kernel/hrtimer.c

   1 /*
   2  *  linux/kernel/hrtimer.c
   3  *
   4  *  Copyright(C) 2005, Thomas Gleixner <tglx@linutronix.de>
   5  *  Copyright(C) 2005, Red Hat, Inc., Ingo Molnar
   6  *
   7  *  High-resolution kernel timers
   8  *
   9  *  In contrast to the low-resolution timeout API implemented in
  10  *  kernel/timer.c, hrtimers provide finer resolution and accuracy
  11  *  depending on system configuration and capabilities.
  12  *
  13  *  These timers are currently used for:
  14  *   - itimers
  15  *   - POSIX timers
  16  *   - nanosleep
  17  *   - precise in-kernel timing
  18  *
  19  *  Started by: Thomas Gleixner and Ingo Molnar
  20  *
  21  *  Credits:
  22  *      based on kernel/timer.c
  23  *
  24  *      Help, testing, suggestions, bugfixes, improvements were
  25  *      provided by:
  26  *
  27  *      George Anzinger, Andrew Morton, Steven Rostedt, Roman Zippel
  28  *      et. al.
  29  *
  30  *  For licencing details see kernel-base/COPYING
  31  */
  32
  33 #include <linux/cpu.h>
  34 #include <linux/module.h>
  35 #include <linux/percpu.h>
  36 #include <linux/hrtimer.h>
  37 #include <linux/notifier.h>
  38 #include <linux/syscalls.h>
  39 #include <linux/interrupt.h>
  40
  41 #include <asm/uaccess.h>
  42
  43 /**
  44  * ktime_get - get the monotonic time in ktime_t format
  45  *
  46  * returns the time in ktime_t format
  47  */
  48 static ktime_t ktime_get(void)
  49 {
  50         struct timespec now;
  51
  52         ktime_get_ts(&now);
  53
  54         return timespec_to_ktime(now);
  55 }
  56
  57 /**
  58  * ktime_get_real - get the real (wall-) time in ktime_t format
  59  *
  60  * returns the time in ktime_t format
  61  */
  62 static ktime_t ktime_get_real(void)
  63 {
  64         struct timespec now;
  65
  66         getnstimeofday(&now);
  67
  68         return timespec_to_ktime(now);
  69 }
  70
  71 EXPORT_SYMBOL_GPL(ktime_get_real);
  72
  73 /*
  74  * The timer bases:
  75  *
  76  * Note: If we want to add new timer bases, we have to skip the two
  77  * clock ids captured by the cpu-timers. We do this by holding empty
  78  * entries rather than doing math adjustment of the clock ids.
  79  * This ensures that we capture erroneous accesses to these clock ids
  80  * rather than moving them into the range of valid clock id's.
  81  */
  82
  83 #define MAX_HRTIMER_BASES 2
  84
  85 static DEFINE_PER_CPU(struct hrtimer_base, hrtimer_bases[MAX_HRTIMER_BASES]) =
  86 {
  87         {
  88                 .index = CLOCK_REALTIME,
  89                 .get_time = &ktime_get_real,
  90                 .resolution = KTIME_REALTIME_RES,
  91         },
  92         {
  93                 .index = CLOCK_MONOTONIC,
  94                 .get_time = &ktime_get,
  95                 .resolution = KTIME_MONOTONIC_RES,
  96         },
  97 };
  98
  99 /**
 100  * ktime_get_ts - get the monotonic clock in timespec format
 101  * @ts:         pointer to timespec variable
 102  *
 103  * The function calculates the monotonic clock from the realtime
 104  * clock and the wall_to_monotonic offset and stores the result
 105  * in normalized timespec format in the variable pointed to by ts.
