
4310        }
4311
4312        if (!curr->sched_class->yield_to_task)
4313                goto out;
4314
4315        if (curr->sched_class != p->sched_class)
4316                goto out;
4317
4318        if (task_running(p_rq, p) || p->state)
4319                goto out;
4320
4321        yielded = curr->sched_class->yield_to_task(rq, p, preempt);
4322        if (yielded) {
4323                schedstat_inc(rq, yld_count);
4324                /*
4325                 * Make p's CPU reschedule; pick_next_entity takes care of
4326                 * fairness.
4327                 */
4328                if (preempt && rq != p_rq)
4329                        resched_task(p_rq->curr);
4330        }
4331
4332out:
4333        double_rq_unlock(rq, p_rq);
4334        local_irq_restore(flags);
4335
4336        if (yielded)
4337                schedule();
4338
4339        return yielded;
4340}
4341EXPORT_SYMBOL_GPL(yield_to);
4342
4343/*
4344 * This task is about to go to sleep on IO. Increment rq->nr_iowait so
4345 * that process accounting knows that this is a task in IO wait state.
4346 */
4347void __sched io_schedule(void)
4348{
4349        struct rq *rq = raw_rq();
4350
4351        delayacct_blkio_start();
4352        atomic_inc(&rq->nr_iowait);
4353        blk_flush_plug(current);
4354        current->in_iowait = 1;
4355        schedule();
4356        current->in_iowait = 0;
4357        atomic_dec(&rq->nr_iowait);
4358        delayacct_blkio_end();
4359}
4360EXPORT_SYMBOL(io_schedule);
4361
4362long __sched io_schedule_timeout(long timeout)
4363{
4364        struct rq *rq = raw_rq();
4365        long ret;
4366
4367        delayacct_blkio_start();
4368        atomic_inc(&rq->nr_iowait);
4369        blk_flush_plug(current);
4370        current->in_iowait = 1;
4371        ret = schedule_timeout(timeout);
4372        current->in_iowait = 0;
4373        atomic_dec(&rq->nr_iowait);
4374        delayacct_blkio_end();
4375        return ret;
4376}
4377
4378/**
4379 * sys_sched_get_priority_max - return maximum RT priority.
4380 * @policy: scheduling class.
4381 *
4382 * this syscall returns the maximum rt_priority that can be used
4383 * by a given scheduling class.
4384 */
4385SYSCALL_DEFINE1(sched_get_priority_max, int, policy)
4386{
4387        int ret = -EINVAL;
4388
4389        switch (policy) {
4390        case SCHED_FIFO:
4391        case SCHED_RR:
4392                ret = MAX_USER_RT_PRIO-1;
4393                break;
4394        case SCHED_NORMAL:
4395        case SCHED_BATCH:
4396        case SCHED_IDLE:
4397                ret = 0;
4398                break;
4399        }
4400        return ret;
4401}
4402
4403/**
4404 * sys_sched_get_priority_min - return minimum RT priority.
4405 * @policy: scheduling class.
4406 *
4407 * this syscall returns the minimum rt_priority that can be used
4408 * by a given scheduling class.
4409 */
4410SYSCALL_DEFINE1(sched_get_priority_min, int, policy)
4411{
4412        int ret = -EINVAL;
4413
4414        switch (policy) {
4415        case SCHED_FIFO:
4416        case SCHED_RR:
4417                ret = 1;
4418                break;
4419        case SCHED_NORMAL:
4420        case SCHED_BATCH:
4421        case SCHED_IDLE:
4422                ret = 0;
4423        }
4424        return ret;
4425}
4426
4427/**
4428 * sys_sched_rr_get_interval - return the default timeslice of a process.
4429 * @pid: pid of the process.
4430 * @interval: userspace pointer to the timeslice value.
4431 *
4432 * this syscall writes the default timeslice value of a given process
4433 * into the user-space timespec buffer. A value of '0' means infinity.
4434 */
4435SYSCALL_DEFINE2(sched_rr_get_interval, pid_t, pid,
4436                struct timespec __user *, interval)
4437{
4438        struct task_struct *p;
4439        unsigned int time_slice;
4440        unsigned long flags;
4441        struct rq *rq;
4442        int retval;
4443        struct timespec t;
4444
4445        if (pid < 0)
4446                return -EINVAL;
4447
4448        retval = -ESRCH;
4449        rcu_read_lock();
4450        p = find_process_by_pid(pid);
4451        if (!p)
4452                goto out_unlock;
4453
4454        retval = security_task_getscheduler(p);
4455        if (retval)
4456                goto out_unlock;
4457
4458        rq = task_rq_lock(p, &flags);
4459        time_slice = p->sched_class->get_rr_interval(rq, p);
4460        task_rq_unlock(rq, p, &flags);
4461
4462        rcu_read_unlock();
4463        jiffies_to_timespec(time_slice, &t);
4464        retval = copy_to_user(interval, &t, sizeof(t)) ? -EFAULT : 0;
4465        return retval;
4466
4467out_unlock:
4468        rcu_read_unlock();
4469        return retval;
4470}
4471
4472static const char stat_nam[] = TASK_STATE_TO_CHAR_STR;
4473
4474void sched_show_task(struct task_struct *p)
4475{
4476        unsigned long free = 0;
4477        unsigned state;
4478
4479        state = p->state ? __ffs(p->state) + 1 : 0;
4480        printk(KERN_INFO "%-15.15s %c", p->comm,
4481                state < sizeof(stat_nam) - 1 ? stat_nam[state] : '?');
4482#if BITS_PER_LONG == 32
4483        if (state == TASK_RUNNING)
4484                printk(KERN_CONT " running  ");
4485        else
4486                printk(KERN_CONT " %08lx ", thread_saved_pc(p));
4487#else
4488        if (state == TASK_RUNNING)
4489                printk(KERN_CONT "  running task    ");
4490        else
4491                printk(KERN_CONT " %016lx ", thread_saved_pc(p));
4492#endif
4493#ifdef CONFIG_DEBUG_STACK_USAGE
4494        free = stack_not_used(p);
4495#endif
4496        printk(KERN_CONT "%5lu %5d %6d 0x%08lx\n", free,
4497                task_pid_nr(p), task_pid_nr(rcu_dereference(p->real_parent)),
4498                (unsigned long)task_thread_info(p)->flags);
4499
4500        show_stack(p, NULL);
4501}
4502
4503void show_state_filter(unsigned long state_filter)
4504{
4505        struct task_struct *g, *p;
4506
4507#if BITS_PER_LONG == 32
4508        printk(KERN_INFO
4509                "  task                PC stack   pid father\n");
4510#else
4511        printk(KERN_INFO
4512                "  task                        PC stack   pid father\n");
4513#endif
4514        rcu_read_lock();
4515        do_each_thread(g, p) {
4516                /*
4517                 * reset the NMI-timeout, listing all files on a slow
4518                 * console might take a lot of time:
4519                 */
4520                touch_nmi_watchdog();
4521                if (!state_filter || (p->state & state_filter))
4522                        sched_show_task(p);
4523        } while_each_thread(g, p);
4524
4525        touch_all_softlockup_watchdogs();
4526
4527#ifdef CONFIG_SCHED_DEBUG
4528        sysrq_sched_debug_show();
4529#endif
4530        rcu_read_unlock();
4531        /*
4532         * Only show locks if all tasks are dumped:
4533         */
4534        if (!state_filter)
4535                debug_show_all_locks();
4536}
4537
4538void __cpuinit init_idle_bootup_task(struct task_struct *idle)
4539{
4540        idle->sched_class = &idle_sched_class;
4541}
4542
4543/**
4544 * init_idle - set up an idle thread for a given CPU
4545 * @idle: task in question
4546 * @cpu: cpu the idle task belongs to
4547 *
4548 * NOTE: this function does not set the idle thread's NEED_RESCHED
4549 * flag, to make booting more robust.
