linux/kernel/hrtimer.c
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   1/*
   2 *  linux/kernel/hrtimer.c
   3 *
   4 *  Copyright(C) 2005-2006, Thomas Gleixner <tglx@linutronix.de>
   5 *  Copyright(C) 2005-2007, Red Hat, Inc., Ingo Molnar
   6 *  Copyright(C) 2006-2007  Timesys Corp., Thomas Gleixner
   7 *
   8 *  High-resolution kernel timers
   9 *
  10 *  In contrast to the low-resolution timeout API implemented in
  11 *  kernel/timer.c, hrtimers provide finer resolution and accuracy
  12 *  depending on system configuration and capabilities.
  13 *
  14 *  These timers are currently used for:
  15 *   - itimers
  16 *   - POSIX timers
  17 *   - nanosleep
  18 *   - precise in-kernel timing
  19 *
  20 *  Started by: Thomas Gleixner and Ingo Molnar
  21 *
  22 *  Credits:
  23 *      based on kernel/timer.c
  24 *
  25 *      Help, testing, suggestions, bugfixes, improvements were
  26 *      provided by:
  27 *
  28 *      George Anzinger, Andrew Morton, Steven Rostedt, Roman Zippel
  29 *      et. al.
  30 *
  31 *  For licencing details see kernel-base/COPYING
  32 */
  33
  34#include <linux/cpu.h>
  35#include <linux/export.h>
  36#include <linux/percpu.h>
  37#include <linux/hrtimer.h>
  38#include <linux/notifier.h>
  39#include <linux/syscalls.h>
  40#include <linux/kallsyms.h>
  41#include <linux/interrupt.h>
  42#include <linux/tick.h>
  43#include <linux/seq_file.h>
  44#include <linux/err.h>
  45#include <linux/debugobjects.h>
  46#include <linux/sched.h>
  47#include <linux/timer.h>
  48
  49#include <asm/uaccess.h>
  50
  51#include <trace/events/timer.h>
  52
  53/*
  54 * The timer bases:
  55 *
  56 * There are more clockids then hrtimer bases. Thus, we index
  57 * into the timer bases by the hrtimer_base_type enum. When trying
  58 * to reach a base using a clockid, hrtimer_clockid_to_base()
  59 * is used to convert from clockid to the proper hrtimer_base_type.
  60 */
  61DEFINE_PER_CPU(struct hrtimer_cpu_base, hrtimer_bases) =
  62{
  63
  64        .clock_base =
  65        {
  66                {
  67                        .index = HRTIMER_BASE_MONOTONIC,
  68                        .clockid = CLOCK_MONOTONIC,
  69                        .get_time = &ktime_get,
  70                        .resolution = KTIME_LOW_RES,
  71                },
  72                {
  73                        .index = HRTIMER_BASE_REALTIME,
  74                        .clockid = CLOCK_REALTIME,
  75                        .get_time = &ktime_get_real,
  76                        .resolution = KTIME_LOW_RES,
  77                },
  78                {
  79                        .index = HRTIMER_BASE_BOOTTIME,
  80                        .clockid = CLOCK_BOOTTIME,
  81                        .get_time = &ktime_get_boottime,
  82                        .resolution = KTIME_LOW_RES,
  83                },
  84        }
  85};
  86
  87static const int hrtimer_clock_to_base_table[MAX_CLOCKS] = {
  88        [CLOCK_REALTIME]        = HRTIMER_BASE_REALTIME,
  89        [CLOCK_MONOTONIC]       = HRTIMER_BASE_MONOTONIC,
  90        [CLOCK_BOOTTIME]        = HRTIMER_BASE_BOOTTIME,
  91};
  92
  93static inline int hrtimer_clockid_to_base(clockid_t clock_id)
  94{
  95        return hrtimer_clock_to_base_table[clock_id];
  96}
  97
  98
  99/*
 100 * Get the coarse grained time at the softirq based on xtime and
 101 * wall_to_monotonic.
 102 */
 103static void hrtimer_get_softirq_time(struct hrtimer_cpu_base *base)
 104{
 105        ktime_t xtim, mono, boot;
 106        struct timespec xts, tom, slp;
 107
 108        get_xtime_and_monotonic_and_sleep_offset(&xts, &tom, &slp);
 109
 110        xtim = timespec_to_ktime(xts);
 111        mono = ktime_add(xtim, timespec_to_ktime(tom));
 112        boot = ktime_add(mono, timespec_to_ktime(slp));
 113        base->clock_base[HRTIMER_BASE_REALTIME].softirq_time = xtim;
 114        base->clock_base[HRTIMER_BASE_MONOTONIC].softirq_time = mono;
 115        base->clock_base[HRTIMER_BASE_BOOTTIME].softirq_time = boot;
 116}
 117
 118/*
 119 * Functions and macros which are different for UP/SMP systems are kept in a
 120 * single place
 121 */
 122#ifdef CONFIG_SMP
 123
 124/*
 125 * We are using hashed locking: holding per_cpu(hrtimer_bases)[n].lock
 126 * means that all timers which are tied to this base via timer->base are
 127 * locked, and the base itself is locked too.
 128 *
 129 * So __run_timers/migrate_timers can safely modify all timers which could
 130 * be found on the lists/queues.
 131 *
 132 * When the timer's base is locked, and the timer removed from list, it is
 133 * possible to set timer->base = NULL and drop the lock: the timer remains
 134 * locked.
 135 */
 136static
 137struct hrtimer_clock_base *lock_hrtimer_base(const struct hrtimer *timer,
 138                                             unsigned long *flags)
 139{
 140        struct hrtimer_clock_base *base;
 141
 142        for (;;) {
 143                base = timer->base;
 144                if (likely(base != NULL)) {
 145                        raw_spin_lock_irqsave(&base->cpu_base->lock, *flags);
 146                        if (likely(base == timer->base))
 147                                return base;
 148                        /* The timer has migrated to another CPU: */
 149                        raw_spin_unlock_irqrestore(&base->cpu_base->lock, *flags);
 150                }
 151                cpu_relax();
 152        }
 153}
 154
 155
 156/*
 157 * Get the preferred target CPU for NOHZ
 158 */
 159static int hrtimer_get_target(int this_cpu, int pinned)
 160{
 161#ifdef CONFIG_NO_HZ
 162        if (!pinned && get_sysctl_timer_migration() && idle_cpu(this_cpu))
 163                return get_nohz_timer_target();
 164#endif
 165        return this_cpu;
 166}
 167
 168/*
 169 * With HIGHRES=y we do not migrate the timer when it is expiring
 170 * before the next event on the target cpu because we cannot reprogram
 171 * the target cpu hardware and we would cause it to fire late.
 172 *
 173 * Called with cpu_base->lock of target cpu held.
 174 */
 175static int
 176hrtimer_check_target(struct hrtimer *timer, struct hrtimer_clock_base *new_base)
 177{
 178#ifdef CONFIG_HIGH_RES_TIMERS
 179        ktime_t expires;
 180
 181        if (!new_base->cpu_base->hres_active)
 182                return 0;
 183
 184        expires = ktime_sub(hrtimer_get_expires(timer), new_base->offset);
 185        return expires.tv64 <= new_base->cpu_base->expires_next.tv64;
 186#else
 187        return 0;
 188#endif
 189}
 190
 191/*
 192 * Switch the timer base to the current CPU when possible.
 193 */
 194static inline struct hrtimer_clock_base *
 195switch_hrtimer_base(struct hrtimer *timer, struct hrtimer_clock_base *base,
 196                    int pinned)
 197{
 198        struct hrtimer_clock_base *new_base;
 199        struct hrtimer_cpu_base *new_cpu_base;
 200        int this_cpu = smp_processor_id();
 201        int cpu = hrtimer_get_target(this_cpu, pinned);
 202        int basenum = base->index;
 203
 204again:
 205        new_cpu_base = &per_cpu(hrtimer_bases, cpu);
 206        new_base = &new_cpu_base->clock_base[basenum];
 207
 208        if (base != new_base) {
 209                /*
 210                 * We are trying to move timer to new_base.
 211                 * However we can't change timer's base while it is running,
 212                 * so we keep it on the same CPU. No hassle vs. reprogramming
 213                 * the event source in the high resolution case. The softirq
 214                 * code will take care of this when the timer function has
 215                 * completed. There is no conflict as we hold the lock until
 216                 * the timer is enqueued.