 106  */
 107 void ktime_get_ts(struct timespec *ts)
 108 {
 109         struct timespec tomono;
 110         unsigned long seq;
 111
 112         do {
 113                 seq = read_seqbegin(&xtime_lock);
 114                 getnstimeofday(ts);
 115                 tomono = wall_to_monotonic;
 116
 117         } while (read_seqretry(&xtime_lock, seq));
 118
 119         set_normalized_timespec(ts, ts->tv_sec + tomono.tv_sec,
 120                                 ts->tv_nsec + tomono.tv_nsec);
 121 }
 122 EXPORT_SYMBOL_GPL(ktime_get_ts);
 123
 124 /*
 125  * Get the coarse grained time at the softirq based on xtime and
 126  * wall_to_monotonic.
 127  */
 128 static void hrtimer_get_softirq_time(struct hrtimer_base *base)
 129 {
 130         ktime_t xtim, tomono;
 131         unsigned long seq;
 132
 133         do {
 134                 seq = read_seqbegin(&xtime_lock);
 135                 xtim = timespec_to_ktime(xtime);
 136                 tomono = timespec_to_ktime(wall_to_monotonic);
 137
 138         } while (read_seqretry(&xtime_lock, seq));
 139
 140         base[CLOCK_REALTIME].softirq_time = xtim;
 141         base[CLOCK_MONOTONIC].softirq_time = ktime_add(xtim, tomono);
 142 }
 143
 144 /*
 145  * Functions and macros which are different for UP/SMP systems are kept in a
 146  * single place
 147  */
 148 #ifdef CONFIG_SMP
 149
 150 #define set_curr_timer(b, t)            do { (b)->curr_timer = (t); } while (0)
 151
 152 /*
 153  * We are using hashed locking: holding per_cpu(hrtimer_bases)[n].lock
 154  * means that all timers which are tied to this base via timer->base are
 155  * locked, and the base itself is locked too.
 156  *
 157  * So __run_timers/migrate_timers can safely modify all timers which could
 158  * be found on the lists/queues.
 159  *
 160  * When the timer's base is locked, and the timer removed from list, it is
 161  * possible to set timer->base = NULL and drop the lock: the timer remains
 162  * locked.
 163  */
 164 static struct hrtimer_base *lock_hrtimer_base(const struct hrtimer *timer,
 165                                               unsigned long *flags)
 166 {
 167         struct hrtimer_base *base;
 168
 169         for (;;) {
 170                 base = timer->base;
 171                 if (likely(base != NULL)) {
 172                         spin_lock_irqsave(&base->lock, *flags);
 173                         if (likely(base == timer->base))
 174                                 return base;
 175                         /* The timer has migrated to another CPU: */
 176                         spin_unlock_irqrestore(&base->lock, *flags);
 177                 }
 178                 cpu_relax();
 179         }
 180 }
 181
 182 /*
 183  * Switch the timer base to the current CPU when possible.
 184  */
 185 static inline struct hrtimer_base *
 186 switch_hrtimer_base(struct hrtimer *timer, struct hrtimer_base *base)
 187 {
 188         struct hrtimer_base *new_base;
 189
 190         new_base = &__get_cpu_var(hrtimer_bases)[base->index];
 191
 192         if (base != new_base) {
 193                 /*
 194                  * We are trying to schedule the timer on the local CPU.
 195                  * However we can't change timer's base while it is running,
 196                  * so we keep it on the same CPU. No hassle vs. reprogramming
 197                  * the event source in the high resolution case. The softirq
 198                  * code will take care of this when the timer function has
 199                  * completed. There is no conflict as we hold the lock until
 200                  * the timer is enqueued.
