linux/kernel/posix-cpu-timers.c
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   1/*
   2 * Implement CPU time clocks for the POSIX clock interface.
   3 */
   4
   5#include <linux/sched.h>
   6#include <linux/posix-timers.h>
   7#include <linux/errno.h>
   8#include <linux/math64.h>
   9#include <asm/uaccess.h>
  10#include <linux/kernel_stat.h>
  11#include <trace/events/timer.h>
  12#include <linux/random.h>
  13#include <linux/tick.h>
  14#include <linux/workqueue.h>
  15
  16/*
  17 * Called after updating RLIMIT_CPU to run cpu timer and update
  18 * tsk->signal->cputime_expires expiration cache if necessary. Needs
  19 * siglock protection since other code may update expiration cache as
  20 * well.
  21 */
  22void update_rlimit_cpu(struct task_struct *task, unsigned long rlim_new)
  23{
  24        cputime_t cputime = secs_to_cputime(rlim_new);
  25
  26        spin_lock_irq(&task->sighand->siglock);
  27        set_process_cpu_timer(task, CPUCLOCK_PROF, &cputime, NULL);
  28        spin_unlock_irq(&task->sighand->siglock);
  29}
  30
  31static int check_clock(const clockid_t which_clock)
  32{
  33        int error = 0;
  34        struct task_struct *p;
  35        const pid_t pid = CPUCLOCK_PID(which_clock);
  36
  37        if (CPUCLOCK_WHICH(which_clock) >= CPUCLOCK_MAX)
  38                return -EINVAL;
  39
  40        if (pid == 0)
  41                return 0;
  42
  43        rcu_read_lock();
  44        p = find_task_by_vpid(pid);
  45        if (!p || !(CPUCLOCK_PERTHREAD(which_clock) ?
  46                   same_thread_group(p, current) : has_group_leader_pid(p))) {
  47                error = -EINVAL;
  48        }
  49        rcu_read_unlock();
  50
  51        return error;
  52}
  53
  54static inline unsigned long long
  55timespec_to_sample(const clockid_t which_clock, const struct timespec *tp)
  56{
  57        unsigned long long ret;
  58
  59        ret = 0;                /* high half always zero when .cpu used */
  60        if (CPUCLOCK_WHICH(which_clock) == CPUCLOCK_SCHED) {
  61                ret = (unsigned long long)tp->tv_sec * NSEC_PER_SEC + tp->tv_nsec;
  62        } else {
  63                ret = cputime_to_expires(timespec_to_cputime(tp));
  64        }
  65        return ret;
  66}
  67
  68static void sample_to_timespec(const clockid_t which_clock,
  69                               unsigned long long expires,
  70                               struct timespec *tp)
  71{
  72        if (CPUCLOCK_WHICH(which_clock) == CPUCLOCK_SCHED)
  73                *tp = ns_to_timespec(expires);
  74        else
  75                cputime_to_timespec((__force cputime_t)expires, tp);
  76}
  77
  78/*
  79 * Update expiry time from increment, and increase overrun count,
  80 * given the current clock sample.
  81 */
  82static void bump_cpu_timer(struct k_itimer *timer,
  83                           unsigned long long now)
  84{
  85        int i;
  86        unsigned long long delta, incr;
  87
  88        if (timer->it.cpu.incr == 0)
  89                return;
  90
  91        if (now < timer->it.cpu.expires)
  92                return;
  93
  94        incr = timer->it.cpu.incr;
  95        delta = now + incr - timer->it.cpu.expires;
  96
  97        /* Don't use (incr*2 < delta), incr*2 might overflow. */
  98        for (i = 0; incr < delta - incr; i++)
  99                incr = incr << 1;
 100
 101        for (; i >= 0; incr >>= 1, i--) {
 102                if (delta < incr)
 103                        continue;
 104
 105                timer->it.cpu.expires += incr;
 106                timer->it_overrun += 1 << i;
 107                delta -= incr;
 108        }
 109}
 110
 111/**
 112 * task_cputime_zero - Check a task_cputime struct for all zero fields.
 113 *
 114 * @cputime:    The struct to compare.
 115 *
 116 * Checks @cputime to see if all fields are zero.  Returns true if all fields
 117 * are zero, false if any field is nonzero.