4550 */
4551void __cpuinit init_idle(struct task_struct *idle, int cpu)
4552{
4553        struct rq *rq = cpu_rq(cpu);
4554        unsigned long flags;
4555
4556        raw_spin_lock_irqsave(&rq->lock, flags);
4557
4558        __sched_fork(idle);
4559        idle->state = TASK_RUNNING;
4560        idle->se.exec_start = sched_clock();
4561
4562        do_set_cpus_allowed(idle, cpumask_of(cpu));
4563        /*
4564         * We're having a chicken and egg problem, even though we are
4565         * holding rq->lock, the cpu isn't yet set to this cpu so the
4566         * lockdep check in task_group() will fail.
4567         *
4568         * Similar case to sched_fork(). / Alternatively we could
4569         * use task_rq_lock() here and obtain the other rq->lock.
4570         *
4571         * Silence PROVE_RCU
4572         */
4573        rcu_read_lock();
4574        __set_task_cpu(idle, cpu);
4575        rcu_read_unlock();
4576
4577        rq->curr = rq->idle = idle;
4578#if defined(CONFIG_SMP)
4579        idle->on_cpu = 1;
4580#endif
4581        raw_spin_unlock_irqrestore(&rq->lock, flags);
4582
4583        /* Set the preempt count _outside_ the spinlocks! */
4584        task_thread_info(idle)->preempt_count = 0;
4585
4586        /*
4587         * The idle tasks have their own, simple scheduling class:
4588         */
4589        idle->sched_class = &idle_sched_class;
4590        ftrace_graph_init_idle_task(idle, cpu);
4591#if defined(CONFIG_SMP)
4592        sprintf(idle->comm, "%s/%d", INIT_TASK_COMM, cpu);
4593#endif
4594}
4595
4596#ifdef CONFIG_SMP
4597void do_set_cpus_allowed(struct task_struct *p, const struct cpumask *new_mask)
4598{
4599        if (p->sched_class && p->sched_class->set_cpus_allowed)
4600                p->sched_class->set_cpus_allowed(p, new_mask);
4601
4602        cpumask_copy(&p->cpus_allowed, new_mask);
4603        p->nr_cpus_allowed = cpumask_weight(new_mask);
4604}
4605
4606/*
4607 * This is how migration works:
4608 *
4609 * 1) we invoke migration_cpu_stop() on the target CPU using
4610 *    stop_one_cpu().
4611 * 2) stopper starts to run (implicitly forcing the migrated thread
4612 *    off the CPU)
4613 * 3) it checks whether the migrated task is still in the wrong runqueue.
4614 * 4) if it's in the wrong runqueue then the migration thread removes
4615 *    it and puts it into the right queue.
4616 * 5) stopper completes and stop_one_cpu() returns and the migration
4617 *    is done.
4618 */
4619
4620/*
4621 * Change a given task's CPU affinity. Migrate the thread to a
4622 * proper CPU and schedule it away if the CPU it's executing on
4623 * is removed from the allowed bitmask.
4624 *
4625 * NOTE: the caller must have a valid reference to the task, the
4626 * task must not exit() & deallocate itself prematurely. The
4627 * call is not atomic; no spinlocks may be held.
4628 */
4629int set_cpus_allowed_ptr(struct task_struct *p, const struct cpumask *new_mask)
4630{
4631        unsigned long flags;
4632        struct rq *rq;
4633        unsigned int dest_cpu;
4634        int ret = 0;
4635
4636        rq = task_rq_lock(p, &flags);
4637
4638        if (cpumask_equal(&p->cpus_allowed, new_mask))
4639                goto out;
4640
4641        if (!cpumask_intersects(new_mask, cpu_active_mask)) {
4642                ret = -EINVAL;
4643                goto out;
4644        }
4645
4646        if (unlikely((p->flags & PF_THREAD_BOUND) && p != current)) {
4647                ret = -EINVAL;
4648                goto out;
4649        }
4650
4651        do_set_cpus_allowed(p, new_mask);
4652
4653        /* Can the task run on the task's current CPU? If so, we're done */
4654        if (cpumask_test_cpu(task_cpu(p), new_mask))
4655                goto out;
4656
4657        dest_cpu = cpumask_any_and(cpu_active_mask, new_mask);
4658        if (p->on_rq) {
4659                struct migration_arg arg = { p, dest_cpu };
4660                /* Need help from migration thread: drop lock and wait. */
4661                task_rq_unlock(rq, p, &flags);
4662                stop_one_cpu(cpu_of(rq), migration_cpu_stop, &arg);
4663                tlb_migrate_finish(p->mm);
4664                return 0;
4665        }
4666out:
4667        task_rq_unlock(rq, p, &flags);
4668
4669        return ret;
4670}
4671EXPORT_SYMBOL_GPL(set_cpus_allowed_ptr);
4672
4673/*
4674 * Move (not current) task off this cpu, onto dest cpu. We're doing
4675 * this because either it can't run here any more (set_cpus_allowed()
4676 * away from this CPU, or CPU going down), or because we're
4677 * attempting to rebalance this task on exec (sched_exec).
4678 *
4679 * So we race with normal scheduler movements, but that's OK, as long
4680 * as the task is no longer on this CPU.
4681 *
4682 * Returns non-zero if task was successfully migrated.
4683 */
4684static int __migrate_task(struct task_struct *p, int src_cpu, int dest_cpu)
4685{
4686        struct rq *rq_dest, *rq_src;
4687        int ret = 0;
4688
4689        if (unlikely(!cpu_active(dest_cpu)))
4690                return ret;
4691
4692        rq_src = cpu_rq(src_cpu);
4693        rq_dest = cpu_rq(dest_cpu);
4694
4695        raw_spin_lock(&p->pi_lock);
4696        double_rq_lock(rq_src, rq_dest);
4697        /* Already moved. */
4698        if (task_cpu(p) != src_cpu)
4699                goto done;
4700        /* Affinity changed (again). */
4701        if (!cpumask_test_cpu(dest_cpu, tsk_cpus_allowed(p)))
4702                goto fail;
4703
4704        /*
4705         * If we're not on a rq, the next wake-up will ensure we're
4706         * placed properly.