 201                  */
 202                 if (unlikely(base->curr_timer == timer))
 203                         return base;
 204
 205                 /* See the comment in lock_timer_base() */
 206                 timer->base = NULL;
 207                 spin_unlock(&base->lock);
 208                 spin_lock(&new_base->lock);
 209                 timer->base = new_base;
 210         }
 211         return new_base;
 212 }
 213
 214 #else /* CONFIG_SMP */
 215
 216 #define set_curr_timer(b, t)            do { } while (0)
 217
 218 static inline struct hrtimer_base *
 219 lock_hrtimer_base(const struct hrtimer *timer, unsigned long *flags)
 220 {
 221         struct hrtimer_base *base = timer->base;
 222
 223         spin_lock_irqsave(&base->lock, *flags);
 224
 225         return base;
 226 }
 227
 228 #define switch_hrtimer_base(t, b)       (b)
 229
 230 #endif  /* !CONFIG_SMP */
 231
 232 /*
 233  * Functions for the union type storage format of ktime_t which are
 234  * too large for inlining:
 235  */
 236 #if BITS_PER_LONG < 64
 237 # ifndef CONFIG_KTIME_SCALAR
 238 /**
 239  * ktime_add_ns - Add a scalar nanoseconds value to a ktime_t variable
 240  * @kt:         addend
 241  * @nsec:       the scalar nsec value to add
 242  *
 243  * Returns the sum of kt and nsec in ktime_t format
 244  */
 245 ktime_t ktime_add_ns(const ktime_t kt, u64 nsec)
 246 {
 247         ktime_t tmp;
 248
 249         if (likely(nsec < NSEC_PER_SEC)) {
 250                 tmp.tv64 = nsec;
 251         } else {
 252                 unsigned long rem = do_div(nsec, NSEC_PER_SEC);
 253
 254                 tmp = ktime_set((long)nsec, rem);
 255         }
 256
 257         return ktime_add(kt, tmp);
 258 }
 259
 260 #else /* CONFIG_KTIME_SCALAR */
 261
 262 # endif /* !CONFIG_KTIME_SCALAR */
 263
 264 /*
 265  * Divide a ktime value by a nanosecond value
 266  */
 267 static unsigned long ktime_divns(const ktime_t kt, s64 div)
 268 {
 269         u64 dclc, inc, dns;
 270         int sft = 0;
 271
 272         dclc = dns = ktime_to_ns(kt);
 273         inc = div;
 274         /* Make sure the divisor is less than 2^32: */
 275         while (div >> 32) {
 276                 sft++;
 277                 div >>= 1;
 278         }
 279         dclc >>= sft;
 280         do_div(dclc, (unsigned long) div);
 281
 282         return (unsigned long) dclc;
 283 }
 284
 285 #else /* BITS_PER_LONG < 64 */
 286 # define ktime_divns(kt, div)           (unsigned long)((kt).tv64 / (div))
 287 #endif /* BITS_PER_LONG >= 64 */
 288
 289 /*
 290  * Counterpart to lock_timer_base above:
 291  */
 292 static inline
 293 void unlock_hrtimer_base(const struct hrtimer *timer, unsigned long *flags)
 294 {
 295         spin_unlock_irqrestore(&timer->base->lock, *flags);
 296 }
 297
 298 /**
 299  * hrtimer_forward - forward the timer expiry
 300  * @timer:      hrtimer to forward
 301  * @now:        forward past this time
 302  * @interval:   the interval to forward
 303  *
 304  * Forward the timer expiry so it will expire in the future.
 305  * Returns the number of overruns.
 306  */
 307 unsigned long
 308 hrtimer_forward(struct hrtimer *timer, ktime_t now, ktime_t interval)
 309 {
 310         unsigned long orun = 1;
 311         ktime_t delta;
 312
 313         delta = ktime_sub(now, timer->expires);
 314
 315         if (delta.tv64 < 0)
 316                 return 0;
 317
 318         if (interval.tv64 < timer->base->resolution.tv64)
 319                 interval.tv64 = timer->base->resolution.tv64;
 320
 321         if (unlikely(delta.tv64 >= interval.tv64)) {
 322                 s64 incr = ktime_to_ns(interval);
 323
 324                 orun = ktime_divns(delta, incr);
 325                 timer->expires = ktime_add_ns(timer->expires, incr * orun);
 326                 if (timer->expires.tv64 > now.tv64)
 327                         return orun;
 328                 /*
 329                  * This (and the ktime_add() below) is the
 330                  * correction for exact:
 331                  */
 332                 orun++;
 333         }
 334         timer->expires = ktime_add(timer->expires, interval);
 335
 336         return orun;
 337 }
 338
 339 /*
 340  * enqueue_hrtimer - internal function to (re)start a timer
 341  *
 342  * The timer is inserted in expiry order. Insertion into the
 343  * red black tree is O(log(n)). Must hold the base lock.