 217                 */
 218                if (unlikely(hrtimer_callback_running(timer)))
 219                        return base;
 220
 221                /* See the comment in lock_timer_base() */
 222                timer->base = NULL;
 223                raw_spin_unlock(&base->cpu_base->lock);
 224                raw_spin_lock(&new_base->cpu_base->lock);
 225
 226                if (cpu != this_cpu && hrtimer_check_target(timer, new_base)) {
 227                        cpu = this_cpu;
 228                        raw_spin_unlock(&new_base->cpu_base->lock);
 229                        raw_spin_lock(&base->cpu_base->lock);
 230                        timer->base = base;
 231                        goto again;
 232                }
 233                timer->base = new_base;
 234        }
 235        return new_base;
 236}
 237
 238#else /* CONFIG_SMP */
 239
 240static inline struct hrtimer_clock_base *
 241lock_hrtimer_base(const struct hrtimer *timer, unsigned long *flags)
 242{
 243        struct hrtimer_clock_base *base = timer->base;
 244
 245        raw_spin_lock_irqsave(&base->cpu_base->lock, *flags);
 246
 247        return base;
 248}
 249
 250# define switch_hrtimer_base(t, b, p)   (b)
 251
 252#endif  /* !CONFIG_SMP */
 253
 254/*
 255 * Functions for the union type storage format of ktime_t which are
 256 * too large for inlining:
 257 */
 258#if BITS_PER_LONG < 64
 259# ifndef CONFIG_KTIME_SCALAR
 260/**
 261 * ktime_add_ns - Add a scalar nanoseconds value to a ktime_t variable
 262 * @kt:         addend
 263 * @nsec:       the scalar nsec value to add
 264 *
 265 * Returns the sum of kt and nsec in ktime_t format
 266 */
 267ktime_t ktime_add_ns(const ktime_t kt, u64 nsec)
 268{
 269        ktime_t tmp;
 270
 271        if (likely(nsec < NSEC_PER_SEC)) {
 272                tmp.tv64 = nsec;
 273        } else {
 274                unsigned long rem = do_div(nsec, NSEC_PER_SEC);
 275
 276                tmp = ktime_set((long)nsec, rem);
 277        }
 278
 279        return ktime_add(kt, tmp);
 280}
 281
 282EXPORT_SYMBOL_GPL(ktime_add_ns);
 283
 284/**
 285 * ktime_sub_ns - Subtract a scalar nanoseconds value from a ktime_t variable
 286 * @kt:         minuend
 287 * @nsec:       the scalar nsec value to subtract
 288 *
 289 * Returns the subtraction of @nsec from @kt in ktime_t format
 290 */
 291ktime_t ktime_sub_ns(const ktime_t kt, u64 nsec)
 292{
 293        ktime_t tmp;
 294
 295        if (likely(nsec < NSEC_PER_SEC)) {
 296                tmp.tv64 = nsec;
 297        } else {
 298                unsigned long rem = do_div(nsec, NSEC_PER_SEC);
 299
 300                tmp = ktime_set((long)nsec, rem);
 301        }
 302
 303        return ktime_sub(kt, tmp);
 304}
 305
 306EXPORT_SYMBOL_GPL(ktime_sub_ns);
 307# endif /* !CONFIG_KTIME_SCALAR */
 308
 309/*
 310 * Divide a ktime value by a nanosecond value
 311 */
 312u64 ktime_divns(const ktime_t kt, s64 div)
 313{
 314        u64 dclc;
 315        int sft = 0;
 316
 317        dclc = ktime_to_ns(kt);
 318        /* Make sure the divisor is less than 2^32: */
 319        while (div >> 32) {
 320                sft++;
 321                div >>= 1;
 322        }
 323        dclc >>= sft;
 324        do_div(dclc, (unsigned long) div);
 325
 326        return dclc;
 327}
 328#endif /* BITS_PER_LONG >= 64 */
 329
 330/*
 331 * Add two ktime values and do a safety check for overflow:
 332 */
 333ktime_t ktime_add_safe(const ktime_t lhs, const ktime_t rhs)
 334{
 335        ktime_t res = ktime_add(lhs, rhs);
 336
 337        /*
 338         * We use KTIME_SEC_MAX here, the maximum timeout which we can
 339         * return to user space in a timespec:
 340         */
 341        if (res.tv64 < 0 || res.tv64 < lhs.tv64 || res.tv64 < rhs.tv64)
 342                res = ktime_set(KTIME_SEC_MAX, 0);
 343
 344        return res;
 345}
 346
 347EXPORT_SYMBOL_GPL(ktime_add_safe);
 348
 349#ifdef CONFIG_DEBUG_OBJECTS_TIMERS
 350
 351static struct debug_obj_descr hrtimer_debug_descr;
 352
 353static void *hrtimer_debug_hint(void *addr)
 354{
 355        return ((struct hrtimer *) addr)->function;
 356}
 357
 358/*
 359 * fixup_init is called when:
 360 * - an active object is initialized
 361 */
 362static int hrtimer_fixup_init(void *addr, enum debug_obj_state state)
 363{
 364        struct hrtimer *timer = addr;
 365
 366        switch (state) {
 367        case ODEBUG_STATE_ACTIVE:
 368                hrtimer_cancel(timer);
 369                debug_object_init(timer, &hrtimer_debug_descr);
 370                return 1;
 371        default:
 372                return 0;
 373        }
 374}
 375
 376/*
 377 * fixup_activate is called when:
 378 * - an active object is activated
 379 * - an unknown object is activated (might be a statically initialized object)
 380 */
 381static int hrtimer_fixup_activate(void *addr, enum debug_obj_state state)
 382{
 383        switch (state) {
 384
 385        case ODEBUG_STATE_NOTAVAILABLE:
 386                WARN_ON_ONCE(1);
 387                return 0;
 388
 389        case ODEBUG_STATE_ACTIVE:
 390                WARN_ON(1);
 391
 392        default:
 393                return 0;
 394        }
 395}
 396
 397/*
 398 * fixup_free is called when:
 399 * - an active object is freed
 400 */
 401static int hrtimer_fixup_free(void *addr, enum debug_obj_state state)
 402{
 403        struct hrtimer *timer = addr;
 404
 405        switch (state) {
 406        case ODEBUG_STATE_ACTIVE:
 407                hrtimer_cancel(timer);
 408                debug_object_free(timer, &hrtimer_debug_descr);
 409                return 1;
 410        default:
 411                return 0;
 412        }
 413}
 414
 415static struct debug_obj_descr hrtimer_debug_descr = {
 416        .name           = "hrtimer",
 417        .debug_hint     = hrtimer_debug_hint,
 418        .fixup_init     = hrtimer_fixup_init,
 419        .fixup_activate = hrtimer_fixup_activate,
 420        .fixup_free     = hrtimer_fixup_free,
 421};
 422
 423static inline void debug_hrtimer_init(struct hrtimer *timer)
 424{
 425        debug_object_init(timer, &hrtimer_debug_descr);
 426}
 427
 428static inline void debug_hrtimer_activate(struct hrtimer *timer)
 429{
 430        debug_object_activate(timer, &hrtimer_debug_descr);
 431}
 432
 433static inline void debug_hrtimer_deactivate(struct hrtimer *timer)
 434{
 435        debug_object_deactivate(timer, &hrtimer_debug_descr);
 436}
 437
 438static inline void debug_hrtimer_free(struct hrtimer *timer)
 439{
 440        debug_object_free(timer, &hrtimer_debug_descr);
 441}
 442
 443static void __hrtimer_init(struct hrtimer *timer, clockid_t clock_id,
 444                           enum hrtimer_mode mode);
 445
 446void hrtimer_init_on_stack(struct hrtimer *timer, clockid_t clock_id,
 447                           enum hrtimer_mode mode)
 448{
 449        debug_object_init_on_stack(timer, &hrtimer_debug_descr);
 450        __hrtimer_init(timer, clock_id, mode);
 451}
 452EXPORT_SYMBOL_GPL(hrtimer_init_on_stack);
 453
 454void destroy_hrtimer_on_stack(struct hrtimer *timer)
 455{
 456        debug_object_free(timer, &hrtimer_debug_descr);
 457}
 458
 459#else
 460static inline void debug_hrtimer_init(struct hrtimer *timer) { }
 461static inline void debug_hrtimer_activate(struct hrtimer *timer) { }
 462static inline void debug_hrtimer_deactivate(struct hrtimer *timer) { }
 463#endif
 464
 465static inline void
 466debug_init(struct hrtimer *timer, clockid_t clockid,
 467           enum hrtimer_mode mode)
 468{
 469        debug_hrtimer_init(timer);
 470        trace_hrtimer_init(timer, clockid, mode);
 471}
 472
 473static inline void debug_activate(struct hrtimer *timer)
 474{
 475        debug_hrtimer_activate(timer);
 476        trace_hrtimer_start(timer);
 477}
 478
 479static inline void debug_deactivate(struct hrtimer *timer)
 480{
 481        debug_hrtimer_deactivate(timer);
 482        trace_hrtimer_cancel(timer);
 483}
 484
 485/* High resolution timer related functions */
 486#ifdef CONFIG_HIGH_RES_TIMERS
 487
 488/*
 489 * High resolution timer enabled ?