4707         */
4708        if (p->on_rq) {
4709                dequeue_task(rq_src, p, 0);
4710                set_task_cpu(p, dest_cpu);
4711                enqueue_task(rq_dest, p, 0);
4712                check_preempt_curr(rq_dest, p, 0);
4713        }
4714done:
4715        ret = 1;
4716fail:
4717        double_rq_unlock(rq_src, rq_dest);
4718        raw_spin_unlock(&p->pi_lock);
4719        return ret;
4720}
4721
4722/*
4723 * migration_cpu_stop - this will be executed by a highprio stopper thread
4724 * and performs thread migration by bumping thread off CPU then
4725 * 'pushing' onto another runqueue.
4726 */
4727static int migration_cpu_stop(void *data)
4728{
4729        struct migration_arg *arg = data;
4730
4731        /*
4732         * The original target cpu might have gone down and we might
4733         * be on another cpu but it doesn't matter.
4734         */
4735        local_irq_disable();
4736        __migrate_task(arg->task, raw_smp_processor_id(), arg->dest_cpu);
4737        local_irq_enable();
4738        return 0;
4739}
4740
4741#ifdef CONFIG_HOTPLUG_CPU
4742
4743/*
4744 * Ensures that the idle task is using init_mm right before its cpu goes
4745 * offline.
4746 */
4747void idle_task_exit(void)
4748{
4749        struct mm_struct *mm = current->active_mm;
4750
4751        BUG_ON(cpu_online(smp_processor_id()));
4752
4753        if (mm != &init_mm)
4754                switch_mm(mm, &init_mm, current);
4755        mmdrop(mm);
4756}
4757
4758/*
4759 * Since this CPU is going 'away' for a while, fold any nr_active delta
4760 * we might have. Assumes we're called after migrate_tasks() so that the
4761 * nr_active count is stable.
4762 *
4763 * Also see the comment "Global load-average calculations".
4764 */
4765static void calc_load_migrate(struct rq *rq)
4766{
4767        long delta = calc_load_fold_active(rq);
4768        if (delta)
4769                atomic_long_add(delta, &calc_load_tasks);
4770}
4771
4772/*
4773 * Migrate all tasks from the rq, sleeping tasks will be migrated by
4774 * try_to_wake_up()->select_task_rq().
4775 *
4776 * Called with rq->lock held even though we'er in stop_machine() and
4777 * there's no concurrency possible, we hold the required locks anyway
4778 * because of lock validation efforts.
4779 */
4780static void migrate_tasks(unsigned int dead_cpu)
4781{
4782        struct rq *rq = cpu_rq(dead_cpu);
4783        struct task_struct *next, *stop = rq->stop;
4784        int dest_cpu;
4785
4786        /*
4787         * Fudge the rq selection such that the below task selection loop
4788         * doesn't get stuck on the currently eligible stop task.
4789         *
4790         * We're currently inside stop_machine() and the rq is either stuck
4791         * in the stop_machine_cpu_stop() loop, or we're executing this code,
4792         * either way we should never end up calling schedule() until we're
4793         * done here.
4794         */
4795        rq->stop = NULL;
4796
4797        for ( ; ; ) {
4798                /*
4799                 * There's this thread running, bail when that's the only
4800                 * remaining thread.
4801                 */
4802                if (rq->nr_running == 1)
4803                        break;
4804
4805                next = pick_next_task(rq);
4806                BUG_ON(!next);
4807                next->sched_class->put_prev_task(rq, next);
4808
4809                /* Find suitable destination for @next, with force if needed. */
4810                dest_cpu = select_fallback_rq(dead_cpu, next);
4811                raw_spin_unlock(&rq->lock);
4812
4813                __migrate_task(next, dead_cpu, dest_cpu);
4814
4815                raw_spin_lock(&rq->lock);
4816        }
4817
4818        rq->stop = stop;
4819}
4820
4821#endif /* CONFIG_HOTPLUG_CPU */
4822
4823#if defined(CONFIG_SCHED_DEBUG) && defined(CONFIG_SYSCTL)
4824
4825static struct ctl_table sd_ctl_dir[] = {
4826        {
4827                .procname       = "sched_domain",
4828                .mode           = 0555,
4829        },
4830        {}
4831};
4832
4833static struct ctl_table sd_ctl_root[] = {
4834        {
4835                .procname       = "kernel",
4836                .mode           = 0555,
4837                .child          = sd_ctl_dir,
4838        },
4839        {}
4840};
4841
4842static struct ctl_table *sd_alloc_ctl_entry(int n)
4843{
4844        struct ctl_table *entry =
4845                kcalloc(n, sizeof(struct ctl_table), GFP_KERNEL);
4846
4847        return entry;
4848}
4849
4850static void sd_free_ctl_entry(struct ctl_table **tablep)
4851{
4852        struct ctl_table *entry;
4853
4854        /*
4855         * In the intermediate directories, both the child directory and
4856         * procname are dynamically allocated and could fail but the mode
4857         * will always be set. In the lowest directory the names are
4858         * static strings and all have proc handlers.
4859         */
4860        for (entry = *tablep; entry->mode; entry++) {
4861                if (entry->child)
4862                        sd_free_ctl_entry(&entry->child);
4863                if (entry->proc_handler == NULL)
4864                        kfree(entry->procname);
4865        }
4866
4867        kfree(*tablep);
4868        *tablep = NULL;
4869}
4870
4871static int min_load_idx = 0;
4872static int max_load_idx = CPU_LOAD_IDX_MAX;
4873
4874static void
4875set_table_entry(struct ctl_table *entry,
4876                const char *procname, void *data, int maxlen,
4877                umode_t mode, proc_handler *proc_handler,
4878                bool load_idx)
4879{
4880        entry->procname = procname;
4881        entry->data = data;
4882        entry->maxlen = maxlen;
4883        entry->mode = mode;
4884        entry->proc_handler = proc_handler;
4885
4886        if (load_idx) {
4887                entry->extra1 = &min_load_idx;
4888                entry->extra2 = &max_load_idx;
4889        }
4890}
4891
4892static struct ctl_table *
4893sd_alloc_ctl_domain_table(struct sched_domain *sd)
4894{
4895        struct ctl_table *table = sd_alloc_ctl_entry(13);
4896
4897        if (table == NULL)
4898                return NULL;
4899
4900        set_table_entry(&table[0], "min_interval", &sd->min_interval,
4901                sizeof(long), 0644, proc_doulongvec_minmax, false);
4902        set_table_entry(&table[1], "max_interval", &sd->max_interval,
4903                sizeof(long), 0644, proc_doulongvec_minmax, false);