 344  */
 345 static void enqueue_hrtimer(struct hrtimer *timer, struct hrtimer_base *base)
 346 {
 347         struct rb_node **link = &base->active.rb_node;
 348         struct rb_node *parent = NULL;
 349         struct hrtimer *entry;
 350
 351         /*
 352          * Find the right place in the rbtree:
 353          */
 354         while (*link) {
 355                 parent = *link;
 356                 entry = rb_entry(parent, struct hrtimer, node);
 357                 /*
 358                  * We dont care about collisions. Nodes with
 359                  * the same expiry time stay together.
 360                  */
 361                 if (timer->expires.tv64 < entry->expires.tv64)
 362                         link = &(*link)->rb_left;
 363                 else
 364                         link = &(*link)->rb_right;
 365         }
 366
 367         /*
 368          * Insert the timer to the rbtree and check whether it
 369          * replaces the first pending timer
 370          */
 371         rb_link_node(&timer->node, parent, link);
 372         rb_insert_color(&timer->node, &base->active);
 373
 374         if (!base->first || timer->expires.tv64 <
 375             rb_entry(base->first, struct hrtimer, node)->expires.tv64)
 376                 base->first = &timer->node;
 377 }
 378
 379 /*
 380  * __remove_hrtimer - internal function to remove a timer
 381  *
 382  * Caller must hold the base lock.
 383  */
 384 static void __remove_hrtimer(struct hrtimer *timer, struct hrtimer_base *base)
 385 {
 386         /*
 387          * Remove the timer from the rbtree and replace the
 388          * first entry pointer if necessary.
 389          */
 390         if (base->first == &timer->node)
 391                 base->first = rb_next(&timer->node);
 392         rb_erase(&timer->node, &base->active);
 393         rb_set_parent(&timer->node, &timer->node);
 394 }
 395
 396 /*
 397  * remove hrtimer, called with base lock held
 398  */
 399 static inline int
 400 remove_hrtimer(struct hrtimer *timer, struct hrtimer_base *base)
 401 {
 402         if (hrtimer_active(timer)) {
 403                 __remove_hrtimer(timer, base);
 404                 return 1;
 405         }
 406         return 0;
 407 }
 408
 409 /**
 410  * hrtimer_start - (re)start an relative timer on the current CPU
 411  * @timer:      the timer to be added
 412  * @tim:        expiry time
 413  * @mode:       expiry mode: absolute (HRTIMER_ABS) or relative (HRTIMER_REL)
 414  *
 415  * Returns:
 416  *  0 on success
 417  *  1 when the timer was active
 418  */
 419 int
 420 hrtimer_start(struct hrtimer *timer, ktime_t tim, const enum hrtimer_mode mode)
 421 {
 422         struct hrtimer_base *base, *new_base;
 423         unsigned long flags;
 424         int ret;
 425
 426         base = lock_hrtimer_base(timer, &flags);
 427
 428         /* Remove an active timer from the queue: */
 429         ret = remove_hrtimer(timer, base);
 430
 431         /* Switch the timer base, if necessary: */
 432         new_base = switch_hrtimer_base(timer, base);
 433
 434         if (mode == HRTIMER_REL) {
 435                 tim = ktime_add(tim, new_base->get_time());
 436                 /*
 437                  * CONFIG_TIME_LOW_RES is a temporary way for architectures
 438                  * to signal that they simply return xtime in
 439                  * do_gettimeoffset(). In this case we want to round up by
 440                  * resolution when starting a relative timer, to avoid short
 441                  * timeouts. This will go away with the GTOD framework.