 490 */
 491static int hrtimer_hres_enabled __read_mostly  = 1;
 492
 493/*
 494 * Enable / Disable high resolution mode
 495 */
 496static int __init setup_hrtimer_hres(char *str)
 497{
 498        if (!strcmp(str, "off"))
 499                hrtimer_hres_enabled = 0;
 500        else if (!strcmp(str, "on"))
 501                hrtimer_hres_enabled = 1;
 502        else
 503                return 0;
 504        return 1;
 505}
 506
 507__setup("highres=", setup_hrtimer_hres);
 508
 509/*
 510 * hrtimer_high_res_enabled - query, if the highres mode is enabled
 511 */
 512static inline int hrtimer_is_hres_enabled(void)
 513{
 514        return hrtimer_hres_enabled;
 515}
 516
 517/*
 518 * Is the high resolution mode active ?
 519 */
 520static inline int hrtimer_hres_active(void)
 521{
 522        return __this_cpu_read(hrtimer_bases.hres_active);
 523}
 524
 525/*
 526 * Reprogram the event source with checking both queues for the
 527 * next event
 528 * Called with interrupts disabled and base->lock held
 529 */
 530static void
 531hrtimer_force_reprogram(struct hrtimer_cpu_base *cpu_base, int skip_equal)
 532{
 533        int i;
 534        struct hrtimer_clock_base *base = cpu_base->clock_base;
 535        ktime_t expires, expires_next;
 536
 537        expires_next.tv64 = KTIME_MAX;
 538
 539        for (i = 0; i < HRTIMER_MAX_CLOCK_BASES; i++, base++) {
 540                struct hrtimer *timer;
 541                struct timerqueue_node *next;
 542
 543                next = timerqueue_getnext(&base->active);
 544                if (!next)
 545                        continue;
 546                timer = container_of(next, struct hrtimer, node);
 547
 548                expires = ktime_sub(hrtimer_get_expires(timer), base->offset);
 549                /*
 550                 * clock_was_set() has changed base->offset so the
 551                 * result might be negative. Fix it up to prevent a
 552                 * false positive in clockevents_program_event()
 553                 */
 554                if (expires.tv64 < 0)
 555                        expires.tv64 = 0;
 556                if (expires.tv64 < expires_next.tv64)
 557                        expires_next = expires;
 558        }
 559
 560        if (skip_equal && expires_next.tv64 == cpu_base->expires_next.tv64)
 561                return;
 562
 563        cpu_base->expires_next.tv64 = expires_next.tv64;
 564
 565        if (cpu_base->expires_next.tv64 != KTIME_MAX)
 566                tick_program_event(cpu_base->expires_next, 1);
 567}
 568
 569/*
 570 * Shared reprogramming for clock_realtime and clock_monotonic
 571 *
 572 * When a timer is enqueued and expires earlier than the already enqueued
 573 * timers, we have to check, whether it expires earlier than the timer for
 574 * which the clock event device was armed.
 575 *
 576 * Called with interrupts disabled and base->cpu_base.lock held
 577 */
 578static int hrtimer_reprogram(struct hrtimer *timer,
 579                             struct hrtimer_clock_base *base)
 580{
 581        struct hrtimer_cpu_base *cpu_base = &__get_cpu_var(hrtimer_bases);
 582        ktime_t expires = ktime_sub(hrtimer_get_expires(timer), base->offset);
 583        int res;
 584
 585        WARN_ON_ONCE(hrtimer_get_expires_tv64(timer) < 0);
 586
 587        /*
 588         * When the callback is running, we do not reprogram the clock event
 589         * device. The timer callback is either running on a different CPU or
 590         * the callback is executed in the hrtimer_interrupt context. The
 591         * reprogramming is handled either by the softirq, which called the
 592         * callback or at the end of the hrtimer_interrupt.
 593         */
 594        if (hrtimer_callback_running(timer))
 595                return 0;
 596
 597        /*
 598         * CLOCK_REALTIME timer might be requested with an absolute
 599         * expiry time which is less than base->offset. Nothing wrong
 600         * about that, just avoid to call into the tick code, which
 601         * has now objections against negative expiry values.
 602         */
 603        if (expires.tv64 < 0)
 604                return -ETIME;
 605
 606        if (expires.tv64 >= cpu_base->expires_next.tv64)
 607                return 0;
 608
 609        /*
 610         * If a hang was detected in the last timer interrupt then we
 611         * do not schedule a timer which is earlier than the expiry
 612         * which we enforced in the hang detection. We want the system
 613         * to make progress.
 614         */
 615        if (cpu_base->hang_detected)
 616                return 0;
 617
 618        /*
 619         * Clockevents returns -ETIME, when the event was in the past.
 620         */
 621        res = tick_program_event(expires, 0);
 622        if (!IS_ERR_VALUE(res))
 623                cpu_base->expires_next = expires;
 624        return res;
 625}
 626
 627/*
 628 * Initialize the high resolution related parts of cpu_base
 629 */
 630static inline void hrtimer_init_hres(struct hrtimer_cpu_base *base)
 631{
 632        base->expires_next.tv64 = KTIME_MAX;
 633        base->hres_active = 0;
 634}
 635
 636/*
 637 * When High resolution timers are active, try to reprogram. Note, that in case
 638 * the state has HRTIMER_STATE_CALLBACK set, no reprogramming and no expiry
 639 * check happens. The timer gets enqueued into the rbtree. The reprogramming
 640 * and expiry check is done in the hrtimer_interrupt or in the softirq.
 641 */
 642static inline int hrtimer_enqueue_reprogram(struct hrtimer *timer,
 643                                            struct hrtimer_clock_base *base)
 644{
 645        return base->cpu_base->hres_active && hrtimer_reprogram(timer, base);
 646}
 647
 648static inline ktime_t hrtimer_update_base(struct hrtimer_cpu_base *base)
 649{
 650        ktime_t *offs_real = &base->clock_base[HRTIMER_BASE_REALTIME].offset;
 651        ktime_t *offs_boot = &base->clock_base[HRTIMER_BASE_BOOTTIME].offset;
 652
 653        return ktime_get_update_offsets(offs_real, offs_boot);
 654}
 655
 656/*
 657 * Retrigger next event is called after clock was set
 658 *
 659 * Called with interrupts disabled via on_each_cpu()
 660 */
 661static void retrigger_next_event(void *arg)
 662{
 663        struct hrtimer_cpu_base *base = &__get_cpu_var(hrtimer_bases);
 664
 665        if (!hrtimer_hres_active())
 666                return;
 667
 668        raw_spin_lock(&base->lock);
 669        hrtimer_update_base(base);
 670        hrtimer_force_reprogram(base, 0);
 671        raw_spin_unlock(&base->lock);
 672}
 673
 674/*
 675 * Switch to high resolution mode
 676 */
 677static int hrtimer_switch_to_hres(void)
 678{
 679        int i, cpu = smp_processor_id();
 680        struct hrtimer_cpu_base *base = &per_cpu(hrtimer_bases, cpu);
 681        unsigned long flags;
 682
 683        if (base->hres_active)
 684                return 1;
 685
 686        local_irq_save(flags);
 687
 688        if (tick_init_highres()) {
 689                local_irq_restore(flags);
 690                printk(KERN_WARNING "Could not switch to high resolution "
 691                                    "mode on CPU %d\n", cpu);
 692                return 0;
 693        }
 694        base->hres_active = 1;
 695        for (i = 0; i < HRTIMER_MAX_CLOCK_BASES; i++)
 696                base->clock_base[i].resolution = KTIME_HIGH_RES;
 697
 698        tick_setup_sched_timer();
 699        /* "Retrigger" the interrupt to get things going */
 700        retrigger_next_event(NULL);
 701        local_irq_restore(flags);
 702        return 1;
 703}
 704
 705/*
 706 * Called from timekeeping code to reprogramm the hrtimer interrupt
 707 * device. If called from the timer interrupt context we defer it to
 708 * softirq context.
 709 */
 710void clock_was_set_delayed(void)
 711{
 712        struct hrtimer_cpu_base *cpu_base = &__get_cpu_var(hrtimer_bases);
 713
 714        cpu_base->clock_was_set = 1;
 715        __raise_softirq_irqoff(HRTIMER_SOFTIRQ);
 716}
 717
 718#else
 719
 720static inline int hrtimer_hres_active(void) { return 0; }
 721static inline int hrtimer_is_hres_enabled(void) { return 0; }
 722static inline int hrtimer_switch_to_hres(void) { return 0; }
 723static inline void
 724hrtimer_force_reprogram(struct hrtimer_cpu_base *base, int skip_equal) { }
 725static inline int hrtimer_enqueue_reprogram(struct hrtimer *timer,
 726                                            struct hrtimer_clock_base *base)
 727{
 728        return 0;
 729}
 730static inline void hrtimer_init_hres(struct hrtimer_cpu_base *base) { }
 731static inline void retrigger_next_event(void *arg) { }
 732
 733#endif /* CONFIG_HIGH_RES_TIMERS */
 734
 735/*
 736 * Clock realtime was set
 737 *
 738 * Change the offset of the realtime clock vs. the monotonic
 739 * clock.
