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
  75#include <asm/tlb.h>
  76#include <asm/irq_regs.h>
  77#include <asm/mutex.h>
  78#ifdef CONFIG_PARAVIRT
  79#include <asm/paravirt.h>
  80#endif
  81
  82#include "sched.h"
  83#include "../workqueue_sched.h"
  84
  85#define CREATE_TRACE_POINTS
  86#include <trace/events/sched.h>
  87
  88void start_bandwidth_timer(struct hrtimer *period_timer, ktime_t period)
  89{
  90        unsigned long delta;
  91        ktime_t soft, hard, now;
  92
  93        for (;;) {
  94                if (hrtimer_active(period_timer))
  95                        break;
  96
  97                now = hrtimer_cb_get_time(period_timer);
  98                hrtimer_forward(period_timer, now, period);
  99
 100                soft = hrtimer_get_softexpires(period_timer);
 101                hard = hrtimer_get_expires(period_timer);
 102                delta = ktime_to_ns(ktime_sub(hard, soft));
 103                __hrtimer_start_range_ns(period_timer, soft, delta,
 104                                         HRTIMER_MODE_ABS_PINNED, 0);
 105        }
 106}
 107
 108DEFINE_MUTEX(sched_domains_mutex);
 109DEFINE_PER_CPU_SHARED_ALIGNED(struct rq, runqueues);
 110
 111static void update_rq_clock_task(struct rq *rq, s64 delta);
 112
 113void update_rq_clock(struct rq *rq)
 114{
 115        s64 delta;
 116
 117        if (rq->skip_clock_update > 0)
 118                return;
 119
 120        delta = sched_clock_cpu(cpu_of(rq)) - rq->clock;
 121        rq->clock += delta;
 122        update_rq_clock_task(rq, delta);
 123}
 124
 125/*
 126 * Debugging: various feature bits
 127 */
 128
 129#define SCHED_FEAT(name, enabled)       \
 130        (1UL << __SCHED_FEAT_##name) * enabled |
 131
 132const_debug unsigned int sysctl_sched_features =
 133#include "features.h"
 134        0;
 135
 136#undef SCHED_FEAT
 137
 138#ifdef CONFIG_SCHED_DEBUG
 139#define SCHED_FEAT(name, enabled)       \
 140        #name ,
 141
 142static __read_mostly char *sched_feat_names[] = {
 143#include "features.h"
 144        NULL
 145};
 146
 147#undef SCHED_FEAT
 148
 149static int sched_feat_show(struct seq_file *m, void *v)
 150{
 151        int i;
 152
 153        for (i = 0; i < __SCHED_FEAT_NR; i++) {
 154                if (!(sysctl_sched_features & (1UL << i)))
 155                        seq_puts(m, "NO_");
 156                seq_printf(m, "%s ", sched_feat_names[i]);
 157        }
 158        seq_puts(m, "\n");
 159
 160        return 0;
 161}
 162
 163#ifdef HAVE_JUMP_LABEL
 164
 165#define jump_label_key__true  jump_label_key_enabled
 166#define jump_label_key__false jump_label_key_disabled
 167
 168#define SCHED_FEAT(name, enabled)       \
 169        jump_label_key__##enabled ,
 170
 171struct jump_label_key sched_feat_keys[__SCHED_FEAT_NR] = {
 172#include "features.h"
 173};
 174
 175#undef SCHED_FEAT
 176
 177static void sched_feat_disable(int i)
 178{
 179        if (jump_label_enabled(&sched_feat_keys[i]))
 180                jump_label_dec(&sched_feat_keys[i]);
 181}
 182
 183static void sched_feat_enable(int i)
 184{
 185        if (!jump_label_enabled(&sched_feat_keys[i]))
 186                jump_label_inc(&sched_feat_keys[i]);
 187}
 188#else
 189static void sched_feat_disable(int i) { };
 190static void sched_feat_enable(int i) { };
 191#endif /* HAVE_JUMP_LABEL */
 192
 193static ssize_t
 194sched_feat_write(struct file *filp, const char __user *ubuf,
 195                size_t cnt, loff_t *ppos)
 196{
 197        char buf[64];
 198        char *cmp;
 199        int neg = 0;
 200        int i;
 201
 202        if (cnt > 63)
 203                cnt = 63;
 204
 205        if (copy_from_user(&buf, ubuf, cnt))
 206                return -EFAULT;
 207
 208        buf[cnt] = 0;
 209        cmp = strstrip(buf);
 210
 211        if (strncmp(cmp, "NO_", 3) == 0) {
 212                neg = 1;
 213                cmp += 3;
 214        }
 215
 216        for (i = 0; i < __SCHED_FEAT_NR; i++) {
 217                if (strcmp(cmp, sched_feat_names[i]) == 0) {
 218                        if (neg) {
 219                                sysctl_sched_features &= ~(1UL << i);
 220                                sched_feat_disable(i);
 221                        } else {
 222                                sysctl_sched_features |= (1UL << i);
 223                                sched_feat_enable(i);
 224                        }
 225                        break;
 226                }
 227        }
 228
 229        if (i == __SCHED_FEAT_NR)
 230                return -EINVAL;
 231
 232        *ppos += cnt;
 233
 234        return cnt;
 235}
 236
 237static int sched_feat_open(struct inode *inode, struct file *filp)
 238{
 239        return single_open(filp, sched_feat_show, NULL);
 240}
 241
 242static const struct file_operations sched_feat_fops = {
 243        .open           = sched_feat_open,
 244        .write          = sched_feat_write,
 245        .read           = seq_read,
 246        .llseek         = seq_lseek,
 247        .release        = single_release,
 248};
 249
 250static __init int sched_init_debug(void)
 251{
 252        debugfs_create_file("sched_features", 0644, NULL, NULL,
 253                        &sched_feat_fops);
 254
 255        return 0;
 256}
 257late_initcall(sched_init_debug);
 258#endif /* CONFIG_SCHED_DEBUG */
 259
 260/*
 261 * Number of tasks to iterate in a single balance run.
 262 * Limited because this is done with IRQs disabled.
 263 */
 264const_debug unsigned int sysctl_sched_nr_migrate = 32;
 265
 266/*
 267 * period over which we average the RT time consumption, measured
 268 * in ms.
 269 *
 270 * default: 1s
 271 */
 272const_debug unsigned int sysctl_sched_time_avg = MSEC_PER_SEC;
 273
 274/*
 275 * period over which we measure -rt task cpu usage in us.
 276 * default: 1s
 277 */
 278unsigned int sysctl_sched_rt_period = 1000000;
 279
 280__read_mostly int scheduler_running;
 281
 282/*
 283 * part of the period that we allow rt tasks to run in us.
 284 * default: 0.95s
 285 */
 286int sysctl_sched_rt_runtime = 950000;
 287
 288
 289
 290/*
 291 * __task_rq_lock - lock the rq @p resides on.
 292 */
 293static inline struct rq *__task_rq_lock(struct task_struct *p)
 294        __acquires(rq->lock)
 295{
 296        struct rq *rq;
 297
 298        lockdep_assert_held(&p->pi_lock);
 299
 300        for (;;) {
 301                rq = task_rq(p);
 302                raw_spin_lock(&rq->lock);
 303                if (likely(rq == task_rq(p)))
 304                        return rq;
 305                raw_spin_unlock(&rq->lock);
 306        }
 307}
 308
 309/*
 310 * task_rq_lock - lock p->pi_lock and lock the rq @p resides on.
 311 */
 312static struct rq *task_rq_lock(struct task_struct *p, unsigned long *flags)
 313        __acquires(p->pi_lock)
 314        __acquires(rq->lock)
 315{
 316        struct rq *rq;
 317
 318        for (;;) {
 319                raw_spin_lock_irqsave(&p->pi_lock, *flags);
 320                rq = task_rq(p);
 321                raw_spin_lock(&rq->lock);
 322                if (likely(rq == task_rq(p)))
 323                        return rq;
 324                raw_spin_unlock(&rq->lock);
 325                raw_spin_unlock_irqrestore(&p->pi_lock, *flags);
 326        }
 327}
 328
 329static void __task_rq_unlock(struct rq *rq)
 330        __releases(rq->lock)
 331{
 332        raw_spin_unlock(&rq->lock);
 333}
 334
 335static inline void
 336task_rq_unlock(struct rq *rq, struct task_struct *p, unsigned long *flags)
 337        __releases(rq->lock)
 338        __releases(p->pi_lock)
 339{
 340        raw_spin_unlock(&rq->lock);
 341        raw_spin_unlock_irqrestore(&p->pi_lock, *flags);
 342}
 343
 344/*
 345 * this_rq_lock - lock this runqueue and disable interrupts.
 346 */
 347static struct rq *this_rq_lock(void)
 348        __acquires(rq->lock)
 349{
 350        struct rq *rq;
 351
 352        local_irq_disable();
 353        rq = this_rq();
 354        raw_spin_lock(&rq->lock);
 355
 356        return rq;
 357}
 358
 359#ifdef CONFIG_SCHED_HRTICK
 360/*
 361 * Use HR-timers to deliver accurate preemption points.
 362 *
 363 * Its all a bit involved since we cannot program an hrt while holding the
 364 * rq->lock. So what we do is store a state in in rq->hrtick_* and ask for a
 365 * reschedule event.
 366 *
 367 * When we get rescheduled we reprogram the hrtick_timer outside of the
 368 * rq->lock.
 369 */
 370
 371static void hrtick_clear(struct rq *rq)
 372{
 373        if (hrtimer_active(&rq->hrtick_timer))
 374                hrtimer_cancel(&rq->hrtick_timer);
 375}
 376
 377/*
 378 * High-resolution timer tick.
 379 * Runs from hardirq context with interrupts disabled.
 380 */
 381static enum hrtimer_restart hrtick(struct hrtimer *timer)
 382{
 383        struct rq *rq = container_of(timer, struct rq, hrtick_timer);
 384
 385        WARN_ON_ONCE(cpu_of(rq) != smp_processor_id());
 386
 387        raw_spin_lock(&rq->lock);
 388        update_rq_clock(rq);
 389        rq->curr->sched_class->task_tick(rq, rq->curr, 1);
 390        raw_spin_unlock(&rq->lock);
 391
 392        return HRTIMER_NORESTART;
 393}
 394
 395#ifdef CONFIG_SMP
 396/*
 397 * called from hardirq (IPI) context
 398 */
 399static void __hrtick_start(void *arg)
 400{
 401        struct rq *rq = arg;
 402
 403        raw_spin_lock(&rq->lock);
 404        hrtimer_restart(&rq->hrtick_timer);
 405        rq->hrtick_csd_pending = 0;
 406        raw_spin_unlock(&rq->lock);
 407}
 408
 409/*
 410 * Called to set the hrtick timer state.
 411 *
 412 * called with rq->lock held and irqs disabled
 413 */
 414void hrtick_start(struct rq *rq, u64 delay)
 415{
 416        struct hrtimer *timer = &rq->hrtick_timer;
 417        ktime_t time = ktime_add_ns(timer->base->get_time(), delay);
 418
 419        hrtimer_set_expires(timer, time);
 420
 421        if (rq == this_rq()) {
 422                hrtimer_restart(timer);
 423        } else if (!rq->hrtick_csd_pending) {
 424                __smp_call_function_single(cpu_of(rq), &rq->hrtick_csd, 0);
 425                rq->hrtick_csd_pending = 1;
 426        }
 427}
 428
 429static int
 430hotplug_hrtick(struct notifier_block *nfb, unsigned long action, void *hcpu)
 431{
 432        int cpu = (int)(long)hcpu;
 433
 434        switch (action) {
 435        case CPU_UP_CANCELED:
 436        case CPU_UP_CANCELED_FROZEN:
 437        case CPU_DOWN_PREPARE:
 438        case CPU_DOWN_PREPARE_FROZEN:
 439        case CPU_DEAD:
 440        case CPU_DEAD_FROZEN:
 441                hrtick_clear(cpu_rq(cpu));
 442                return NOTIFY_OK;
 443        }
 444
 445        return NOTIFY_DONE;
 446}
 447
 448static __init void init_hrtick(void)
 449{
 450        hotcpu_notifier(hotplug_hrtick, 0);
 451}
 452#else
 453/*
 454 * Called to set the hrtick timer state.
 455 *
 456 * called with rq->lock held and irqs disabled
 457 */
 458void hrtick_start(struct rq *rq, u64 delay)
 459{
 460        __hrtimer_start_range_ns(&rq->hrtick_timer, ns_to_ktime(delay), 0,
 461                        HRTIMER_MODE_REL_PINNED, 0);
 462}
 463
 464static inline void init_hrtick(void)
 465{
 466}
 467#endif /* CONFIG_SMP */
 468
 469static void init_rq_hrtick(struct rq *rq)
 470{
 471#ifdef CONFIG_SMP
 472        rq->hrtick_csd_pending = 0;
 473
 474        rq->hrtick_csd.flags = 0;
 475        rq->hrtick_csd.func = __hrtick_start;
 476        rq->hrtick_csd.info = rq;
 477#endif
 478
 479        hrtimer_init(&rq->hrtick_timer, CLOCK_MONOTONIC, HRTIMER_MODE_REL);
 480        rq->hrtick_timer.function = hrtick;
 481}
 482#else   /* CONFIG_SCHED_HRTICK */
 483static inline void hrtick_clear(struct rq *rq)
 484{
 485}
 486
 487static inline void init_rq_hrtick(struct rq *rq)
 488{
 489}
 490
 491static inline void init_hrtick(void)
 492{
 493}
 494#endif  /* CONFIG_SCHED_HRTICK */
 495
 496/*
 497 * resched_task - mark a task 'to be rescheduled now'.
 498 *
 499 * On UP this means the setting of the need_resched flag, on SMP it
 500 * might also involve a cross-CPU call to trigger the scheduler on
 501 * the target CPU.
 502 */
 503#ifdef CONFIG_SMP
 504
 505#ifndef tsk_is_polling
 506#define tsk_is_polling(t) test_tsk_thread_flag(t, TIF_POLLING_NRFLAG)
 507#endif
 508
 509void resched_task(struct task_struct *p)
 510{
 511        int cpu;
 512
 513        assert_raw_spin_locked(&task_rq(p)->lock);
 514
 515        if (test_tsk_need_resched(p))
 516                return;
 517
 518        set_tsk_need_resched(p);
 519
 520        cpu = task_cpu(p);
 521        if (cpu == smp_processor_id())
 522                return;
 523
 524        /* NEED_RESCHED must be visible before we test polling */
 525        smp_mb();
 526        if (!tsk_is_polling(p))
 527                smp_send_reschedule(cpu);
 528}
 529
 530void resched_cpu(int cpu)
 531{
 532        struct rq *rq = cpu_rq(cpu);
 533        unsigned long flags;
 534
 535        if (!raw_spin_trylock_irqsave(&rq->lock, flags))
 536                return;
 537        resched_task(cpu_curr(cpu));
 538        raw_spin_unlock_irqrestore(&rq->lock, flags);
 539}
 540
 541#ifdef CONFIG_NO_HZ
 542/*
 543 * In the semi idle case, use the nearest busy cpu for migrating timers
 544 * from an idle cpu.  This is good for power-savings.
 545 *
 546 * We don't do similar optimization for completely idle system, as
 547 * selecting an idle cpu will add more delays to the timers than intended
 548 * (as that cpu's timer base may not be uptodate wrt jiffies etc).
 549 */
 550int get_nohz_timer_target(void)
 551{
 552        int cpu = smp_processor_id();
 553        int i;
 554        struct sched_domain *sd;
 555
 556        rcu_read_lock();
 557        for_each_domain(cpu, sd) {
 558                for_each_cpu(i, sched_domain_span(sd)) {
 559                        if (!idle_cpu(i)) {
 560                                cpu = i;
 561                                goto unlock;
 562                        }
 563                }
 564        }
 565unlock:
 566        rcu_read_unlock();
 567        return cpu;
 568}
 569/*
 570 * When add_timer_on() enqueues a timer into the timer wheel of an
 571 * idle CPU then this timer might expire before the next timer event
 572 * which is scheduled to wake up that CPU. In case of a completely
 573 * idle system the next event might even be infinite time into the
 574 * future. wake_up_idle_cpu() ensures that the CPU is woken up and
 575 * leaves the inner idle loop so the newly added timer is taken into
 576 * account when the CPU goes back to idle and evaluates the timer
 577 * wheel for the next timer event.
 578 */
 579void wake_up_idle_cpu(int cpu)
 580{
 581        struct rq *rq = cpu_rq(cpu);
 582
 583        if (cpu == smp_processor_id())
 584                return;
 585
 586        /*
 587         * This is safe, as this function is called with the timer
 588         * wheel base lock of (cpu) held. When the CPU is on the way
 589         * to idle and has not yet set rq->curr to idle then it will
 590         * be serialized on the timer wheel base lock and take the new
 591         * timer into account automatically.
 592         */
 593        if (rq->curr != rq->idle)
 594                return;
 595
 596        /*
 597         * We can set TIF_RESCHED on the idle task of the other CPU
 598         * lockless. The worst case is that the other CPU runs the
 599         * idle task through an additional NOOP schedule()
 600         */
 601        set_tsk_need_resched(rq->idle);
 602
 603        /* NEED_RESCHED must be visible before we test polling */
 604        smp_mb();
 605        if (!tsk_is_polling(rq->idle))
 606                smp_send_reschedule(cpu);
 607}
 608
 609static inline bool got_nohz_idle_kick(void)
 610{
 611        int cpu = smp_processor_id();
 612        return idle_cpu(cpu) && test_bit(NOHZ_BALANCE_KICK, nohz_flags(cpu));
 613}
 614
 615#else /* CONFIG_NO_HZ */
 616
 617static inline bool got_nohz_idle_kick(void)
 618{
 619        return false;
 620}
 621
 622#endif /* CONFIG_NO_HZ */
 623
 624void sched_avg_update(struct rq *rq)
 625{
 626        s64 period = sched_avg_period();
 627
 628        while ((s64)(rq->clock - rq->age_stamp) > period) {
 629                /*
 630                 * Inline assembly required to prevent the compiler
 631                 * optimising this loop into a divmod call.
 632                 * See __iter_div_u64_rem() for another example of this.
 633                 */
 634                asm("" : "+rm" (rq->age_stamp));
 635                rq->age_stamp += period;
 636                rq->rt_avg /= 2;
 637        }
 638}
 639
 640#else /* !CONFIG_SMP */
 641void resched_task(struct task_struct *p)
 642{
 643        assert_raw_spin_locked(&task_rq(p)->lock);
 644        set_tsk_need_resched(p);
 645}
 646#endif /* CONFIG_SMP */
 647
 648#if defined(CONFIG_RT_GROUP_SCHED) || (defined(CONFIG_FAIR_GROUP_SCHED) && \
 649                        (defined(CONFIG_SMP) || defined(CONFIG_CFS_BANDWIDTH)))
 650/*
 651 * Iterate task_group tree rooted at *from, calling @down when first entering a
 652 * node and @up when leaving it for the final time.
 653 *
 654 * Caller must hold rcu_lock or sufficient equivalent.
 655 */
 656int walk_tg_tree_from(struct task_group *from,
 657                             tg_visitor down, tg_visitor up, void *data)
 658{
 659        struct task_group *parent, *child;
 660        int ret;
 661
 662        parent = from;
 663
 664down:
 665        ret = (*down)(parent, data);
 666        if (ret)
 667                goto out;
 668        list_for_each_entry_rcu(child, &parent->children, siblings) {
 669                parent = child;
 670                goto down;
 671
 672up:
 673                continue;
 674        }
 675        ret = (*up)(parent, data);
 676        if (ret || parent == from)
 677                goto out;
 678
 679        child = parent;
 680        parent = parent->parent;
 681        if (parent)
 682                goto up;
 683out:
 684        return ret;
 685}
 686
 687int tg_nop(struct task_group *tg, void *data)
 688{
 689        return 0;
 690}
 691#endif
 692
 693void update_cpu_load(struct rq *this_rq);
 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
 743#ifdef CONFIG_IRQ_TIME_ACCOUNTING
 744
 745/*
 746 * There are no locks covering percpu hardirq/softirq time.
 747 * They are only modified in account_system_vtime, on corresponding CPU
 748 * with interrupts disabled. So, writes are safe.
 749 * They are read and saved off onto struct rq in update_rq_clock().
 750 * This may result in other CPU reading this CPU's irq time and can
 751 * race with irq/account_system_vtime on this CPU. We would either get old
 752 * or new value with a side effect of accounting a slice of irq time to wrong
 753 * task when irq is in progress while we read rq->clock. That is a worthy
 754 * compromise in place of having locks on each irq in account_system_time.
 755 */
 756static DEFINE_PER_CPU(u64, cpu_hardirq_time);
 757static DEFINE_PER_CPU(u64, cpu_softirq_time);
 758
 759static DEFINE_PER_CPU(u64, irq_start_time);
 760static int sched_clock_irqtime;
 761
 762void enable_sched_clock_irqtime(void)
 763{
 764        sched_clock_irqtime = 1;
 765}
 766
 767void disable_sched_clock_irqtime(void)
 768{
 769        sched_clock_irqtime = 0;
 770}
 771
 772#ifndef CONFIG_64BIT
 773static DEFINE_PER_CPU(seqcount_t, irq_time_seq);
 774
 775static inline void irq_time_write_begin(void)
 776{
 777        __this_cpu_inc(irq_time_seq.sequence);
 778        smp_wmb();
 779}
 780
 781static inline void irq_time_write_end(void)
 782{
 783        smp_wmb();
 784        __this_cpu_inc(irq_time_seq.sequence);
 785}
 786
 787static inline u64 irq_time_read(int cpu)
 788{
 789        u64 irq_time;
 790        unsigned seq;
 791
 792        do {
 793                seq = read_seqcount_begin(&per_cpu(irq_time_seq, cpu));
 794                irq_time = per_cpu(cpu_softirq_time, cpu) +
 795                           per_cpu(cpu_hardirq_time, cpu);
 796        } while (read_seqcount_retry(&per_cpu(irq_time_seq, cpu), seq));
 797
 798        return irq_time;
 799}
 800#else /* CONFIG_64BIT */
 801static inline void irq_time_write_begin(void)
 802{
 803}
 804
 805static inline void irq_time_write_end(void)
 806{
 807}
 808
 809static inline u64 irq_time_read(int cpu)
 810{
 811        return per_cpu(cpu_softirq_time, cpu) + per_cpu(cpu_hardirq_time, cpu);
 812}
 813#endif /* CONFIG_64BIT */
 814
 815/*
 816 * Called before incrementing preempt_count on {soft,}irq_enter
 817 * and before decrementing preempt_count on {soft,}irq_exit.
 818 */
 819void account_system_vtime(struct task_struct *curr)
 820{
 821        unsigned long flags;
 822        s64 delta;
 823        int cpu;
 824
 825        if (!sched_clock_irqtime)
 826                return;
 827
 828        local_irq_save(flags);
 829
 830        cpu = smp_processor_id();
 831        delta = sched_clock_cpu(cpu) - __this_cpu_read(irq_start_time);
 832        __this_cpu_add(irq_start_time, delta);
 833
 834        irq_time_write_begin();
 835        /*
 836         * We do not account for softirq time from ksoftirqd here.
 837         * We want to continue accounting softirq time to ksoftirqd thread
 838         * in that case, so as not to confuse scheduler with a special task
 839         * that do not consume any time, but still wants to run.
 840         */
 841        if (hardirq_count())
 842                __this_cpu_add(cpu_hardirq_time, delta);
 843        else if (in_serving_softirq() && curr != this_cpu_ksoftirqd())
 844                __this_cpu_add(cpu_softirq_time, delta);
 845
 846        irq_time_write_end();
 847        local_irq_restore(flags);
 848}
 849EXPORT_SYMBOL_GPL(account_system_vtime);
 850
 851#endif /* CONFIG_IRQ_TIME_ACCOUNTING */
 852
 853#ifdef CONFIG_PARAVIRT
 854static inline u64 steal_ticks(u64 steal)
 855{
 856        if (unlikely(steal > NSEC_PER_SEC))
 857                return div_u64(steal, TICK_NSEC);
 858
 859        return __iter_div_u64_rem(steal, TICK_NSEC, &steal);
 860}
 861#endif
 862
 863static void update_rq_clock_task(struct rq *rq, s64 delta)
 864{
 865/*
 866 * In theory, the compile should just see 0 here, and optimize out the call
 867 * to sched_rt_avg_update. But I don't trust it...
 868 */
 869#if defined(CONFIG_IRQ_TIME_ACCOUNTING) || defined(CONFIG_PARAVIRT_TIME_ACCOUNTING)
 870        s64 steal = 0, irq_delta = 0;
 871#endif
 872#ifdef CONFIG_IRQ_TIME_ACCOUNTING
 873        irq_delta = irq_time_read(cpu_of(rq)) - rq->prev_irq_time;
 874
 875        /*
 876         * Since irq_time is only updated on {soft,}irq_exit, we might run into
 877         * this case when a previous update_rq_clock() happened inside a
 878         * {soft,}irq region.