 118 */
 119static inline int task_cputime_zero(const struct task_cputime *cputime)
 120{
 121        if (!cputime->utime && !cputime->stime && !cputime->sum_exec_runtime)
 122                return 1;
 123        return 0;
 124}
 125
 126static inline unsigned long long prof_ticks(struct task_struct *p)
 127{
 128        cputime_t utime, stime;
 129
 130        task_cputime(p, &utime, &stime);
 131
 132        return cputime_to_expires(utime + stime);
 133}
 134static inline unsigned long long virt_ticks(struct task_struct *p)
 135{
 136        cputime_t utime;
 137
 138        task_cputime(p, &utime, NULL);
 139
 140        return cputime_to_expires(utime);
 141}
 142
 143static int
 144posix_cpu_clock_getres(const clockid_t which_clock, struct timespec *tp)
 145{
 146        int error = check_clock(which_clock);
 147        if (!error) {
 148                tp->tv_sec = 0;
 149                tp->tv_nsec = ((NSEC_PER_SEC + HZ - 1) / HZ);
 150                if (CPUCLOCK_WHICH(which_clock) == CPUCLOCK_SCHED) {
 151                        /*
 152                         * If sched_clock is using a cycle counter, we
 153                         * don't have any idea of its true resolution
 154                         * exported, but it is much more than 1s/HZ.
 155                         */
 156                        tp->tv_nsec = 1;
 157                }
 158        }
 159        return error;
 160}
 161
 162static int
 163posix_cpu_clock_set(const clockid_t which_clock, const struct timespec *tp)
 164{
 165        /*
 166         * You can never reset a CPU clock, but we check for other errors
 167         * in the call before failing with EPERM.
 168         */
 169        int error = check_clock(which_clock);
 170        if (error == 0) {
 171                error = -EPERM;
 172        }
 173        return error;
 174}
 175
 176
 177/*
 178 * Sample a per-thread clock for the given task.
 179 */
 180static int cpu_clock_sample(const clockid_t which_clock, struct task_struct *p,
 181                            unsigned long long *sample)
 182{
 183        switch (CPUCLOCK_WHICH(which_clock)) {
 184        default:
 185                return -EINVAL;
 186        case CPUCLOCK_PROF:
 187                *sample = prof_ticks(p);
 188                break;
 189        case CPUCLOCK_VIRT:
 190                *sample = virt_ticks(p);
 191                break;
 192        case CPUCLOCK_SCHED:
 193                *sample = task_sched_runtime(p);
 194                break;
 195        }
 196        return 0;
 197}
 198
 199static void update_gt_cputime(struct task_cputime *a, struct task_cputime *b)
 200{
 201        if (b->utime > a->utime)
 202                a->utime = b->utime;
 203
 204        if (b->stime > a->stime)
 205                a->stime = b->stime;
 206
 207        if (b->sum_exec_runtime > a->sum_exec_runtime)
 208                a->sum_exec_runtime = b->sum_exec_runtime;
 209}
 210
 211void thread_group_cputimer(struct task_struct *tsk, struct task_cputime *times)
 212{
 213        struct thread_group_cputimer *cputimer = &tsk->signal->cputimer;
 214        struct task_cputime sum;
 215        unsigned long flags;
 216
 217        if (!cputimer->running) {
 218                /*
 219                 * The POSIX timer interface allows for absolute time expiry
 220                 * values through the TIMER_ABSTIME flag, therefore we have
 221                 * to synchronize the timer to the clock every time we start
 222                 * it.
 223                 */
 224                thread_group_cputime(tsk, &sum);
 225                raw_spin_lock_irqsave(&cputimer->lock, flags);
 226                cputimer->running = 1;
 227                update_gt_cputime(&cputimer->cputime, &sum);
 228        } else
 229                raw_spin_lock_irqsave(&cputimer->lock, flags);
 230        *times = cputimer->cputime;
 231        raw_spin_unlock_irqrestore(&cputimer->lock, flags);
 232}
 233
 234/*
 235 * Sample a process (thread group) clock for the given group_leader task.
 236 * Must be called with tasklist_lock held for reading.
 237 */
 238static int cpu_clock_sample_group(const clockid_t which_clock,
 239                                  struct task_struct *p,
 240                                  unsigned long long *sample)
 241{
 242        struct task_cputime cputime;
 243
 244        switch (CPUCLOCK_WHICH(which_clock)) {
 245        default:
 246                return -EINVAL;
 247        case CPUCLOCK_PROF:
 248                thread_group_cputime(p, &cputime);
 249                *sample = cputime_to_expires(cputime.utime + cputime.stime);
 250                break;
 251        case CPUCLOCK_VIRT:
 252                thread_group_cputime(p, &cputime);
 253                *sample = cputime_to_expires(cputime.utime);
 254                break;
 255        case CPUCLOCK_SCHED:
 256                thread_group_cputime(p, &cputime);
 257                *sample = cputime.sum_exec_runtime;
 258                break;
 259        }
 260        return 0;
 261}
 262
 263
 264static int posix_cpu_clock_get(const clockid_t which_clock, struct timespec *tp)
 265{
 266        const pid_t pid = CPUCLOCK_PID(which_clock);
 267        int error = -EINVAL;
 268        unsigned long long rtn;
 269
 270        if (pid == 0) {
 271                /*
 272                 * Special case constant value for our own clocks.