 740 *
 741 * We might have to reprogram the high resolution timer interrupt. On
 742 * SMP we call the architecture specific code to retrigger _all_ high
 743 * resolution timer interrupts. On UP we just disable interrupts and
 744 * call the high resolution interrupt code.
 745 */
 746void clock_was_set(void)
 747{
 748#ifdef CONFIG_HIGH_RES_TIMERS
 749        /* Retrigger the CPU local events everywhere */
 750        on_each_cpu(retrigger_next_event, NULL, 1);
 751#endif
 752        timerfd_clock_was_set();
 753}
 754
 755/*
 756 * During resume we might have to reprogram the high resolution timer
 757 * interrupt (on the local CPU):
 758 */
 759void hrtimers_resume(void)
 760{
 761        WARN_ONCE(!irqs_disabled(),
 762                  KERN_INFO "hrtimers_resume() called with IRQs enabled!");
 763
 764        retrigger_next_event(NULL);
 765        timerfd_clock_was_set();
 766}
 767
 768static inline void timer_stats_hrtimer_set_start_info(struct hrtimer *timer)
 769{
 770#ifdef CONFIG_TIMER_STATS
 771        if (timer->start_site)
 772                return;
 773        timer->start_site = __builtin_return_address(0);
 774        memcpy(timer->start_comm, current->comm, TASK_COMM_LEN);
 775        timer->start_pid = current->pid;
 776#endif
 777}
 778
 779static inline void timer_stats_hrtimer_clear_start_info(struct hrtimer *timer)
 780{
 781#ifdef CONFIG_TIMER_STATS
 782        timer->start_site = NULL;
 783#endif
 784}
 785
 786static inline void timer_stats_account_hrtimer(struct hrtimer *timer)
 787{
 788#ifdef CONFIG_TIMER_STATS
 789        if (likely(!timer_stats_active))
 790                return;
 791        timer_stats_update_stats(timer, timer->start_pid, timer->start_site,
 792                                 timer->function, timer->start_comm, 0);
 793#endif
 794}
 795
 796/*
 797 * Counterpart to lock_hrtimer_base above:
 798 */
 799static inline
 800void unlock_hrtimer_base(const struct hrtimer *timer, unsigned long *flags)
 801{
 802        raw_spin_unlock_irqrestore(&timer->base->cpu_base->lock, *flags);
 803}
 804
 805/**
 806 * hrtimer_forward - forward the timer expiry
 807 * @timer:      hrtimer to forward
 808 * @now:        forward past this time
 809 * @interval:   the interval to forward
 810 *
 811 * Forward the timer expiry so it will expire in the future.
 812 * Returns the number of overruns.
 813 */
 814u64 hrtimer_forward(struct hrtimer *timer, ktime_t now, ktime_t interval)
 815{
 816        u64 orun = 1;
 817        ktime_t delta;
 818
 819        delta = ktime_sub(now, hrtimer_get_expires(timer));
 820
 821        if (delta.tv64 < 0)
 822                return 0;
 823
 824        if (interval.tv64 < timer->base->resolution.tv64)
 825                interval.tv64 = timer->base->resolution.tv64;
 826
 827        if (unlikely(delta.tv64 >= interval.tv64)) {
 828                s64 incr = ktime_to_ns(interval);
 829
 830                orun = ktime_divns(delta, incr);
 831                hrtimer_add_expires_ns(timer, incr * orun);
 832                if (hrtimer_get_expires_tv64(timer) > now.tv64)
 833                        return orun;
 834                /*
 835                 * This (and the ktime_add() below) is the
 836                 * correction for exact:
 837                 */
 838                orun++;
 839        }
 840        hrtimer_add_expires(timer, interval);
 841
 842        return orun;
 843}
 844EXPORT_SYMBOL_GPL(hrtimer_forward);
 845
 846/*
 847 * enqueue_hrtimer - internal function to (re)start a timer
 848 *
 849 * The timer is inserted in expiry order. Insertion into the
 850 * red black tree is O(log(n)). Must hold the base lock.
 851 *
 852 * Returns 1 when the new timer is the leftmost timer in the tree.
 853 */
 854static int enqueue_hrtimer(struct hrtimer *timer,
 855                           struct hrtimer_clock_base *base)
 856{
 857        debug_activate(timer);
 858
 859        timerqueue_add(&base->active, &timer->node);
 860        base->cpu_base->active_bases |= 1 << base->index;
 861
 862        /*
 863         * HRTIMER_STATE_ENQUEUED is or'ed to the current state to preserve the
 864         * state of a possibly running callback.
 865         */
 866        timer->state |= HRTIMER_STATE_ENQUEUED;
 867
 868        return (&timer->node == base->active.next);
 869}
 870
 871/*
 872 * __remove_hrtimer - internal function to remove a timer
 873 *
 874 * Caller must hold the base lock.
 875 *
 876 * High resolution timer mode reprograms the clock event device when the
 877 * timer is the one which expires next. The caller can disable this by setting
 878 * reprogram to zero. This is useful, when the context does a reprogramming
 879 * anyway (e.g. timer interrupt)
 880 */
 881static void __remove_hrtimer(struct hrtimer *timer,
 882                             struct hrtimer_clock_base *base,
 883                             unsigned long newstate, int reprogram)
 884{
 885        struct timerqueue_node *next_timer;
 886        if (!(timer->state & HRTIMER_STATE_ENQUEUED))
 887                goto out;
 888
 889        next_timer = timerqueue_getnext(&base->active);
 890        timerqueue_del(&base->active, &timer->node);
 891        if (&timer->node == next_timer) {
 892#ifdef CONFIG_HIGH_RES_TIMERS
 893                /* Reprogram the clock event device. if enabled */
 894                if (reprogram && hrtimer_hres_active()) {
 895                        ktime_t expires;
 896
 897                        expires = ktime_sub(hrtimer_get_expires(timer),
 898                                            base->offset);
 899                        if (base->cpu_base->expires_next.tv64 == expires.tv64)
 900                                hrtimer_force_reprogram(base->cpu_base, 1);
 901                }
 902#endif
 903        }
 904        if (!timerqueue_getnext(&base->active))
 905                base->cpu_base->active_bases &= ~(1 << base->index);
 906out:
 907        timer->state = newstate;
 908}
 909
 910/*
 911 * remove hrtimer, called with base lock held
 912 */
 913static inline int
 914remove_hrtimer(struct hrtimer *timer, struct hrtimer_clock_base *base)
 915{
 916        if (hrtimer_is_queued(timer)) {
 917                unsigned long state;
 918                int reprogram;
 919
 920                /*
 921                 * Remove the timer and force reprogramming when high
 922                 * resolution mode is active and the timer is on the current
 923                 * CPU. If we remove a timer on another CPU, reprogramming is
 924                 * skipped. The interrupt event on this CPU is fired and
 925                 * reprogramming happens in the interrupt handler. This is a
 926                 * rare case and less expensive than a smp call.
 927                 */
 928                debug_deactivate(timer);
 929                timer_stats_hrtimer_clear_start_info(timer);
 930                reprogram = base->cpu_base == &__get_cpu_var(hrtimer_bases);
 931                /*
 932                 * We must preserve the CALLBACK state flag here,
 933                 * otherwise we could move the timer base in
 934                 * switch_hrtimer_base.
 935                 */
 936                state = timer->state & HRTIMER_STATE_CALLBACK;
 937                __remove_hrtimer(timer, base, state, reprogram);
 938                return 1;
 939        }
 940        return 0;
 941}
 942
 943int __hrtimer_start_range_ns(struct hrtimer *timer, ktime_t tim,
 944                unsigned long delta_ns, const enum hrtimer_mode mode,
 945                int wakeup)
 946{
 947        struct hrtimer_clock_base *base, *new_base;
 948        unsigned long flags;
 949        int ret, leftmost;
 950
 951        base = lock_hrtimer_base(timer, &flags);
 952
 953        /* Remove an active timer from the queue: */
 954        ret = remove_hrtimer(timer, base);
 955
 956        /* Switch the timer base, if necessary: */
 957        new_base = switch_hrtimer_base(timer, base, mode & HRTIMER_MODE_PINNED);
 958
 959        if (mode & HRTIMER_MODE_REL) {
 960                tim = ktime_add_safe(tim, new_base->get_time());
 961                /*
 962                 * CONFIG_TIME_LOW_RES is a temporary way for architectures
 963                 * to signal that they simply return xtime in
 964                 * do_gettimeoffset(). In this case we want to round up by
 965                 * resolution when starting a relative timer, to avoid short
 966                 * timeouts. This will go away with the GTOD framework.