 879         *
 880         * When this happens, we stop ->clock_task and only update the
 881         * prev_irq_time stamp to account for the part that fit, so that a next
 882         * update will consume the rest. This ensures ->clock_task is
 883         * monotonic.
 884         *
 885         * It does however cause some slight miss-attribution of {soft,}irq
 886         * time, a more accurate solution would be to update the irq_time using
 887         * the current rq->clock timestamp, except that would require using
 888         * atomic ops.
 889         */
 890        if (irq_delta > delta)
 891                irq_delta = delta;
 892
 893        rq->prev_irq_time += irq_delta;
 894        delta -= irq_delta;
 895#endif
 896#ifdef CONFIG_PARAVIRT_TIME_ACCOUNTING
 897        if (static_branch((&paravirt_steal_rq_enabled))) {
 898                u64 st;
 899
 900                steal = paravirt_steal_clock(cpu_of(rq));
 901                steal -= rq->prev_steal_time_rq;
 902
 903                if (unlikely(steal > delta))
 904                        steal = delta;
 905
 906                st = steal_ticks(steal);
 907                steal = st * TICK_NSEC;
 908
 909                rq->prev_steal_time_rq += steal;
 910
 911                delta -= steal;
 912        }
 913#endif
 914
 915        rq->clock_task += delta;
 916
 917#if defined(CONFIG_IRQ_TIME_ACCOUNTING) || defined(CONFIG_PARAVIRT_TIME_ACCOUNTING)
 918        if ((irq_delta + steal) && sched_feat(NONTASK_POWER))
 919                sched_rt_avg_update(rq, irq_delta + steal);
 920#endif
 921}
 922
 923#ifdef CONFIG_IRQ_TIME_ACCOUNTING
 924static int irqtime_account_hi_update(void)
 925{
 926        u64 *cpustat = kcpustat_this_cpu->cpustat;
 927        unsigned long flags;
 928        u64 latest_ns;
 929        int ret = 0;
 930
 931        local_irq_save(flags);
 932        latest_ns = this_cpu_read(cpu_hardirq_time);
 933        if (nsecs_to_cputime64(latest_ns) > cpustat[CPUTIME_IRQ])
 934                ret = 1;
 935        local_irq_restore(flags);
 936        return ret;
 937}
 938
 939static int irqtime_account_si_update(void)
 940{
 941        u64 *cpustat = kcpustat_this_cpu->cpustat;
 942        unsigned long flags;
 943        u64 latest_ns;
 944        int ret = 0;
 945
 946        local_irq_save(flags);
 947        latest_ns = this_cpu_read(cpu_softirq_time);
 948        if (nsecs_to_cputime64(latest_ns) > cpustat[CPUTIME_SOFTIRQ])
 949                ret = 1;
 950        local_irq_restore(flags);
 951        return ret;
 952}
 953
 954#else /* CONFIG_IRQ_TIME_ACCOUNTING */
 955
 956#define sched_clock_irqtime     (0)
 957
 958#endif
 959
 960void sched_set_stop_task(int cpu, struct task_struct *stop)
 961{
 962        struct sched_param param = { .sched_priority = MAX_RT_PRIO - 1 };
 963        struct task_struct *old_stop = cpu_rq(cpu)->stop;
 964
 965        if (stop) {
 966                /*
 967                 * Make it appear like a SCHED_FIFO task, its something
 968                 * userspace knows about and won't get confused about.
 969                 *
 970                 * Also, it will make PI more or less work without too
 971                 * much confusion -- but then, stop work should not
 972                 * rely on PI working anyway.
 973                 */
 974                sched_setscheduler_nocheck(stop, SCHED_FIFO, &param);
 975
 976                stop->sched_class = &stop_sched_class;
 977        }
 978
 979        cpu_rq(cpu)->stop = stop;
 980
 981        if (old_stop) {
 982                /*
 983                 * Reset it back to a normal scheduling class so that
 984                 * it can die in pieces.
 985                 */
 986                old_stop->sched_class = &rt_sched_class;
 987        }
 988}
 989
 990/*
 991 * __normal_prio - return the priority that is based on the static prio
 992 */
 993static inline int __normal_prio(struct task_struct *p)
 994{
 995        return p->static_prio;
 996}
 997
 998/*
 999 * Calculate the expected normal priority: i.e. priority
1000 * without taking RT-inheritance into account. Might be
1001 * boosted by interactivity modifiers. Changes upon fork,
1002 * setprio syscalls, and whenever the interactivity
1003 * estimator recalculates.
1004 */
1005static inline int normal_prio(struct task_struct *p)
1006{
1007        int prio;
1008
1009        if (task_has_rt_policy(p))
1010                prio = MAX_RT_PRIO-1 - p->rt_priority;
1011        else
1012                prio = __normal_prio(p);
1013        return prio;
1014}
1015
1016/*
1017 * Calculate the current priority, i.e. the priority
1018 * taken into account by the scheduler. This value might
1019 * be boosted by RT tasks, or might be boosted by
1020 * interactivity modifiers. Will be RT if the task got
1021 * RT-boosted. If not then it returns p->normal_prio.
1022 */
1023static int effective_prio(struct task_struct *p)
1024{
1025        p->normal_prio = normal_prio(p);
1026        /*
1027         * If we are RT tasks or we were boosted to RT priority,
1028         * keep the priority unchanged. Otherwise, update priority
1029         * to the normal priority:
1030         */
1031        if (!rt_prio(p->prio))
1032                return p->normal_prio;
1033        return p->prio;
1034}
1035
1036/**
1037 * task_curr - is this task currently executing on a CPU?
1038 * @p: the task in question.
1039 */
1040inline int task_curr(const struct task_struct *p)
1041{
1042        return cpu_curr(task_cpu(p)) == p;
1043}
1044
1045static inline void check_class_changed(struct rq *rq, struct task_struct *p,
1046                                       const struct sched_class *prev_class,
1047                                       int oldprio)
1048{
1049        if (prev_class != p->sched_class) {
1050                if (prev_class->switched_from)
1051                        prev_class->switched_from(rq, p);
1052                p->sched_class->switched_to(rq, p);
1053        } else if (oldprio != p->prio)
1054                p->sched_class->prio_changed(rq, p, oldprio);
1055}
1056
1057void check_preempt_curr(struct rq *rq, struct task_struct *p, int flags)
1058{
1059        const struct sched_class *class;
1060
1061        if (p->sched_class == rq->curr->sched_class) {
1062                rq->curr->sched_class->check_preempt_curr(rq, p, flags);
1063        } else {
1064                for_each_class(class) {
1065                        if (class == rq->curr->sched_class)
1066                                break;
1067                        if (class == p->sched_class) {
1068                                resched_task(rq->curr);
1069                                break;
1070                        }
1071                }
1072        }
1073
1074        /*
1075         * A queue event has occurred, and we're going to schedule.  In
1076         * this case, we can save a useless back to back clock update.
1077         */
1078        if (rq->curr->on_rq && test_tsk_need_resched(rq->curr))
1079                rq->skip_clock_update = 1;
1080}
1081
1082#ifdef CONFIG_SMP
1083void set_task_cpu(struct task_struct *p, unsigned int new_cpu)
1084{
1085#ifdef CONFIG_SCHED_DEBUG
1086        /*
1087         * We should never call set_task_cpu() on a blocked task,
1088         * ttwu() will sort out the placement.
1089         */
1090        WARN_ON_ONCE(p->state != TASK_RUNNING && p->state != TASK_WAKING &&
1091                        !(task_thread_info(p)->preempt_count & PREEMPT_ACTIVE));
1092
1093#ifdef CONFIG_LOCKDEP
1094        /*
1095         * The caller should hold either p->pi_lock or rq->lock, when changing
1096         * a task's CPU. ->pi_lock for waking tasks, rq->lock for runnable tasks.
1097         *
1098         * sched_move_task() holds both and thus holding either pins the cgroup,
1099         * see set_task_rq().
1100         *
1101         * Furthermore, all task_rq users should acquire both locks, see
1102         * task_rq_lock().
1103         */
1104        WARN_ON_ONCE(debug_locks && !(lockdep_is_held(&p->pi_lock) ||
1105                                      lockdep_is_held(&task_rq(p)->lock)));
1106#endif
1107#endif
1108
1109        trace_sched_migrate_task(p, new_cpu);
1110
1111        if (task_cpu(p) != new_cpu) {
1112                p->se.nr_migrations++;
1113                perf_sw_event(PERF_COUNT_SW_CPU_MIGRATIONS, 1, NULL, 0);
1114        }
1115
1116        __set_task_cpu(p, new_cpu);
1117}
1118
1119struct migration_arg {
1120        struct task_struct *task;
1121        int dest_cpu;
1122};
1123
1124static int migration_cpu_stop(void *data);
1125
1126/*
1127 * wait_task_inactive - wait for a thread to unschedule.
1128 *
1129 * If @match_state is nonzero, it's the @p->state value just checked and
1130 * not expected to change.  If it changes, i.e. @p might have woken up,
1131 * then return zero.  When we succeed in waiting for @p to be off its CPU,
1132 * we return a positive number (its total switch count).  If a second call
1133 * a short while later returns the same number, the caller can be sure that
1134 * @p has remained unscheduled the whole time.
1135 *
1136 * The caller must ensure that the task *will* unschedule sometime soon,
1137 * else this function might spin for a *long* time. This function can't
1138 * be called with interrupts off, or it may introduce deadlock with
1139 * smp_call_function() if an IPI is sent by the same process we are
1140 * waiting to become inactive.
1141 */
1142unsigned long wait_task_inactive(struct task_struct *p, long match_state)
1143{
1144        unsigned long flags;
1145        int running, on_rq;
1146        unsigned long ncsw;
1147        struct rq *rq;
1148
1149        for (;;) {
1150                /*
1151                 * We do the initial early heuristics without holding
1152                 * any task-queue locks at all. We'll only try to get
1153                 * the runqueue lock when things look like they will
1154                 * work out!
1155                 */
1156                rq = task_rq(p);
1157
1158                /*
1159                 * If the task is actively running on another CPU
1160                 * still, just relax and busy-wait without holding
1161                 * any locks.
1162                 *
1163                 * NOTE! Since we don't hold any locks, it's not
1164                 * even sure that "rq" stays as the right runqueue!
1165                 * But we don't care, since "task_running()" will
1166                 * return false if the runqueue has changed and p
1167                 * is actually now running somewhere else!
1168                 */
1169                while (task_running(rq, p)) {
1170                        if (match_state && unlikely(p->state != match_state))
1171                                return 0;
1172                        cpu_relax();
1173                }
1174
1175                /*
1176                 * Ok, time to look more closely! We need the rq
1177                 * lock now, to be *sure*. If we're wrong, we'll
1178                 * just go back and repeat.
1179                 */
1180                rq = task_rq_lock(p, &flags);
1181                trace_sched_wait_task(p);
1182                running = task_running(rq, p);
1183                on_rq = p->on_rq;
1184                ncsw = 0;
1185                if (!match_state || p->state == match_state)
1186                        ncsw = p->nvcsw | LONG_MIN; /* sets MSB */
1187                task_rq_unlock(rq, p, &flags);
1188
1189                /*
1190                 * If it changed from the expected state, bail out now.
1191                 */
1192                if (unlikely(!ncsw))
1193                        break;
1194
1195                /*
1196                 * Was it really running after all now that we
1197                 * checked with the proper locks actually held?
1198                 *
1199                 * Oops. Go back and try again..
1200                 */
1201                if (unlikely(running)) {
1202                        cpu_relax();
1203                        continue;
1204                }
1205
1206                /*
1207                 * It's not enough that it's not actively running,
1208                 * it must be off the runqueue _entirely_, and not
1209                 * preempted!
1210                 *
1211                 * So if it was still runnable (but just not actively
1212                 * running right now), it's preempted, and we should
1213                 * yield - it could be a while.
1214                 */
1215                if (unlikely(on_rq)) {
1216                        ktime_t to = ktime_set(0, NSEC_PER_SEC/HZ);
1217
1218                        set_current_state(TASK_UNINTERRUPTIBLE);
1219                        schedule_hrtimeout(&to, HRTIMER_MODE_REL);
1220                        continue;
1221                }
1222
1223                /*
1224                 * Ahh, all good. It wasn't running, and it wasn't
1225                 * runnable, which means that it will never become
1226                 * running in the future either. We're all done!
1227                 */
1228                break;
1229        }
1230
1231        return ncsw;
1232}
1233
1234/***
1235 * kick_process - kick a running thread to enter/exit the kernel
1236 * @p: the to-be-kicked thread
1237 *
1238 * Cause a process which is running on another CPU to enter
1239 * kernel-mode, without any delay. (to get signals handled.)
1240 *
1241 * NOTE: this function doesn't have to take the runqueue lock,
1242 * because all it wants to ensure is that the remote task enters
1243 * the kernel. If the IPI races and the task has been migrated
1244 * to another CPU then no harm is done and the purpose has been
1245 * achieved as well.
1246 */
1247void kick_process(struct task_struct *p)
1248{
1249        int cpu;
1250
1251        preempt_disable();
1252        cpu = task_cpu(p);
1253        if ((cpu != smp_processor_id()) && task_curr(p))
1254                smp_send_reschedule(cpu);
1255        preempt_enable();
1256}
1257EXPORT_SYMBOL_GPL(kick_process);
1258#endif /* CONFIG_SMP */
1259
1260#ifdef CONFIG_SMP
1261/*
1262 * ->cpus_allowed is protected by both rq->lock and p->pi_lock
1263 */
1264static int select_fallback_rq(int cpu, struct task_struct *p)
1265{
1266        int dest_cpu;
1267        const struct cpumask *nodemask = cpumask_of_node(cpu_to_node(cpu));
1268
1269        /* Look for allowed, online CPU in same node. */
1270        for_each_cpu_and(dest_cpu, nodemask, cpu_active_mask)
1271                if (cpumask_test_cpu(dest_cpu, tsk_cpus_allowed(p)))
1272                        return dest_cpu;
1273
1274        /* Any allowed, online CPU? */
1275        dest_cpu = cpumask_any_and(tsk_cpus_allowed(p), cpu_active_mask);
1276        if (dest_cpu < nr_cpu_ids)
1277                return dest_cpu;
1278
1279        /* No more Mr. Nice Guy. */
1280        dest_cpu = cpuset_cpus_allowed_fallback(p);
1281        /*
1282         * Don't tell them about moving exiting tasks or
1283         * kernel threads (both mm NULL), since they never
1284         * leave kernel.
1285         */
1286        if (p->mm && printk_ratelimit()) {
1287                printk(KERN_INFO "process %d (%s) no longer affine to cpu%d\n",
1288                                task_pid_nr(p), p->comm, cpu);
1289        }
1290
1291        return dest_cpu;
1292}
1293
1294/*
1295 * The caller (fork, wakeup) owns p->pi_lock, ->cpus_allowed is stable.
1296 */
1297static inline
1298int select_task_rq(struct task_struct *p, int sd_flags, int wake_flags)
1299{
1300        int cpu = p->sched_class->select_task_rq(p, sd_flags, wake_flags);
1301
1302        /*
1303         * In order not to call set_task_cpu() on a blocking task we need
1304         * to rely on ttwu() to place the task on a valid ->cpus_allowed
1305         * cpu.
1306         *
1307         * Since this is common to all placement strategies, this lives here.
1308         *
1309         * [ this allows ->select_task() to simply return task_cpu(p) and
1310         *   not worry about this generic constraint ]
1311         */
1312        if (unlikely(!cpumask_test_cpu(cpu, tsk_cpus_allowed(p)) ||
1313                     !cpu_online(cpu)))
1314                cpu = select_fallback_rq(task_cpu(p), p);
1315
1316        return cpu;
1317}
1318
1319static void update_avg(u64 *avg, u64 sample)
1320{
1321        s64 diff = sample - *avg;
1322        *avg += diff >> 3;
1323}
1324#endif
1325
1326static void
1327ttwu_stat(struct task_struct *p, int cpu, int wake_flags)
1328{
1329#ifdef CONFIG_SCHEDSTATS
1330        struct rq *rq = this_rq();
1331
1332#ifdef CONFIG_SMP
1333        int this_cpu = smp_processor_id();
1334
1335        if (cpu == this_cpu) {
1336                schedstat_inc(rq, ttwu_local);
1337                schedstat_inc(p, se.statistics.nr_wakeups_local);
1338        } else {
1339                struct sched_domain *sd;
1340
1341                schedstat_inc(p, se.statistics.nr_wakeups_remote);
1342                rcu_read_lock();
1343                for_each_domain(this_cpu, sd) {
1344                        if (cpumask_test_cpu(cpu, sched_domain_span(sd))) {
1345                                schedstat_inc(sd, ttwu_wake_remote);
1346                                break;
1347                        }
1348                }
1349                rcu_read_unlock();
1350        }
1351
1352        if (wake_flags & WF_MIGRATED)
1353                schedstat_inc(p, se.statistics.nr_wakeups_migrate);
1354
1355#endif /* CONFIG_SMP */
1356
1357        schedstat_inc(rq, ttwu_count);
1358        schedstat_inc(p, se.statistics.nr_wakeups);
1359
1360        if (wake_flags & WF_SYNC)
1361                schedstat_inc(p, se.statistics.nr_wakeups_sync);
1362
1363#endif /* CONFIG_SCHEDSTATS */
1364}
1365
1366static void ttwu_activate(struct rq *rq, struct task_struct *p, int en_flags)
1367{
1368        activate_task(rq, p, en_flags);
1369        p->on_rq = 1;
1370
1371        /* if a worker is waking up, notify workqueue */
1372        if (p->flags & PF_WQ_WORKER)
1373                wq_worker_waking_up(p, cpu_of(rq));
1374}
1375
1376/*
1377 * Mark the task runnable and perform wakeup-preemption.
1378 */
1379static void
1380ttwu_do_wakeup(struct rq *rq, struct task_struct *p, int wake_flags)
1381{
1382        trace_sched_wakeup(p, true);
1383        check_preempt_curr(rq, p, wake_flags);
1384
1385        p->state = TASK_RUNNING;
1386#ifdef CONFIG_SMP
1387        if (p->sched_class->task_woken)
1388                p->sched_class->task_woken(rq, p);
1389
1390        if (rq->idle_stamp) {
1391                u64 delta = rq->clock - rq->idle_stamp;
1392                u64 max = 2*sysctl_sched_migration_cost;
1393
1394                if (delta > max)
1395                        rq->avg_idle = max;
1396                else
1397                        update_avg(&rq->avg_idle, delta);
1398                rq->idle_stamp = 0;
1399        }
1400#endif
1401}
1402
1403static void
1404ttwu_do_activate(struct rq *rq, struct task_struct *p, int wake_flags)
1405{
1406#ifdef CONFIG_SMP
1407        if (p->sched_contributes_to_load)
1408                rq->nr_uninterruptible--;
1409#endif
1410
1411        ttwu_activate(rq, p, ENQUEUE_WAKEUP | ENQUEUE_WAKING);
1412        ttwu_do_wakeup(rq, p, wake_flags);
1413}
1414
1415/*
1416 * Called in case the task @p isn't fully descheduled from its runqueue,
1417 * in this case we must do a remote wakeup. Its a 'light' wakeup though,
1418 * since all we need to do is flip p->state to TASK_RUNNING, since
1419 * the task is still ->on_rq.
1420 */
1421static int ttwu_remote(struct task_struct *p, int wake_flags)
1422{
1423        struct rq *rq;
1424        int ret = 0;
1425
1426        rq = __task_rq_lock(p);
1427        if (p->on_rq) {
1428                ttwu_do_wakeup(rq, p, wake_flags);
1429                ret = 1;
1430        }
1431        __task_rq_unlock(rq);
1432
1433        return ret;
1434}
1435
1436#ifdef CONFIG_SMP
1437static void sched_ttwu_pending(void)
1438{
1439        struct rq *rq = this_rq();
1440        struct llist_node *llist = llist_del_all(&rq->wake_list);
1441        struct task_struct *p;
1442
1443        raw_spin_lock(&rq->lock);
1444
1445        while (llist) {
1446                p = llist_entry(llist, struct task_struct, wake_entry);
1447                llist = llist_next(llist);
1448                ttwu_do_activate(rq, p, 0);
1449        }
1450
1451        raw_spin_unlock(&rq->lock);
1452}
1453
1454void scheduler_ipi(void)
1455{
1456        if (llist_empty(&this_rq()->wake_list) && !got_nohz_idle_kick())
1457                return;
1458
1459        /*
1460         * Not all reschedule IPI handlers call irq_enter/irq_exit, since
1461         * traditionally all their work was done from the interrupt return
1462         * path. Now that we actually do some work, we need to make sure
1463         * we do call them.
1464         *
1465         * Some archs already do call them, luckily irq_enter/exit nest
1466         * properly.
1467         *
1468         * Arguably we should visit all archs and update all handlers,
1469         * however a fair share of IPIs are still resched only so this would
1470         * somewhat pessimize the simple resched case.
1471         */
1472        irq_enter();
1473        sched_ttwu_pending();
1474
1475        /*
1476         * Check if someone kicked us for doing the nohz idle load balance.
1477         */
1478        if (unlikely(got_nohz_idle_kick() && !need_resched())) {
1479                this_rq()->idle_balance = 1;
1480                raise_softirq_irqoff(SCHED_SOFTIRQ);
1481        }
1482        irq_exit();
1483}
1484
1485static void ttwu_queue_remote(struct task_struct *p, int cpu)
1486{
1487        if (llist_add(&p->wake_entry, &cpu_rq(cpu)->wake_list))
1488                smp_send_reschedule(cpu);
1489}
1490
1491#ifdef __ARCH_WANT_INTERRUPTS_ON_CTXSW
1492static int ttwu_activate_remote(struct task_struct *p, int wake_flags)
1493{
1494        struct rq *rq;
1495        int ret = 0;
1496
1497        rq = __task_rq_lock(p);
1498        if (p->on_cpu) {
1499                ttwu_activate(rq, p, ENQUEUE_WAKEUP);
1500                ttwu_do_wakeup(rq, p, wake_flags);
1501                ret = 1;
1502        }
1503        __task_rq_unlock(rq);
1504
1505        return ret;
1506
1507}
1508#endif /* __ARCH_WANT_INTERRUPTS_ON_CTXSW */
1509
1510static inline int ttwu_share_cache(int this_cpu, int that_cpu)
1511{
1512        return per_cpu(sd_llc_id, this_cpu) == per_cpu(sd_llc_id, that_cpu);
1513}
1514#endif /* CONFIG_SMP */
1515
1516static void ttwu_queue(struct task_struct *p, int cpu)
1517{
1518        struct rq *rq = cpu_rq(cpu);
1519
1520#if defined(CONFIG_SMP)
1521        if (sched_feat(TTWU_QUEUE) && !ttwu_share_cache(smp_processor_id(), cpu)) {
1522                sched_clock_cpu(cpu); /* sync clocks x-cpu */
1523                ttwu_queue_remote(p, cpu);
1524                return;
1525        }
1526#endif
1527
1528        raw_spin_lock(&rq->lock);
1529        ttwu_do_activate(rq, p, 0);
1530        raw_spin_unlock(&rq->lock);
1531}
1532
1533/**
1534 * try_to_wake_up - wake up a thread
1535 * @p: the thread to be awakened
1536 * @state: the mask of task states that can be woken
1537 * @wake_flags: wake modifier flags (WF_*)
1538 *
1539 * Put it on the run-queue if it's not already there. The "current"
1540 * thread is always on the run-queue (except when the actual
1541 * re-schedule is in progress), and as such you're allowed to do
1542 * the simpler "current->state = TASK_RUNNING" to mark yourself
1543 * runnable without the overhead of this.
1544 *
1545 * Returns %true if @p was woken up, %false if it was already running
1546 * or @state didn't match @p's state.
1547 */
1548static int
1549try_to_wake_up(struct task_struct *p, unsigned int state, int wake_flags)
1550{
1551        unsigned long flags;
1552        int cpu, success = 0;
1553
1554        smp_wmb();
1555        raw_spin_lock_irqsave(&p->pi_lock, flags);
1556        if (!(p->state & state))
1557                goto out;
1558
1559        success = 1; /* we're going to change ->state */
1560        cpu = task_cpu(p);
1561
1562        if (p->on_rq && ttwu_remote(p, wake_flags))
1563                goto stat;
1564
1565#ifdef CONFIG_SMP
1566        /*
1567         * If the owning (remote) cpu is still in the middle of schedule() with
1568         * this task as prev, wait until its done referencing the task.