4904        set_table_entry(&table[2], "busy_idx", &sd->busy_idx,
4905                sizeof(int), 0644, proc_dointvec_minmax, true);
4906        set_table_entry(&table[3], "idle_idx", &sd->idle_idx,
4907                sizeof(int), 0644, proc_dointvec_minmax, true);
4908        set_table_entry(&table[4], "newidle_idx", &sd->newidle_idx,
4909                sizeof(int), 0644, proc_dointvec_minmax, true);
4910        set_table_entry(&table[5], "wake_idx", &sd->wake_idx,
4911                sizeof(int), 0644, proc_dointvec_minmax, true);
4912        set_table_entry(&table[6], "forkexec_idx", &sd->forkexec_idx,
4913                sizeof(int), 0644, proc_dointvec_minmax, true);
4914        set_table_entry(&table[7], "busy_factor", &sd->busy_factor,
4915                sizeof(int), 0644, proc_dointvec_minmax, false);
4916        set_table_entry(&table[8], "imbalance_pct", &sd->imbalance_pct,
4917                sizeof(int), 0644, proc_dointvec_minmax, false);
4918        set_table_entry(&table[9], "cache_nice_tries",
4919                &sd->cache_nice_tries,
4920                sizeof(int), 0644, proc_dointvec_minmax, false);
4921        set_table_entry(&table[10], "flags", &sd->flags,
4922                sizeof(int), 0644, proc_dointvec_minmax, false);
4923        set_table_entry(&table[11], "name", sd->name,
4924                CORENAME_MAX_SIZE, 0444, proc_dostring, false);
4925        /* &table[12] is terminator */
4926
4927        return table;
4928}
4929
4930static ctl_table *sd_alloc_ctl_cpu_table(int cpu)
4931{
4932        struct ctl_table *entry, *table;
4933        struct sched_domain *sd;
4934        int domain_num = 0, i;
4935        char buf[32];
4936
4937        for_each_domain(cpu, sd)
4938                domain_num++;
4939        entry = table = sd_alloc_ctl_entry(domain_num + 1);
4940        if (table == NULL)
4941                return NULL;
4942
4943        i = 0;
4944        for_each_domain(cpu, sd) {
4945                snprintf(buf, 32, "domain%d", i);
4946                entry->procname = kstrdup(buf, GFP_KERNEL);
4947                entry->mode = 0555;
4948                entry->child = sd_alloc_ctl_domain_table(sd);
4949                entry++;
4950                i++;
4951        }
4952        return table;
4953}
4954
4955static struct ctl_table_header *sd_sysctl_header;
4956static void register_sched_domain_sysctl(void)
4957{
4958        int i, cpu_num = num_possible_cpus();
4959        struct ctl_table *entry = sd_alloc_ctl_entry(cpu_num + 1);
4960        char buf[32];
4961
4962        WARN_ON(sd_ctl_dir[0].child);
4963        sd_ctl_dir[0].child = entry;
4964
4965        if (entry == NULL)
4966                return;
4967
4968        for_each_possible_cpu(i) {
4969                snprintf(buf, 32, "cpu%d", i);
4970                entry->procname = kstrdup(buf, GFP_KERNEL);
4971                entry->mode = 0555;
4972                entry->child = sd_alloc_ctl_cpu_table(i);
4973                entry++;
4974        }
4975
4976        WARN_ON(sd_sysctl_header);
4977        sd_sysctl_header = register_sysctl_table(sd_ctl_root);
4978}
4979
4980/* may be called multiple times per register */
4981static void unregister_sched_domain_sysctl(void)
4982{
4983        if (sd_sysctl_header)
4984                unregister_sysctl_table(sd_sysctl_header);
4985        sd_sysctl_header = NULL;
4986        if (sd_ctl_dir[0].child)
4987                sd_free_ctl_entry(&sd_ctl_dir[0].child);
4988}
4989#else
4990static void register_sched_domain_sysctl(void)
4991{
4992}
4993static void unregister_sched_domain_sysctl(void)
4994{
4995}
4996#endif
4997
4998static void set_rq_online(struct rq *rq)
4999{
5000        if (!rq->online) {
5001                const struct sched_class *class;
5002
5003                cpumask_set_cpu(rq->cpu, rq->rd->online);
5004                rq->online = 1;
5005
5006                for_each_class(class) {
5007                        if (class->rq_online)
5008                                class->rq_online(rq);
5009                }
5010        }
5011}
5012
5013static void set_rq_offline(struct rq *rq)
5014{
5015        if (rq->online) {
5016                const struct sched_class *class;
5017
5018                for_each_class(class) {
5019                        if (class->rq_offline)
5020                                class->rq_offline(rq);
5021                }
5022
5023                cpumask_clear_cpu(rq->cpu, rq->rd->online);
5024                rq->online = 0;
5025        }
5026}
5027
5028/*
5029 * migration_call - callback that gets triggered when a CPU is added.
5030 * Here we can start up the necessary migration thread for the new CPU.
5031 */
5032static int __cpuinit
5033migration_call(struct notifier_block *nfb, unsigned long action, void *hcpu)
5034{
5035        int cpu = (long)hcpu;
5036        unsigned long flags;
5037        struct rq *rq = cpu_rq(cpu);
5038
5039        switch (action & ~CPU_TASKS_FROZEN) {
5040
5041        case CPU_UP_PREPARE:
5042                rq->calc_load_update = calc_load_update;
5043                break;
5044
5045        case CPU_ONLINE:
5046                /* Update our root-domain */
5047                raw_spin_lock_irqsave(&rq->lock, flags);
5048                if (rq->rd) {
5049                        BUG_ON(!cpumask_test_cpu(cpu, rq->rd->span));
5050
5051                        set_rq_online(rq);
5052                }
5053                raw_spin_unlock_irqrestore(&rq->lock, flags);
5054                break;
5055
5056#ifdef CONFIG_HOTPLUG_CPU
5057        case CPU_DYING:
5058                sched_ttwu_pending();
5059                /* Update our root-domain */
5060                raw_spin_lock_irqsave(&rq->lock, flags);
5061                if (rq->rd) {
5062                        BUG_ON(!cpumask_test_cpu(cpu, rq->rd->span));
5063                        set_rq_offline(rq);
5064                }
5065                migrate_tasks(cpu);
5066                BUG_ON(rq->nr_running != 1); /* the migration thread */
5067                raw_spin_unlock_irqrestore(&rq->lock, flags);
5068                break;
5069
5070        case CPU_DEAD:
5071                calc_load_migrate(rq);
5072                break;
5073#endif
5074        }
5075
5076        update_max_interval();
5077
5078        return NOTIFY_OK;
5079}
5080
5081/*
5082 * Register at high priority so that task migration (migrate_all_tasks)
5083 * happens before everything else.  This has to be lower priority than
5084 * the notifier in the perf_event subsystem, though.