 967                 */
 968#ifdef CONFIG_TIME_LOW_RES
 969                tim = ktime_add_safe(tim, base->resolution);
 970#endif
 971        }
 972
 973        hrtimer_set_expires_range_ns(timer, tim, delta_ns);
 974
 975        timer_stats_hrtimer_set_start_info(timer);
 976
 977        leftmost = enqueue_hrtimer(timer, new_base);
 978
 979        /*
 980         * Only allow reprogramming if the new base is on this CPU.
 981         * (it might still be on another CPU if the timer was pending)
 982         *
 983         * XXX send_remote_softirq() ?
 984         */
 985        if (leftmost && new_base->cpu_base == &__get_cpu_var(hrtimer_bases)
 986                && hrtimer_enqueue_reprogram(timer, new_base)) {
 987                if (wakeup) {
 988                        /*
 989                         * We need to drop cpu_base->lock to avoid a
 990                         * lock ordering issue vs. rq->lock.
 991                         */
 992                        raw_spin_unlock(&new_base->cpu_base->lock);
 993                        raise_softirq_irqoff(HRTIMER_SOFTIRQ);
 994                        local_irq_restore(flags);
 995                        return ret;
 996                } else {
 997                        __raise_softirq_irqoff(HRTIMER_SOFTIRQ);
 998                }
 999        }
1000
1001        unlock_hrtimer_base(timer, &flags);
1002
1003        return ret;
1004}
1005
1006/**
1007 * hrtimer_start_range_ns - (re)start an hrtimer on the current CPU
1008 * @timer:      the timer to be added
1009 * @tim:        expiry time
1010 * @delta_ns:   "slack" range for the timer
1011 * @mode:       expiry mode: absolute (HRTIMER_ABS) or relative (HRTIMER_REL)
1012 *
1013 * Returns:
1014 *  0 on success
1015 *  1 when the timer was active
1016 */
1017int hrtimer_start_range_ns(struct hrtimer *timer, ktime_t tim,
1018                unsigned long delta_ns, const enum hrtimer_mode mode)
1019{
1020        return __hrtimer_start_range_ns(timer, tim, delta_ns, mode, 1);
1021}
1022EXPORT_SYMBOL_GPL(hrtimer_start_range_ns);
1023
1024/**
1025 * hrtimer_start - (re)start an hrtimer on the current CPU
1026 * @timer:      the timer to be added
1027 * @tim:        expiry time
1028 * @mode:       expiry mode: absolute (HRTIMER_ABS) or relative (HRTIMER_REL)
1029 *
1030 * Returns:
1031 *  0 on success
1032 *  1 when the timer was active
1033 */
1034int
1035hrtimer_start(struct hrtimer *timer, ktime_t tim, const enum hrtimer_mode mode)
1036{
1037        return __hrtimer_start_range_ns(timer, tim, 0, mode, 1);
1038}
1039EXPORT_SYMBOL_GPL(hrtimer_start);
1040
1041
1042/**
1043 * hrtimer_try_to_cancel - try to deactivate a timer
1044 * @timer:      hrtimer to stop
1045 *
1046 * Returns:
1047 *  0 when the timer was not active
1048 *  1 when the timer was active
1049 * -1 when the timer is currently excuting the callback function and
1050 *    cannot be stopped
1051 */
1052int hrtimer_try_to_cancel(struct hrtimer *timer)
1053{
1054        struct hrtimer_clock_base *base;
1055        unsigned long flags;
1056        int ret = -1;
1057
1058        base = lock_hrtimer_base(timer, &flags);
1059
1060        if (!hrtimer_callback_running(timer))
1061                ret = remove_hrtimer(timer, base);
1062
1063        unlock_hrtimer_base(timer, &flags);
1064
1065        return ret;
1066
1067}
1068EXPORT_SYMBOL_GPL(hrtimer_try_to_cancel);
1069
1070/**
1071 * hrtimer_cancel - cancel a timer and wait for the handler to finish.
1072 * @timer:      the timer to be cancelled
1073 *
1074 * Returns:
1075 *  0 when the timer was not active
1076 *  1 when the timer was active
1077 */
1078int hrtimer_cancel(struct hrtimer *timer)
1079{
1080        for (;;) {
1081                int ret = hrtimer_try_to_cancel(timer);
1082
1083                if (ret >= 0)
1084                        return ret;
1085                cpu_relax();
1086        }
1087}
1088EXPORT_SYMBOL_GPL(hrtimer_cancel);
1089
1090/**
1091 * hrtimer_get_remaining - get remaining time for the timer
1092 * @timer:      the timer to read
1093 */
1094ktime_t hrtimer_get_remaining(const struct hrtimer *timer)
1095{
1096        unsigned long flags;
1097        ktime_t rem;
1098
1099        lock_hrtimer_base(timer, &flags);
1100        rem = hrtimer_expires_remaining(timer);
1101        unlock_hrtimer_base(timer, &flags);
1102
1103        return rem;
1104}
1105EXPORT_SYMBOL_GPL(hrtimer_get_remaining);
1106
1107#ifdef CONFIG_NO_HZ
1108/**
1109 * hrtimer_get_next_event - get the time until next expiry event
1110 *
1111 * Returns the delta to the next expiry event or KTIME_MAX if no timer
1112 * is pending.
1113 */
1114ktime_t hrtimer_get_next_event(void)
1115{
1116        struct hrtimer_cpu_base *cpu_base = &__get_cpu_var(hrtimer_bases);
1117        struct hrtimer_clock_base *base = cpu_base->clock_base;
1118        ktime_t delta, mindelta = { .tv64 = KTIME_MAX };
1119        unsigned long flags;
1120        int i;
1121
1122        raw_spin_lock_irqsave(&cpu_base->lock, flags);
1123
1124        if (!hrtimer_hres_active()) {
1125                for (i = 0; i < HRTIMER_MAX_CLOCK_BASES; i++, base++) {
1126                        struct hrtimer *timer;
1127                        struct timerqueue_node *next;
1128
1129                        next = timerqueue_getnext(&base->active);
1130                        if (!next)
1131                                continue;
1132
1133                        timer = container_of(next, struct hrtimer, node);
1134                        delta.tv64 = hrtimer_get_expires_tv64(timer);
1135                        delta = ktime_sub(delta, base->get_time());
1136                        if (delta.tv64 < mindelta.tv64)
1137                                mindelta.tv64 = delta.tv64;
1138                }
1139        }
1140
1141        raw_spin_unlock_irqrestore(&cpu_base->lock, flags);
1142
1143        if (mindelta.tv64 < 0)
1144                mindelta.tv64 = 0;
1145        return mindelta;
1146}
1147#endif
1148
1149static void __hrtimer_init(struct hrtimer *timer, clockid_t clock_id,
1150                           enum hrtimer_mode mode)
1151{
1152        struct hrtimer_cpu_base *cpu_base;
1153        int base;
1154
1155        memset(timer, 0, sizeof(struct hrtimer));
1156
1157        cpu_base = &__raw_get_cpu_var(hrtimer_bases);
1158
1159        if (clock_id == CLOCK_REALTIME && mode != HRTIMER_MODE_ABS)
1160                clock_id = CLOCK_MONOTONIC;
1161
1162        base = hrtimer_clockid_to_base(clock_id);
1163        timer->base = &cpu_base->clock_base[base];
1164        timerqueue_init(&timer->node);
1165
1166#ifdef CONFIG_TIMER_STATS
1167        timer->start_site = NULL;
1168        timer->start_pid = -1;
1169        memset(timer->start_comm, 0, TASK_COMM_LEN);
1170#endif
1171}
1172
1173/**
1174 * hrtimer_init - initialize a timer to the given clock
1175 * @timer:      the timer to be initialized
1176 * @clock_id:   the clock to be used
1177 * @mode:       timer mode abs/rel
1178 */
1179void hrtimer_init(struct hrtimer *timer, clockid_t clock_id,
1180                  enum hrtimer_mode mode)
1181{
1182        debug_init(timer, clock_id, mode);
1183        __hrtimer_init(timer, clock_id, mode);
1184}
1185EXPORT_SYMBOL_GPL(hrtimer_init);
1186
1187/**
1188 * hrtimer_get_res - get the timer resolution for a clock
1189 * @which_clock: which clock to query
1190 * @tp:          pointer to timespec variable to store the resolution
1191 *
1192 * Store the resolution of the clock selected by @which_clock in the
1193 * variable pointed to by @tp.