1569         */
1570        while (p->on_cpu) {
1571#ifdef __ARCH_WANT_INTERRUPTS_ON_CTXSW
1572                /*
1573                 * In case the architecture enables interrupts in
1574                 * context_switch(), we cannot busy wait, since that
1575                 * would lead to deadlocks when an interrupt hits and
1576                 * tries to wake up @prev. So bail and do a complete
1577                 * remote wakeup.
1578                 */
1579                if (ttwu_activate_remote(p, wake_flags))
1580                        goto stat;
1581#else
1582                cpu_relax();
1583#endif
1584        }
1585        /*
1586         * Pairs with the smp_wmb() in finish_lock_switch().
1587         */
1588        smp_rmb();
1589
1590        p->sched_contributes_to_load = !!task_contributes_to_load(p);
1591        p->state = TASK_WAKING;
1592
1593        if (p->sched_class->task_waking)
1594                p->sched_class->task_waking(p);
1595
1596        cpu = select_task_rq(p, SD_BALANCE_WAKE, wake_flags);
1597        if (task_cpu(p) != cpu) {
1598                wake_flags |= WF_MIGRATED;
1599                set_task_cpu(p, cpu);
1600        }
1601#endif /* CONFIG_SMP */
1602
1603        ttwu_queue(p, cpu);
1604stat:
1605        ttwu_stat(p, cpu, wake_flags);
1606out:
1607        raw_spin_unlock_irqrestore(&p->pi_lock, flags);
1608
1609        return success;
1610}
1611
1612/**
1613 * try_to_wake_up_local - try to wake up a local task with rq lock held
1614 * @p: the thread to be awakened
1615 *
1616 * Put @p on the run-queue if it's not already there. The caller must
1617 * ensure that this_rq() is locked, @p is bound to this_rq() and not
1618 * the current task.
1619 */
1620static void try_to_wake_up_local(struct task_struct *p)
1621{
1622        struct rq *rq = task_rq(p);
1623
1624        BUG_ON(rq != this_rq());
1625        BUG_ON(p == current);
1626        lockdep_assert_held(&rq->lock);
1627
1628        if (!raw_spin_trylock(&p->pi_lock)) {
1629                raw_spin_unlock(&rq->lock);
1630                raw_spin_lock(&p->pi_lock);
1631                raw_spin_lock(&rq->lock);
1632        }
1633
1634        if (!(p->state & TASK_NORMAL))
1635                goto out;
1636
1637        if (!p->on_rq)
1638                ttwu_activate(rq, p, ENQUEUE_WAKEUP);
1639
1640        ttwu_do_wakeup(rq, p, 0);
1641        ttwu_stat(p, smp_processor_id(), 0);
1642out:
1643        raw_spin_unlock(&p->pi_lock);
1644}
1645
1646/**
1647 * wake_up_process - Wake up a specific process
1648 * @p: The process to be woken up.
1649 *
1650 * Attempt to wake up the nominated process and move it to the set of runnable
1651 * processes.  Returns 1 if the process was woken up, 0 if it was already
1652 * running.
1653 *
1654 * It may be assumed that this function implies a write memory barrier before
1655 * changing the task state if and only if any tasks are woken up.
1656 */
1657int wake_up_process(struct task_struct *p)
1658{
1659        return try_to_wake_up(p, TASK_ALL, 0);
1660}
1661EXPORT_SYMBOL(wake_up_process);
1662
1663int wake_up_state(struct task_struct *p, unsigned int state)
1664{
1665        return try_to_wake_up(p, state, 0);
1666}
1667
1668/*
1669 * Perform scheduler related setup for a newly forked process p.
1670 * p is forked by current.
1671 *
1672 * __sched_fork() is basic setup used by init_idle() too:
1673 */
1674static void __sched_fork(struct task_struct *p)
1675{
1676        p->on_rq                        = 0;
1677
1678        p->se.on_rq                     = 0;
1679        p->se.exec_start                = 0;
1680        p->se.sum_exec_runtime          = 0;
1681        p->se.prev_sum_exec_runtime     = 0;
1682        p->se.nr_migrations             = 0;
1683        p->se.vruntime                  = 0;
1684        INIT_LIST_HEAD(&p->se.group_node);
1685
1686#ifdef CONFIG_SCHEDSTATS
1687        memset(&p->se.statistics, 0, sizeof(p->se.statistics));
1688#endif
1689
1690        INIT_LIST_HEAD(&p->rt.run_list);
1691
1692#ifdef CONFIG_PREEMPT_NOTIFIERS
1693        INIT_HLIST_HEAD(&p->preempt_notifiers);
1694#endif
1695}
1696
1697/*
1698 * fork()/clone()-time setup:
1699 */
1700void sched_fork(struct task_struct *p)
1701{
1702        unsigned long flags;
1703        int cpu = get_cpu();
1704
1705        __sched_fork(p);
1706        /*
1707         * We mark the process as running here. This guarantees that
1708         * nobody will actually run it, and a signal or other external
1709         * event cannot wake it up and insert it on the runqueue either.
1710         */
1711        p->state = TASK_RUNNING;
1712
1713        /*
1714         * Make sure we do not leak PI boosting priority to the child.
1715         */
1716        p->prio = current->normal_prio;
1717
1718        /*
1719         * Revert to default priority/policy on fork if requested.
1720         */
1721        if (unlikely(p->sched_reset_on_fork)) {
1722                if (task_has_rt_policy(p)) {
1723                        p->policy = SCHED_NORMAL;
1724                        p->static_prio = NICE_TO_PRIO(0);
1725                        p->rt_priority = 0;
1726                } else if (PRIO_TO_NICE(p->static_prio) < 0)
1727                        p->static_prio = NICE_TO_PRIO(0);
1728
1729                p->prio = p->normal_prio = __normal_prio(p);
1730                set_load_weight(p);
1731
1732                /*
1733                 * We don't need the reset flag anymore after the fork. It has
1734                 * fulfilled its duty:
1735                 */
1736                p->sched_reset_on_fork = 0;
1737        }
1738
1739        if (!rt_prio(p->prio))
1740                p->sched_class = &fair_sched_class;
1741
1742        if (p->sched_class->task_fork)
1743                p->sched_class->task_fork(p);
1744
1745        /*
1746         * The child is not yet in the pid-hash so no cgroup attach races,
1747         * and the cgroup is pinned to this child due to cgroup_fork()
1748         * is ran before sched_fork().
1749         *
1750         * Silence PROVE_RCU.
1751         */
1752        raw_spin_lock_irqsave(&p->pi_lock, flags);
1753        set_task_cpu(p, cpu);
1754        raw_spin_unlock_irqrestore(&p->pi_lock, flags);
1755
1756#if defined(CONFIG_SCHEDSTATS) || defined(CONFIG_TASK_DELAY_ACCT)
1757        if (likely(sched_info_on()))
1758                memset(&p->sched_info, 0, sizeof(p->sched_info));
1759#endif
1760#if defined(CONFIG_SMP)
1761        p->on_cpu = 0;
1762#endif
1763#ifdef CONFIG_PREEMPT_COUNT
1764        /* Want to start with kernel preemption disabled. */
1765        task_thread_info(p)->preempt_count = 1;
1766#endif
1767#ifdef CONFIG_SMP
1768        plist_node_init(&p->pushable_tasks, MAX_PRIO);
1769#endif
1770
1771        put_cpu();
1772}
1773
1774/*
1775 * wake_up_new_task - wake up a newly created task for the first time.
1776 *
1777 * This function will do some initial scheduler statistics housekeeping
1778 * that must be done for every newly created context, then puts the task
1779 * on the runqueue and wakes it.
1780 */
1781void wake_up_new_task(struct task_struct *p)
1782{
1783        unsigned long flags;
1784        struct rq *rq;
1785
1786        raw_spin_lock_irqsave(&p->pi_lock, flags);
1787#ifdef CONFIG_SMP
1788        /*
1789         * Fork balancing, do it here and not earlier because:
1790         *  - cpus_allowed can change in the fork path
1791         *  - any previously selected cpu might disappear through hotplug
1792         */
1793        set_task_cpu(p, select_task_rq(p, SD_BALANCE_FORK, 0));
1794#endif
1795
1796        rq = __task_rq_lock(p);
1797        activate_task(rq, p, 0);
1798        p->on_rq = 1;
1799        trace_sched_wakeup_new(p, true);
1800        check_preempt_curr(rq, p, WF_FORK);
1801#ifdef CONFIG_SMP
1802        if (p->sched_class->task_woken)
1803                p->sched_class->task_woken(rq, p);
1804#endif
1805        task_rq_unlock(rq, p, &flags);
1806}
1807
1808#ifdef CONFIG_PREEMPT_NOTIFIERS
1809
1810/**
1811 * preempt_notifier_register - tell me when current is being preempted & rescheduled
1812 * @notifier: notifier struct to register
1813 */
1814void preempt_notifier_register(struct preempt_notifier *notifier)
1815{
1816        hlist_add_head(&notifier->link, &current->preempt_notifiers);
1817}
1818EXPORT_SYMBOL_GPL(preempt_notifier_register);
1819
1820/**
1821 * preempt_notifier_unregister - no longer interested in preemption notifications
1822 * @notifier: notifier struct to unregister
1823 *
1824 * This is safe to call from within a preemption notifier.
1825 */
1826void preempt_notifier_unregister(struct preempt_notifier *notifier)
1827{
1828        hlist_del(&notifier->link);
1829}
1830EXPORT_SYMBOL_GPL(preempt_notifier_unregister);
1831
1832static void fire_sched_in_preempt_notifiers(struct task_struct *curr)
1833{
1834        struct preempt_notifier *notifier;
1835        struct hlist_node *node;
1836
1837        hlist_for_each_entry(notifier, node, &curr->preempt_notifiers, link)
1838                notifier->ops->sched_in(notifier, raw_smp_processor_id());
1839}
1840
1841static void
1842fire_sched_out_preempt_notifiers(struct task_struct *curr,
1843                                 struct task_struct *next)
1844{
1845        struct preempt_notifier *notifier;
1846        struct hlist_node *node;
1847
1848        hlist_for_each_entry(notifier, node, &curr->preempt_notifiers, link)
1849                notifier->ops->sched_out(notifier, next);
1850}
1851
1852#else /* !CONFIG_PREEMPT_NOTIFIERS */
1853
1854static void fire_sched_in_preempt_notifiers(struct task_struct *curr)
1855{
1856}
1857
1858static void
1859fire_sched_out_preempt_notifiers(struct task_struct *curr,
1860                                 struct task_struct *next)
1861{
1862}
1863
1864#endif /* CONFIG_PREEMPT_NOTIFIERS */
1865
1866/**
1867 * prepare_task_switch - prepare to switch tasks
1868 * @rq: the runqueue preparing to switch
1869 * @prev: the current task that is being switched out
1870 * @next: the task we are going to switch to.
1871 *
1872 * This is called with the rq lock held and interrupts off. It must
1873 * be paired with a subsequent finish_task_switch after the context
1874 * switch.
1875 *
1876 * prepare_task_switch sets up locking and calls architecture specific
1877 * hooks.
1878 */
1879static inline void
1880prepare_task_switch(struct rq *rq, struct task_struct *prev,
1881                    struct task_struct *next)
1882{
1883        sched_info_switch(prev, next);
1884        perf_event_task_sched_out(prev, next);
1885        fire_sched_out_preempt_notifiers(prev, next);
1886        prepare_lock_switch(rq, next);
1887        prepare_arch_switch(next);
1888        trace_sched_switch(prev, next);
1889}
1890
1891/**
1892 * finish_task_switch - clean up after a task-switch
1893 * @rq: runqueue associated with task-switch
1894 * @prev: the thread we just switched away from.
1895 *
1896 * finish_task_switch must be called after the context switch, paired
1897 * with a prepare_task_switch call before the context switch.
1898 * finish_task_switch will reconcile locking set up by prepare_task_switch,
1899 * and do any other architecture-specific cleanup actions.
1900 *
1901 * Note that we may have delayed dropping an mm in context_switch(). If
1902 * so, we finish that here outside of the runqueue lock. (Doing it
1903 * with the lock held can cause deadlocks; see schedule() for
1904 * details.)
1905 */
1906static void finish_task_switch(struct rq *rq, struct task_struct *prev)
1907        __releases(rq->lock)
1908{
1909        struct mm_struct *mm = rq->prev_mm;
1910        long prev_state;
1911
1912        rq->prev_mm = NULL;
1913
1914        /*
1915         * A task struct has one reference for the use as "current".
1916         * If a task dies, then it sets TASK_DEAD in tsk->state and calls
1917         * schedule one last time. The schedule call will never return, and
1918         * the scheduled task must drop that reference.
1919         * The test for TASK_DEAD must occur while the runqueue locks are
1920         * still held, otherwise prev could be scheduled on another cpu, die
1921         * there before we look at prev->state, and then the reference would
1922         * be dropped twice.
1923         *              Manfred Spraul <manfred@colorfullife.com>
1924         */
1925        prev_state = prev->state;
1926        finish_arch_switch(prev);
1927#ifdef __ARCH_WANT_INTERRUPTS_ON_CTXSW
1928        local_irq_disable();
1929#endif /* __ARCH_WANT_INTERRUPTS_ON_CTXSW */
1930        perf_event_task_sched_in(prev, current);
1931#ifdef __ARCH_WANT_INTERRUPTS_ON_CTXSW
1932        local_irq_enable();
1933#endif /* __ARCH_WANT_INTERRUPTS_ON_CTXSW */
1934        finish_lock_switch(rq, prev);
1935
1936        fire_sched_in_preempt_notifiers(current);
1937        if (mm)
1938                mmdrop(mm);
1939        if (unlikely(prev_state == TASK_DEAD)) {
1940                /*
1941                 * Remove function-return probe instances associated with this
1942                 * task and put them back on the free list.
1943                 */
1944                kprobe_flush_task(prev);
1945                put_task_struct(prev);
1946        }
1947}
1948
1949#ifdef CONFIG_SMP
1950
1951/* assumes rq->lock is held */
1952static inline void pre_schedule(struct rq *rq, struct task_struct *prev)
1953{
1954        if (prev->sched_class->pre_schedule)
1955                prev->sched_class->pre_schedule(rq, prev);
1956}
1957
1958/* rq->lock is NOT held, but preemption is disabled */
1959static inline void post_schedule(struct rq *rq)
1960{
1961        if (rq->post_schedule) {
1962                unsigned long flags;
1963
1964                raw_spin_lock_irqsave(&rq->lock, flags);
1965                if (rq->curr->sched_class->post_schedule)
1966                        rq->curr->sched_class->post_schedule(rq);
1967                raw_spin_unlock_irqrestore(&rq->lock, flags);
1968
1969                rq->post_schedule = 0;
1970        }
1971}
1972
1973#else
1974
1975static inline void pre_schedule(struct rq *rq, struct task_struct *p)
1976{
1977}
1978
1979static inline void post_schedule(struct rq *rq)
1980{
1981}
1982
1983#endif
1984
1985/**
1986 * schedule_tail - first thing a freshly forked thread must call.
1987 * @prev: the thread we just switched away from.
1988 */
1989asmlinkage void schedule_tail(struct task_struct *prev)
1990        __releases(rq->lock)
1991{
1992        struct rq *rq = this_rq();
1993
1994        finish_task_switch(rq, prev);
1995
1996        /*
1997         * FIXME: do we need to worry about rq being invalidated by the
1998         * task_switch?
1999         */
2000        post_schedule(rq);
2001
2002#ifdef __ARCH_WANT_UNLOCKED_CTXSW
2003        /* In this case, finish_task_switch does not reenable preemption */
2004        preempt_enable();
2005#endif
2006        if (current->set_child_tid)
2007                put_user(task_pid_vnr(current), current->set_child_tid);
2008}
2009
2010/*
2011 * context_switch - switch to the new MM and the new
2012 * thread's register state.
2013 */
2014static inline void
2015context_switch(struct rq *rq, struct task_struct *prev,
2016               struct task_struct *next)
2017{
2018        struct mm_struct *mm, *oldmm;
2019
2020        prepare_task_switch(rq, prev, next);
2021
2022        mm = next->mm;
2023        oldmm = prev->active_mm;
2024        /*
2025         * For paravirt, this is coupled with an exit in switch_to to
2026         * combine the page table reload and the switch backend into
2027         * one hypercall.
2028         */
2029        arch_start_context_switch(prev);
2030
2031        if (!mm) {
2032                next->active_mm = oldmm;
2033                atomic_inc(&oldmm->mm_count);
2034                enter_lazy_tlb(oldmm, next);
2035        } else
2036                switch_mm(oldmm, mm, next);
2037
2038        if (!prev->mm) {
2039                prev->active_mm = NULL;
2040                rq->prev_mm = oldmm;
2041        }
2042        /*
2043         * Since the runqueue lock will be released by the next
2044         * task (which is an invalid locking op but in the case
2045         * of the scheduler it's an obvious special-case), so we
2046         * do an early lockdep release here:
2047         */
2048#ifndef __ARCH_WANT_UNLOCKED_CTXSW
2049        spin_release(&rq->lock.dep_map, 1, _THIS_IP_);
2050#endif
2051
2052        /* Here we just switch the register state and the stack. */
2053        switch_to(prev, next, prev);
2054
2055        barrier();
2056        /*
2057         * this_rq must be evaluated again because prev may have moved
2058         * CPUs since it called schedule(), thus the 'rq' on its stack
2059         * frame will be invalid.
2060         */
2061        finish_task_switch(this_rq(), prev);
2062}
2063
2064/*
2065 * nr_running, nr_uninterruptible and nr_context_switches:
2066 *
2067 * externally visible scheduler statistics: current number of runnable
2068 * threads, current number of uninterruptible-sleeping threads, total
2069 * number of context switches performed since bootup.
2070 */
2071unsigned long nr_running(void)
2072{
2073        unsigned long i, sum = 0;
2074
2075        for_each_online_cpu(i)
2076                sum += cpu_rq(i)->nr_running;
2077
2078        return sum;
2079}
2080
2081unsigned long nr_uninterruptible(void)
2082{
2083        unsigned long i, sum = 0;
2084
2085        for_each_possible_cpu(i)
2086                sum += cpu_rq(i)->nr_uninterruptible;
2087
2088        /*
2089         * Since we read the counters lockless, it might be slightly
2090         * inaccurate. Do not allow it to go below zero though:
2091         */
2092        if (unlikely((long)sum < 0))
2093                sum = 0;
2094
2095        return sum;
2096}
2097
2098unsigned long long nr_context_switches(void)
2099{
2100        int i;
2101        unsigned long long sum = 0;
2102
2103        for_each_possible_cpu(i)
2104                sum += cpu_rq(i)->nr_switches;
2105
2106        return sum;
2107}
2108
2109unsigned long nr_iowait(void)
2110{
2111        unsigned long i, sum = 0;
2112
2113        for_each_possible_cpu(i)
2114                sum += atomic_read(&cpu_rq(i)->nr_iowait);
2115
2116        return sum;
2117}
2118
2119unsigned long nr_iowait_cpu(int cpu)
2120{
2121        struct rq *this = cpu_rq(cpu);
2122        return atomic_read(&this->nr_iowait);
2123}
2124
2125unsigned long this_cpu_load(void)
2126{
2127        struct rq *this = this_rq();
2128        return this->cpu_load[0];
2129}
2130
2131
2132/* Variables and functions for calc_load */
2133static atomic_long_t calc_load_tasks;
2134static unsigned long calc_load_update;
2135unsigned long avenrun[3];
2136EXPORT_SYMBOL(avenrun);
2137
2138static long calc_load_fold_active(struct rq *this_rq)
2139{
2140        long nr_active, delta = 0;
2141
2142        nr_active = this_rq->nr_running;
2143        nr_active += (long) this_rq->nr_uninterruptible;
2144
2145        if (nr_active != this_rq->calc_load_active) {
2146                delta = nr_active - this_rq->calc_load_active;
2147                this_rq->calc_load_active = nr_active;
2148        }
2149
2150        return delta;
2151}
2152
2153static unsigned long
2154calc_load(unsigned long load, unsigned long exp, unsigned long active)
2155{
2156        load *= exp;
2157        load += active * (FIXED_1 - exp);
2158        load += 1UL << (FSHIFT - 1);
2159        return load >> FSHIFT;
2160}
2161
2162#ifdef CONFIG_NO_HZ
2163/*
2164 * For NO_HZ we delay the active fold to the next LOAD_FREQ update.
2165 *
2166 * When making the ILB scale, we should try to pull this in as well.
2167 */
2168static atomic_long_t calc_load_tasks_idle;
2169
2170void calc_load_account_idle(struct rq *this_rq)
2171{
2172        long delta;
2173
2174        delta = calc_load_fold_active(this_rq);
2175        if (delta)
2176                atomic_long_add(delta, &calc_load_tasks_idle);
2177}
2178
2179static long calc_load_fold_idle(void)
2180{
2181        long delta = 0;
2182
2183        /*
2184         * Its got a race, we don't care...
2185         */
2186        if (atomic_long_read(&calc_load_tasks_idle))
2187                delta = atomic_long_xchg(&calc_load_tasks_idle, 0);
2188
2189        return delta;
2190}
2191
2192/**
2193 * fixed_power_int - compute: x^n, in O(log n) time
2194 *
2195 * @x:         base of the power
2196 * @frac_bits: fractional bits of @x
2197 * @n:         power to raise @x to.
2198 *
2199 * By exploiting the relation between the definition of the natural power
2200 * function: x^n := x*x*...*x (x multiplied by itself for n times), and
2201 * the binary encoding of numbers used by computers: n := \Sum n_i * 2^i,
2202 * (where: n_i \elem {0, 1}, the binary vector representing n),
2203 * we find: x^n := x^(\Sum n_i * 2^i) := \Prod x^(n_i * 2^i), which is
2204 * of course trivially computable in O(log_2 n), the length of our binary
2205 * vector.
2206 */
2207static unsigned long
2208fixed_power_int(unsigned long x, unsigned int frac_bits, unsigned int n)
2209{
2210        unsigned long result = 1UL << frac_bits;
2211
2212        if (n) for (;;) {
2213                if (n & 1) {
2214                        result *= x;
2215                        result += 1UL << (frac_bits - 1);
2216                        result >>= frac_bits;
2217                }
2218                n >>= 1;
2219                if (!n)
2220                        break;
2221                x *= x;
2222                x += 1UL << (frac_bits - 1);
2223                x >>= frac_bits;
2224        }
2225
2226        return result;
2227}
2228
2229/*
2230 * a1 = a0 * e + a * (1 - e)
2231 *
2232 * a2 = a1 * e + a * (1 - e)
2233 *    = (a0 * e + a * (1 - e)) * e + a * (1 - e)
2234 *    = a0 * e^2 + a * (1 - e) * (1 + e)
2235 *
2236 * a3 = a2 * e + a * (1 - e)
2237 *    = (a0 * e^2 + a * (1 - e) * (1 + e)) * e + a * (1 - e)
2238 *    = a0 * e^3 + a * (1 - e) * (1 + e + e^2)
2239 *
2240 *  ...
2241 *
2242 * an = a0 * e^n + a * (1 - e) * (1 + e + ... + e^n-1) [1]
2243 *    = a0 * e^n + a * (1 - e) * (1 - e^n)/(1 - e)
2244 *    = a0 * e^n + a * (1 - e^n)
2245 *
2246 * [1] application of the geometric series:
2247 *
2248 *              n         1 - x^(n+1)
2249 *     S_n := \Sum x^i = -------------
2250 *             i=0          1 - x
2251 */
2252static unsigned long
2253calc_load_n(unsigned long load, unsigned long exp,
2254            unsigned long active, unsigned int n)
2255{
2256
2257        return calc_load(load, fixed_power_int(exp, FSHIFT, n), active);
2258}
2259
2260/*
2261 * NO_HZ can leave us missing all per-cpu ticks calling
2262 * calc_load_account_active(), but since an idle CPU folds its delta into
2263 * calc_load_tasks_idle per calc_load_account_idle(), all we need to do is fold
2264 * in the pending idle delta if our idle period crossed a load cycle boundary.
2265 *
2266 * Once we've updated the global active value, we need to apply the exponential
2267 * weights adjusted to the number of cycles missed.
2268 */
2269static void calc_global_nohz(unsigned long ticks)
2270{
2271        long delta, active, n;
2272
2273        if (time_before(jiffies, calc_load_update))
2274                return;
2275
2276        /*
2277         * If we crossed a calc_load_update boundary, make sure to fold
2278         * any pending idle changes, the respective CPUs might have
2279         * missed the tick driven calc_load_account_active() update
2280         * due to NO_HZ.
2281         */
2282        delta = calc_load_fold_idle();
2283        if (delta)
2284                atomic_long_add(delta, &calc_load_tasks);
2285
2286        /*
2287         * If we were idle for multiple load cycles, apply them.