 442                  */
 443 #ifdef CONFIG_TIME_LOW_RES
 444                 tim = ktime_add(tim, base->resolution);
 445 #endif
 446         }
 447         timer->expires = tim;
 448
 449         enqueue_hrtimer(timer, new_base);
 450
 451         unlock_hrtimer_base(timer, &flags);
 452
 453         return ret;
 454 }
 455 EXPORT_SYMBOL_GPL(hrtimer_start);
 456
 457 /**
 458  * hrtimer_try_to_cancel - try to deactivate a timer
 459  * @timer:      hrtimer to stop
 460  *
 461  * Returns:
 462  *  0 when the timer was not active
 463  *  1 when the timer was active
 464  * -1 when the timer is currently excuting the callback function and
 465  *    cannot be stopped
 466  */
 467 int hrtimer_try_to_cancel(struct hrtimer *timer)
 468 {
 469         struct hrtimer_base *base;
 470         unsigned long flags;
 471         int ret = -1;
 472
 473         base = lock_hrtimer_base(timer, &flags);
 474
 475         if (base->curr_timer != timer)
 476                 ret = remove_hrtimer(timer, base);
 477
 478         unlock_hrtimer_base(timer, &flags);
 479
 480         return ret;
 481
 482 }
 483 EXPORT_SYMBOL_GPL(hrtimer_try_to_cancel);
 484
 485 /**
 486  * hrtimer_cancel - cancel a timer and wait for the handler to finish.
 487  * @timer:      the timer to be cancelled
 488  *
 489  * Returns:
 490  *  0 when the timer was not active
 491  *  1 when the timer was active
 492  */
 493 int hrtimer_cancel(struct hrtimer *timer)
 494 {
 495         for (;;) {
 496                 int ret = hrtimer_try_to_cancel(timer);
 497
 498                 if (ret >= 0)
 499                         return ret;
 500                 cpu_relax();
 501         }
 502 }
 503 EXPORT_SYMBOL_GPL(hrtimer_cancel);
 504
 505 /**
 506  * hrtimer_get_remaining - get remaining time for the timer
 507  * @timer:      the timer to read
 508  */
 509 ktime_t hrtimer_get_remaining(const struct hrtimer *timer)
 510 {
 511         struct hrtimer_base *base;
 512         unsigned long flags;
 513         ktime_t rem;
 514
 515         base = lock_hrtimer_base(timer, &flags);
 516         rem = ktime_sub(timer->expires, timer->base->get_time());
 517         unlock_hrtimer_base(timer, &flags);
 518
 519         return rem;
 520 }
 521 EXPORT_SYMBOL_GPL(hrtimer_get_remaining);
 522
 523 #ifdef CONFIG_NO_IDLE_HZ
 524 /**
 525  * hrtimer_get_next_event - get the time until next expiry event
 526  *
 527  * Returns the delta to the next expiry event or KTIME_MAX if no timer
 528  * is pending.