1194 */
1195int hrtimer_get_res(const clockid_t which_clock, struct timespec *tp)
1196{
1197        struct hrtimer_cpu_base *cpu_base;
1198        int base = hrtimer_clockid_to_base(which_clock);
1199
1200        cpu_base = &__raw_get_cpu_var(hrtimer_bases);
1201        *tp = ktime_to_timespec(cpu_base->clock_base[base].resolution);
1202
1203        return 0;
1204}
1205EXPORT_SYMBOL_GPL(hrtimer_get_res);
1206
1207static void __run_hrtimer(struct hrtimer *timer, ktime_t *now)
1208{
1209        struct hrtimer_clock_base *base = timer->base;
1210        struct hrtimer_cpu_base *cpu_base = base->cpu_base;
1211        enum hrtimer_restart (*fn)(struct hrtimer *);
1212        int restart;
1213
1214        WARN_ON(!irqs_disabled());
1215
1216        debug_deactivate(timer);
1217        __remove_hrtimer(timer, base, HRTIMER_STATE_CALLBACK, 0);
1218        timer_stats_account_hrtimer(timer);
1219        fn = timer->function;
1220
1221        /*
1222         * Because we run timers from hardirq context, there is no chance
1223         * they get migrated to another cpu, therefore its safe to unlock
1224         * the timer base.
1225         */
1226        raw_spin_unlock(&cpu_base->lock);
1227        trace_hrtimer_expire_entry(timer, now);
1228        restart = fn(timer);
1229        trace_hrtimer_expire_exit(timer);
1230        raw_spin_lock(&cpu_base->lock);
1231
1232        /*
1233         * Note: We clear the CALLBACK bit after enqueue_hrtimer and
1234         * we do not reprogramm the event hardware. Happens either in
1235         * hrtimer_start_range_ns() or in hrtimer_interrupt()
1236         */
1237        if (restart != HRTIMER_NORESTART) {
1238                BUG_ON(timer->state != HRTIMER_STATE_CALLBACK);
1239                enqueue_hrtimer(timer, base);
1240        }
1241
1242        WARN_ON_ONCE(!(timer->state & HRTIMER_STATE_CALLBACK));
1243
1244        timer->state &= ~HRTIMER_STATE_CALLBACK;
1245}
1246
1247#ifdef CONFIG_HIGH_RES_TIMERS
1248
1249/*
1250 * High resolution timer interrupt
1251 * Called with interrupts disabled
1252 */
1253void hrtimer_interrupt(struct clock_event_device *dev)
1254{
1255        struct hrtimer_cpu_base *cpu_base = &__get_cpu_var(hrtimer_bases);
1256        ktime_t expires_next, now, entry_time, delta;
1257        int i, retries = 0;
1258
1259        BUG_ON(!cpu_base->hres_active);
1260        cpu_base->nr_events++;
1261        dev->next_event.tv64 = KTIME_MAX;
1262
1263        raw_spin_lock(&cpu_base->lock);
1264        entry_time = now = hrtimer_update_base(cpu_base);
1265retry:
1266        expires_next.tv64 = KTIME_MAX;
1267        /*
1268         * We set expires_next to KTIME_MAX here with cpu_base->lock
1269         * held to prevent that a timer is enqueued in our queue via
1270         * the migration code. This does not affect enqueueing of
1271         * timers which run their callback and need to be requeued on
1272         * this CPU.
1273         */
1274        cpu_base->expires_next.tv64 = KTIME_MAX;
1275
1276        for (i = 0; i < HRTIMER_MAX_CLOCK_BASES; i++) {
1277                struct hrtimer_clock_base *base;
1278                struct timerqueue_node *node;
1279                ktime_t basenow;
1280
1281                if (!(cpu_base->active_bases & (1 << i)))
1282                        continue;
1283
1284                base = cpu_base->clock_base + i;
1285                basenow = ktime_add(now, base->offset);
1286
1287                while ((node = timerqueue_getnext(&base->active))) {
1288                        struct hrtimer *timer;
1289
1290                        timer = container_of(node, struct hrtimer, node);
1291
1292                        /*
1293                         * The immediate goal for using the softexpires is
1294                         * minimizing wakeups, not running timers at the
1295                         * earliest interrupt after their soft expiration.
1296                         * This allows us to avoid using a Priority Search
1297                         * Tree, which can answer a stabbing querry for
1298                         * overlapping intervals and instead use the simple
1299                         * BST we already have.
1300                         * We don't add extra wakeups by delaying timers that
1301                         * are right-of a not yet expired timer, because that
1302                         * timer will have to trigger a wakeup anyway.
1303                         */
1304
1305                        if (basenow.tv64 < hrtimer_get_softexpires_tv64(timer)) {
1306                                ktime_t expires;
1307
1308                                expires = ktime_sub(hrtimer_get_expires(timer),
1309                                                    base->offset);
1310                                if (expires.tv64 < expires_next.tv64)
1311                                        expires_next = expires;
1312                                break;
1313                        }
1314
1315                        __run_hrtimer(timer, &basenow);
1316                }
1317        }
1318
1319        /*
1320         * Store the new expiry value so the migration code can verify
1321         * against it.
1322         */
1323        cpu_base->expires_next = expires_next;
1324        raw_spin_unlock(&cpu_base->lock);
1325
1326        /* Reprogramming necessary ? */
1327        if (expires_next.tv64 == KTIME_MAX ||
1328            !tick_program_event(expires_next, 0)) {
1329                cpu_base->hang_detected = 0;
1330                return;
1331        }
1332
1333        /*
1334         * The next timer was already expired due to:
1335         * - tracing
1336         * - long lasting callbacks
1337         * - being scheduled away when running in a VM
1338         *
1339         * We need to prevent that we loop forever in the hrtimer
1340         * interrupt routine. We give it 3 attempts to avoid
1341         * overreacting on some spurious event.
1342         *
1343         * Acquire base lock for updating the offsets and retrieving
1344         * the current time.
1345         */
1346        raw_spin_lock(&cpu_base->lock);
1347        now = hrtimer_update_base(cpu_base);
1348        cpu_base->nr_retries++;
1349        if (++retries < 3)
1350                goto retry;
1351        /*
1352         * Give the system a chance to do something else than looping
1353         * here. We stored the entry time, so we know exactly how long
1354         * we spent here. We schedule the next event this amount of
1355         * time away.
1356         */
1357        cpu_base->nr_hangs++;
1358        cpu_base->hang_detected = 1;
1359        raw_spin_unlock(&cpu_base->lock);
1360        delta = ktime_sub(now, entry_time);
1361        if (delta.tv64 > cpu_base->max_hang_time.tv64)
1362                cpu_base->max_hang_time = delta;
1363        /*
1364         * Limit it to a sensible value as we enforce a longer
1365         * delay. Give the CPU at least 100ms to catch up.
1366         */
1367        if (delta.tv64 > 100 * NSEC_PER_MSEC)
1368                expires_next = ktime_add_ns(now, 100 * NSEC_PER_MSEC);
1369        else
1370                expires_next = ktime_add(now, delta);
1371        tick_program_event(expires_next, 1);
1372        printk_once(KERN_WARNING "hrtimer: interrupt took %llu ns\n",
1373                    ktime_to_ns(delta));
1374}
1375
1376/*
1377 * local version of hrtimer_peek_ahead_timers() called with interrupts
1378 * disabled.
1379 */
1380static void __hrtimer_peek_ahead_timers(void)
1381{
1382        struct tick_device *td;
1383
1384        if (!hrtimer_hres_active())
1385                return;
1386
1387        td = &__get_cpu_var(tick_cpu_device);
1388        if (td && td->evtdev)
1389                hrtimer_interrupt(td->evtdev);
1390}
1391
1392/**
1393 * hrtimer_peek_ahead_timers -- run soft-expired timers now
1394 *
1395 * hrtimer_peek_ahead_timers will peek at the timer queue of
1396 * the current cpu and check if there are any timers for which
1397 * the soft expires time has passed. If any such timers exist,
1398 * they are run immediately and then removed from the timer queue.