2288         */
2289        if (ticks >= LOAD_FREQ) {
2290                n = ticks / LOAD_FREQ;
2291
2292                active = atomic_long_read(&calc_load_tasks);
2293                active = active > 0 ? active * FIXED_1 : 0;
2294
2295                avenrun[0] = calc_load_n(avenrun[0], EXP_1, active, n);
2296                avenrun[1] = calc_load_n(avenrun[1], EXP_5, active, n);
2297                avenrun[2] = calc_load_n(avenrun[2], EXP_15, active, n);
2298
2299                calc_load_update += n * LOAD_FREQ;
2300        }
2301
2302        /*
2303         * Its possible the remainder of the above division also crosses
2304         * a LOAD_FREQ period, the regular check in calc_global_load()
2305         * which comes after this will take care of that.
2306         *
2307         * Consider us being 11 ticks before a cycle completion, and us
2308         * sleeping for 4*LOAD_FREQ + 22 ticks, then the above code will
2309         * age us 4 cycles, and the test in calc_global_load() will
2310         * pick up the final one.
2311         */
2312}
2313#else
2314void calc_load_account_idle(struct rq *this_rq)
2315{
2316}
2317
2318static inline long calc_load_fold_idle(void)
2319{
2320        return 0;
2321}
2322
2323static void calc_global_nohz(unsigned long ticks)
2324{
2325}
2326#endif
2327
2328/**
2329 * get_avenrun - get the load average array
2330 * @loads:      pointer to dest load array
2331 * @offset:     offset to add
2332 * @shift:      shift count to shift the result left
2333 *
2334 * These values are estimates at best, so no need for locking.
2335 */
2336void get_avenrun(unsigned long *loads, unsigned long offset, int shift)
2337{
2338        loads[0] = (avenrun[0] + offset) << shift;
2339        loads[1] = (avenrun[1] + offset) << shift;
2340        loads[2] = (avenrun[2] + offset) << shift;
2341}
2342
2343/*
2344 * calc_load - update the avenrun load estimates 10 ticks after the
2345 * CPUs have updated calc_load_tasks.
2346 */
2347void calc_global_load(unsigned long ticks)
2348{
2349        long active;
2350
2351        calc_global_nohz(ticks);
2352
2353        if (time_before(jiffies, calc_load_update + 10))
2354                return;
2355
2356        active = atomic_long_read(&calc_load_tasks);
2357        active = active > 0 ? active * FIXED_1 : 0;
2358
2359        avenrun[0] = calc_load(avenrun[0], EXP_1, active);
2360        avenrun[1] = calc_load(avenrun[1], EXP_5, active);
2361        avenrun[2] = calc_load(avenrun[2], EXP_15, active);
2362
2363        calc_load_update += LOAD_FREQ;
2364}
2365
2366/*
2367 * Called from update_cpu_load() to periodically update this CPU's
2368 * active count.
2369 */
2370static void calc_load_account_active(struct rq *this_rq)
2371{
2372        long delta;
2373
2374        if (time_before(jiffies, this_rq->calc_load_update))
2375                return;
2376
2377        delta  = calc_load_fold_active(this_rq);
2378        delta += calc_load_fold_idle();
2379        if (delta)
2380                atomic_long_add(delta, &calc_load_tasks);
2381
2382        this_rq->calc_load_update += LOAD_FREQ;
2383}
2384
2385/*
2386 * The exact cpuload at various idx values, calculated at every tick would be
2387 * load = (2^idx - 1) / 2^idx * load + 1 / 2^idx * cur_load
2388 *
2389 * If a cpu misses updates for n-1 ticks (as it was idle) and update gets called
2390 * on nth tick when cpu may be busy, then we have:
2391 * load = ((2^idx - 1) / 2^idx)^(n-1) * load
2392 * load = (2^idx - 1) / 2^idx) * load + 1 / 2^idx * cur_load
2393 *
2394 * decay_load_missed() below does efficient calculation of
2395 * load = ((2^idx - 1) / 2^idx)^(n-1) * load
2396 * avoiding 0..n-1 loop doing load = ((2^idx - 1) / 2^idx) * load
2397 *
2398 * The calculation is approximated on a 128 point scale.
2399 * degrade_zero_ticks is the number of ticks after which load at any
2400 * particular idx is approximated to be zero.
2401 * degrade_factor is a precomputed table, a row for each load idx.
2402 * Each column corresponds to degradation factor for a power of two ticks,
2403 * based on 128 point scale.
2404 * Example:
2405 * row 2, col 3 (=12) says that the degradation at load idx 2 after
2406 * 8 ticks is 12/128 (which is an approximation of exact factor 3^8/4^8).
2407 *
2408 * With this power of 2 load factors, we can degrade the load n times
2409 * by looking at 1 bits in n and doing as many mult/shift instead of
2410 * n mult/shifts needed by the exact degradation.
2411 */
2412#define DEGRADE_SHIFT           7
2413static const unsigned char
2414                degrade_zero_ticks[CPU_LOAD_IDX_MAX] = {0, 8, 32, 64, 128};
2415static const unsigned char
2416                degrade_factor[CPU_LOAD_IDX_MAX][DEGRADE_SHIFT + 1] = {
2417                                        {0, 0, 0, 0, 0, 0, 0, 0},
2418                                        {64, 32, 8, 0, 0, 0, 0, 0},
2419                                        {96, 72, 40, 12, 1, 0, 0},
2420                                        {112, 98, 75, 43, 15, 1, 0},
2421                                        {120, 112, 98, 76, 45, 16, 2} };
2422
2423/*
2424 * Update cpu_load for any missed ticks, due to tickless idle. The backlog
2425 * would be when CPU is idle and so we just decay the old load without
2426 * adding any new load.
2427 */
2428static unsigned long
2429decay_load_missed(unsigned long load, unsigned long missed_updates, int idx)
2430{
2431        int j = 0;
2432
2433        if (!missed_updates)
2434                return load;
2435
2436        if (missed_updates >= degrade_zero_ticks[idx])
2437                return 0;
2438
2439        if (idx == 1)
2440                return load >> missed_updates;
2441
2442        while (missed_updates) {
2443                if (missed_updates % 2)
2444                        load = (load * degrade_factor[idx][j]) >> DEGRADE_SHIFT;
2445
2446                missed_updates >>= 1;
2447                j++;
2448        }
2449        return load;
2450}
2451
2452/*
2453 * Update rq->cpu_load[] statistics. This function is usually called every
2454 * scheduler tick (TICK_NSEC). With tickless idle this will not be called
2455 * every tick. We fix it up based on jiffies.
2456 */
2457void update_cpu_load(struct rq *this_rq)
2458{
2459        unsigned long this_load = this_rq->load.weight;
2460        unsigned long curr_jiffies = jiffies;
2461        unsigned long pending_updates;
2462        int i, scale;
2463
2464        this_rq->nr_load_updates++;
2465
2466        /* Avoid repeated calls on same jiffy, when moving in and out of idle */
2467        if (curr_jiffies == this_rq->last_load_update_tick)
2468                return;
2469
2470        pending_updates = curr_jiffies - this_rq->last_load_update_tick;
2471        this_rq->last_load_update_tick = curr_jiffies;
2472
2473        /* Update our load: */
2474        this_rq->cpu_load[0] = this_load; /* Fasttrack for idx 0 */
2475        for (i = 1, scale = 2; i < CPU_LOAD_IDX_MAX; i++, scale += scale) {
2476                unsigned long old_load, new_load;
2477
2478                /* scale is effectively 1 << i now, and >> i divides by scale */
2479
2480                old_load = this_rq->cpu_load[i];
2481                old_load = decay_load_missed(old_load, pending_updates - 1, i);
2482                new_load = this_load;
2483                /*
2484                 * Round up the averaging division if load is increasing. This
2485                 * prevents us from getting stuck on 9 if the load is 10, for
2486                 * example.
2487                 */
2488                if (new_load > old_load)
2489                        new_load += scale - 1;
2490
2491                this_rq->cpu_load[i] = (old_load * (scale - 1) + new_load) >> i;
2492        }
2493
2494        sched_avg_update(this_rq);
2495}
2496
2497static void update_cpu_load_active(struct rq *this_rq)
2498{
2499        update_cpu_load(this_rq);
2500
2501        calc_load_account_active(this_rq);
2502}
2503
2504#ifdef CONFIG_SMP
2505
2506/*
2507 * sched_exec - execve() is a valuable balancing opportunity, because at
2508 * this point the task has the smallest effective memory and cache footprint.
2509 */
2510void sched_exec(void)
2511{
2512        struct task_struct *p = current;
2513        unsigned long flags;
2514        int dest_cpu;
2515
2516        raw_spin_lock_irqsave(&p->pi_lock, flags);
2517        dest_cpu = p->sched_class->select_task_rq(p, SD_BALANCE_EXEC, 0);
2518        if (dest_cpu == smp_processor_id())
2519                goto unlock;
2520
2521        if (likely(cpu_active(dest_cpu))) {
2522                struct migration_arg arg = { p, dest_cpu };
2523
2524                raw_spin_unlock_irqrestore(&p->pi_lock, flags);
2525                stop_one_cpu(task_cpu(p), migration_cpu_stop, &arg);
2526                return;
2527        }
2528unlock:
2529        raw_spin_unlock_irqrestore(&p->pi_lock, flags);
2530}
2531
2532#endif
2533
2534DEFINE_PER_CPU(struct kernel_stat, kstat);
2535DEFINE_PER_CPU(struct kernel_cpustat, kernel_cpustat);
2536
2537EXPORT_PER_CPU_SYMBOL(kstat);
2538EXPORT_PER_CPU_SYMBOL(kernel_cpustat);
2539
2540/*
2541 * Return any ns on the sched_clock that have not yet been accounted in
2542 * @p in case that task is currently running.
2543 *
2544 * Called with task_rq_lock() held on @rq.
2545 */
2546static u64 do_task_delta_exec(struct task_struct *p, struct rq *rq)
2547{
2548        u64 ns = 0;
2549
2550        if (task_current(rq, p)) {
2551                update_rq_clock(rq);
2552                ns = rq->clock_task - p->se.exec_start;
2553                if ((s64)ns < 0)
2554                        ns = 0;
2555        }
2556
2557        return ns;
2558}
2559
2560unsigned long long task_delta_exec(struct task_struct *p)
2561{
2562        unsigned long flags;
2563        struct rq *rq;
2564        u64 ns = 0;
2565
2566        rq = task_rq_lock(p, &flags);
2567        ns = do_task_delta_exec(p, rq);
2568        task_rq_unlock(rq, p, &flags);
2569
2570        return ns;
2571}
2572
2573/*
2574 * Return accounted runtime for the task.
2575 * In case the task is currently running, return the runtime plus current's
2576 * pending runtime that have not been accounted yet.
2577 */
2578unsigned long long task_sched_runtime(struct task_struct *p)
2579{
2580        unsigned long flags;
2581        struct rq *rq;
2582        u64 ns = 0;
2583
2584        rq = task_rq_lock(p, &flags);
2585        ns = p->se.sum_exec_runtime + do_task_delta_exec(p, rq);
2586        task_rq_unlock(rq, p, &flags);
2587
2588        return ns;
2589}
2590
2591#ifdef CONFIG_CGROUP_CPUACCT
2592struct cgroup_subsys cpuacct_subsys;
2593struct cpuacct root_cpuacct;
2594#endif
2595
2596static inline void task_group_account_field(struct task_struct *p, int index,
2597                                            u64 tmp)
2598{
2599#ifdef CONFIG_CGROUP_CPUACCT
2600        struct kernel_cpustat *kcpustat;
2601        struct cpuacct *ca;
2602#endif
2603        /*
2604         * Since all updates are sure to touch the root cgroup, we
2605         * get ourselves ahead and touch it first. If the root cgroup
2606         * is the only cgroup, then nothing else should be necessary.
2607         *
2608         */
2609        __get_cpu_var(kernel_cpustat).cpustat[index] += tmp;
2610
2611#ifdef CONFIG_CGROUP_CPUACCT
2612        if (unlikely(!cpuacct_subsys.active))
2613                return;
2614
2615        rcu_read_lock();
2616        ca = task_ca(p);
2617        while (ca && (ca != &root_cpuacct)) {
2618                kcpustat = this_cpu_ptr(ca->cpustat);
2619                kcpustat->cpustat[index] += tmp;
2620                ca = parent_ca(ca);
2621        }
2622        rcu_read_unlock();
2623#endif
2624}
2625
2626
2627/*
2628 * Account user cpu time to a process.
2629 * @p: the process that the cpu time gets accounted to
2630 * @cputime: the cpu time spent in user space since the last update
2631 * @cputime_scaled: cputime scaled by cpu frequency
2632 */
2633void account_user_time(struct task_struct *p, cputime_t cputime,
2634                       cputime_t cputime_scaled)
2635{
2636        int index;
2637
2638        /* Add user time to process. */
2639        p->utime += cputime;
2640        p->utimescaled += cputime_scaled;
2641        account_group_user_time(p, cputime);
2642
2643        index = (TASK_NICE(p) > 0) ? CPUTIME_NICE : CPUTIME_USER;
2644
2645        /* Add user time to cpustat. */
2646        task_group_account_field(p, index, (__force u64) cputime);
2647
2648        /* Account for user time used */
2649        acct_update_integrals(p);
2650}
2651
2652/*
2653 * Account guest cpu time to a process.
2654 * @p: the process that the cpu time gets accounted to
2655 * @cputime: the cpu time spent in virtual machine since the last update
2656 * @cputime_scaled: cputime scaled by cpu frequency
2657 */
2658static void account_guest_time(struct task_struct *p, cputime_t cputime,
2659                               cputime_t cputime_scaled)
2660{
2661        u64 *cpustat = kcpustat_this_cpu->cpustat;
2662
2663        /* Add guest time to process. */
2664        p->utime += cputime;
2665        p->utimescaled += cputime_scaled;
2666        account_group_user_time(p, cputime);
2667        p->gtime += cputime;
2668
2669        /* Add guest time to cpustat. */
2670        if (TASK_NICE(p) > 0) {
2671                cpustat[CPUTIME_NICE] += (__force u64) cputime;
2672                cpustat[CPUTIME_GUEST_NICE] += (__force u64) cputime;
2673        } else {
2674                cpustat[CPUTIME_USER] += (__force u64) cputime;
2675                cpustat[CPUTIME_GUEST] += (__force u64) cputime;
2676        }
2677}
2678
2679/*
2680 * Account system cpu time to a process and desired cpustat field
2681 * @p: the process that the cpu time gets accounted to
2682 * @cputime: the cpu time spent in kernel space since the last update
2683 * @cputime_scaled: cputime scaled by cpu frequency
2684 * @target_cputime64: pointer to cpustat field that has to be updated
2685 */
2686static inline
2687void __account_system_time(struct task_struct *p, cputime_t cputime,
2688                        cputime_t cputime_scaled, int index)
2689{
2690        /* Add system time to process. */
2691        p->stime += cputime;
2692        p->stimescaled += cputime_scaled;
2693        account_group_system_time(p, cputime);
2694
2695        /* Add system time to cpustat. */
2696        task_group_account_field(p, index, (__force u64) cputime);
2697
2698        /* Account for system time used */
2699        acct_update_integrals(p);
2700}
2701
2702/*
2703 * Account system cpu time to a process.
2704 * @p: the process that the cpu time gets accounted to
2705 * @hardirq_offset: the offset to subtract from hardirq_count()
2706 * @cputime: the cpu time spent in kernel space since the last update
2707 * @cputime_scaled: cputime scaled by cpu frequency
2708 */
2709void account_system_time(struct task_struct *p, int hardirq_offset,
2710                         cputime_t cputime, cputime_t cputime_scaled)
2711{
2712        int index;
2713
2714        if ((p->flags & PF_VCPU) && (irq_count() - hardirq_offset == 0)) {
2715                account_guest_time(p, cputime, cputime_scaled);
2716                return;
2717        }
2718
2719        if (hardirq_count() - hardirq_offset)
2720                index = CPUTIME_IRQ;
2721        else if (in_serving_softirq())
2722                index = CPUTIME_SOFTIRQ;
2723        else
2724                index = CPUTIME_SYSTEM;
2725
2726        __account_system_time(p, cputime, cputime_scaled, index);
2727}
2728
2729/*
2730 * Account for involuntary wait time.
2731 * @cputime: the cpu time spent in involuntary wait
2732 */
2733void account_steal_time(cputime_t cputime)
2734{
2735        u64 *cpustat = kcpustat_this_cpu->cpustat;
2736
2737        cpustat[CPUTIME_STEAL] += (__force u64) cputime;
2738}
2739
2740/*
2741 * Account for idle time.
2742 * @cputime: the cpu time spent in idle wait
2743 */
2744void account_idle_time(cputime_t cputime)
2745{
2746        u64 *cpustat = kcpustat_this_cpu->cpustat;
2747        struct rq *rq = this_rq();
2748
2749        if (atomic_read(&rq->nr_iowait) > 0)
2750                cpustat[CPUTIME_IOWAIT] += (__force u64) cputime;
2751        else
2752                cpustat[CPUTIME_IDLE] += (__force u64) cputime;
2753}
2754
2755static __always_inline bool steal_account_process_tick(void)
2756{
2757#ifdef CONFIG_PARAVIRT
2758        if (static_branch(&paravirt_steal_enabled)) {
2759                u64 steal, st = 0;
2760
2761                steal = paravirt_steal_clock(smp_processor_id());
2762                steal -= this_rq()->prev_steal_time;
2763
2764                st = steal_ticks(steal);
2765                this_rq()->prev_steal_time += st * TICK_NSEC;
2766
2767                account_steal_time(st);
2768                return st;
2769        }
2770#endif
2771        return false;
2772}
2773
2774#ifndef CONFIG_VIRT_CPU_ACCOUNTING
2775
2776#ifdef CONFIG_IRQ_TIME_ACCOUNTING
2777/*
2778 * Account a tick to a process and cpustat
2779 * @p: the process that the cpu time gets accounted to
2780 * @user_tick: is the tick from userspace
2781 * @rq: the pointer to rq
2782 *
2783 * Tick demultiplexing follows the order
2784 * - pending hardirq update
2785 * - pending softirq update
2786 * - user_time
2787 * - idle_time
2788 * - system time
2789 *   - check for guest_time
2790 *   - else account as system_time
2791 *
2792 * Check for hardirq is done both for system and user time as there is
2793 * no timer going off while we are on hardirq and hence we may never get an
2794 * opportunity to update it solely in system time.
2795 * p->stime and friends are only updated on system time and not on irq
2796 * softirq as those do not count in task exec_runtime any more.
2797 */
2798static void irqtime_account_process_tick(struct task_struct *p, int user_tick,
2799                                                struct rq *rq)
2800{
2801        cputime_t one_jiffy_scaled = cputime_to_scaled(cputime_one_jiffy);
2802        u64 *cpustat = kcpustat_this_cpu->cpustat;
2803
2804        if (steal_account_process_tick())
2805                return;
2806
2807        if (irqtime_account_hi_update()) {
2808                cpustat[CPUTIME_IRQ] += (__force u64) cputime_one_jiffy;
2809        } else if (irqtime_account_si_update()) {
2810                cpustat[CPUTIME_SOFTIRQ] += (__force u64) cputime_one_jiffy;
2811        } else if (this_cpu_ksoftirqd() == p) {
2812                /*
2813                 * ksoftirqd time do not get accounted in cpu_softirq_time.
2814                 * So, we have to handle it separately here.
2815                 * Also, p->stime needs to be updated for ksoftirqd.
2816                 */
2817                __account_system_time(p, cputime_one_jiffy, one_jiffy_scaled,
2818                                        CPUTIME_SOFTIRQ);
2819        } else if (user_tick) {
2820                account_user_time(p, cputime_one_jiffy, one_jiffy_scaled);
2821        } else if (p == rq->idle) {
2822                account_idle_time(cputime_one_jiffy);
2823        } else if (p->flags & PF_VCPU) { /* System time or guest time */
2824                account_guest_time(p, cputime_one_jiffy, one_jiffy_scaled);
2825        } else {
2826                __account_system_time(p, cputime_one_jiffy, one_jiffy_scaled,
2827                                        CPUTIME_SYSTEM);
2828        }
2829}
2830
2831static void irqtime_account_idle_ticks(int ticks)
2832{
2833        int i;
2834        struct rq *rq = this_rq();
2835
2836        for (i = 0; i < ticks; i++)
2837                irqtime_account_process_tick(current, 0, rq);
2838}
2839#else /* CONFIG_IRQ_TIME_ACCOUNTING */
2840static void irqtime_account_idle_ticks(int ticks) {}
2841static void irqtime_account_process_tick(struct task_struct *p, int user_tick,
2842                                                struct rq *rq) {}
2843#endif /* CONFIG_IRQ_TIME_ACCOUNTING */
2844
2845/*
2846 * Account a single tick of cpu time.
2847 * @p: the process that the cpu time gets accounted to
2848 * @user_tick: indicates if the tick is a user or a system tick
2849 */
2850void account_process_tick(struct task_struct *p, int user_tick)
2851{
2852        cputime_t one_jiffy_scaled = cputime_to_scaled(cputime_one_jiffy);
2853        struct rq *rq = this_rq();
2854
2855        if (sched_clock_irqtime) {
2856                irqtime_account_process_tick(p, user_tick, rq);
2857                return;
2858        }
2859
2860        if (steal_account_process_tick())
2861                return;
2862
2863        if (user_tick)
2864                account_user_time(p, cputime_one_jiffy, one_jiffy_scaled);
2865        else if ((p != rq->idle) || (irq_count() != HARDIRQ_OFFSET))
2866                account_system_time(p, HARDIRQ_OFFSET, cputime_one_jiffy,
2867                                    one_jiffy_scaled);
2868        else
2869                account_idle_time(cputime_one_jiffy);
2870}
2871
2872/*
2873 * Account multiple ticks of steal time.
2874 * @p: the process from which the cpu time has been stolen
2875 * @ticks: number of stolen ticks
2876 */
2877void account_steal_ticks(unsigned long ticks)
2878{
2879        account_steal_time(jiffies_to_cputime(ticks));
2880}
2881
2882/*
2883 * Account multiple ticks of idle time.
2884 * @ticks: number of stolen ticks
2885 */
2886void account_idle_ticks(unsigned long ticks)
2887{
2888
2889        if (sched_clock_irqtime) {
2890                irqtime_account_idle_ticks(ticks);
2891                return;
2892        }
2893
2894        account_idle_time(jiffies_to_cputime(ticks));
2895}
2896
2897#endif
2898
2899/*
2900 * Use precise platform statistics if available:
2901 */
2902#ifdef CONFIG_VIRT_CPU_ACCOUNTING
2903void task_times(struct task_struct *p, cputime_t *ut, cputime_t *st)
2904{
2905        *ut = p->utime;
2906        *st = p->stime;
2907}
2908
2909void thread_group_times(struct task_struct *p, cputime_t *ut, cputime_t *st)
2910{
2911        struct task_cputime cputime;
2912
2913        thread_group_cputime(p, &cputime);
2914
2915        *ut = cputime.utime;
2916        *st = cputime.stime;
2917}
2918#else
2919
2920#ifndef nsecs_to_cputime
2921# define nsecs_to_cputime(__nsecs)      nsecs_to_jiffies(__nsecs)
2922#endif
2923
2924void task_times(struct task_struct *p, cputime_t *ut, cputime_t *st)
2925{
2926        cputime_t rtime, utime = p->utime, total = utime + p->stime;
2927
2928        /*
2929         * Use CFS's precise accounting:
2930         */
2931        rtime = nsecs_to_cputime(p->se.sum_exec_runtime);
2932
2933        if (total) {
2934                u64 temp = (__force u64) rtime;
2935
2936                temp *= (__force u64) utime;
2937                do_div(temp, (__force u32) total);
2938                utime = (__force cputime_t) temp;
2939        } else
2940                utime = rtime;
2941
2942        /*
2943         * Compare with previous values, to keep monotonicity:
2944         */
2945        p->prev_utime = max(p->prev_utime, utime);
2946        p->prev_stime = max(p->prev_stime, rtime - p->prev_utime);
2947
2948        *ut = p->prev_utime;
2949        *st = p->prev_stime;
2950}
2951
2952/*
2953 * Must be called with siglock held.