5085 */
5086static struct notifier_block __cpuinitdata migration_notifier = {
5087        .notifier_call = migration_call,
5088        .priority = CPU_PRI_MIGRATION,
5089};
5090
5091static int __cpuinit sched_cpu_active(struct notifier_block *nfb,
5092                                      unsigned long action, void *hcpu)
5093{
5094        switch (action & ~CPU_TASKS_FROZEN) {
5095        case CPU_STARTING:
5096        case CPU_DOWN_FAILED:
5097                set_cpu_active((long)hcpu, true);
5098                return NOTIFY_OK;
5099        default:
5100                return NOTIFY_DONE;
5101        }
5102}
5103
5104static int __cpuinit sched_cpu_inactive(struct notifier_block *nfb,
5105                                        unsigned long action, void *hcpu)
5106{
5107        switch (action & ~CPU_TASKS_FROZEN) {
5108        case CPU_DOWN_PREPARE:
5109                set_cpu_active((long)hcpu, false);
5110                return NOTIFY_OK;
5111        default:
5112                return NOTIFY_DONE;
5113        }
5114}
5115
5116static int __init migration_init(void)
5117{
5118        void *cpu = (void *)(long)smp_processor_id();
5119        int err;
5120
5121        /* Initialize migration for the boot CPU */
5122        err = migration_call(&migration_notifier, CPU_UP_PREPARE, cpu);
5123        BUG_ON(err == NOTIFY_BAD);
5124        migration_call(&migration_notifier, CPU_ONLINE, cpu);
5125        register_cpu_notifier(&migration_notifier);
5126
5127        /* Register cpu active notifiers */
5128        cpu_notifier(sched_cpu_active, CPU_PRI_SCHED_ACTIVE);
5129        cpu_notifier(sched_cpu_inactive, CPU_PRI_SCHED_INACTIVE);
5130
5131        return 0;
5132}
5133early_initcall(migration_init);
5134#endif
5135
5136#ifdef CONFIG_SMP
5137
5138static cpumask_var_t sched_domains_tmpmask; /* sched_domains_mutex */
5139
5140#ifdef CONFIG_SCHED_DEBUG
5141
5142static __read_mostly int sched_debug_enabled;
5143
5144static int __init sched_debug_setup(char *str)
5145{
5146        sched_debug_enabled = 1;
5147
5148        return 0;
5149}
5150early_param("sched_debug", sched_debug_setup);
5151
5152static inline bool sched_debug(void)
5153{
5154        return sched_debug_enabled;
5155}
5156
5157static int sched_domain_debug_one(struct sched_domain *sd, int cpu, int level,
5158                                  struct cpumask *groupmask)
5159{
5160        struct sched_group *group = sd->groups;
5161        char str[256];
5162
5163        cpulist_scnprintf(str, sizeof(str), sched_domain_span(sd));
5164        cpumask_clear(groupmask);
5165
5166        printk(KERN_DEBUG "%*s domain %d: ", level, "", level);
5167
5168        if (!(sd->flags & SD_LOAD_BALANCE)) {
5169                printk("does not load-balance\n");
5170                if (sd->parent)
5171                        printk(KERN_ERR "ERROR: !SD_LOAD_BALANCE domain"
5172                                        " has parent");
5173                return -1;
5174        }
5175
5176        printk(KERN_CONT "span %s level %s\n", str, sd->name);
5177
5178        if (!cpumask_test_cpu(cpu, sched_domain_span(sd))) {
5179                printk(KERN_ERR "ERROR: domain->span does not contain "
5180                                "CPU%d\n", cpu);
5181        }
5182        if (!cpumask_test_cpu(cpu, sched_group_cpus(group))) {
5183                printk(KERN_ERR "ERROR: domain->groups does not contain"
5184                                " CPU%d\n", cpu);
5185        }
5186
5187        printk(KERN_DEBUG "%*s groups:", level + 1, "");
5188        do {
5189                if (!group) {
5190                        printk("\n");
5191                        printk(KERN_ERR "ERROR: group is NULL\n");
5192                        break;
5193                }
5194
5195                /*
5196                 * Even though we initialize ->power to something semi-sane,
5197                 * we leave power_orig unset. This allows us to detect if
5198                 * domain iteration is still funny without causing /0 traps.
5199                 */
5200                if (!group->sgp->power_orig) {
5201                        printk(KERN_CONT "\n");
5202                        printk(KERN_ERR "ERROR: domain->cpu_power not "
5203                                        "set\n");
5204                        break;
5205                }
5206
5207                if (!cpumask_weight(sched_group_cpus(group))) {
5208                        printk(KERN_CONT "\n");
5209                        printk(KERN_ERR "ERROR: empty group\n");
5210                        break;
5211                }
5212
5213                if (!(sd->flags & SD_OVERLAP) &&
5214                    cpumask_intersects(groupmask, sched_group_cpus(group))) {
5215                        printk(KERN_CONT "\n");
5216                        printk(KERN_ERR "ERROR: repeated CPUs\n");
5217                        break;
5218                }
5219
5220                cpumask_or(groupmask, groupmask, sched_group_cpus(group));
5221
5222                cpulist_scnprintf(str, sizeof(str), sched_group_cpus(group));
5223
5224                printk(KERN_CONT " %s", str);
5225                if (group->sgp->power != SCHED_POWER_SCALE) {
5226                        printk(KERN_CONT " (cpu_power = %d)",
5227                                group->sgp->power);
5228                }
5229
5230                group = group->next;
5231        } while (group != sd->groups);
5232        printk(KERN_CONT "\n");
5233
5234        if (!cpumask_equal(sched_domain_span(sd), groupmask))
5235                printk(KERN_ERR "ERROR: groups don't span domain->span\n");
5236
5237        if (sd->parent &&
5238            !cpumask_subset(groupmask, sched_domain_span(sd->parent)))
5239                printk(KERN_ERR "ERROR: parent span is not a superset "
5240                        "of domain->span\n");
5241        return 0;
5242}
5243
5244static void sched_domain_debug(struct sched_domain *sd, int cpu)
5245{
5246        int level = 0;
5247
5248        if (!sched_debug_enabled)
5249                return;
5250
5251        if (!sd) {
5252                printk(KERN_DEBUG "CPU%d attaching NULL sched-domain.\n", cpu);
5253                return;
5254        }
5255
5256        printk(KERN_DEBUG "CPU%d attaching sched-domain:\n", cpu);
5257
5258        for (;;) {
5259                if (sched_domain_debug_one(sd, cpu, level, sched_domains_tmpmask))
5260                        break;
5261                level++;
5262                sd = sd->parent;
5263                if (!sd)
5264                        break;
5265        }
5266}
5267#else /* !CONFIG_SCHED_DEBUG */
5268# define sched_domain_debug(sd, cpu) do { } while (0)
5269static inline bool sched_debug(void)
5270{
5271        return false;
5272}
5273#endif /* CONFIG_SCHED_DEBUG */
5274
5275static int sd_degenerate(struct sched_domain *sd)
5276{
5277        if (cpumask_weight(sched_domain_span(sd)) == 1)
5278                return 1;
5279
5280        /* Following flags need at least 2 groups */