 529  */
 530 ktime_t hrtimer_get_next_event(void)
 531 {
 532         struct hrtimer_base *base = __get_cpu_var(hrtimer_bases);
 533         ktime_t delta, mindelta = { .tv64 = KTIME_MAX };
 534         unsigned long flags;
 535         int i;
 536
 537         for (i = 0; i < MAX_HRTIMER_BASES; i++, base++) {
 538                 struct hrtimer *timer;
 539
 540                 spin_lock_irqsave(&base->lock, flags);
 541                 if (!base->first) {
 542                         spin_unlock_irqrestore(&base->lock, flags);
 543                         continue;
 544                 }
 545                 timer = rb_entry(base->first, struct hrtimer, node);
 546                 delta.tv64 = timer->expires.tv64;
 547                 spin_unlock_irqrestore(&base->lock, flags);
 548                 delta = ktime_sub(delta, base->get_time());
 549                 if (delta.tv64 < mindelta.tv64)
 550                         mindelta.tv64 = delta.tv64;
 551         }
 552         if (mindelta.tv64 < 0)
 553                 mindelta.tv64 = 0;
 554         return mindelta;
 555 }
 556 #endif
 557
 558 /**
 559  * hrtimer_init - initialize a timer to the given clock
 560  * @timer:      the timer to be initialized
 561  * @clock_id:   the clock to be used
 562  * @mode:       timer mode abs/rel
 563  */
 564 void hrtimer_init(struct hrtimer *timer, clockid_t clock_id,
 565                   enum hrtimer_mode mode)
 566 {
 567         struct hrtimer_base *bases;
 568
 569         memset(timer, 0, sizeof(struct hrtimer));
 570
 571         bases = __raw_get_cpu_var(hrtimer_bases);
 572
 573         if (clock_id == CLOCK_REALTIME && mode != HRTIMER_ABS)
 574                 clock_id = CLOCK_MONOTONIC;
 575
 576         timer->base = &bases[clock_id];
 577         rb_set_parent(&timer->node, &timer->node);
 578 }
 579 EXPORT_SYMBOL_GPL(hrtimer_init);
 580
 581 /**
 582  * hrtimer_get_res - get the timer resolution for a clock
 583  * @which_clock: which clock to query
 584  * @tp:          pointer to timespec variable to store the resolution
 585  *
 586  * Store the resolution of the clock selected by which_clock in the
 587  * variable pointed to by tp.
 588  */
 589 int hrtimer_get_res(const clockid_t which_clock, struct timespec *tp)
 590 {
 591         struct hrtimer_base *bases;
 592
 593         bases = __raw_get_cpu_var(hrtimer_bases);
 594         *tp = ktime_to_timespec(bases[which_clock].resolution);
 595
 596         return 0;
 597 }
 598 EXPORT_SYMBOL_GPL(hrtimer_get_res);
 599
 600 /*
 601  * Expire the per base hrtimer-queue:
 602  */
 603 static inline void run_hrtimer_queue(struct hrtimer_base *base)
 604 {
 605         struct rb_node *node;
 606
 607         if (!base->first)
 608                 return;
 609
 610         if (base->get_softirq_time)
 611                 base->softirq_time = base->get_softirq_time();
 612
 613         spin_lock_irq(&base->lock);
 614
 615         while ((node = base->first)) {
 616                 struct hrtimer *timer;
 617                 int (*fn)(struct hrtimer *);
 618                 int restart;
 619
 620                 timer = rb_entry(node, struct hrtimer, node);
 621                 if (base->softirq_time.tv64 <= timer->expires.tv64)
 622                         break;
 623
 624                 fn = timer->function;
 625                 set_curr_timer(base, timer);
 626                 __remove_hrtimer(timer, base);
 627                 spin_unlock_irq(&base->lock);
 628
 629                 restart = fn(timer);
 630
 631                 spin_lock_irq(&base->lock);
 632
 633                 if (restart != HRTIMER_NORESTART) {
 634                         BUG_ON(hrtimer_active(timer));
 635                         enqueue_hrtimer(timer, base);
 636                 }