2954 */
2955void thread_group_times(struct task_struct *p, cputime_t *ut, cputime_t *st)
2956{
2957        struct signal_struct *sig = p->signal;
2958        struct task_cputime cputime;
2959        cputime_t rtime, utime, total;
2960
2961        thread_group_cputime(p, &cputime);
2962
2963        total = cputime.utime + cputime.stime;
2964        rtime = nsecs_to_cputime(cputime.sum_exec_runtime);
2965
2966        if (total) {
2967                u64 temp = (__force u64) rtime;
2968
2969                temp *= (__force u64) cputime.utime;
2970                do_div(temp, (__force u32) total);
2971                utime = (__force cputime_t) temp;
2972        } else
2973                utime = rtime;
2974
2975        sig->prev_utime = max(sig->prev_utime, utime);
2976        sig->prev_stime = max(sig->prev_stime, rtime - sig->prev_utime);
2977
2978        *ut = sig->prev_utime;
2979        *st = sig->prev_stime;
2980}
2981#endif
2982
2983/*
2984 * This function gets called by the timer code, with HZ frequency.
2985 * We call it with interrupts disabled.
2986 */
2987void scheduler_tick(void)
2988{
2989        int cpu = smp_processor_id();
2990        struct rq *rq = cpu_rq(cpu);
2991        struct task_struct *curr = rq->curr;
2992
2993        sched_clock_tick();
2994
2995        raw_spin_lock(&rq->lock);
2996        update_rq_clock(rq);
2997        update_cpu_load_active(rq);
2998        curr->sched_class->task_tick(rq, curr, 0);
2999        raw_spin_unlock(&rq->lock);
3000
3001        perf_event_task_tick();
3002
3003#ifdef CONFIG_SMP
3004        rq->idle_balance = idle_cpu(cpu);
3005        trigger_load_balance(rq, cpu);
3006#endif
3007}
3008
3009notrace unsigned long get_parent_ip(unsigned long addr)
3010{
3011        if (in_lock_functions(addr)) {
3012                addr = CALLER_ADDR2;
3013                if (in_lock_functions(addr))
3014                        addr = CALLER_ADDR3;
3015        }
3016        return addr;
3017}
3018
3019#if defined(CONFIG_PREEMPT) && (defined(CONFIG_DEBUG_PREEMPT) || \
3020                                defined(CONFIG_PREEMPT_TRACER))
3021
3022void __kprobes add_preempt_count(int val)
3023{
3024#ifdef CONFIG_DEBUG_PREEMPT
3025        /*
3026         * Underflow?
3027         */
3028        if (DEBUG_LOCKS_WARN_ON((preempt_count() < 0)))
3029                return;
3030#endif
3031        preempt_count() += val;
3032#ifdef CONFIG_DEBUG_PREEMPT
3033        /*
3034         * Spinlock count overflowing soon?
3035         */
3036        DEBUG_LOCKS_WARN_ON((preempt_count() & PREEMPT_MASK) >=
3037                                PREEMPT_MASK - 10);
3038#endif
3039        if (preempt_count() == val)
3040                trace_preempt_off(CALLER_ADDR0, get_parent_ip(CALLER_ADDR1));
3041}
3042EXPORT_SYMBOL(add_preempt_count);
3043
3044void __kprobes sub_preempt_count(int val)
3045{
3046#ifdef CONFIG_DEBUG_PREEMPT
3047        /*
3048         * Underflow?
3049         */
3050        if (DEBUG_LOCKS_WARN_ON(val > preempt_count()))
3051                return;
3052        /*
3053         * Is the spinlock portion underflowing?
3054         */
3055        if (DEBUG_LOCKS_WARN_ON((val < PREEMPT_MASK) &&
3056                        !(preempt_count() & PREEMPT_MASK)))
3057                return;
3058#endif
3059
3060        if (preempt_count() == val)
3061                trace_preempt_on(CALLER_ADDR0, get_parent_ip(CALLER_ADDR1));
3062        preempt_count() -= val;
3063}
3064EXPORT_SYMBOL(sub_preempt_count);
3065
3066#endif
3067
3068/*
3069 * Print scheduling while atomic bug:
3070 */
3071static noinline void __schedule_bug(struct task_struct *prev)
3072{
3073        struct pt_regs *regs = get_irq_regs();
3074
3075        if (oops_in_progress)
3076                return;
3077
3078        printk(KERN_ERR "BUG: scheduling while atomic: %s/%d/0x%08x\n",
3079                prev->comm, prev->pid, preempt_count());
3080
3081        debug_show_held_locks(prev);
3082        print_modules();
3083        if (irqs_disabled())
3084                print_irqtrace_events(prev);
3085
3086        if (regs)
3087                show_regs(regs);
3088        else
3089                dump_stack();
3090}
3091
3092/*
3093 * Various schedule()-time debugging checks and statistics:
3094 */
3095static inline void schedule_debug(struct task_struct *prev)
3096{
3097        /*
3098         * Test if we are atomic. Since do_exit() needs to call into
3099         * schedule() atomically, we ignore that path for now.
3100         * Otherwise, whine if we are scheduling when we should not be.
3101         */
3102        if (unlikely(in_atomic_preempt_off() && !prev->exit_state))
3103                __schedule_bug(prev);
3104        rcu_sleep_check();
3105
3106        profile_hit(SCHED_PROFILING, __builtin_return_address(0));
3107
3108        schedstat_inc(this_rq(), sched_count);
3109}
3110
3111static void put_prev_task(struct rq *rq, struct task_struct *prev)
3112{
3113        if (prev->on_rq || rq->skip_clock_update < 0)
3114                update_rq_clock(rq);
3115        prev->sched_class->put_prev_task(rq, prev);
3116}
3117
3118/*
3119 * Pick up the highest-prio task:
3120 */
3121static inline struct task_struct *
3122pick_next_task(struct rq *rq)
3123{
3124        const struct sched_class *class;
3125        struct task_struct *p;
3126
3127        /*
3128         * Optimization: we know that if all tasks are in
3129         * the fair class we can call that function directly:
3130         */
3131        if (likely(rq->nr_running == rq->cfs.h_nr_running)) {
3132                p = fair_sched_class.pick_next_task(rq);
3133                if (likely(p))
3134                        return p;
3135        }
3136
3137        for_each_class(class) {
3138                p = class->pick_next_task(rq);
3139                if (p)
3140                        return p;
3141        }
3142
3143        BUG(); /* the idle class will always have a runnable task */
3144}
3145
3146/*
3147 * __schedule() is the main scheduler function.
3148 */
3149static void __sched __schedule(void)
3150{
3151        struct task_struct *prev, *next;
3152        unsigned long *switch_count;
3153        struct rq *rq;
3154        int cpu;
3155
3156need_resched:
3157        preempt_disable();
3158        cpu = smp_processor_id();
3159        rq = cpu_rq(cpu);
3160        rcu_note_context_switch(cpu);
3161        prev = rq->curr;
3162
3163        schedule_debug(prev);
3164
3165        if (sched_feat(HRTICK))
3166                hrtick_clear(rq);
3167
3168        raw_spin_lock_irq(&rq->lock);
3169
3170        switch_count = &prev->nivcsw;
3171        if (prev->state && !(preempt_count() & PREEMPT_ACTIVE)) {
3172                if (unlikely(signal_pending_state(prev->state, prev))) {
3173                        prev->state = TASK_RUNNING;
3174                } else {
3175                        deactivate_task(rq, prev, DEQUEUE_SLEEP);
3176                        prev->on_rq = 0;
3177
3178                        /*
3179                         * If a worker went to sleep, notify and ask workqueue
3180                         * whether it wants to wake up a task to maintain
3181                         * concurrency.
3182                         */
3183                        if (prev->flags & PF_WQ_WORKER) {
3184                                struct task_struct *to_wakeup;
3185
3186                                to_wakeup = wq_worker_sleeping(prev, cpu);
3187                                if (to_wakeup)
3188                                        try_to_wake_up_local(to_wakeup);
3189                        }
3190                }
3191                switch_count = &prev->nvcsw;
3192        }
3193
3194        pre_schedule(rq, prev);
3195
3196        if (unlikely(!rq->nr_running))
3197                idle_balance(cpu, rq);
3198
3199        put_prev_task(rq, prev);
3200        next = pick_next_task(rq);
3201        clear_tsk_need_resched(prev);
3202        rq->skip_clock_update = 0;
3203
3204        if (likely(prev != next)) {
3205                rq->nr_switches++;
3206                rq->curr = next;
3207                ++*switch_count;
3208
3209                context_switch(rq, prev, next); /* unlocks the rq */
3210                /*
3211                 * The context switch have flipped the stack from under us
3212                 * and restored the local variables which were saved when
3213                 * this task called schedule() in the past. prev == current
3214                 * is still correct, but it can be moved to another cpu/rq.
3215                 */
3216                cpu = smp_processor_id();
3217                rq = cpu_rq(cpu);
3218        } else
3219                raw_spin_unlock_irq(&rq->lock);
3220
3221        post_schedule(rq);
3222
3223        preempt_enable_no_resched();
3224        if (need_resched())
3225                goto need_resched;
3226}
3227
3228static inline void sched_submit_work(struct task_struct *tsk)
3229{
3230        if (!tsk->state)
3231                return;
3232        /*
3233         * If we are going to sleep and we have plugged IO queued,
3234         * make sure to submit it to avoid deadlocks.
3235         */
3236        if (blk_needs_flush_plug(tsk))
3237                blk_schedule_flush_plug(tsk);
3238}
3239
3240asmlinkage void __sched schedule(void)
3241{
3242        struct task_struct *tsk = current;
3243
3244        sched_submit_work(tsk);
3245        __schedule();
3246}
3247EXPORT_SYMBOL(schedule);
3248
3249#ifdef CONFIG_MUTEX_SPIN_ON_OWNER
3250
3251static inline bool owner_running(struct mutex *lock, struct task_struct *owner)
3252{
3253        if (lock->owner != owner)
3254                return false;
3255
3256        /*
3257         * Ensure we emit the owner->on_cpu, dereference _after_ checking
3258         * lock->owner still matches owner, if that fails, owner might
3259         * point to free()d memory, if it still matches, the rcu_read_lock()
3260         * ensures the memory stays valid.
3261         */
3262        barrier();
3263
3264        return owner->on_cpu;
3265}
3266
3267/*
3268 * Look out! "owner" is an entirely speculative pointer
3269 * access and not reliable.
3270 */
3271int mutex_spin_on_owner(struct mutex *lock, struct task_struct *owner)
3272{
3273        if (!sched_feat(OWNER_SPIN))
3274                return 0;
3275
3276        rcu_read_lock();
3277        while (owner_running(lock, owner)) {
3278                if (need_resched())
3279                        break;
3280
3281                arch_mutex_cpu_relax();
3282        }
3283        rcu_read_unlock();
3284
3285        /*
3286         * We break out the loop above on need_resched() and when the
3287         * owner changed, which is a sign for heavy contention. Return
3288         * success only when lock->owner is NULL.
3289         */
3290        return lock->owner == NULL;
3291}
3292#endif
3293
3294#ifdef CONFIG_PREEMPT
3295/*
3296 * this is the entry point to schedule() from in-kernel preemption
3297 * off of preempt_enable. Kernel preemptions off return from interrupt
3298 * occur there and call schedule directly.
3299 */
3300asmlinkage void __sched notrace preempt_schedule(void)
3301{
3302        struct thread_info *ti = current_thread_info();
3303
3304        /*
3305         * If there is a non-zero preempt_count or interrupts are disabled,
3306         * we do not want to preempt the current task. Just return..
3307         */
3308        if (likely(ti->preempt_count || irqs_disabled()))
3309                return;
3310
3311        do {
3312                add_preempt_count_notrace(PREEMPT_ACTIVE);
3313                __schedule();
3314                sub_preempt_count_notrace(PREEMPT_ACTIVE);
3315
3316                /*
3317                 * Check again in case we missed a preemption opportunity
3318                 * between schedule and now.
3319                 */
3320                barrier();
3321        } while (need_resched());
3322}
3323EXPORT_SYMBOL(preempt_schedule);
3324
3325/*
3326 * this is the entry point to schedule() from kernel preemption
3327 * off of irq context.
3328 * Note, that this is called and return with irqs disabled. This will
3329 * protect us against recursive calling from irq.
3330 */
3331asmlinkage void __sched preempt_schedule_irq(void)
3332{
3333        struct thread_info *ti = current_thread_info();
3334
3335        /* Catch callers which need to be fixed */
3336        BUG_ON(ti->preempt_count || !irqs_disabled());
3337
3338        do {
3339                add_preempt_count(PREEMPT_ACTIVE);
3340                local_irq_enable();
3341                __schedule();
3342                local_irq_disable();
3343                sub_preempt_count(PREEMPT_ACTIVE);
3344
3345                /*
3346                 * Check again in case we missed a preemption opportunity
3347                 * between schedule and now.
3348                 */
3349                barrier();
3350        } while (need_resched());
3351}
3352
3353#endif /* CONFIG_PREEMPT */
3354
3355int default_wake_function(wait_queue_t *curr, unsigned mode, int wake_flags,
3356                          void *key)
3357{
3358        return try_to_wake_up(curr->private, mode, wake_flags);
3359}
3360EXPORT_SYMBOL(default_wake_function);
3361
3362/*
3363 * The core wakeup function. Non-exclusive wakeups (nr_exclusive == 0) just
3364 * wake everything up. If it's an exclusive wakeup (nr_exclusive == small +ve
3365 * number) then we wake all the non-exclusive tasks and one exclusive task.
3366 *
3367 * There are circumstances in which we can try to wake a task which has already
3368 * started to run but is not in state TASK_RUNNING. try_to_wake_up() returns
3369 * zero in this (rare) case, and we handle it by continuing to scan the queue.
3370 */
3371static void __wake_up_common(wait_queue_head_t *q, unsigned int mode,
3372                        int nr_exclusive, int wake_flags, void *key)
3373{
3374        wait_queue_t *curr, *next;
3375
3376        list_for_each_entry_safe(curr, next, &q->task_list, task_list) {
3377                unsigned flags = curr->flags;
3378
3379                if (curr->func(curr, mode, wake_flags, key) &&
3380                                (flags & WQ_FLAG_EXCLUSIVE) && !--nr_exclusive)
3381                        break;
3382        }
3383}
3384
3385/**
3386 * __wake_up - wake up threads blocked on a waitqueue.
3387 * @q: the waitqueue
3388 * @mode: which threads
3389 * @nr_exclusive: how many wake-one or wake-many threads to wake up
3390 * @key: is directly passed to the wakeup function
3391 *
3392 * It may be assumed that this function implies a write memory barrier before
3393 * changing the task state if and only if any tasks are woken up.
3394 */
3395void __wake_up(wait_queue_head_t *q, unsigned int mode,
3396                        int nr_exclusive, void *key)
3397{
3398        unsigned long flags;
3399
3400        spin_lock_irqsave(&q->lock, flags);
3401        __wake_up_common(q, mode, nr_exclusive, 0, key);
3402        spin_unlock_irqrestore(&q->lock, flags);
3403}
3404EXPORT_SYMBOL(__wake_up);
3405
3406/*
3407 * Same as __wake_up but called with the spinlock in wait_queue_head_t held.
3408 */
3409void __wake_up_locked(wait_queue_head_t *q, unsigned int mode)
3410{
3411        __wake_up_common(q, mode, 1, 0, NULL);
3412}
3413EXPORT_SYMBOL_GPL(__wake_up_locked);
3414
3415void __wake_up_locked_key(wait_queue_head_t *q, unsigned int mode, void *key)
3416{
3417        __wake_up_common(q, mode, 1, 0, key);
3418}
3419EXPORT_SYMBOL_GPL(__wake_up_locked_key);
3420
3421/**
3422 * __wake_up_sync_key - wake up threads blocked on a waitqueue.
3423 * @q: the waitqueue
3424 * @mode: which threads
3425 * @nr_exclusive: how many wake-one or wake-many threads to wake up
3426 * @key: opaque value to be passed to wakeup targets
3427 *
3428 * The sync wakeup differs that the waker knows that it will schedule
3429 * away soon, so while the target thread will be woken up, it will not
3430 * be migrated to another CPU - ie. the two threads are 'synchronized'
3431 * with each other. This can prevent needless bouncing between CPUs.
3432 *
3433 * On UP it can prevent extra preemption.
3434 *
3435 * It may be assumed that this function implies a write memory barrier before
3436 * changing the task state if and only if any tasks are woken up.
3437 */
3438void __wake_up_sync_key(wait_queue_head_t *q, unsigned int mode,
3439                        int nr_exclusive, void *key)
3440{
3441        unsigned long flags;
3442        int wake_flags = WF_SYNC;
3443
3444        if (unlikely(!q))
3445                return;
3446
3447        if (unlikely(!nr_exclusive))
3448                wake_flags = 0;
3449
3450        spin_lock_irqsave(&q->lock, flags);
3451        __wake_up_common(q, mode, nr_exclusive, wake_flags, key);
3452        spin_unlock_irqrestore(&q->lock, flags);
3453}
3454EXPORT_SYMBOL_GPL(__wake_up_sync_key);
3455
3456/*
3457 * __wake_up_sync - see __wake_up_sync_key()
3458 */
3459void __wake_up_sync(wait_queue_head_t *q, unsigned int mode, int nr_exclusive)
3460{
3461        __wake_up_sync_key(q, mode, nr_exclusive, NULL);
3462}
3463EXPORT_SYMBOL_GPL(__wake_up_sync);      /* For internal use only */
3464
3465/**
3466 * complete: - signals a single thread waiting on this completion
3467 * @x:  holds the state of this particular completion
3468 *
3469 * This will wake up a single thread waiting on this completion. Threads will be
3470 * awakened in the same order in which they were queued.
3471 *
3472 * See also complete_all(), wait_for_completion() and related routines.
3473 *
3474 * It may be assumed that this function implies a write memory barrier before
3475 * changing the task state if and only if any tasks are woken up.
3476 */
3477void complete(struct completion *x)
3478{
3479        unsigned long flags;
3480
3481        spin_lock_irqsave(&x->wait.lock, flags);
3482        x->done++;
3483        __wake_up_common(&x->wait, TASK_NORMAL, 1, 0, NULL);
3484        spin_unlock_irqrestore(&x->wait.lock, flags);
3485}
3486EXPORT_SYMBOL(complete);
3487
3488/**
3489 * complete_all: - signals all threads waiting on this completion
3490 * @x:  holds the state of this particular completion
3491 *
3492 * This will wake up all threads waiting on this particular completion event.
3493 *
3494 * It may be assumed that this function implies a write memory barrier before
3495 * changing the task state if and only if any tasks are woken up.
3496 */
3497void complete_all(struct completion *x)
3498{
3499        unsigned long flags;
3500
3501        spin_lock_irqsave(&x->wait.lock, flags);
3502        x->done += UINT_MAX/2;
3503        __wake_up_common(&x->wait, TASK_NORMAL, 0, 0, NULL);
3504        spin_unlock_irqrestore(&x->wait.lock, flags);
3505}
3506EXPORT_SYMBOL(complete_all);
3507
3508static inline long __sched
3509do_wait_for_common(struct completion *x, long timeout, int state)
3510{
3511        if (!x->done) {
3512                DECLARE_WAITQUEUE(wait, current);
3513
3514                __add_wait_queue_tail_exclusive(&x->wait, &wait);
3515                do {
3516                        if (signal_pending_state(state, current)) {
3517                                timeout = -ERESTARTSYS;
3518                                break;
3519                        }
3520                        __set_current_state(state);
3521                        spin_unlock_irq(&x->wait.lock);
3522                        timeout = schedule_timeout(timeout);
3523                        spin_lock_irq(&x->wait.lock);
3524                } while (!x->done && timeout);
3525                __remove_wait_queue(&x->wait, &wait);
3526                if (!x->done)
3527                        return timeout;
3528        }
3529        x->done--;
3530        return timeout ?: 1;
3531}
3532
3533static long __sched
3534wait_for_common(struct completion *x, long timeout, int state)
3535{
3536        might_sleep();
3537
3538        spin_lock_irq(&x->wait.lock);
3539        timeout = do_wait_for_common(x, timeout, state);
3540        spin_unlock_irq(&x->wait.lock);
3541        return timeout;
3542}
3543
3544/**
3545 * wait_for_completion: - waits for completion of a task
3546 * @x:  holds the state of this particular completion
3547 *
3548 * This waits to be signaled for completion of a specific task. It is NOT
3549 * interruptible and there is no timeout.
3550 *
3551 * See also similar routines (i.e. wait_for_completion_timeout()) with timeout
3552 * and interrupt capability. Also see complete().
3553 */
3554void __sched wait_for_completion(struct completion *x)
3555{
3556        wait_for_common(x, MAX_SCHEDULE_TIMEOUT, TASK_UNINTERRUPTIBLE);
3557}
3558EXPORT_SYMBOL(wait_for_completion);
3559
3560/**
3561 * wait_for_completion_timeout: - waits for completion of a task (w/timeout)
3562 * @x:  holds the state of this particular completion
3563 * @timeout:  timeout value in jiffies
3564 *
3565 * This waits for either a completion of a specific task to be signaled or for a
3566 * specified timeout to expire. The timeout is in jiffies. It is not
3567 * interruptible.
3568 *
3569 * The return value is 0 if timed out, and positive (at least 1, or number of
3570 * jiffies left till timeout) if completed.
3571 */
3572unsigned long __sched
3573wait_for_completion_timeout(struct completion *x, unsigned long timeout)
3574{
3575        return wait_for_common(x, timeout, TASK_UNINTERRUPTIBLE);
3576}
3577EXPORT_SYMBOL(wait_for_completion_timeout);
3578
3579/**
3580 * wait_for_completion_interruptible: - waits for completion of a task (w/intr)
3581 * @x:  holds the state of this particular completion
3582 *
3583 * This waits for completion of a specific task to be signaled. It is
3584 * interruptible.
3585 *
3586 * The return value is -ERESTARTSYS if interrupted, 0 if completed.
3587 */
3588int __sched wait_for_completion_interruptible(struct completion *x)
3589{
3590        long t = wait_for_common(x, MAX_SCHEDULE_TIMEOUT, TASK_INTERRUPTIBLE);
3591        if (t == -ERESTARTSYS)
3592                return t;
3593        return 0;
3594}
3595EXPORT_SYMBOL(wait_for_completion_interruptible);
3596
3597/**
3598 * wait_for_completion_interruptible_timeout: - waits for completion (w/(to,intr))
3599 * @x:  holds the state of this particular completion
3600 * @timeout:  timeout value in jiffies
3601 *
3602 * This waits for either a completion of a specific task to be signaled or for a
3603 * specified timeout to expire. It is interruptible. The timeout is in jiffies.
3604 *
3605 * The return value is -ERESTARTSYS if interrupted, 0 if timed out,
3606 * positive (at least 1, or number of jiffies left till timeout) if completed.
3607 */
3608long __sched
3609wait_for_completion_interruptible_timeout(struct completion *x,
3610                                          unsigned long timeout)
3611{
3612        return wait_for_common(x, timeout, TASK_INTERRUPTIBLE);
3613}
3614EXPORT_SYMBOL(wait_for_completion_interruptible_timeout);
3615
3616/**
3617 * wait_for_completion_killable: - waits for completion of a task (killable)
3618 * @x:  holds the state of this particular completion
3619 *
3620 * This waits to be signaled for completion of a specific task. It can be
3621 * interrupted by a kill signal.
3622 *
3623 * The return value is -ERESTARTSYS if interrupted, 0 if completed.
3624 */
3625int __sched wait_for_completion_killable(struct completion *x)
3626{
3627        long t = wait_for_common(x, MAX_SCHEDULE_TIMEOUT, TASK_KILLABLE);
3628        if (t == -ERESTARTSYS)
3629                return t;
3630        return 0;
3631}
3632EXPORT_SYMBOL(wait_for_completion_killable);
3633
3634/**
3635 * wait_for_completion_killable_timeout: - waits for completion of a task (w/(to,killable))
3636 * @x:  holds the state of this particular completion
3637 * @timeout:  timeout value in jiffies
3638 *
3639 * This waits for either a completion of a specific task to be
3640 * signaled or for a specified timeout to expire. It can be
3641 * interrupted by a kill signal. The timeout is in jiffies.
3642 *
3643 * The return value is -ERESTARTSYS if interrupted, 0 if timed out,
3644 * positive (at least 1, or number of jiffies left till timeout) if completed.
3645 */
3646long __sched
3647wait_for_completion_killable_timeout(struct completion *x,
3648                                     unsigned long timeout)
3649{
3650        return wait_for_common(x, timeout, TASK_KILLABLE);
3651}
3652EXPORT_SYMBOL(wait_for_completion_killable_timeout);
3653
3654/**
3655 *      try_wait_for_completion - try to decrement a completion without blocking
3656 *      @x:     completion structure
3657 *
3658 *      Returns: 0 if a decrement cannot be done without blocking
3659 *               1 if a decrement succeeded.
3660 *
3661 *      If a completion is being used as a counting completion,
3662 *      attempt to decrement the counter without blocking. This
3663 *      enables us to avoid waiting if the resource the completion
3664 *      is protecting is not available.