5281        if (sd->flags & (SD_LOAD_BALANCE |
5282                         SD_BALANCE_NEWIDLE |
5283                         SD_BALANCE_FORK |
5284                         SD_BALANCE_EXEC |
5285                         SD_SHARE_CPUPOWER |
5286                         SD_SHARE_PKG_RESOURCES)) {
5287                if (sd->groups != sd->groups->next)
5288                        return 0;
5289        }
5290
5291        /* Following flags don't use groups */
5292        if (sd->flags & (SD_WAKE_AFFINE))
5293                return 0;
5294
5295        return 1;
5296}
5297
5298static int
5299sd_parent_degenerate(struct sched_domain *sd, struct sched_domain *parent)
5300{
5301        unsigned long cflags = sd->flags, pflags = parent->flags;
5302
5303        if (sd_degenerate(parent))
5304                return 1;
5305
5306        if (!cpumask_equal(sched_domain_span(sd), sched_domain_span(parent)))
5307                return 0;
5308
5309        /* Flags needing groups don't count if only 1 group in parent */
5310        if (parent->groups == parent->groups->next) {
5311                pflags &= ~(SD_LOAD_BALANCE |
5312                                SD_BALANCE_NEWIDLE |
5313                                SD_BALANCE_FORK |
5314                                SD_BALANCE_EXEC |
5315                                SD_SHARE_CPUPOWER |
5316                                SD_SHARE_PKG_RESOURCES);
5317                if (nr_node_ids == 1)
5318                        pflags &= ~SD_SERIALIZE;
5319        }
5320        if (~cflags & pflags)
5321                return 0;
5322
5323        return 1;
5324}
5325
5326static void free_rootdomain(struct rcu_head *rcu)
5327{
5328        struct root_domain *rd = container_of(rcu, struct root_domain, rcu);
5329
5330        cpupri_cleanup(&rd->cpupri);
5331        free_cpumask_var(rd->rto_mask);
5332        free_cpumask_var(rd->online);
5333        free_cpumask_var(rd->span);
5334        kfree(rd);
5335}
5336
5337static void rq_attach_root(struct rq *rq, struct root_domain *rd)
5338{
5339        struct root_domain *old_rd = NULL;
5340        unsigned long flags;
5341
5342        raw_spin_lock_irqsave(&rq->lock, flags);
5343
5344        if (rq->rd) {
5345                old_rd = rq->rd;
5346
5347                if (cpumask_test_cpu(rq->cpu, old_rd->online))
5348                        set_rq_offline(rq);
5349
5350                cpumask_clear_cpu(rq->cpu, old_rd->span);
5351
5352                /*
5353                 * If we dont want to free the old_rt yet then
5354                 * set old_rd to NULL to skip the freeing later
5355                 * in this function:
5356                 */
5357                if (!atomic_dec_and_test(&old_rd->refcount))
5358                        old_rd = NULL;
5359        }
5360
5361        atomic_inc(&rd->refcount);
5362        rq->rd = rd;
5363
5364        cpumask_set_cpu(rq->cpu, rd->span);
5365        if (cpumask_test_cpu(rq->cpu, cpu_active_mask))
5366                set_rq_online(rq);
5367
5368        raw_spin_unlock_irqrestore(&rq->lock, flags);
5369
5370        if (old_rd)
5371                call_rcu_sched(&old_rd->rcu, free_rootdomain);
5372}
5373
5374static int init_rootdomain(struct root_domain *rd)
5375{
5376        memset(rd, 0, sizeof(*rd));
5377
5378        if (!alloc_cpumask_var(&rd->span, GFP_KERNEL))
5379                goto out;
5380        if (!alloc_cpumask_var(&rd->online, GFP_KERNEL))
5381                goto free_span;
5382        if (!alloc_cpumask_var(&rd->rto_mask, GFP_KERNEL))
5383                goto free_online;
5384
5385        if (cpupri_init(&rd->cpupri) != 0)
5386                goto free_rto_mask;
5387        return 0;
5388
5389free_rto_mask:
5390        free_cpumask_var(rd->rto_mask);
5391free_online:
5392        free_cpumask_var(rd->online);
5393free_span:
5394        free_cpumask_var(rd->span);
5395out:
5396        return -ENOMEM;
5397}
5398
5399/*
5400 * By default the system creates a single root-domain with all cpus as
5401 * members (mimicking the global state we have today).
5402 */
5403struct root_domain def_root_domain;
5404
5405static void init_defrootdomain(void)
5406{
5407        init_rootdomain(&def_root_domain);
5408
5409        atomic_set(&def_root_domain.refcount, 1);
5410}
5411
5412static struct root_domain *alloc_rootdomain(void)
5413{
5414        struct root_domain *rd;
5415
5416        rd = kmalloc(sizeof(*rd), GFP_KERNEL);
5417        if (!rd)
5418                return NULL;
5419
5420        if (init_rootdomain(rd) != 0) {
5421                kfree(rd);
5422                return NULL;
5423        }
5424
5425        return rd;
5426}
5427
5428static void free_sched_groups(struct sched_group *sg, int free_sgp)
5429{
5430        struct sched_group *tmp, *first;
5431
5432        if (!sg)
5433                return;
5434
5435        first = sg;
5436        do {
5437                tmp = sg->next;
5438
5439                if (free_sgp && atomic_dec_and_test(&sg->sgp->ref))
5440                        kfree(sg->sgp);
5441
5442                kfree(sg);
5443                sg = tmp;
5444        } while (sg != first);
5445}
5446
5447static void free_sched_domain(struct rcu_head *rcu)
5448{
5449        struct sched_domain *sd = container_of(rcu, struct sched_domain, rcu);
5450
5451        /*
5452         * If its an overlapping domain it has private groups, iterate and
5453         * nuke them all.
5454         */
5455        if (sd->flags & SD_OVERLAP) {
5456                free_sched_groups(sd->groups, 1);
5457        } else if (atomic_dec_and_test(&sd->groups->ref)) {
5458                kfree(sd->groups->sgp);
5459                kfree(sd->groups);
5460        }
5461        kfree(sd);
5462}
5463
5464static void destroy_sched_domain(struct sched_domain *sd, int cpu)
5465{
5466        call_rcu(&sd->rcu, free_sched_domain);
5467}
5468
5469static void destroy_sched_domains(struct sched_domain *sd, int cpu)
5470{
5471        for (; sd; sd = sd->parent)
5472                destroy_sched_domain(sd, cpu);
5473}
5474
5475/*
5476 * Keep a special pointer to the highest sched_domain that has
5477 * SD_SHARE_PKG_RESOURCE set (Last Level Cache Domain) for this
5478 * allows us to avoid some pointer chasing select_idle_sibling().
5479 *
5480 * Also keep a unique ID per domain (we use the first cpu number in
5481 * the cpumask of the domain), this allows us to quickly tell if
5482 * two cpus are in the same cache domain, see cpus_share_cache().
5483 */
5484DEFINE_PER_CPU(struct sched_domain *, sd_llc);
5485DEFINE_PER_CPU(int, sd_llc_id);
5486
5487static void update_top_cache_domain(int cpu)
5488{
5489        struct sched_domain *sd;
5490        int id = cpu;
5491
5492        sd = highest_flag_domain(cpu, SD_SHARE_PKG_RESOURCES);
5493        if (sd)
5494                id = cpumask_first(sched_domain_span(sd));
5495
5496        rcu_assign_pointer(per_cpu(sd_llc, cpu), sd);
5497        per_cpu(sd_llc_id, cpu) = id;
5498}
5499
5500/*
5501 * Attach the domain 'sd' to 'cpu' as its base domain. Callers must
5502 * hold the hotplug lock.