 637         }
 638         set_curr_timer(base, NULL);
 639         spin_unlock_irq(&base->lock);
 640 }
 641
 642 /*
 643  * Called from timer softirq every jiffy, expire hrtimers:
 644  */
 645 void hrtimer_run_queues(void)
 646 {
 647         struct hrtimer_base *base = __get_cpu_var(hrtimer_bases);
 648         int i;
 649
 650         hrtimer_get_softirq_time(base);
 651
 652         for (i = 0; i < MAX_HRTIMER_BASES; i++)
 653                 run_hrtimer_queue(&base[i]);
 654 }
 655
 656 /*
 657  * Sleep related functions:
 658  */
 659 static int hrtimer_wakeup(struct hrtimer *timer)
 660 {
 661         struct hrtimer_sleeper *t =
 662                 container_of(timer, struct hrtimer_sleeper, timer);
 663         struct task_struct *task = t->task;
 664
 665         t->task = NULL;
 666         if (task)
 667                 wake_up_process(task);
 668
 669         return HRTIMER_NORESTART;
 670 }
 671
 672 void hrtimer_init_sleeper(struct hrtimer_sleeper *sl, struct task_struct *task)
 673 {
 674         sl->timer.function = hrtimer_wakeup;
 675         sl->task = task;
 676 }
 677
 678 static int __sched do_nanosleep(struct hrtimer_sleeper *t, enum hrtimer_mode mode)
 679 {
 680         hrtimer_init_sleeper(t, current);
 681
 682         do {
 683                 set_current_state(TASK_INTERRUPTIBLE);
 684                 hrtimer_start(&t->timer, t->timer.expires, mode);
 685
 686                 schedule();
 687
 688                 hrtimer_cancel(&t->timer);
 689                 mode = HRTIMER_ABS;
 690
 691         } while (t->task && !signal_pending(current));
 692
 693         return t->task == NULL;
 694 }
 695
 696 long __sched hrtimer_nanosleep_restart(struct restart_block *restart)
 697 {
 698         struct hrtimer_sleeper t;
 699         struct timespec __user *rmtp;
 700         struct timespec tu;
 701         ktime_t time;
 702
 703         restart->fn = do_no_restart_syscall;
 704
 705         hrtimer_init(&t.timer, restart->arg0, HRTIMER_ABS);
 706         t.timer.expires.tv64 = ((u64)restart->arg3 << 32) | (u64) restart->arg2;
 707
 708         if (do_nanosleep(&t, HRTIMER_ABS))
 709                 return 0;
 710
 711         rmtp = (struct timespec __user *) restart->arg1;
 712         if (rmtp) {
 713                 time = ktime_sub(t.timer.expires, t.timer.base->get_time());
 714                 if (time.tv64 <= 0)
 715                         return 0;
 716                 tu = ktime_to_timespec(time);
 717                 if (copy_to_user(rmtp, &tu, sizeof(tu)))
 718                         return -EFAULT;
 719         }
 720
 721         restart->fn = hrtimer_nanosleep_restart;
 722
 723         /* The other values in restart are already filled in */
 724         return -ERESTART_RESTARTBLOCK;
 725 }
 726
 727 long hrtimer_nanosleep(struct timespec *rqtp, struct timespec __user *rmtp,
 728                        const enum hrtimer_mode mode, const clockid_t clockid)
 729 {
 730         struct restart_block *restart;
 731         struct hrtimer_sleeper t;
 732         struct timespec tu;
 733         ktime_t rem;
 734
 735         hrtimer_init(&t.timer, clockid, mode);
 736         t.timer.expires = timespec_to_ktime(*rqtp);
 737         if (do_nanosleep(&t, mode))
 738                 return 0;
 739
 740         /* Absolute timers do not update the rmtp value and restart: */
 741         if (mode == HRTIMER_ABS)
 742                 return -ERESTARTNOHAND;
 743
 744         if (rmtp) {
 745                 rem = ktime_sub(t.timer.expires, t.timer.base->get_time());
 746                 if (rem.tv64 <= 0)
 747                         return 0;
 748                 tu = ktime_to_timespec(rem);
 749                 if (copy_to_user(rmtp, &tu, sizeof(tu)))