3665 */
3666bool try_wait_for_completion(struct completion *x)
3667{
3668        unsigned long flags;
3669        int ret = 1;
3670
3671        spin_lock_irqsave(&x->wait.lock, flags);
3672        if (!x->done)
3673                ret = 0;
3674        else
3675                x->done--;
3676        spin_unlock_irqrestore(&x->wait.lock, flags);
3677        return ret;
3678}
3679EXPORT_SYMBOL(try_wait_for_completion);
3680
3681/**
3682 *      completion_done - Test to see if a completion has any waiters
3683 *      @x:     completion structure
3684 *
3685 *      Returns: 0 if there are waiters (wait_for_completion() in progress)
3686 *               1 if there are no waiters.
3687 *
3688 */
3689bool completion_done(struct completion *x)
3690{
3691        unsigned long flags;
3692        int ret = 1;
3693
3694        spin_lock_irqsave(&x->wait.lock, flags);
3695        if (!x->done)
3696                ret = 0;
3697        spin_unlock_irqrestore(&x->wait.lock, flags);
3698        return ret;
3699}
3700EXPORT_SYMBOL(completion_done);
3701
3702static long __sched
3703sleep_on_common(wait_queue_head_t *q, int state, long timeout)
3704{
3705        unsigned long flags;
3706        wait_queue_t wait;
3707
3708        init_waitqueue_entry(&wait, current);
3709
3710        __set_current_state(state);
3711
3712        spin_lock_irqsave(&q->lock, flags);
3713        __add_wait_queue(q, &wait);
3714        spin_unlock(&q->lock);
3715        timeout = schedule_timeout(timeout);
3716        spin_lock_irq(&q->lock);
3717        __remove_wait_queue(q, &wait);
3718        spin_unlock_irqrestore(&q->lock, flags);
3719
3720        return timeout;
3721}
3722
3723void __sched interruptible_sleep_on(wait_queue_head_t *q)
3724{
3725        sleep_on_common(q, TASK_INTERRUPTIBLE, MAX_SCHEDULE_TIMEOUT);
3726}
3727EXPORT_SYMBOL(interruptible_sleep_on);
3728
3729long __sched
3730interruptible_sleep_on_timeout(wait_queue_head_t *q, long timeout)
3731{
3732        return sleep_on_common(q, TASK_INTERRUPTIBLE, timeout);
3733}
3734EXPORT_SYMBOL(interruptible_sleep_on_timeout);
3735
3736void __sched sleep_on(wait_queue_head_t *q)
3737{
3738        sleep_on_common(q, TASK_UNINTERRUPTIBLE, MAX_SCHEDULE_TIMEOUT);
3739}
3740EXPORT_SYMBOL(sleep_on);
3741
3742long __sched sleep_on_timeout(wait_queue_head_t *q, long timeout)
3743{
3744        return sleep_on_common(q, TASK_UNINTERRUPTIBLE, timeout);
3745}
3746EXPORT_SYMBOL(sleep_on_timeout);
3747
3748#ifdef CONFIG_RT_MUTEXES
3749
3750/*
3751 * rt_mutex_setprio - set the current priority of a task
3752 * @p: task
3753 * @prio: prio value (kernel-internal form)
3754 *
3755 * This function changes the 'effective' priority of a task. It does
3756 * not touch ->normal_prio like __setscheduler().
3757 *
3758 * Used by the rt_mutex code to implement priority inheritance logic.
3759 */
3760void rt_mutex_setprio(struct task_struct *p, int prio)
3761{
3762        int oldprio, on_rq, running;
3763        struct rq *rq;
3764        const struct sched_class *prev_class;
3765
3766        BUG_ON(prio < 0 || prio > MAX_PRIO);
3767
3768        rq = __task_rq_lock(p);
3769
3770        trace_sched_pi_setprio(p, prio);
3771        oldprio = p->prio;
3772        prev_class = p->sched_class;
3773        on_rq = p->on_rq;
3774        running = task_current(rq, p);
3775        if (on_rq)
3776                dequeue_task(rq, p, 0);
3777        if (running)
3778                p->sched_class->put_prev_task(rq, p);
3779
3780        if (rt_prio(prio))
3781                p->sched_class = &rt_sched_class;
3782        else
3783                p->sched_class = &fair_sched_class;
3784
3785        p->prio = prio;
3786
3787        if (running)
3788                p->sched_class->set_curr_task(rq);
3789        if (on_rq)
3790                enqueue_task(rq, p, oldprio < prio ? ENQUEUE_HEAD : 0);
3791
3792        check_class_changed(rq, p, prev_class, oldprio);
3793        __task_rq_unlock(rq);
3794}
3795
3796#endif
3797
3798void set_user_nice(struct task_struct *p, long nice)
3799{
3800        int old_prio, delta, on_rq;
3801        unsigned long flags;
3802        struct rq *rq;
3803
3804        if (TASK_NICE(p) == nice || nice < -20 || nice > 19)
3805                return;
3806        /*
3807         * We have to be careful, if called from sys_setpriority(),
3808         * the task might be in the middle of scheduling on another CPU.
3809         */
3810        rq = task_rq_lock(p, &flags);
3811        /*
3812         * The RT priorities are set via sched_setscheduler(), but we still
3813         * allow the 'normal' nice value to be set - but as expected
3814         * it wont have any effect on scheduling until the task is
3815         * SCHED_FIFO/SCHED_RR:
3816         */
3817        if (task_has_rt_policy(p)) {
3818                p->static_prio = NICE_TO_PRIO(nice);
3819                goto out_unlock;
3820        }
3821        on_rq = p->on_rq;
3822        if (on_rq)
3823                dequeue_task(rq, p, 0);
3824
3825        p->static_prio = NICE_TO_PRIO(nice);
3826        set_load_weight(p);
3827        old_prio = p->prio;
3828        p->prio = effective_prio(p);
3829        delta = p->prio - old_prio;
3830
3831        if (on_rq) {
3832                enqueue_task(rq, p, 0);
3833                /*
3834                 * If the task increased its priority or is running and
3835                 * lowered its priority, then reschedule its CPU:
3836                 */
3837                if (delta < 0 || (delta > 0 && task_running(rq, p)))
3838                        resched_task(rq->curr);
3839        }
3840out_unlock:
3841        task_rq_unlock(rq, p, &flags);
3842}
3843EXPORT_SYMBOL(set_user_nice);
3844
3845/*
3846 * can_nice - check if a task can reduce its nice value
3847 * @p: task
3848 * @nice: nice value
3849 */
3850int can_nice(const struct task_struct *p, const int nice)
3851{
3852        /* convert nice value [19,-20] to rlimit style value [1,40] */
3853        int nice_rlim = 20 - nice;
3854
3855        return (nice_rlim <= task_rlimit(p, RLIMIT_NICE) ||
3856                capable(CAP_SYS_NICE));
3857}
3858
3859#ifdef __ARCH_WANT_SYS_NICE
3860
3861/*
3862 * sys_nice - change the priority of the current process.
3863 * @increment: priority increment
3864 *
3865 * sys_setpriority is a more generic, but much slower function that
3866 * does similar things.
3867 */
3868SYSCALL_DEFINE1(nice, int, increment)
3869{
3870        long nice, retval;
3871
3872        /*
3873         * Setpriority might change our priority at the same moment.
3874         * We don't have to worry. Conceptually one call occurs first
3875         * and we have a single winner.
3876         */
3877        if (increment < -40)
3878                increment = -40;
3879        if (increment > 40)
3880                increment = 40;
3881
3882        nice = TASK_NICE(current) + increment;
3883        if (nice < -20)
3884                nice = -20;
3885        if (nice > 19)
3886                nice = 19;
3887
3888        if (increment < 0 && !can_nice(current, nice))
3889                return -EPERM;
3890
3891        retval = security_task_setnice(current, nice);
3892        if (retval)
3893                return retval;
3894
3895        set_user_nice(current, nice);
3896        return 0;
3897}
3898
3899#endif
3900
3901/**
3902 * task_prio - return the priority value of a given task.
3903 * @p: the task in question.
3904 *
3905 * This is the priority value as seen by users in /proc.
3906 * RT tasks are offset by -200. Normal tasks are centered
3907 * around 0, value goes from -16 to +15.
3908 */
3909int task_prio(const struct task_struct *p)
3910{
3911        return p->prio - MAX_RT_PRIO;
3912}
3913
3914/**
3915 * task_nice - return the nice value of a given task.
3916 * @p: the task in question.
3917 */
3918int task_nice(const struct task_struct *p)
3919{
3920        return TASK_NICE(p);
3921}
3922EXPORT_SYMBOL(task_nice);
3923
3924/**
3925 * idle_cpu - is a given cpu idle currently?
3926 * @cpu: the processor in question.
3927 */
3928int idle_cpu(int cpu)
3929{
3930        struct rq *rq = cpu_rq(cpu);
3931
3932        if (rq->curr != rq->idle)
3933                return 0;
3934
3935        if (rq->nr_running)
3936                return 0;
3937
3938#ifdef CONFIG_SMP
3939        if (!llist_empty(&rq->wake_list))
3940                return 0;
3941#endif
3942
3943        return 1;
3944}
3945
3946/**
3947 * idle_task - return the idle task for a given cpu.
3948 * @cpu: the processor in question.
3949 */
3950struct task_struct *idle_task(int cpu)
3951{
3952        return cpu_rq(cpu)->idle;
3953}
3954
3955/**
3956 * find_process_by_pid - find a process with a matching PID value.
3957 * @pid: the pid in question.
3958 */
3959static struct task_struct *find_process_by_pid(pid_t pid)
3960{
3961        return pid ? find_task_by_vpid(pid) : current;
3962}
3963
3964/* Actually do priority change: must hold rq lock. */
3965static void
3966__setscheduler(struct rq *rq, struct task_struct *p, int policy, int prio)
3967{
3968        p->policy = policy;
3969        p->rt_priority = prio;
3970        p->normal_prio = normal_prio(p);
3971        /* we are holding p->pi_lock already */
3972        p->prio = rt_mutex_getprio(p);
3973        if (rt_prio(p->prio))
3974                p->sched_class = &rt_sched_class;
3975        else
3976                p->sched_class = &fair_sched_class;
3977        set_load_weight(p);
3978}
3979
3980/*
3981 * check the target process has a UID that matches the current process's
3982 */
3983static bool check_same_owner(struct task_struct *p)
3984{
3985        const struct cred *cred = current_cred(), *pcred;
3986        bool match;
3987
3988        rcu_read_lock();
3989        pcred = __task_cred(p);
3990        if (cred->user->user_ns == pcred->user->user_ns)
3991                match = (cred->euid == pcred->euid ||
3992                         cred->euid == pcred->uid);
3993        else
3994                match = false;
3995        rcu_read_unlock();
3996        return match;
3997}
3998
3999static int __sched_setscheduler(struct task_struct *p, int policy,
4000                                const struct sched_param *param, bool user)
4001{
4002        int retval, oldprio, oldpolicy = -1, on_rq, running;
4003        unsigned long flags;
4004        const struct sched_class *prev_class;
4005        struct rq *rq;
4006        int reset_on_fork;
4007
4008        /* may grab non-irq protected spin_locks */
4009        BUG_ON(in_interrupt());
4010recheck:
4011        /* double check policy once rq lock held */
4012        if (policy < 0) {
4013                reset_on_fork = p->sched_reset_on_fork;
4014                policy = oldpolicy = p->policy;
4015        } else {
4016                reset_on_fork = !!(policy & SCHED_RESET_ON_FORK);
4017                policy &= ~SCHED_RESET_ON_FORK;
4018
4019                if (policy != SCHED_FIFO && policy != SCHED_RR &&
4020                                policy != SCHED_NORMAL && policy != SCHED_BATCH &&
4021                                policy != SCHED_IDLE)
4022                        return -EINVAL;
4023        }
4024
4025        /*
4026         * Valid priorities for SCHED_FIFO and SCHED_RR are
4027         * 1..MAX_USER_RT_PRIO-1, valid priority for SCHED_NORMAL,
4028         * SCHED_BATCH and SCHED_IDLE is 0.
4029         */
4030        if (param->sched_priority < 0 ||
4031            (p->mm && param->sched_priority > MAX_USER_RT_PRIO-1) ||
4032            (!p->mm && param->sched_priority > MAX_RT_PRIO-1))
4033                return -EINVAL;
4034        if (rt_policy(policy) != (param->sched_priority != 0))
4035                return -EINVAL;
4036
4037        /*
4038         * Allow unprivileged RT tasks to decrease priority:
4039         */
4040        if (user && !capable(CAP_SYS_NICE)) {
4041                if (rt_policy(policy)) {
4042                        unsigned long rlim_rtprio =
4043                                        task_rlimit(p, RLIMIT_RTPRIO);
4044
4045                        /* can't set/change the rt policy */
4046                        if (policy != p->policy && !rlim_rtprio)
4047                                return -EPERM;
4048
4049                        /* can't increase priority */
4050                        if (param->sched_priority > p->rt_priority &&
4051                            param->sched_priority > rlim_rtprio)
4052                                return -EPERM;
4053                }
4054
4055                /*
4056                 * Treat SCHED_IDLE as nice 20. Only allow a switch to
4057                 * SCHED_NORMAL if the RLIMIT_NICE would normally permit it.
4058                 */
4059                if (p->policy == SCHED_IDLE && policy != SCHED_IDLE) {
4060                        if (!can_nice(p, TASK_NICE(p)))
4061                                return -EPERM;
4062                }
4063
4064                /* can't change other user's priorities */
4065                if (!check_same_owner(p))
4066                        return -EPERM;
4067
4068                /* Normal users shall not reset the sched_reset_on_fork flag */
4069                if (p->sched_reset_on_fork && !reset_on_fork)
4070                        return -EPERM;
4071        }
4072
4073        if (user) {
4074                retval = security_task_setscheduler(p);
4075                if (retval)
4076                        return retval;
4077        }
4078
4079        /*
4080         * make sure no PI-waiters arrive (or leave) while we are
4081         * changing the priority of the task:
4082         *
4083         * To be able to change p->policy safely, the appropriate
4084         * runqueue lock must be held.
4085         */
4086        rq = task_rq_lock(p, &flags);
4087
4088        /*
4089         * Changing the policy of the stop threads its a very bad idea
4090         */
4091        if (p == rq->stop) {
4092                task_rq_unlock(rq, p, &flags);
4093                return -EINVAL;
4094        }
4095
4096        /*
4097         * If not changing anything there's no need to proceed further:
4098         */
4099        if (unlikely(policy == p->policy && (!rt_policy(policy) ||
4100                        param->sched_priority == p->rt_priority))) {
4101
4102                __task_rq_unlock(rq);
4103                raw_spin_unlock_irqrestore(&p->pi_lock, flags);
4104                return 0;
4105        }
4106
4107#ifdef CONFIG_RT_GROUP_SCHED
4108        if (user) {
4109                /*
4110                 * Do not allow realtime tasks into groups that have no runtime
4111                 * assigned.
4112                 */
4113                if (rt_bandwidth_enabled() && rt_policy(policy) &&
4114                                task_group(p)->rt_bandwidth.rt_runtime == 0 &&
4115                                !task_group_is_autogroup(task_group(p))) {
4116                        task_rq_unlock(rq, p, &flags);
4117                        return -EPERM;
4118                }
4119        }
4120#endif
4121
4122        /* recheck policy now with rq lock held */
4123        if (unlikely(oldpolicy != -1 && oldpolicy != p->policy)) {
4124                policy = oldpolicy = -1;
4125                task_rq_unlock(rq, p, &flags);
4126                goto recheck;
4127        }
4128        on_rq = p->on_rq;
4129        running = task_current(rq, p);
4130        if (on_rq)
4131                dequeue_task(rq, p, 0);
4132        if (running)
4133                p->sched_class->put_prev_task(rq, p);
4134
4135        p->sched_reset_on_fork = reset_on_fork;
4136
4137        oldprio = p->prio;
4138        prev_class = p->sched_class;
4139        __setscheduler(rq, p, policy, param->sched_priority);
4140
4141        if (running)
4142                p->sched_class->set_curr_task(rq);
4143        if (on_rq)
4144                enqueue_task(rq, p, 0);
4145
4146        check_class_changed(rq, p, prev_class, oldprio);
4147        task_rq_unlock(rq, p, &flags);
4148
4149        rt_mutex_adjust_pi(p);
4150
4151        return 0;
4152}
4153
4154/**
4155 * sched_setscheduler - change the scheduling policy and/or RT priority of a thread.
4156 * @p: the task in question.
4157 * @policy: new policy.
4158 * @param: structure containing the new RT priority.
4159 *
4160 * NOTE that the task may be already dead.
4161 */
4162int sched_setscheduler(struct task_struct *p, int policy,
4163                       const struct sched_param *param)
4164{
4165        return __sched_setscheduler(p, policy, param, true);
4166}
4167EXPORT_SYMBOL_GPL(sched_setscheduler);
4168
4169/**
4170 * sched_setscheduler_nocheck - change the scheduling policy and/or RT priority of a thread from kernelspace.
4171 * @p: the task in question.
4172 * @policy: new policy.
4173 * @param: structure containing the new RT priority.
4174 *
4175 * Just like sched_setscheduler, only don't bother checking if the
4176 * current context has permission.  For example, this is needed in
4177 * stop_machine(): we create temporary high priority worker threads,
4178 * but our caller might not have that capability.
4179 */
4180int sched_setscheduler_nocheck(struct task_struct *p, int policy,
4181                               const struct sched_param *param)
4182{
4183        return __sched_setscheduler(p, policy, param, false);
4184}
4185
4186static int
4187do_sched_setscheduler(pid_t pid, int policy, struct sched_param __user *param)
4188{
4189        struct sched_param lparam;
4190        struct task_struct *p;
4191        int retval;
4192
4193        if (!param || pid < 0)
4194                return -EINVAL;
4195        if (copy_from_user(&lparam, param, sizeof(struct sched_param)))
4196                return -EFAULT;
4197
4198        rcu_read_lock();
4199        retval = -ESRCH;
4200        p = find_process_by_pid(pid);
4201        if (p != NULL)
4202                retval = sched_setscheduler(p, policy, &lparam);
4203        rcu_read_unlock();
4204
4205        return retval;
4206}
4207
4208/**
4209 * sys_sched_setscheduler - set/change the scheduler policy and RT priority
4210 * @pid: the pid in question.
4211 * @policy: new policy.
4212 * @param: structure containing the new RT priority.
4213 */
4214SYSCALL_DEFINE3(sched_setscheduler, pid_t, pid, int, policy,
4215                struct sched_param __user *, param)
4216{
4217        /* negative values for policy are not valid */
4218        if (policy < 0)
4219                return -EINVAL;
4220
4221        return do_sched_setscheduler(pid, policy, param);
4222}
4223
4224/**
4225 * sys_sched_setparam - set/change the RT priority of a thread
4226 * @pid: the pid in question.
4227 * @param: structure containing the new RT priority.
4228 */
4229SYSCALL_DEFINE2(sched_setparam, pid_t, pid, struct sched_param __user *, param)
4230{
4231        return do_sched_setscheduler(pid, -1, param);
4232}
4233
4234/**
4235 * sys_sched_getscheduler - get the policy (scheduling class) of a thread
4236 * @pid: the pid in question.
4237 */
4238SYSCALL_DEFINE1(sched_getscheduler, pid_t, pid)
4239{
4240        struct task_struct *p;
4241        int retval;
4242
4243        if (pid < 0)
4244                return -EINVAL;
4245
4246        retval = -ESRCH;
4247        rcu_read_lock();
4248        p = find_process_by_pid(pid);
4249        if (p) {
4250                retval = security_task_getscheduler(p);
4251                if (!retval)
4252                        retval = p->policy
4253                                | (p->sched_reset_on_fork ? SCHED_RESET_ON_FORK : 0);
4254        }
4255        rcu_read_unlock();
4256        return retval;
4257}
4258
4259/**
4260 * sys_sched_getparam - get the RT priority of a thread
4261 * @pid: the pid in question.
4262 * @param: structure containing the RT priority.
4263 */
4264SYSCALL_DEFINE2(sched_getparam, pid_t, pid, struct sched_param __user *, param)
4265{
4266        struct sched_param lp;
4267        struct task_struct *p;
4268        int retval;
4269
4270        if (!param || pid < 0)
4271                return -EINVAL;
4272
4273        rcu_read_lock();
4274        p = find_process_by_pid(pid);
4275        retval = -ESRCH;
4276        if (!p)
4277                goto out_unlock;
4278
4279        retval = security_task_getscheduler(p);
4280        if (retval)
4281                goto out_unlock;
4282
4283        lp.sched_priority = p->rt_priority;
4284        rcu_read_unlock();
4285
4286        /*
4287         * This one might sleep, we cannot do it with a spinlock held ...
4288         */
4289        retval = copy_to_user(param, &lp, sizeof(*param)) ? -EFAULT : 0;
4290
4291        return retval;
4292
4293out_unlock:
4294        rcu_read_unlock();
4295        return retval;
4296}
4297
4298long sched_setaffinity(pid_t pid, const struct cpumask *in_mask)
4299{
4300        cpumask_var_t cpus_allowed, new_mask;
4301        struct task_struct *p;
4302        int retval;
4303
4304        get_online_cpus();
4305        rcu_read_lock();
4306
4307        p = find_process_by_pid(pid);
4308        if (!p) {
4309                rcu_read_unlock();
4310                put_online_cpus();
4311                return -ESRCH;
4312        }
4313
4314        /* Prevent p going away */
4315        get_task_struct(p);
4316        rcu_read_unlock();
4317
4318        if (!alloc_cpumask_var(&cpus_allowed, GFP_KERNEL)) {
4319                retval = -ENOMEM;
4320                goto out_put_task;
4321        }
4322        if (!alloc_cpumask_var(&new_mask, GFP_KERNEL)) {
4323                retval = -ENOMEM;
4324                goto out_free_cpus_allowed;
4325        }
4326        retval = -EPERM;
4327        if (!check_same_owner(p) && !ns_capable(task_user_ns(p), CAP_SYS_NICE))
4328                goto out_unlock;
4329
4330        retval = security_task_setscheduler(p);
4331        if (retval)
4332                goto out_unlock;
4333
4334        cpuset_cpus_allowed(p, cpus_allowed);
4335        cpumask_and(new_mask, in_mask, cpus_allowed);
4336again:
4337        retval = set_cpus_allowed_ptr(p, new_mask);
4338
4339        if (!retval) {
4340                cpuset_cpus_allowed(p, cpus_allowed);
4341                if (!cpumask_subset(new_mask, cpus_allowed)) {
4342                        /*
4343                         * We must have raced with a concurrent cpuset
4344                         * update. Just reset the cpus_allowed to the
4345                         * cpuset's cpus_allowed
4346                         */
4347                        cpumask_copy(new_mask, cpus_allowed);
4348                        goto again;
4349                }
4350        }
4351out_unlock:
4352        free_cpumask_var(new_mask);
4353out_free_cpus_allowed:
4354        free_cpumask_var(cpus_allowed);
4355out_put_task:
4356        put_task_struct(p);
4357        put_online_cpus();
4358        return retval;
4359}
4360
4361static int get_user_cpu_mask(unsigned long __user *user_mask_ptr, unsigned len,
4362                             struct cpumask *new_mask)
4363{
4364        if (len < cpumask_size())
4365                cpumask_clear(new_mask);
4366        else if (len > cpumask_size())
4367                len = cpumask_size();
4368
4369        return copy_from_user(new_mask, user_mask_ptr, len) ? -EFAULT : 0;
4370}
4371
4372/**
4373 * sys_sched_setaffinity - set the cpu affinity of a process
4374 * @pid: pid of the process
4375 * @len: length in bytes of the bitmask pointed to by user_mask_ptr
4376 * @user_mask_ptr: user-space pointer to the new cpu mask
4377 */
4378SYSCALL_DEFINE3(sched_setaffinity, pid_t, pid, unsigned int, len,
4379                unsigned long __user *, user_mask_ptr)
4380{
4381        cpumask_var_t new_mask;
4382        int retval;
4383
4384        if (!alloc_cpumask_var(&new_mask, GFP_KERNEL))
4385                return -ENOMEM;
4386
4387        retval = get_user_cpu_mask(user_mask_ptr, len, new_mask);
4388        if (retval == 0)
4389                retval = sched_setaffinity(pid, new_mask);
4390        free_cpumask_var(new_mask);
4391        return retval;
4392}
4393
4394long sched_getaffinity(pid_t pid, struct cpumask *mask)
4395{
4396        struct task_struct *p;
4397        unsigned long flags;
4398        int retval;
4399
4400        get_online_cpus();
4401        rcu_read_lock();
4402
4403        retval = -ESRCH;
4404        p = find_process_by_pid(pid);
4405        if (!p)
4406                goto out_unlock;
4407
4408        retval = security_task_getscheduler(p);
4409        if (retval)
4410                goto out_unlock;
4411
4412        raw_spin_lock_irqsave(&p->pi_lock, flags);
4413        cpumask_and(mask, &p->cpus_allowed, cpu_online_mask);
4414        raw_spin_unlock_irqrestore(&p->pi_lock, flags);
4415
4416out_unlock:
4417        rcu_read_unlock();
4418        put_online_cpus();
4419
4420        return retval;
4421}
4422
4423/**
4424 * sys_sched_getaffinity - get the cpu affinity of a process
4425 * @pid: pid of the process
4426 * @len: length in bytes of the bitmask pointed to by user_mask_ptr
4427 * @user_mask_ptr: user-space pointer to hold the current cpu mask
4428 */
4429SYSCALL_DEFINE3(sched_getaffinity, pid_t, pid, unsigned int, len,
4430                unsigned long __user *, user_mask_ptr)
4431{
4432        int ret;
4433        cpumask_var_t mask;
4434
4435        if ((len * BITS_PER_BYTE) < nr_cpu_ids)
4436                return -EINVAL;
4437        if (len & (sizeof(unsigned long)-1))
4438                return -EINVAL;
4439
4440        if (!alloc_cpumask_var(&mask, GFP_KERNEL))
4441                return -ENOMEM;
4442
4443        ret = sched_getaffinity(pid, mask);
4444        if (ret == 0) {
4445                size_t retlen = min_t(size_t, len, cpumask_size());
4446
4447                if (copy_to_user(user_mask_ptr, mask, retlen))
4448                        ret = -EFAULT;
4449                else
4450                        ret = retlen;
4451        }
4452        free_cpumask_var(mask);
4453
4454        return ret;
4455}
4456
4457/**
4458 * sys_sched_yield - yield the current processor to other threads.