1399 *
1400 */
1401void hrtimer_peek_ahead_timers(void)
1402{
1403        unsigned long flags;
1404
1405        local_irq_save(flags);
1406        __hrtimer_peek_ahead_timers();
1407        local_irq_restore(flags);
1408}
1409
1410static void run_hrtimer_softirq(struct softirq_action *h)
1411{
1412        struct hrtimer_cpu_base *cpu_base = &__get_cpu_var(hrtimer_bases);
1413
1414        if (cpu_base->clock_was_set) {
1415                cpu_base->clock_was_set = 0;
1416                clock_was_set();
1417        }
1418
1419        hrtimer_peek_ahead_timers();
1420}
1421
1422#else /* CONFIG_HIGH_RES_TIMERS */
1423
1424static inline void __hrtimer_peek_ahead_timers(void) { }
1425
1426#endif  /* !CONFIG_HIGH_RES_TIMERS */
1427
1428/*
1429 * Called from timer softirq every jiffy, expire hrtimers:
1430 *
1431 * For HRT its the fall back code to run the softirq in the timer
1432 * softirq context in case the hrtimer initialization failed or has
1433 * not been done yet.
1434 */
1435void hrtimer_run_pending(void)
1436{
1437        if (hrtimer_hres_active())
1438                return;
1439
1440        /*
1441         * This _is_ ugly: We have to check in the softirq context,
1442         * whether we can switch to highres and / or nohz mode. The
1443         * clocksource switch happens in the timer interrupt with
1444         * xtime_lock held. Notification from there only sets the
1445         * check bit in the tick_oneshot code, otherwise we might
1446         * deadlock vs. xtime_lock.
1447         */
1448        if (tick_check_oneshot_change(!hrtimer_is_hres_enabled()))
1449                hrtimer_switch_to_hres();
1450}
1451
1452/*
1453 * Called from hardirq context every jiffy
1454 */
1455void hrtimer_run_queues(void)
1456{
1457        struct timerqueue_node *node;
1458        struct hrtimer_cpu_base *cpu_base = &__get_cpu_var(hrtimer_bases);
1459        struct hrtimer_clock_base *base;
1460        int index, gettime = 1;
1461
1462        if (hrtimer_hres_active())
1463                return;
1464
1465        for (index = 0; index < HRTIMER_MAX_CLOCK_BASES; index++) {
1466                base = &cpu_base->clock_base[index];
1467                if (!timerqueue_getnext(&base->active))
1468                        continue;
1469
1470                if (gettime) {
1471                        hrtimer_get_softirq_time(cpu_base);
1472                        gettime = 0;
1473                }
1474
1475                raw_spin_lock(&cpu_base->lock);
1476
1477                while ((node = timerqueue_getnext(&base->active))) {
1478                        struct hrtimer *timer;
1479
1480                        timer = container_of(node, struct hrtimer, node);
1481                        if (base->softirq_time.tv64 <=
1482                                        hrtimer_get_expires_tv64(timer))
1483                                break;
1484
1485                        __run_hrtimer(timer, &base->softirq_time);
1486                }
1487                raw_spin_unlock(&cpu_base->lock);
1488        }
1489}
1490
1491/*
1492 * Sleep related functions:
1493 */
1494static enum hrtimer_restart hrtimer_wakeup(struct hrtimer *timer)
1495{
1496        struct hrtimer_sleeper *t =
1497                container_of(timer, struct hrtimer_sleeper, timer);
1498        struct task_struct *task = t->task;
1499
1500        t->task = NULL;
1501        if (task)
1502                wake_up_process(task);
1503
1504        return HRTIMER_NORESTART;
1505}
1506
1507void hrtimer_init_sleeper(struct hrtimer_sleeper *sl, struct task_struct *task)
1508{
1509        sl->timer.function = hrtimer_wakeup;
1510        sl->task = task;
1511}
1512EXPORT_SYMBOL_GPL(hrtimer_init_sleeper);
1513
1514static int __sched do_nanosleep(struct hrtimer_sleeper *t, enum hrtimer_mode mode)
1515{
1516        hrtimer_init_sleeper(t, current);
1517
1518        do {
1519                set_current_state(TASK_INTERRUPTIBLE);
1520                hrtimer_start_expires(&t->timer, mode);
1521                if (!hrtimer_active(&t->timer))
1522                        t->task = NULL;
1523
1524                if (likely(t->task))
1525                        schedule();
1526
1527                hrtimer_cancel(&t->timer);
1528                mode = HRTIMER_MODE_ABS;
1529
1530        } while (t->task && !signal_pending(current));
1531
1532        __set_current_state(TASK_RUNNING);
1533
1534        return t->task == NULL;
1535}
1536
1537static int update_rmtp(struct hrtimer *timer, struct timespec __user *rmtp)
1538{
1539        struct timespec rmt;
1540        ktime_t rem;
1541
1542        rem = hrtimer_expires_remaining(timer);
1543        if (rem.tv64 <= 0)
1544                return 0;
1545        rmt = ktime_to_timespec(rem);
1546
1547        if (copy_to_user(rmtp, &rmt, sizeof(*rmtp)))
1548                return -EFAULT;
1549
1550        return 1;
1551}
1552
1553long __sched hrtimer_nanosleep_restart(struct restart_block *restart)
1554{
1555        struct hrtimer_sleeper t;
1556        struct timespec __user  *rmtp;
1557        int ret = 0;
1558
1559        hrtimer_init_on_stack(&t.timer, restart->nanosleep.clockid,
1560                                HRTIMER_MODE_ABS);
1561        hrtimer_set_expires_tv64(&t.timer, restart->nanosleep.expires);
1562
1563        if (do_nanosleep(&t, HRTIMER_MODE_ABS))
1564                goto out;
1565
1566        rmtp = restart->nanosleep.rmtp;
1567        if (rmtp) {
1568                ret = update_rmtp(&t.timer, rmtp);
1569                if (ret <= 0)
1570                        goto out;
1571        }
1572
1573        /* The other values in restart are already filled in */
1574        ret = -ERESTART_RESTARTBLOCK;
1575out:
1576        destroy_hrtimer_on_stack(&t.timer);
1577        return ret;
1578}
1579
1580long hrtimer_nanosleep(struct timespec *rqtp, struct timespec __user *rmtp,
1581                       const enum hrtimer_mode mode, const clockid_t clockid)
1582{
1583        struct restart_block *restart;
1584        struct hrtimer_sleeper t;
1585        int ret = 0;
1586        unsigned long slack;
1587
1588        slack = current->timer_slack_ns;
1589        if (rt_task(current))
1590                slack = 0;
1591
1592        hrtimer_init_on_stack(&t.timer, clockid, mode);
1593        hrtimer_set_expires_range_ns(&t.timer, timespec_to_ktime(*rqtp), slack);
1594        if (do_nanosleep(&t, mode))
1595                goto out;
1596
1597        /* Absolute timers do not update the rmtp value and restart: */
1598        if (mode == HRTIMER_MODE_ABS) {
1599                ret = -ERESTARTNOHAND;
1600                goto out;
1601        }
1602
1603        if (rmtp) {
1604                ret = update_rmtp(&t.timer, rmtp);
1605                if (ret <= 0)
1606                        goto out;
1607        }
1608
1609        restart = &current_thread_info()->restart_block;
1610        restart->fn = hrtimer_nanosleep_restart;
1611        restart->nanosleep.clockid = t.timer.base->clockid;
1612        restart->nanosleep.rmtp = rmtp;
1613        restart->nanosleep.expires = hrtimer_get_expires_tv64(&t.timer);
1614
1615        ret = -ERESTART_RESTARTBLOCK;
1616out:
1617        destroy_hrtimer_on_stack(&t.timer);
1618        return ret;
1619}
1620
1621SYSCALL_DEFINE2(nanosleep, struct timespec __user *, rqtp,
1622                struct timespec __user *, rmtp)
1623{
1624        struct timespec tu;
1625
1626        if (copy_from_user(&tu, rqtp, sizeof(tu)))
1627                return -EFAULT;
1628
1629        if (!timespec_valid(&tu))
1630                return -EINVAL;
1631
1632        return hrtimer_nanosleep(&tu, rmtp, HRTIMER_MODE_REL, CLOCK_MONOTONIC);
1633}
1634
1635/*
1636 * Functions related to boot-time initialization:
1637 */
1638static void __cpuinit init_hrtimers_cpu(int cpu)
1639{
1640        struct hrtimer_cpu_base *cpu_base = &per_cpu(hrtimer_bases, cpu);
1641        int i;
1642
1643        raw_spin_lock_init(&cpu_base->lock);
1644
1645        for (i = 0; i < HRTIMER_MAX_CLOCK_BASES; i++) {
1646                cpu_base->clock_base[i].cpu_base = cpu_base;
1647                timerqueue_init_head(&cpu_base->clock_base[i].active);
1648        }
1649
1650        hrtimer_init_hres(cpu_base);
1651}
1652
1653#ifdef CONFIG_HOTPLUG_CPU
1654
1655static void migrate_hrtimer_list(struct hrtimer_clock_base *old_base,
1656                                struct hrtimer_clock_base *new_base)
1657{
1658        struct hrtimer *timer;
1659        struct timerqueue_node *node;
1660
1661        while ((node = timerqueue_getnext(&old_base->active))) {
1662                timer = container_of(node, struct hrtimer, node);
1663                BUG_ON(hrtimer_callback_running(timer));
1664                debug_deactivate(timer);
1665
1666                /*
1667                 * Mark it as STATE_MIGRATE not INACTIVE otherwise the
1668                 * timer could be seen as !active and just vanish away
1669                 * under us on another CPU
1670                 */
1671                __remove_hrtimer(timer, old_base, HRTIMER_STATE_MIGRATE, 0);
1672                timer->base = new_base;
1673                /*
1674                 * Enqueue the timers on the new cpu. This does not
1675                 * reprogram the event device in case the timer
1676                 * expires before the earliest on this CPU, but we run
1677                 * hrtimer_interrupt after we migrated everything to
1678                 * sort out already expired timers and reprogram the
1679                 * event device.