 750                         return -EFAULT;
 751         }
 752
 753         restart = &current_thread_info()->restart_block;
 754         restart->fn = hrtimer_nanosleep_restart;
 755         restart->arg0 = (unsigned long) t.timer.base->index;
 756         restart->arg1 = (unsigned long) rmtp;
 757         restart->arg2 = t.timer.expires.tv64 & 0xFFFFFFFF;
 758         restart->arg3 = t.timer.expires.tv64 >> 32;
 759
 760         return -ERESTART_RESTARTBLOCK;
 761 }
 762
 763 asmlinkage long
 764 sys_nanosleep(struct timespec __user *rqtp, struct timespec __user *rmtp)
 765 {
 766         struct timespec tu;
 767
 768         if (copy_from_user(&tu, rqtp, sizeof(tu)))
 769                 return -EFAULT;
 770
 771         if (!timespec_valid(&tu))
 772                 return -EINVAL;
 773
 774         return hrtimer_nanosleep(&tu, rmtp, HRTIMER_REL, CLOCK_MONOTONIC);
 775 }
 776
 777 /*
 778  * Functions related to boot-time initialization:
 779  */
 780 static void __devinit init_hrtimers_cpu(int cpu)
 781 {
 782         struct hrtimer_base *base = per_cpu(hrtimer_bases, cpu);
 783         int i;
 784
 785         for (i = 0; i < MAX_HRTIMER_BASES; i++, base++) {
 786                 spin_lock_init(&base->lock);
 787                 lockdep_set_class(&base->lock, &base->lock_key);
 788         }
 789 }
 790
 791 #ifdef CONFIG_HOTPLUG_CPU
 792
 793 static void migrate_hrtimer_list(struct hrtimer_base *old_base,
 794                                 struct hrtimer_base *new_base)
 795 {
 796         struct hrtimer *timer;
 797         struct rb_node *node;
 798
 799         while ((node = rb_first(&old_base->active))) {
 800                 timer = rb_entry(node, struct hrtimer, node);
 801                 __remove_hrtimer(timer, old_base);
 802                 timer->base = new_base;
 803                 enqueue_hrtimer(timer, new_base);
 804         }
 805 }
 806
 807 static void migrate_hrtimers(int cpu)
 808 {
 809         struct hrtimer_base *old_base, *new_base;
 810         int i;
 811
 812         BUG_ON(cpu_online(cpu));
 813         old_base = per_cpu(hrtimer_bases, cpu);
 814         new_base = get_cpu_var(hrtimer_bases);
 815
 816         local_irq_disable();
 817
 818         for (i = 0; i < MAX_HRTIMER_BASES; i++) {
 819
 820                 spin_lock(&new_base->lock);
 821                 spin_lock(&old_base->lock);
 822
 823                 BUG_ON(old_base->curr_timer);
 824
 825                 migrate_hrtimer_list(old_base, new_base);
 826
 827                 spin_unlock(&old_base->lock);
 828                 spin_unlock(&new_base->lock);
 829                 old_base++;
 830                 new_base++;
 831         }
 832
 833         local_irq_enable();
 834         put_cpu_var(hrtimer_bases);
 835 }
 836 #endif /* CONFIG_HOTPLUG_CPU */
 837
 838 static int __cpuinit hrtimer_cpu_notify(struct notifier_block *self,
 839                                         unsigned long action, void *hcpu)
 840 {
 841         long cpu = (long)hcpu;
 842
 843         switch (action) {
 844
 845         case CPU_UP_PREPARE:
 846                 init_hrtimers_cpu(cpu);
 847                 break;
 848
 849 #ifdef CONFIG_HOTPLUG_CPU
 850         case CPU_DEAD:
 851                 migrate_hrtimers(cpu);
 852                 break;
 853 #endif
 854
 855         default:
 856                 break;
 857         }
 858
 859         return NOTIFY_OK;
 860 }
 861
 862 static struct notifier_block __cpuinitdata hrtimers_nb = {
 863         .notifier_call = hrtimer_cpu_notify,
 864 };
 865
 866 void __init hrtimers_init(void)
 867 {
 868         hrtimer_cpu_notify(&hrtimers_nb, (unsigned long)CPU_UP_PREPARE,
 869                           (void *)(long)smp_processor_id());
 870         register_cpu_notifier(&hrtimers_nb);
 871 }
 872