4459 *
4460 * This function yields the current CPU to other tasks. If there are no
4461 * other threads running on this CPU then this function will return.
4462 */
4463SYSCALL_DEFINE0(sched_yield)
4464{
4465        struct rq *rq = this_rq_lock();
4466
4467        schedstat_inc(rq, yld_count);
4468        current->sched_class->yield_task(rq);
4469
4470        /*
4471         * Since we are going to call schedule() anyway, there's
4472         * no need to preempt or enable interrupts:
4473         */
4474        __release(rq->lock);
4475        spin_release(&rq->lock.dep_map, 1, _THIS_IP_);
4476        do_raw_spin_unlock(&rq->lock);
4477        preempt_enable_no_resched();
4478
4479        schedule();
4480
4481        return 0;
4482}
4483
4484static inline int should_resched(void)
4485{
4486        return need_resched() && !(preempt_count() & PREEMPT_ACTIVE);
4487}
4488
4489static void __cond_resched(void)
4490{
4491        add_preempt_count(PREEMPT_ACTIVE);
4492        __schedule();
4493        sub_preempt_count(PREEMPT_ACTIVE);
4494}
4495
4496int __sched _cond_resched(void)
4497{
4498        if (should_resched()) {
4499                __cond_resched();
4500                return 1;
4501        }
4502        return 0;
4503}
4504EXPORT_SYMBOL(_cond_resched);
4505
4506/*
4507 * __cond_resched_lock() - if a reschedule is pending, drop the given lock,
4508 * call schedule, and on return reacquire the lock.
4509 *
4510 * This works OK both with and without CONFIG_PREEMPT. We do strange low-level
4511 * operations here to prevent schedule() from being called twice (once via
4512 * spin_unlock(), once by hand).
4513 */
4514int __cond_resched_lock(spinlock_t *lock)
4515{
4516        int resched = should_resched();
4517        int ret = 0;
4518
4519        lockdep_assert_held(lock);
4520
4521        if (spin_needbreak(lock) || resched) {
4522                spin_unlock(lock);
4523                if (resched)
4524                        __cond_resched();
4525                else
4526                        cpu_relax();
4527                ret = 1;
4528                spin_lock(lock);
4529        }
4530        return ret;
4531}
4532EXPORT_SYMBOL(__cond_resched_lock);
4533
4534int __sched __cond_resched_softirq(void)
4535{
4536        BUG_ON(!in_softirq());
4537
4538        if (should_resched()) {
4539                local_bh_enable();
4540                __cond_resched();
4541                local_bh_disable();
4542                return 1;
4543        }
4544        return 0;
4545}
4546EXPORT_SYMBOL(__cond_resched_softirq);
4547
4548/**
4549 * yield - yield the current processor to other threads.
4550 *
4551 * This is a shortcut for kernel-space yielding - it marks the
4552 * thread runnable and calls sys_sched_yield().
4553 */
4554void __sched yield(void)
4555{
4556        set_current_state(TASK_RUNNING);
4557        sys_sched_yield();
4558}
4559EXPORT_SYMBOL(yield);
4560
4561/**
4562 * yield_to - yield the current processor to another thread in
4563 * your thread group, or accelerate that thread toward the
4564 * processor it's on.
4565 * @p: target task
4566 * @preempt: whether task preemption is allowed or not
4567 *
4568 * It's the caller's job to ensure that the target task struct
4569 * can't go away on us before we can do any checks.
4570 *
4571 * Returns true if we indeed boosted the target task.
4572 */
4573bool __sched yield_to(struct task_struct *p, bool preempt)
4574{
4575        struct task_struct *curr = current;
4576        struct rq *rq, *p_rq;
4577        unsigned long flags;
4578        bool yielded = 0;
4579
4580        local_irq_save(flags);
4581        rq = this_rq();
4582
4583again:
4584        p_rq = task_rq(p);
4585        double_rq_lock(rq, p_rq);
4586        while (task_rq(p) != p_rq) {
4587                double_rq_unlock(rq, p_rq);
4588                goto again;
4589        }
4590
4591        if (!curr->sched_class->yield_to_task)
4592                goto out;
4593
4594        if (curr->sched_class != p->sched_class)
4595                goto out;
4596
4597        if (task_running(p_rq, p) || p->state)
4598                goto out;
4599
4600        yielded = curr->sched_class->yield_to_task(rq, p, preempt);
4601        if (yielded) {
4602                schedstat_inc(rq, yld_count);
4603                /*
4604                 * Make p's CPU reschedule; pick_next_entity takes care of
4605                 * fairness.
4606                 */
4607                if (preempt && rq != p_rq)
4608                        resched_task(p_rq->curr);
4609        } else {
4610                /*
4611                 * We might have set it in task_yield_fair(), but are
4612                 * not going to schedule(), so don't want to skip
4613                 * the next update.
4614                 */
4615                rq->skip_clock_update = 0;
4616        }
4617
4618out:
4619        double_rq_unlock(rq, p_rq);
4620        local_irq_restore(flags);
4621
4622        if (yielded)
4623                schedule();
4624
4625        return yielded;
4626}
4627EXPORT_SYMBOL_GPL(yield_to);
4628
4629/*
4630 * This task is about to go to sleep on IO. Increment rq->nr_iowait so
4631 * that process accounting knows that this is a task in IO wait state.
4632 */
4633void __sched io_schedule(void)
4634{
4635        struct rq *rq = raw_rq();
4636
4637        delayacct_blkio_start();
4638        atomic_inc(&rq->nr_iowait);
4639        blk_flush_plug(current);
4640        current->in_iowait = 1;
4641        schedule();
4642        current->in_iowait = 0;
4643        atomic_dec(&rq->nr_iowait);
4644        delayacct_blkio_end();
4645}
4646EXPORT_SYMBOL(io_schedule);
4647
4648long __sched io_schedule_timeout(long timeout)
4649{
4650        struct rq *rq = raw_rq();
4651        long ret;
4652
4653        delayacct_blkio_start();
4654        atomic_inc(&rq->nr_iowait);
4655        blk_flush_plug(current);
4656        current->in_iowait = 1;
4657        ret = schedule_timeout(timeout);
4658        current->in_iowait = 0;
4659        atomic_dec(&rq->nr_iowait);
4660        delayacct_blkio_end();
4661        return ret;
4662}
4663
4664/**
4665 * sys_sched_get_priority_max - return maximum RT priority.
4666 * @policy: scheduling class.
4667 *
4668 * this syscall returns the maximum rt_priority that can be used
4669 * by a given scheduling class.
4670 */
4671SYSCALL_DEFINE1(sched_get_priority_max, int, policy)
4672{
4673        int ret = -EINVAL;
4674
4675        switch (policy) {
4676        case SCHED_FIFO:
4677        case SCHED_RR:
4678                ret = MAX_USER_RT_PRIO-1;
4679                break;
4680        case SCHED_NORMAL:
4681        case SCHED_BATCH:
4682        case SCHED_IDLE:
4683                ret = 0;
4684                break;
4685        }
4686        return ret;
4687}
4688
4689/**
4690 * sys_sched_get_priority_min - return minimum RT priority.
4691 * @policy: scheduling class.
4692 *
4693 * this syscall returns the minimum rt_priority that can be used
4694 * by a given scheduling class.
4695 */
4696SYSCALL_DEFINE1(sched_get_priority_min, int, policy)
4697{
4698        int ret = -EINVAL;
4699
4700        switch (policy) {
4701        case SCHED_FIFO:
4702        case SCHED_RR:
4703                ret = 1;
4704                break;
4705        case SCHED_NORMAL:
4706        case SCHED_BATCH:
4707        case SCHED_IDLE:
4708                ret = 0;
4709        }
4710        return ret;
4711}
4712
4713/**
4714 * sys_sched_rr_get_interval - return the default timeslice of a process.
4715 * @pid: pid of the process.
4716 * @interval: userspace pointer to the timeslice value.
4717 *
4718 * this syscall writes the default timeslice value of a given process
4719 * into the user-space timespec buffer. A value of '0' means infinity.
4720 */
4721SYSCALL_DEFINE2(sched_rr_get_interval, pid_t, pid,
4722                struct timespec __user *, interval)
4723{
4724        struct task_struct *p;
4725        unsigned int time_slice;
4726        unsigned long flags;
4727        struct rq *rq;
4728        int retval;
4729        struct timespec t;
4730
4731        if (pid < 0)
4732                return -EINVAL;
4733
4734        retval = -ESRCH;
4735        rcu_read_lock();
4736        p = find_process_by_pid(pid);
4737        if (!p)
4738                goto out_unlock;
4739
4740        retval = security_task_getscheduler(p);
4741        if (retval)
4742                goto out_unlock;
4743
4744        rq = task_rq_lock(p, &flags);
4745        time_slice = p->sched_class->get_rr_interval(rq, p);
4746        task_rq_unlock(rq, p, &flags);
4747
4748        rcu_read_unlock();
4749        jiffies_to_timespec(time_slice, &t);
4750        retval = copy_to_user(interval, &t, sizeof(t)) ? -EFAULT : 0;
4751        return retval;
4752
4753out_unlock:
4754        rcu_read_unlock();
4755        return retval;
4756}
4757
4758static const char stat_nam[] = TASK_STATE_TO_CHAR_STR;
4759
4760void sched_show_task(struct task_struct *p)
4761{
4762        unsigned long free = 0;
4763        unsigned state;
4764
4765        state = p->state ? __ffs(p->state) + 1 : 0;
4766        printk(KERN_INFO "%-15.15s %c", p->comm,
4767                state < sizeof(stat_nam) - 1 ? stat_nam[state] : '?');
4768#if BITS_PER_LONG == 32
4769        if (state == TASK_RUNNING)
4770                printk(KERN_CONT " running  ");
4771        else
4772                printk(KERN_CONT " %08lx ", thread_saved_pc(p));
4773#else
4774        if (state == TASK_RUNNING)
4775                printk(KERN_CONT "  running task    ");
4776        else
4777                printk(KERN_CONT " %016lx ", thread_saved_pc(p));
4778#endif
4779#ifdef CONFIG_DEBUG_STACK_USAGE
4780        free = stack_not_used(p);
4781#endif
4782        printk(KERN_CONT "%5lu %5d %6d 0x%08lx\n", free,
4783                task_pid_nr(p), task_pid_nr(rcu_dereference(p->real_parent)),
4784                (unsigned long)task_thread_info(p)->flags);
4785
4786        show_stack(p, NULL);
4787}
4788
4789void show_state_filter(unsigned long state_filter)
4790{
4791        struct task_struct *g, *p;
4792
4793#if BITS_PER_LONG == 32
4794        printk(KERN_INFO
4795                "  task                PC stack   pid father\n");
4796#else
4797        printk(KERN_INFO
4798                "  task                        PC stack   pid father\n");
4799#endif
4800        rcu_read_lock();
4801        do_each_thread(g, p) {
4802                /*
4803                 * reset the NMI-timeout, listing all files on a slow
4804                 * console might take a lot of time:
4805                 */
4806                touch_nmi_watchdog();
4807                if (!state_filter || (p->state & state_filter))
4808                        sched_show_task(p);
4809        } while_each_thread(g, p);
4810
4811        touch_all_softlockup_watchdogs();
4812
4813#ifdef CONFIG_SCHED_DEBUG
4814        sysrq_sched_debug_show();
4815#endif
4816        rcu_read_unlock();
4817        /*
4818         * Only show locks if all tasks are dumped:
4819         */
4820        if (!state_filter)
4821                debug_show_all_locks();
4822}
4823
4824void __cpuinit init_idle_bootup_task(struct task_struct *idle)
4825{
4826        idle->sched_class = &idle_sched_class;
4827}
4828
4829/**
4830 * init_idle - set up an idle thread for a given CPU
4831 * @idle: task in question
4832 * @cpu: cpu the idle task belongs to
4833 *
4834 * NOTE: this function does not set the idle thread's NEED_RESCHED
4835 * flag, to make booting more robust.
4836 */
4837void __cpuinit init_idle(struct task_struct *idle, int cpu)
4838{
4839        struct rq *rq = cpu_rq(cpu);
4840        unsigned long flags;
4841
4842        raw_spin_lock_irqsave(&rq->lock, flags);
4843
4844        __sched_fork(idle);
4845        idle->state = TASK_RUNNING;
4846        idle->se.exec_start = sched_clock();
4847
4848        do_set_cpus_allowed(idle, cpumask_of(cpu));
4849        /*
4850         * We're having a chicken and egg problem, even though we are
4851         * holding rq->lock, the cpu isn't yet set to this cpu so the
4852         * lockdep check in task_group() will fail.
4853         *
4854         * Similar case to sched_fork(). / Alternatively we could
4855         * use task_rq_lock() here and obtain the other rq->lock.
4856         *
4857         * Silence PROVE_RCU
4858         */
4859        rcu_read_lock();
4860        __set_task_cpu(idle, cpu);
4861        rcu_read_unlock();
4862
4863        rq->curr = rq->idle = idle;
4864#if defined(CONFIG_SMP)
4865        idle->on_cpu = 1;
4866#endif
4867        raw_spin_unlock_irqrestore(&rq->lock, flags);
4868
4869        /* Set the preempt count _outside_ the spinlocks! */
4870        task_thread_info(idle)->preempt_count = 0;
4871
4872        /*
4873         * The idle tasks have their own, simple scheduling class:
4874         */
4875        idle->sched_class = &idle_sched_class;
4876        ftrace_graph_init_idle_task(idle, cpu);
4877#if defined(CONFIG_SMP)
4878        sprintf(idle->comm, "%s/%d", INIT_TASK_COMM, cpu);
4879#endif
4880}
4881
4882#ifdef CONFIG_SMP
4883void do_set_cpus_allowed(struct task_struct *p, const struct cpumask *new_mask)
4884{
4885        if (p->sched_class && p->sched_class->set_cpus_allowed)
4886                p->sched_class->set_cpus_allowed(p, new_mask);
4887
4888        cpumask_copy(&p->cpus_allowed, new_mask);
4889        p->rt.nr_cpus_allowed = cpumask_weight(new_mask);
4890}
4891
4892/*
4893 * This is how migration works:
4894 *
4895 * 1) we invoke migration_cpu_stop() on the target CPU using
4896 *    stop_one_cpu().
4897 * 2) stopper starts to run (implicitly forcing the migrated thread
4898 *    off the CPU)
4899 * 3) it checks whether the migrated task is still in the wrong runqueue.
4900 * 4) if it's in the wrong runqueue then the migration thread removes
4901 *    it and puts it into the right queue.
4902 * 5) stopper completes and stop_one_cpu() returns and the migration
4903 *    is done.
4904 */
4905
4906/*
4907 * Change a given task's CPU affinity. Migrate the thread to a
4908 * proper CPU and schedule it away if the CPU it's executing on
4909 * is removed from the allowed bitmask.
4910 *
4911 * NOTE: the caller must have a valid reference to the task, the
4912 * task must not exit() & deallocate itself prematurely. The
4913 * call is not atomic; no spinlocks may be held.
4914 */
4915int set_cpus_allowed_ptr(struct task_struct *p, const struct cpumask *new_mask)
4916{
4917        unsigned long flags;
4918        struct rq *rq;
4919        unsigned int dest_cpu;
4920        int ret = 0;
4921
4922        rq = task_rq_lock(p, &flags);
4923
4924        if (cpumask_equal(&p->cpus_allowed, new_mask))
4925                goto out;
4926
4927        if (!cpumask_intersects(new_mask, cpu_active_mask)) {
4928                ret = -EINVAL;
4929                goto out;
4930        }
4931
4932        if (unlikely((p->flags & PF_THREAD_BOUND) && p != current)) {
4933                ret = -EINVAL;
4934                goto out;
4935        }
4936
4937        do_set_cpus_allowed(p, new_mask);
4938
4939        /* Can the task run on the task's current CPU? If so, we're done */
4940        if (cpumask_test_cpu(task_cpu(p), new_mask))
4941                goto out;
4942
4943        dest_cpu = cpumask_any_and(cpu_active_mask, new_mask);
4944        if (p->on_rq) {
4945                struct migration_arg arg = { p, dest_cpu };
4946                /* Need help from migration thread: drop lock and wait. */
4947                task_rq_unlock(rq, p, &flags);
4948                stop_one_cpu(cpu_of(rq), migration_cpu_stop, &arg);
4949                tlb_migrate_finish(p->mm);
4950                return 0;
4951        }
4952out:
4953        task_rq_unlock(rq, p, &flags);
4954
4955        return ret;
4956}
4957EXPORT_SYMBOL_GPL(set_cpus_allowed_ptr);
4958
4959/*
4960 * Move (not current) task off this cpu, onto dest cpu. We're doing
4961 * this because either it can't run here any more (set_cpus_allowed()
4962 * away from this CPU, or CPU going down), or because we're
4963 * attempting to rebalance this task on exec (sched_exec).
4964 *
4965 * So we race with normal scheduler movements, but that's OK, as long
4966 * as the task is no longer on this CPU.
4967 *
4968 * Returns non-zero if task was successfully migrated.
4969 */
4970static int __migrate_task(struct task_struct *p, int src_cpu, int dest_cpu)
4971{
4972        struct rq *rq_dest, *rq_src;
4973        int ret = 0;
4974
4975        if (unlikely(!cpu_active(dest_cpu)))
4976                return ret;
4977
4978        rq_src = cpu_rq(src_cpu);
4979        rq_dest = cpu_rq(dest_cpu);
4980
4981        raw_spin_lock(&p->pi_lock);
4982        double_rq_lock(rq_src, rq_dest);
4983        /* Already moved. */
4984        if (task_cpu(p) != src_cpu)
4985                goto done;
4986        /* Affinity changed (again). */
4987        if (!cpumask_test_cpu(dest_cpu, tsk_cpus_allowed(p)))
4988                goto fail;
4989
4990        /*
4991         * If we're not on a rq, the next wake-up will ensure we're
4992         * placed properly.
4993         */
4994        if (p->on_rq) {
4995                dequeue_task(rq_src, p, 0);
4996                set_task_cpu(p, dest_cpu);
4997                enqueue_task(rq_dest, p, 0);
4998                check_preempt_curr(rq_dest, p, 0);
4999        }
5000done:
5001        ret = 1;
5002fail:
5003        double_rq_unlock(rq_src, rq_dest);
5004        raw_spin_unlock(&p->pi_lock);
5005        return ret;
5006}
5007
5008/*
5009 * migration_cpu_stop - this will be executed by a highprio stopper thread
5010 * and performs thread migration by bumping thread off CPU then
5011 * 'pushing' onto another runqueue.
5012 */
5013static int migration_cpu_stop(void *data)
5014{
5015        struct migration_arg *arg = data;
5016
5017        /*
5018         * The original target cpu might have gone down and we might
5019         * be on another cpu but it doesn't matter.
5020         */
5021        local_irq_disable();
5022        __migrate_task(arg->task, raw_smp_processor_id(), arg->dest_cpu);
5023        local_irq_enable();
5024        return 0;
5025}
5026
5027#ifdef CONFIG_HOTPLUG_CPU
5028
5029/*
5030 * Ensures that the idle task is using init_mm right before its cpu goes
5031 * offline.
5032 */
5033void idle_task_exit(void)
5034{
5035        struct mm_struct *mm = current->active_mm;
5036
5037        BUG_ON(cpu_online(smp_processor_id()));
5038
5039        if (mm != &init_mm)
5040                switch_mm(mm, &init_mm, current);
5041        mmdrop(mm);
5042}
5043
5044/*
5045 * While a dead CPU has no uninterruptible tasks queued at this point,
5046 * it might still have a nonzero ->nr_uninterruptible counter, because
5047 * for performance reasons the counter is not stricly tracking tasks to
5048 * their home CPUs. So we just add the counter to another CPU's counter,
5049 * to keep the global sum constant after CPU-down:
5050 */
5051static void migrate_nr_uninterruptible(struct rq *rq_src)
5052{
5053        struct rq *rq_dest = cpu_rq(cpumask_any(cpu_active_mask));
5054
5055        rq_dest->nr_uninterruptible += rq_src->nr_uninterruptible;
5056        rq_src->nr_uninterruptible = 0;
5057}
5058
5059/*
5060 * remove the tasks which were accounted by rq from calc_load_tasks.
5061 */
5062static void calc_global_load_remove(struct rq *rq)
5063{
5064        atomic_long_sub(rq->calc_load_active, &calc_load_tasks);
5065        rq->calc_load_active = 0;
5066}
5067
5068/*
5069 * Migrate all tasks from the rq, sleeping tasks will be migrated by
5070 * try_to_wake_up()->select_task_rq().
5071 *
5072 * Called with rq->lock held even though we'er in stop_machine() and
5073 * there's no concurrency possible, we hold the required locks anyway
5074 * because of lock validation efforts.
5075 */
5076static void migrate_tasks(unsigned int dead_cpu)
5077{
5078        struct rq *rq = cpu_rq(dead_cpu);
5079        struct task_struct *next, *stop = rq->stop;
5080        int dest_cpu;
5081
5082        /*
5083         * Fudge the rq selection such that the below task selection loop
5084         * doesn't get stuck on the currently eligible stop task.
5085         *
5086         * We're currently inside stop_machine() and the rq is either stuck
5087         * in the stop_machine_cpu_stop() loop, or we're executing this code,
5088         * either way we should never end up calling schedule() until we're
5089         * done here.
5090         */
5091        rq->stop = NULL;
5092
5093        /* Ensure any throttled groups are reachable by pick_next_task */
5094        unthrottle_offline_cfs_rqs(rq);
5095
5096        for ( ; ; ) {
5097                /*
5098                 * There's this thread running, bail when that's the only
5099                 * remaining thread.
5100                 */
5101                if (rq->nr_running == 1)
5102                        break;
5103
5104                next = pick_next_task(rq);
5105                BUG_ON(!next);
5106                next->sched_class->put_prev_task(rq, next);
5107
5108                /* Find suitable destination for @next, with force if needed. */
5109                dest_cpu = select_fallback_rq(dead_cpu, next);
5110                raw_spin_unlock(&rq->lock);
5111
5112                __migrate_task(next, dead_cpu, dest_cpu);
5113
5114                raw_spin_lock(&rq->lock);
5115        }
5116
5117        rq->stop = stop;
5118}
5119
5120#endif /* CONFIG_HOTPLUG_CPU */
5121
5122#if defined(CONFIG_SCHED_DEBUG) && defined(CONFIG_SYSCTL)
5123
5124static struct ctl_table sd_ctl_dir[] = {
5125        {
5126                .procname       = "sched_domain",
5127                .mode           = 0555,
5128        },
5129        {}
5130};
5131
5132static struct ctl_table sd_ctl_root[] = {
5133        {
5134                .procname       = "kernel",
5135                .mode           = 0555,
5136                .child          = sd_ctl_dir,
5137        },
5138        {}
5139};
5140
5141static struct ctl_table *sd_alloc_ctl_entry(int n)
5142{
5143        struct ctl_table *entry =
5144                kcalloc(n, sizeof(struct ctl_table), GFP_KERNEL);
5145
5146        return entry;
5147}
5148
5149static void sd_free_ctl_entry(struct ctl_table **tablep)
5150{
5151        struct ctl_table *entry;
5152
5153        /*
5154         * In the intermediate directories, both the child directory and
5155         * procname are dynamically allocated and could fail but the mode
5156         * will always be set. In the lowest directory the names are
5157         * static strings and all have proc handlers.