 273                 * We don't have to do any lookup to find ourselves.
 274                 */
 275                if (CPUCLOCK_PERTHREAD(which_clock)) {
 276                        /*
 277                         * Sampling just ourselves we can do with no locking.
 278                         */
 279                        error = cpu_clock_sample(which_clock,
 280                                                 current, &rtn);
 281                } else {
 282                        read_lock(&tasklist_lock);
 283                        error = cpu_clock_sample_group(which_clock,
 284                                                       current, &rtn);
 285                        read_unlock(&tasklist_lock);
 286                }
 287        } else {
 288                /*
 289                 * Find the given PID, and validate that the caller
 290                 * should be able to see it.
 291                 */
 292                struct task_struct *p;
 293                rcu_read_lock();
 294                p = find_task_by_vpid(pid);
 295                if (p) {
 296                        if (CPUCLOCK_PERTHREAD(which_clock)) {
 297                                if (same_thread_group(p, current)) {
 298                                        error = cpu_clock_sample(which_clock,
 299                                                                 p, &rtn);
 300                                }
 301                        } else {
 302                                read_lock(&tasklist_lock);
 303                                if (thread_group_leader(p) && p->sighand) {
 304                                        error =
 305                                            cpu_clock_sample_group(which_clock,
 306                                                                   p, &rtn);
 307                                }
 308                                read_unlock(&tasklist_lock);
 309                        }
 310                }
 311                rcu_read_unlock();
 312        }
 313
 314        if (error)
 315                return error;
 316        sample_to_timespec(which_clock, rtn, tp);
 317        return 0;
 318}
 319
 320
 321/*
 322 * Validate the clockid_t for a new CPU-clock timer, and initialize the timer.
 323 * This is called from sys_timer_create() and do_cpu_nanosleep() with the
 324 * new timer already all-zeros initialized.
 325 */
 326static int posix_cpu_timer_create(struct k_itimer *new_timer)
 327{
 328        int ret = 0;
 329        const pid_t pid = CPUCLOCK_PID(new_timer->it_clock);
 330        struct task_struct *p;
 331
 332        if (CPUCLOCK_WHICH(new_timer->it_clock) >= CPUCLOCK_MAX)
 333                return -EINVAL;
 334
 335        INIT_LIST_HEAD(&new_timer->it.cpu.entry);
 336
 337        rcu_read_lock();
 338        if (CPUCLOCK_PERTHREAD(new_timer->it_clock)) {
 339                if (pid == 0) {
 340                        p = current;
 341                } else {
 342                        p = find_task_by_vpid(pid);
 343                        if (p && !same_thread_group(p, current))
 344                                p = NULL;
 345                }
 346        } else {
 347                if (pid == 0) {
 348                        p = current->group_leader;
 349                } else {
 350                        p = find_task_by_vpid(pid);
 351                        if (p && !has_group_leader_pid(p))
 352                                p = NULL;
 353                }
 354        }
 355        new_timer->it.cpu.task = p;
 356        if (p) {
 357                get_task_struct(p);
 358        } else {
 359                ret = -EINVAL;
 360        }
 361        rcu_read_unlock();
 362
 363        return ret;
 364}
 365
 366/*
 367 * Clean up a CPU-clock timer that is about to be destroyed.
 368 * This is called from timer deletion with the timer already locked.
 369 * If we return TIMER_RETRY, it's necessary to release the timer's lock
 370 * and try again.  (This happens when the timer is in the middle of firing.)
 371 */
 372static int posix_cpu_timer_del(struct k_itimer *timer)
 373{
 374        struct task_struct *p = timer->it.cpu.task;
 375        int ret = 0;
 376
 377        if (likely(p != NULL)) {
 378                read_lock(&tasklist_lock);
 379                if (unlikely(p->sighand == NULL)) {
 380                        /*
 381                         * We raced with the reaping of the task.
 382                         * The deletion should have cleared us off the list.
 383                         */
 384                        BUG_ON(!list_empty(&timer->it.cpu.entry));
 385                } else {
 386                        spin_lock(&p->sighand->siglock);
 387                        if (timer->it.cpu.firing)
 388                                ret = TIMER_RETRY;
 389                        else
 390                                list_del(&timer->it.cpu.entry);
 391                        spin_unlock(&p->sighand->siglock);
 392                }
 393                read_unlock(&tasklist_lock);
 394
 395                if (!ret)
 396                        put_task_struct(p);
 397        }
 398
 399        return ret;
 400}
 401
 402static void cleanup_timers_list(struct list_head *head,
 403                                unsigned long long curr)
 404{
 405        struct cpu_timer_list *timer, *next;
 406
 407        list_for_each_entry_safe(timer, next, head, entry)
 408                list_del_init(&timer->entry);
 409}
 410
 411/*
 412 * Clean out CPU timers still ticking when a thread exited.  The task
 413 * pointer is cleared, and the expiry time is replaced with the residual
 414 * time for later timer_gettime calls to return.