5503 */
5504static void
5505cpu_attach_domain(struct sched_domain *sd, struct root_domain *rd, int cpu)
5506{
5507        struct rq *rq = cpu_rq(cpu);
5508        struct sched_domain *tmp;
5509
5510        /* Remove the sched domains which do not contribute to scheduling. */
5511        for (tmp = sd; tmp; ) {
5512                struct sched_domain *parent = tmp->parent;
5513                if (!parent)
5514                        break;
5515
5516                if (sd_parent_degenerate(tmp, parent)) {
5517                        tmp->parent = parent->parent;
5518                        if (parent->parent)
5519                                parent->parent->child = tmp;
5520                        destroy_sched_domain(parent, cpu);
5521                } else
5522                        tmp = tmp->parent;
5523        }
5524
5525        if (sd && sd_degenerate(sd)) {
5526                tmp = sd;
5527                sd = sd->parent;
5528                destroy_sched_domain(tmp, cpu);
5529                if (sd)
5530                        sd->child = NULL;
5531        }
5532
5533        sched_domain_debug(sd, cpu);
5534
5535        rq_attach_root(rq, rd);
5536        tmp = rq->sd;
5537        rcu_assign_pointer(rq->sd, sd);
5538        destroy_sched_domains(tmp, cpu);
5539
5540        update_top_cache_domain(cpu);
5541}
5542
5543/* cpus with isolated domains */
5544static cpumask_var_t cpu_isolated_map;
5545
5546/* Setup the mask of cpus configured for isolated domains */
5547static int __init isolated_cpu_setup(char *str)
5548{
5549        alloc_bootmem_cpumask_var(&cpu_isolated_map);
5550        cpulist_parse(str, cpu_isolated_map);
5551        return 1;
5552}
5553
5554__setup("isolcpus=", isolated_cpu_setup);
5555
5556static const struct cpumask *cpu_cpu_mask(int cpu)
5557{
5558        return cpumask_of_node(cpu_to_node(cpu));
5559}
5560
5561struct sd_data {
5562        struct sched_domain **__percpu sd;
5563        struct sched_group **__percpu sg;
5564        struct sched_group_power **__percpu sgp;
5565};
5566
5567struct s_data {
5568        struct sched_domain ** __percpu sd;
5569        struct root_domain      *rd;
5570};
5571
5572enum s_alloc {
5573        sa_rootdomain,
5574        sa_sd,
5575        sa_sd_storage,
5576        sa_none,
5577};
5578
5579struct sched_domain_topology_level;
5580
5581typedef struct sched_domain *(*sched_domain_init_f)(struct sched_domain_topology_level *tl, int cpu);
5582typedef const struct cpumask *(*sched_domain_mask_f)(int cpu);
5583
5584#define SDTL_OVERLAP    0x01
5585
5586struct sched_domain_topology_level {
5587        sched_domain_init_f init;
5588        sched_domain_mask_f mask;
5589        int                 flags;
5590        int                 numa_level;
5591        struct sd_data      data;
5592};
5593
5594/*
5595 * Build an iteration mask that can exclude certain CPUs from the upwards
5596 * domain traversal.
5597 *
5598 * Asymmetric node setups can result in situations where the domain tree is of
5599 * unequal depth, make sure to skip domains that already cover the entire
5600 * range.
5601 *
5602 * In that case build_sched_domains() will have terminated the iteration early
5603 * and our sibling sd spans will be empty. Domains should always include the
5604 * cpu they're built on, so check that.
5605 *
5606 */
5607static void build_group_mask(struct sched_domain *sd, struct sched_group *sg)
5608{
5609        const struct cpumask *span = sched_domain_span(sd);
5610        struct sd_data *sdd = sd->private;
5611        struct sched_domain *sibling;
5612        int i;
5613
5614        for_each_cpu(i, span) {
5615                sibling = *per_cpu_ptr(sdd->sd, i);
5616                if (!cpumask_test_cpu(i, sched_domain_span(sibling)))
5617                        continue;
5618
5619                cpumask_set_cpu(i, sched_group_mask(sg));
5620        }
5621}
5622
5623/*
5624 * Return the canonical balance cpu for this group, this is the first cpu
5625 * of this group that's also in the iteration mask.
5626 */
5627int group_balance_cpu(struct sched_group *sg)
5628{
5629        return cpumask_first_and(sched_group_cpus(sg), sched_group_mask(sg));
5630}
5631
5632static int
5633build_overlap_sched_groups(struct sched_domain *sd, int cpu)
5634{
5635        struct sched_group *first = NULL, *last = NULL, *groups = NULL, *sg;
5636        const struct cpumask *span = sched_domain_span(sd);
5637        struct cpumask *covered = sched_domains_tmpmask;
5638        struct sd_data *sdd = sd->private;
5639        struct sched_domain *child;
5640        int i;
5641
5642        cpumask_clear(covered);
5643
5644        for_each_cpu(i, span) {
5645                struct cpumask *sg_span;
5646
5647                if (cpumask_test_cpu(i, covered))
5648                        continue;
5649
5650                child = *per_cpu_ptr(sdd->sd, i);
5651
5652                /* See the comment near build_group_mask(). */
5653                if (!cpumask_test_cpu(i, sched_domain_span(child)))
5654                        continue;
5655
5656                sg = kzalloc_node(sizeof(struct sched_group) + cpumask_size(),
5657                                GFP_KERNEL, cpu_to_node(cpu));
5658
5659                if (!sg)
5660                        goto fail;
5661
5662                sg_span = sched_group_cpus(sg);
5663                if (child->child) {
5664                        child = child->child;
5665                        cpumask_copy(sg_span, sched_domain_span(child));
5666                } else
5667                        cpumask_set_cpu(i, sg_span);
5668
5669                cpumask_or(covered, covered, sg_span);
5670
5671                sg->sgp = *per_cpu_ptr(sdd->sgp, i);
5672                if (atomic_inc_return(&sg->sgp->ref) == 1)
5673                        build_group_mask(sd, sg);
5674
5675                /*
5676                 * Initialize sgp->power such that even if we mess up the
5677                 * domains and no possible iteration will get us here, we won't
5678                 * die on a /0 trap.
5679                 */
5680                sg->sgp->power = SCHED_POWER_SCALE * cpumask_weight(sg_span);
5681
5682                /*
5683                 * Make sure the first group of this domain contains the
5684                 * canonical balance cpu. Otherwise the sched_domain iteration
5685                 * breaks. See update_sg_lb_stats().
5686                 */
5687                if ((!groups && cpumask_test_cpu(cpu, sg_span)) ||
5688                    group_balance_cpu(sg) == cpu)
5689                        groups = sg;
5690
5691                if (!first)
5692                        first = sg;
5693                if (last)
5694                        last->next = sg;
5695                last = sg;
5696                last->next = first;
5697        }
5698        sd->groups = groups;
5699
5700        return 0;
5701
5702fail:
5703        free_sched_groups(first, 0);
5704
5705        return -ENOMEM;
5706}
5707
5708static int get_group(int cpu, struct sd_data *sdd, struct sched_group **sg)
5709{
5710        struct sched_domain *sd = *per_cpu_ptr(sdd->sd, cpu);
5711        struct sched_domain *child = sd->child;
5712
5713        if (child)
5714                cpu = cpumask_first(sched_domain_span(child));
5715
5716        if (sg) {
5717                *sg = *per_cpu_ptr(sdd->sg, cpu);
5718                (*sg)->sgp = *per_cpu_ptr(sdd->sgp, cpu);
5719                atomic_set(&(*sg)->sgp->ref, 1); /* for claim_allocations */
5720        }
5721
5722        return cpu;
5723}
5724
5725/*
5726 * build_sched_groups will build a circular linked list of the groups
5727 * covered by the given span, and will set each group's ->cpumask correctly,
5728 * and ->cpu_power to 0.