5158         */
5159        for (entry = *tablep; entry->mode; entry++) {
5160                if (entry->child)
5161                        sd_free_ctl_entry(&entry->child);
5162                if (entry->proc_handler == NULL)
5163                        kfree(entry->procname);
5164        }
5165
5166        kfree(*tablep);
5167        *tablep = NULL;
5168}
5169
5170static void
5171set_table_entry(struct ctl_table *entry,
5172                const char *procname, void *data, int maxlen,
5173                umode_t mode, proc_handler *proc_handler)
5174{
5175        entry->procname = procname;
5176        entry->data = data;
5177        entry->maxlen = maxlen;
5178        entry->mode = mode;
5179        entry->proc_handler = proc_handler;
5180}
5181
5182static struct ctl_table *
5183sd_alloc_ctl_domain_table(struct sched_domain *sd)
5184{
5185        struct ctl_table *table = sd_alloc_ctl_entry(13);
5186
5187        if (table == NULL)
5188                return NULL;
5189
5190        set_table_entry(&table[0], "min_interval", &sd->min_interval,
5191                sizeof(long), 0644, proc_doulongvec_minmax);
5192        set_table_entry(&table[1], "max_interval", &sd->max_interval,
5193                sizeof(long), 0644, proc_doulongvec_minmax);
5194        set_table_entry(&table[2], "busy_idx", &sd->busy_idx,
5195                sizeof(int), 0644, proc_dointvec_minmax);
5196        set_table_entry(&table[3], "idle_idx", &sd->idle_idx,
5197                sizeof(int), 0644, proc_dointvec_minmax);
5198        set_table_entry(&table[4], "newidle_idx", &sd->newidle_idx,
5199                sizeof(int), 0644, proc_dointvec_minmax);
5200        set_table_entry(&table[5], "wake_idx", &sd->wake_idx,
5201                sizeof(int), 0644, proc_dointvec_minmax);
5202        set_table_entry(&table[6], "forkexec_idx", &sd->forkexec_idx,
5203                sizeof(int), 0644, proc_dointvec_minmax);
5204        set_table_entry(&table[7], "busy_factor", &sd->busy_factor,
5205                sizeof(int), 0644, proc_dointvec_minmax);
5206        set_table_entry(&table[8], "imbalance_pct", &sd->imbalance_pct,
5207                sizeof(int), 0644, proc_dointvec_minmax);
5208        set_table_entry(&table[9], "cache_nice_tries",
5209                &sd->cache_nice_tries,
5210                sizeof(int), 0644, proc_dointvec_minmax);
5211        set_table_entry(&table[10], "flags", &sd->flags,
5212                sizeof(int), 0644, proc_dointvec_minmax);
5213        set_table_entry(&table[11], "name", sd->name,
5214                CORENAME_MAX_SIZE, 0444, proc_dostring);
5215        /* &table[12] is terminator */
5216
5217        return table;
5218}
5219
5220static ctl_table *sd_alloc_ctl_cpu_table(int cpu)
5221{
5222        struct ctl_table *entry, *table;
5223        struct sched_domain *sd;
5224        int domain_num = 0, i;
5225        char buf[32];
5226
5227        for_each_domain(cpu, sd)
5228                domain_num++;
5229        entry = table = sd_alloc_ctl_entry(domain_num + 1);
5230        if (table == NULL)
5231                return NULL;
5232
5233        i = 0;
5234        for_each_domain(cpu, sd) {
5235                snprintf(buf, 32, "domain%d", i);
5236                entry->procname = kstrdup(buf, GFP_KERNEL);
5237                entry->mode = 0555;
5238                entry->child = sd_alloc_ctl_domain_table(sd);
5239                entry++;
5240                i++;
5241        }
5242        return table;
5243}
5244
5245static struct ctl_table_header *sd_sysctl_header;
5246static void register_sched_domain_sysctl(void)
5247{
5248        int i, cpu_num = num_possible_cpus();
5249        struct ctl_table *entry = sd_alloc_ctl_entry(cpu_num + 1);
5250        char buf[32];
5251
5252        WARN_ON(sd_ctl_dir[0].child);
5253        sd_ctl_dir[0].child = entry;
5254
5255        if (entry == NULL)
5256                return;
5257
5258        for_each_possible_cpu(i) {
5259                snprintf(buf, 32, "cpu%d", i);
5260                entry->procname = kstrdup(buf, GFP_KERNEL);
5261                entry->mode = 0555;
5262                entry->child = sd_alloc_ctl_cpu_table(i);
5263                entry++;
5264        }
5265
5266        WARN_ON(sd_sysctl_header);
5267        sd_sysctl_header = register_sysctl_table(sd_ctl_root);
5268}
5269
5270/* may be called multiple times per register */
5271static void unregister_sched_domain_sysctl(void)
5272{
5273        if (sd_sysctl_header)
5274                unregister_sysctl_table(sd_sysctl_header);
5275        sd_sysctl_header = NULL;
5276        if (sd_ctl_dir[0].child)
5277                sd_free_ctl_entry(&sd_ctl_dir[0].child);
5278}
5279#else
5280static void register_sched_domain_sysctl(void)
5281{
5282}
5283static void unregister_sched_domain_sysctl(void)
5284{
5285}
5286#endif
5287
5288static void set_rq_online(struct rq *rq)
5289{
5290        if (!rq->online) {
5291                const struct sched_class *class;
5292
5293                cpumask_set_cpu(rq->cpu, rq->rd->online);
5294                rq->online = 1;
5295
5296                for_each_class(class) {
5297                        if (class->rq_online)
5298                                class->rq_online(rq);
5299                }
5300        }
5301}
5302
5303static void set_rq_offline(struct rq *rq)
5304{
5305        if (rq->online) {
5306                const struct sched_class *class;
5307
5308                for_each_class(class) {
5309                        if (class->rq_offline)
5310                                class->rq_offline(rq);
5311                }
5312
5313                cpumask_clear_cpu(rq->cpu, rq->rd->online);
5314                rq->online = 0;
5315        }
5316}
5317
5318/*
5319 * migration_call - callback that gets triggered when a CPU is added.
5320 * Here we can start up the necessary migration thread for the new CPU.
5321 */
5322static int __cpuinit
5323migration_call(struct notifier_block *nfb, unsigned long action, void *hcpu)
5324{
5325        int cpu = (long)hcpu;
5326        unsigned long flags;
5327        struct rq *rq = cpu_rq(cpu);
5328
5329        switch (action & ~CPU_TASKS_FROZEN) {
5330
5331        case CPU_UP_PREPARE:
5332                rq->calc_load_update = calc_load_update;
5333                break;
5334
5335        case CPU_ONLINE:
5336                /* Update our root-domain */
5337                raw_spin_lock_irqsave(&rq->lock, flags);
5338                if (rq->rd) {
5339                        BUG_ON(!cpumask_test_cpu(cpu, rq->rd->span));
5340
5341                        set_rq_online(rq);
5342                }
5343                raw_spin_unlock_irqrestore(&rq->lock, flags);
5344                break;
5345
5346#ifdef CONFIG_HOTPLUG_CPU
5347        case CPU_DYING:
5348                sched_ttwu_pending();
5349                /* Update our root-domain */
5350                raw_spin_lock_irqsave(&rq->lock, flags);
5351                if (rq->rd) {
5352                        BUG_ON(!cpumask_test_cpu(cpu, rq->rd->span));
5353                        set_rq_offline(rq);
5354                }
5355                migrate_tasks(cpu);
5356                BUG_ON(rq->nr_running != 1); /* the migration thread */
5357                raw_spin_unlock_irqrestore(&rq->lock, flags);
5358
5359                migrate_nr_uninterruptible(rq);
5360                calc_global_load_remove(rq);
5361                break;
5362#endif
5363        }
5364
5365        update_max_interval();
5366
5367        return NOTIFY_OK;
5368}
5369
5370/*
5371 * Register at high priority so that task migration (migrate_all_tasks)
5372 * happens before everything else.  This has to be lower priority than
5373 * the notifier in the perf_event subsystem, though.
5374 */
5375static struct notifier_block __cpuinitdata migration_notifier = {
5376        .notifier_call = migration_call,
5377        .priority = CPU_PRI_MIGRATION,
5378};
5379
5380static int __cpuinit sched_cpu_active(struct notifier_block *nfb,
5381                                      unsigned long action, void *hcpu)
5382{
5383        switch (action & ~CPU_TASKS_FROZEN) {
5384        case CPU_ONLINE:
5385        case CPU_DOWN_FAILED:
5386                set_cpu_active((long)hcpu, true);
5387                return NOTIFY_OK;
5388        default:
5389                return NOTIFY_DONE;
5390        }
5391}
5392
5393static int __cpuinit sched_cpu_inactive(struct notifier_block *nfb,
5394                                        unsigned long action, void *hcpu)
5395{
5396        switch (action & ~CPU_TASKS_FROZEN) {
5397        case CPU_DOWN_PREPARE:
5398                set_cpu_active((long)hcpu, false);
5399                return NOTIFY_OK;
5400        default:
5401                return NOTIFY_DONE;
5402        }
5403}
5404
5405static int __init migration_init(void)
5406{
5407        void *cpu = (void *)(long)smp_processor_id();
5408        int err;
5409
5410        /* Initialize migration for the boot CPU */
5411        err = migration_call(&migration_notifier, CPU_UP_PREPARE, cpu);
5412        BUG_ON(err == NOTIFY_BAD);
5413        migration_call(&migration_notifier, CPU_ONLINE, cpu);
5414        register_cpu_notifier(&migration_notifier);
5415
5416        /* Register cpu active notifiers */
5417        cpu_notifier(sched_cpu_active, CPU_PRI_SCHED_ACTIVE);
5418        cpu_notifier(sched_cpu_inactive, CPU_PRI_SCHED_INACTIVE);
5419
5420        return 0;
5421}
5422early_initcall(migration_init);
5423#endif
5424
5425#ifdef CONFIG_SMP
5426
5427static cpumask_var_t sched_domains_tmpmask; /* sched_domains_mutex */
5428
5429#ifdef CONFIG_SCHED_DEBUG
5430
5431static __read_mostly int sched_domain_debug_enabled;
5432
5433static int __init sched_domain_debug_setup(char *str)
5434{
5435        sched_domain_debug_enabled = 1;
5436
5437        return 0;
5438}
5439early_param("sched_debug", sched_domain_debug_setup);
5440
5441static int sched_domain_debug_one(struct sched_domain *sd, int cpu, int level,
5442                                  struct cpumask *groupmask)
5443{
5444        struct sched_group *group = sd->groups;
5445        char str[256];
5446
5447        cpulist_scnprintf(str, sizeof(str), sched_domain_span(sd));
5448        cpumask_clear(groupmask);
5449
5450        printk(KERN_DEBUG "%*s domain %d: ", level, "", level);
5451
5452        if (!(sd->flags & SD_LOAD_BALANCE)) {
5453                printk("does not load-balance\n");
5454                if (sd->parent)
5455                        printk(KERN_ERR "ERROR: !SD_LOAD_BALANCE domain"
5456                                        " has parent");
5457                return -1;
5458        }
5459
5460        printk(KERN_CONT "span %s level %s\n", str, sd->name);
5461
5462        if (!cpumask_test_cpu(cpu, sched_domain_span(sd))) {
5463                printk(KERN_ERR "ERROR: domain->span does not contain "
5464                                "CPU%d\n", cpu);
5465        }
5466        if (!cpumask_test_cpu(cpu, sched_group_cpus(group))) {
5467                printk(KERN_ERR "ERROR: domain->groups does not contain"
5468                                " CPU%d\n", cpu);
5469        }
5470
5471        printk(KERN_DEBUG "%*s groups:", level + 1, "");
5472        do {
5473                if (!group) {
5474                        printk("\n");
5475                        printk(KERN_ERR "ERROR: group is NULL\n");
5476                        break;
5477                }
5478
5479                if (!group->sgp->power) {
5480                        printk(KERN_CONT "\n");
5481                        printk(KERN_ERR "ERROR: domain->cpu_power not "
5482                                        "set\n");
5483                        break;
5484                }
5485
5486                if (!cpumask_weight(sched_group_cpus(group))) {
5487                        printk(KERN_CONT "\n");
5488                        printk(KERN_ERR "ERROR: empty group\n");
5489                        break;
5490                }
5491
5492                if (cpumask_intersects(groupmask, sched_group_cpus(group))) {
5493                        printk(KERN_CONT "\n");
5494                        printk(KERN_ERR "ERROR: repeated CPUs\n");
5495                        break;
5496                }
5497
5498                cpumask_or(groupmask, groupmask, sched_group_cpus(group));
5499
5500                cpulist_scnprintf(str, sizeof(str), sched_group_cpus(group));
5501
5502                printk(KERN_CONT " %s", str);
5503                if (group->sgp->power != SCHED_POWER_SCALE) {
5504                        printk(KERN_CONT " (cpu_power = %d)",
5505                                group->sgp->power);
5506                }
5507
5508                group = group->next;
5509        } while (group != sd->groups);
5510        printk(KERN_CONT "\n");
5511
5512        if (!cpumask_equal(sched_domain_span(sd), groupmask))
5513                printk(KERN_ERR "ERROR: groups don't span domain->span\n");
5514
5515        if (sd->parent &&
5516            !cpumask_subset(groupmask, sched_domain_span(sd->parent)))
5517                printk(KERN_ERR "ERROR: parent span is not a superset "
5518                        "of domain->span\n");
5519        return 0;
5520}
5521
5522static void sched_domain_debug(struct sched_domain *sd, int cpu)
5523{
5524        int level = 0;
5525
5526        if (!sched_domain_debug_enabled)
5527                return;
5528
5529        if (!sd) {
5530                printk(KERN_DEBUG "CPU%d attaching NULL sched-domain.\n", cpu);
5531                return;
5532        }
5533
5534        printk(KERN_DEBUG "CPU%d attaching sched-domain:\n", cpu);
5535
5536        for (;;) {
5537                if (sched_domain_debug_one(sd, cpu, level, sched_domains_tmpmask))
5538                        break;
5539                level++;
5540                sd = sd->parent;
5541                if (!sd)
5542                        break;
5543        }
5544}
5545#else /* !CONFIG_SCHED_DEBUG */
5546# define sched_domain_debug(sd, cpu) do { } while (0)
5547#endif /* CONFIG_SCHED_DEBUG */
5548
5549static int sd_degenerate(struct sched_domain *sd)
5550{
5551        if (cpumask_weight(sched_domain_span(sd)) == 1)
5552                return 1;
5553
5554        /* Following flags need at least 2 groups */
5555        if (sd->flags & (SD_LOAD_BALANCE |
5556                         SD_BALANCE_NEWIDLE |
5557                         SD_BALANCE_FORK |
5558                         SD_BALANCE_EXEC |
5559                         SD_SHARE_CPUPOWER |
5560                         SD_SHARE_PKG_RESOURCES)) {
5561                if (sd->groups != sd->groups->next)
5562                        return 0;
5563        }
5564
5565        /* Following flags don't use groups */
5566        if (sd->flags & (SD_WAKE_AFFINE))
5567                return 0;
5568
5569        return 1;
5570}
5571
5572static int
5573sd_parent_degenerate(struct sched_domain *sd, struct sched_domain *parent)
5574{
5575        unsigned long cflags = sd->flags, pflags = parent->flags;
5576
5577        if (sd_degenerate(parent))
5578                return 1;
5579
5580        if (!cpumask_equal(sched_domain_span(sd), sched_domain_span(parent)))
5581                return 0;
5582
5583        /* Flags needing groups don't count if only 1 group in parent */
5584        if (parent->groups == parent->groups->next) {
5585                pflags &= ~(SD_LOAD_BALANCE |
5586                                SD_BALANCE_NEWIDLE |
5587                                SD_BALANCE_FORK |
5588                                SD_BALANCE_EXEC |
5589                                SD_SHARE_CPUPOWER |
5590                                SD_SHARE_PKG_RESOURCES);
5591                if (nr_node_ids == 1)
5592                        pflags &= ~SD_SERIALIZE;
5593        }
5594        if (~cflags & pflags)
5595                return 0;
5596
5597        return 1;
5598}
5599
5600static void free_rootdomain(struct rcu_head *rcu)
5601{
5602        struct root_domain *rd = container_of(rcu, struct root_domain, rcu);
5603
5604        cpupri_cleanup(&rd->cpupri);
5605        free_cpumask_var(rd->rto_mask);
5606        free_cpumask_var(rd->online);
5607        free_cpumask_var(rd->span);
5608        kfree(rd);
5609}
5610
5611static void rq_attach_root(struct rq *rq, struct root_domain *rd)
5612{
5613        struct root_domain *old_rd = NULL;
5614        unsigned long flags;
5615
5616        raw_spin_lock_irqsave(&rq->lock, flags);
5617
5618        if (rq->rd) {
5619                old_rd = rq->rd;
5620
5621                if (cpumask_test_cpu(rq->cpu, old_rd->online))
5622                        set_rq_offline(rq);
5623
5624                cpumask_clear_cpu(rq->cpu, old_rd->span);
5625
5626                /*
5627                 * If we dont want to free the old_rt yet then
5628                 * set old_rd to NULL to skip the freeing later
5629                 * in this function:
5630                 */
5631                if (!atomic_dec_and_test(&old_rd->refcount))
5632                        old_rd = NULL;
5633        }
5634
5635        atomic_inc(&rd->refcount);
5636        rq->rd = rd;
5637
5638        cpumask_set_cpu(rq->cpu, rd->span);
5639        if (cpumask_test_cpu(rq->cpu, cpu_active_mask))
5640                set_rq_online(rq);
5641
5642        raw_spin_unlock_irqrestore(&rq->lock, flags);
5643
5644        if (old_rd)
5645                call_rcu_sched(&old_rd->rcu, free_rootdomain);
5646}
5647
5648static int init_rootdomain(struct root_domain *rd)
5649{
5650        memset(rd, 0, sizeof(*rd));
5651
5652        if (!alloc_cpumask_var(&rd->span, GFP_KERNEL))
5653                goto out;
5654        if (!alloc_cpumask_var(&rd->online, GFP_KERNEL))
5655                goto free_span;
5656        if (!alloc_cpumask_var(&rd->rto_mask, GFP_KERNEL))
5657                goto free_online;
5658
5659        if (cpupri_init(&rd->cpupri) != 0)
5660                goto free_rto_mask;
5661        return 0;
5662
5663free_rto_mask:
5664        free_cpumask_var(rd->rto_mask);
5665free_online:
5666        free_cpumask_var(rd->online);
5667free_span:
5668        free_cpumask_var(rd->span);
5669out:
5670        return -ENOMEM;
5671}
5672
5673/*
5674 * By default the system creates a single root-domain with all cpus as
5675 * members (mimicking the global state we have today).
5676 */
5677struct root_domain def_root_domain;
5678
5679static void init_defrootdomain(void)
5680{
5681        init_rootdomain(&def_root_domain);
5682
5683        atomic_set(&def_root_domain.refcount, 1);
5684}
5685
5686static struct root_domain *alloc_rootdomain(void)
5687{
5688        struct root_domain *rd;
5689
5690        rd = kmalloc(sizeof(*rd), GFP_KERNEL);
5691        if (!rd)
5692                return NULL;
5693
5694        if (init_rootdomain(rd) != 0) {
5695                kfree(rd);
5696                return NULL;
5697        }
5698
5699        return rd;
5700}
5701
5702static void free_sched_groups(struct sched_group *sg, int free_sgp)
5703{
5704        struct sched_group *tmp, *first;
5705
5706        if (!sg)
5707                return;
5708
5709        first = sg;
5710        do {
5711                tmp = sg->next;
5712
5713                if (free_sgp && atomic_dec_and_test(&sg->sgp->ref))
5714                        kfree(sg->sgp);
5715
5716                kfree(sg);
5717                sg = tmp;
5718        } while (sg != first);
5719}
5720
5721static void free_sched_domain(struct rcu_head *rcu)
5722{
5723        struct sched_domain *sd = container_of(rcu, struct sched_domain, rcu);
5724
5725        /*
5726         * If its an overlapping domain it has private groups, iterate and
5727         * nuke them all.
5728         */
5729        if (sd->flags & SD_OVERLAP) {
5730                free_sched_groups(sd->groups, 1);
5731        } else if (atomic_dec_and_test(&sd->groups->ref)) {
5732                kfree(sd->groups->sgp);
5733                kfree(sd->groups);
5734        }
5735        kfree(sd);
5736}
5737
5738static void destroy_sched_domain(struct sched_domain *sd, int cpu)
5739{
5740        call_rcu(&sd->rcu, free_sched_domain);
5741}
5742
5743static void destroy_sched_domains(struct sched_domain *sd, int cpu)
5744{
5745        for (; sd; sd = sd->parent)
5746                destroy_sched_domain(sd, cpu);
5747}
5748
5749/*
5750 * Keep a special pointer to the highest sched_domain that has
5751 * SD_SHARE_PKG_RESOURCE set (Last Level Cache Domain) for this
5752 * allows us to avoid some pointer chasing select_idle_sibling().
5753 *
5754 * Also keep a unique ID per domain (we use the first cpu number in
5755 * the cpumask of the domain), this allows us to quickly tell if
5756 * two cpus are in the same cache domain, see ttwu_share_cache().
5757 */
5758DEFINE_PER_CPU(struct sched_domain *, sd_llc);
5759DEFINE_PER_CPU(int, sd_llc_id);
5760
5761static void update_top_cache_domain(int cpu)
5762{
5763        struct sched_domain *sd;
5764        int id = cpu;
5765
5766        sd = highest_flag_domain(cpu, SD_SHARE_PKG_RESOURCES);
5767        if (sd)
5768                id = cpumask_first(sched_domain_span(sd));
5769
5770        rcu_assign_pointer(per_cpu(sd_llc, cpu), sd);
5771        per_cpu(sd_llc_id, cpu) = id;
5772}
5773
5774/*
5775 * Attach the domain 'sd' to 'cpu' as its base domain. Callers must
5776 * hold the hotplug lock.
5777 */
5778static void
5779cpu_attach_domain(struct sched_domain *sd, struct root_domain *rd, int cpu)
5780{
5781        struct rq *rq = cpu_rq(cpu);
5782        struct sched_domain *tmp;
5783
5784        /* Remove the sched domains which do not contribute to scheduling. */
5785        for (tmp = sd; tmp; ) {
5786                struct sched_domain *parent = tmp->parent;
5787                if (!parent)
5788                        break;
5789
5790                if (sd_parent_degenerate(tmp, parent)) {
5791                        tmp->parent = parent->parent;
5792                        if (parent->parent)
5793                                parent->parent->child = tmp;
5794                        destroy_sched_domain(parent, cpu);
5795                } else
5796                        tmp = tmp->parent;
5797        }
5798
5799        if (sd && sd_degenerate(sd)) {
5800                tmp = sd;
5801                sd = sd->parent;
5802                destroy_sched_domain(tmp, cpu);
5803                if (sd)
5804                        sd->child = NULL;
5805        }
5806
5807        sched_domain_debug(sd, cpu);
5808
5809        rq_attach_root(rq, rd);
5810        tmp = rq->sd;
5811        rcu_assign_pointer(rq->sd, sd);
5812        destroy_sched_domains(tmp, cpu);
5813
5814        update_top_cache_domain(cpu);
5815}
5816
5817/* cpus with isolated domains */
5818static cpumask_var_t cpu_isolated_map;
5819
5820/* Setup the mask of cpus configured for isolated domains */
5821static int __init isolated_cpu_setup(char *str)
5822{
5823        alloc_bootmem_cpumask_var(&cpu_isolated_map);
5824        cpulist_parse(str, cpu_isolated_map);
5825        return 1;
5826}
5827
5828__setup("isolcpus=", isolated_cpu_setup);
5829
5830#ifdef CONFIG_NUMA
5831
5832/**
5833 * find_next_best_node - find the next node to include in a sched_domain
5834 * @node: node whose sched_domain we're building
5835 * @used_nodes: nodes already in the sched_domain
5836 *
5837 * Find the next node to include in a given scheduling domain. Simply
5838 * finds the closest node not already in the @used_nodes map.
5839 *
5840 * Should use nodemask_t.
5841 */
5842static int find_next_best_node(int node, nodemask_t *used_nodes)
5843{
5844        int i, n, val, min_val, best_node = -1;
5845
5846        min_val = INT_MAX;
5847