1680                 */
1681                enqueue_hrtimer(timer, new_base);
1682
1683                /* Clear the migration state bit */
1684                timer->state &= ~HRTIMER_STATE_MIGRATE;
1685        }
1686}
1687
1688static void migrate_hrtimers(int scpu)
1689{
1690        struct hrtimer_cpu_base *old_base, *new_base;
1691        int i;
1692
1693        BUG_ON(cpu_online(scpu));
1694        tick_cancel_sched_timer(scpu);
1695
1696        local_irq_disable();
1697        old_base = &per_cpu(hrtimer_bases, scpu);
1698        new_base = &__get_cpu_var(hrtimer_bases);
1699        /*
1700         * The caller is globally serialized and nobody else
1701         * takes two locks at once, deadlock is not possible.
1702         */
1703        raw_spin_lock(&new_base->lock);
1704        raw_spin_lock_nested(&old_base->lock, SINGLE_DEPTH_NESTING);
1705
1706        for (i = 0; i < HRTIMER_MAX_CLOCK_BASES; i++) {
1707                migrate_hrtimer_list(&old_base->clock_base[i],
1708                                     &new_base->clock_base[i]);
1709        }
1710
1711        raw_spin_unlock(&old_base->lock);
1712        raw_spin_unlock(&new_base->lock);
1713
1714        /* Check, if we got expired work to do */
1715        __hrtimer_peek_ahead_timers();
1716        local_irq_enable();
1717}
1718
1719#endif /* CONFIG_HOTPLUG_CPU */
1720
1721static int __cpuinit hrtimer_cpu_notify(struct notifier_block *self,
1722                                        unsigned long action, void *hcpu)
1723{
1724        int scpu = (long)hcpu;
1725
1726        switch (action) {
1727
1728        case CPU_UP_PREPARE:
1729        case CPU_UP_PREPARE_FROZEN:
1730                init_hrtimers_cpu(scpu);
1731                break;
1732
1733#ifdef CONFIG_HOTPLUG_CPU
1734        case CPU_DYING:
1735        case CPU_DYING_FROZEN:
1736                clockevents_notify(CLOCK_EVT_NOTIFY_CPU_DYING, &scpu);
1737                break;
1738        case CPU_DEAD:
1739        case CPU_DEAD_FROZEN:
1740        {
1741                clockevents_notify(CLOCK_EVT_NOTIFY_CPU_DEAD, &scpu);
1742                migrate_hrtimers(scpu);
1743                break;
1744        }
1745#endif
1746
1747        default:
1748                break;
1749        }
1750
1751        return NOTIFY_OK;
1752}
1753
1754static struct notifier_block __cpuinitdata hrtimers_nb = {
1755        .notifier_call = hrtimer_cpu_notify,
1756};
1757
1758void __init hrtimers_init(void)
1759{
1760        hrtimer_cpu_notify(&hrtimers_nb, (unsigned long)CPU_UP_PREPARE,
1761                          (void *)(long)smp_processor_id());
1762        register_cpu_notifier(&hrtimers_nb);
1763#ifdef CONFIG_HIGH_RES_TIMERS
1764        open_softirq(HRTIMER_SOFTIRQ, run_hrtimer_softirq);
1765#endif
1766}
1767
1768/**
1769 * schedule_hrtimeout_range_clock - sleep until timeout
1770 * @expires:    timeout value (ktime_t)
1771 * @delta:      slack in expires timeout (ktime_t)
1772 * @mode:       timer mode, HRTIMER_MODE_ABS or HRTIMER_MODE_REL
1773 * @clock:      timer clock, CLOCK_MONOTONIC or CLOCK_REALTIME
1774 */
1775int __sched
1776schedule_hrtimeout_range_clock(ktime_t *expires, unsigned long delta,
1777                               const enum hrtimer_mode mode, int clock)
1778{
1779        struct hrtimer_sleeper t;
1780
1781        /*
1782         * Optimize when a zero timeout value is given. It does not
1783         * matter whether this is an absolute or a relative time.
1784         */
1785        if (expires && !expires->tv64) {
1786                __set_current_state(TASK_RUNNING);
1787                return 0;
1788        }
1789
1790        /*
1791         * A NULL parameter means "infinite"
1792         */
1793        if (!expires) {
1794                schedule();
1795                __set_current_state(TASK_RUNNING);
1796                return -EINTR;
1797        }
1798
1799        hrtimer_init_on_stack(&t.timer, clock, mode);
1800        hrtimer_set_expires_range_ns(&t.timer, *expires, delta);
1801
1802        hrtimer_init_sleeper(&t, current);
1803
1804        hrtimer_start_expires(&t.timer, mode);
1805        if (!hrtimer_active(&t.timer))
1806                t.task = NULL;
1807
1808        if (likely(t.task))
1809                schedule();
1810
1811        hrtimer_cancel(&t.timer);
1812        destroy_hrtimer_on_stack(&t.timer);
1813
1814        __set_current_state(TASK_RUNNING);
1815
1816        return !t.task ? 0 : -EINTR;
1817}
1818
1819/**
1820 * schedule_hrtimeout_range - sleep until timeout
1821 * @expires:    timeout value (ktime_t)
1822 * @delta:      slack in expires timeout (ktime_t)
1823 * @mode:       timer mode, HRTIMER_MODE_ABS or HRTIMER_MODE_REL
1824 *
1825 * Make the current task sleep until the given expiry time has
1826 * elapsed. The routine will return immediately unless
1827 * the current task state has been set (see set_current_state()).
1828 *
1829 * The @delta argument gives the kernel the freedom to schedule the
1830 * actual wakeup to a time that is both power and performance friendly.
1831 * The kernel give the normal best effort behavior for "@expires+@delta",
1832 * but may decide to fire the timer earlier, but no earlier than @expires.
1833 *
1834 * You can set the task state as follows -
1835 *
1836 * %TASK_UNINTERRUPTIBLE - at least @timeout time is guaranteed to
1837 * pass before the routine returns.
1838 *
1839 * %TASK_INTERRUPTIBLE - the routine may return early if a signal is
1840 * delivered to the current task.
1841 *
1842 * The current task state is guaranteed to be TASK_RUNNING when this
1843 * routine returns.
1844 *
1845 * Returns 0 when the timer has expired otherwise -EINTR
1846 */
1847int __sched schedule_hrtimeout_range(ktime_t *expires, unsigned long delta,
1848                                     const enum hrtimer_mode mode)
1849{
1850        return schedule_hrtimeout_range_clock(expires, delta, mode,
1851                                              CLOCK_MONOTONIC);
1852}
1853EXPORT_SYMBOL_GPL(schedule_hrtimeout_range);
1854
1855/**
1856 * schedule_hrtimeout - sleep until timeout
1857 * @expires:    timeout value (ktime_t)
1858 * @mode:       timer mode, HRTIMER_MODE_ABS or HRTIMER_MODE_REL
1859 *
1860 * Make the current task sleep until the given expiry time has
1861 * elapsed. The routine will return immediately unless
1862 * the current task state has been set (see set_current_state()).
1863 *
1864 * You can set the task state as follows -
1865 *
1866 * %TASK_UNINTERRUPTIBLE - at least @timeout time is guaranteed to
1867 * pass before the routine returns.
1868 *
1869 * %TASK_INTERRUPTIBLE - the routine may return early if a signal is
1870 * delivered to the current task.
1871 *
1872 * The current task state is guaranteed to be TASK_RUNNING when this
1873 * routine returns.
1874 *
1875 * Returns 0 when the timer has expired otherwise -EINTR
1876 */
1877int __sched schedule_hrtimeout(ktime_t *expires,
1878                               const enum hrtimer_mode mode)
1879{
1880        return schedule_hrtimeout_range(expires, 0, mode);
1881}
1882EXPORT_SYMBOL_GPL(schedule_hrtimeout);
1883
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