5729 *
5730 * Assumes the sched_domain tree is fully constructed
5731 */
5732static int
5733build_sched_groups(struct sched_domain *sd, int cpu)
5734{
5735        struct sched_group *first = NULL, *last = NULL;
5736        struct sd_data *sdd = sd->private;
5737        const struct cpumask *span = sched_domain_span(sd);
5738        struct cpumask *covered;
5739        int i;
5740
5741        get_group(cpu, sdd, &sd->groups);
5742        atomic_inc(&sd->groups->ref);
5743
5744        if (cpu != cpumask_first(sched_domain_span(sd)))
5745                return 0;
5746
5747        lockdep_assert_held(&sched_domains_mutex);
5748        covered = sched_domains_tmpmask;
5749
5750        cpumask_clear(covered);
5751
5752        for_each_cpu(i, span) {
5753                struct sched_group *sg;
5754                int group = get_group(i, sdd, &sg);
5755                int j;
5756
5757                if (cpumask_test_cpu(i, covered))
5758                        continue;
5759
5760                cpumask_clear(sched_group_cpus(sg));
5761                sg->sgp->power = 0;
5762                cpumask_setall(sched_group_mask(sg));
5763
5764                for_each_cpu(j, span) {
5765                        if (get_group(j, sdd, NULL) != group)
5766                                continue;
5767
5768                        cpumask_set_cpu(j, covered);
5769                        cpumask_set_cpu(j, sched_group_cpus(sg));
5770                }
5771
5772                if (!first)
5773                        first = sg;
5774                if (last)
5775                        last->next = sg;
5776                last = sg;
5777        }
5778        last->next = first;
5779
5780        return 0;
5781}
5782
5783/*
5784 * Initialize sched groups cpu_power.
5785 *
5786 * cpu_power indicates the capacity of sched group, which is used while
5787 * distributing the load between different sched groups in a sched domain.
5788 * Typically cpu_power for all the groups in a sched domain will be same unless
5789 * there are asymmetries in the topology. If there are asymmetries, group
5790 * having more cpu_power will pickup more load compared to the group having
5791 * less cpu_power.
5792 */
5793static void init_sched_groups_power(int cpu, struct sched_domain *sd)
5794{
5795        struct sched_group *sg = sd->groups;
5796
5797        WARN_ON(!sd || !sg);
5798
5799        do {
5800                sg->group_weight = cpumask_weight(sched_group_cpus(sg));
5801                sg = sg->next;
5802        } while (sg != sd->groups);
5803
5804        if (cpu != group_balance_cpu(sg))
5805                return;
5806
5807        update_group_power(sd, cpu);
5808        atomic_set(&sg->sgp->nr_busy_cpus, sg->group_weight);
5809}
5810
5811int __weak arch_sd_sibling_asym_packing(void)
5812{
5813       return 0*SD_ASYM_PACKING;
5814}
5815
5816/*
5817 * Initializers for schedule domains
5818 * Non-inlined to reduce accumulated stack pressure in build_sched_domains()
5819 */
5820
5821#ifdef CONFIG_SCHED_DEBUG
5822# define SD_INIT_NAME(sd, type)         sd->name = #type
5823#else
5824# define SD_INIT_NAME(sd, type)         do { } while (0)
5825#endif
5826
5827#define SD_INIT_FUNC(type)                                              \
5828static noinline struct sched_domain *                                   \
5829sd_init_##type(struct sched_domain_topology_level *tl, int cpu)         \
5830{                                                                       \
5831        struct sched_domain *sd = *per_cpu_ptr(tl->data.sd, cpu);       \
5832        *sd = SD_##type##_INIT;                                         \
5833        SD_INIT_NAME(sd, type);                                         \
5834        sd->private = &tl->data;                                        \
5835        return sd;                                                      \
5836}
5837
5838SD_INIT_FUNC(CPU)
5839#ifdef CONFIG_SCHED_SMT
5840 SD_INIT_FUNC(SIBLING)
5841#endif
5842#ifdef CONFIG_SCHED_MC
5843 SD_INIT_FUNC(MC)
5844#endif
5845#ifdef CONFIG_SCHED_BOOK
5846 SD_INIT_FUNC(BOOK)
5847#endif
5848
5849static int default_relax_domain_level = -1;
5850int sched_domain_level_max;
5851
5852static int __init setup_relax_domain_level(char *str)
5853{
5854        if (kstrtoint(str, 0, &default_relax_domain_level))
5855                pr_warn("Unable to set relax_domain_level\n");
5856
5857        return 1;
5858}
5859__setup("relax_domain_level=", setup_relax_domain_level);
5860
5861static void set_domain_attribute(struct sched_domain *sd,
5862                                 struct sched_domain_attr *attr)
5863{
5864        int request;
5865
5866        if (!attr || attr->relax_domain_level < 0) {
5867                if (default_relax_domain_level < 0)
5868                        return;
5869                else
5870                        request = default_relax_domain_level;
5871        } else
5872                request = attr->relax_domain_level;
5873        if (request < sd->level) {
5874                /* turn off idle balance on this domain */
5875                sd->flags &= ~(SD_BALANCE_WAKE|SD_BALANCE_NEWIDLE);
5876        } else {
5877                /* turn on idle balance on this domain */
5878                sd->flags |= (SD_BALANCE_WAKE|SD_BALANCE_NEWIDLE);
5879        }
5880}
5881
5882static void __sdt_free(const struct cpumask *cpu_map);
5883static int __sdt_alloc(const struct cpumask *cpu_map);
5884
5885static void __free_domain_allocs(struct s_data *d, enum s_alloc what,
5886                                 const struct cpumask *cpu_map)
5887{
5888        switch (what) {
5889        case sa_rootdomain:
5890                if (!atomic_read(&d->rd->refcount))
5891                        free_rootdomain(&d->rd->rcu); /* fall through */
5892        case sa_sd:
5893                free_percpu(d->sd); /* fall through */
5894        case sa_sd_storage:
5895                __sdt_free(cpu_map); /* fall through */
5896        case sa_none:
5897                break;
5898        }
5899}
5900
5901static enum s_alloc __visit_domain_allocation_hell(struct s_data *d,
5902                                                   const struct cpumask *cpu_map)
5903{
5904        memset(d, 0, sizeof(*d));
5905
5906        if (__sdt_alloc(cpu_map))
5907                return sa_sd_storage;
5908        d->sd = alloc_percpu(struct sched_domain *);
5909        if (!d->sd)
5910                return sa_sd_storage;
5911        d->rd = alloc_rootdomain();
5912        if (!d->rd)
5913                return sa_sd;