 415 * This must be called with the siglock held.
 416 */
 417static void cleanup_timers(struct list_head *head,
 418                           cputime_t utime, cputime_t stime,
 419                           unsigned long long sum_exec_runtime)
 420{
 421
 422        cputime_t ptime = utime + stime;
 423
 424        cleanup_timers_list(head, cputime_to_expires(ptime));
 425        cleanup_timers_list(++head, cputime_to_expires(utime));
 426        cleanup_timers_list(++head, sum_exec_runtime);
 427}
 428
 429/*
 430 * These are both called with the siglock held, when the current thread
 431 * is being reaped.  When the final (leader) thread in the group is reaped,
 432 * posix_cpu_timers_exit_group will be called after posix_cpu_timers_exit.
 433 */
 434void posix_cpu_timers_exit(struct task_struct *tsk)
 435{
 436        cputime_t utime, stime;
 437
 438        add_device_randomness((const void*) &tsk->se.sum_exec_runtime,
 439                                                sizeof(unsigned long long));
 440        task_cputime(tsk, &utime, &stime);
 441        cleanup_timers(tsk->cpu_timers,
 442                       utime, stime, tsk->se.sum_exec_runtime);
 443
 444}
 445void posix_cpu_timers_exit_group(struct task_struct *tsk)
 446{
 447        struct signal_struct *const sig = tsk->signal;
 448        cputime_t utime, stime;
 449
 450        task_cputime(tsk, &utime, &stime);
 451        cleanup_timers(tsk->signal->cpu_timers,
 452                       utime + sig->utime, stime + sig->stime,
 453                       tsk->se.sum_exec_runtime + sig->sum_sched_runtime);
 454}
 455
 456static void clear_dead_task(struct k_itimer *itimer, unsigned long long now)
 457{
 458        struct cpu_timer_list *timer = &itimer->it.cpu;
 459
 460        /*
 461         * That's all for this thread or process.
 462         * We leave our residual in expires to be reported.
 463         */
 464        put_task_struct(timer->task);
 465        timer->task = NULL;
 466        if (timer->expires < now) {
 467                timer->expires = 0;
 468        } else {
 469                timer->expires -= now;
 470        }
 471}
 472
 473static inline int expires_gt(cputime_t expires, cputime_t new_exp)
 474{
 475        return expires == 0 || expires > new_exp;
 476}
 477
 478/*
 479 * Insert the timer on the appropriate list before any timers that
 480 * expire later.  This must be called with the tasklist_lock held
 481 * for reading, interrupts disabled and p->sighand->siglock taken.
 482 */
 483static void arm_timer(struct k_itimer *timer)
 484{
 485        struct task_struct *p = timer->it.cpu.task;
 486        struct list_head *head, *listpos;
 487        struct task_cputime *cputime_expires;
 488        struct cpu_timer_list *const nt = &timer->it.cpu;
 489        struct cpu_timer_list *next;
 490
 491        if (CPUCLOCK_PERTHREAD(timer->it_clock)) {
 492                head = p->cpu_timers;
 493                cputime_expires = &p->cputime_expires;
 494        } else {
 495                head = p->signal->cpu_timers;
 496                cputime_expires = &p->signal->cputime_expires;
 497        }
 498        head += CPUCLOCK_WHICH(timer->it_clock);
 499
 500        listpos = head;
 501        list_for_each_entry(next, head, entry) {
 502                if (nt->expires < next->expires)
 503                        break;
 504                listpos = &next->entry;
 505        }
 506        list_add(&nt->entry, listpos);
 507
 508        if (listpos == head) {
 509                unsigned long long exp = nt->expires;
 510
 511                /*
 512                 * We are the new earliest-expiring POSIX 1.b timer, hence
 513                 * need to update expiration cache. Take into account that
 514                 * for process timers we share expiration cache with itimers
 515                 * and RLIMIT_CPU and for thread timers with RLIMIT_RTTIME.
 516                 */
 517
 518                switch (CPUCLOCK_WHICH(timer->it_clock)) {
 519                case CPUCLOCK_PROF:
 520                        if (expires_gt(cputime_expires->prof_exp, expires_to_cputime(exp)))
 521                                cputime_expires->prof_exp = expires_to_cputime(exp);
 522                        break;
 523                case CPUCLOCK_VIRT:
 524                        if (expires_gt(cputime_expires->virt_exp, expires_to_cputime(exp)))
 525                                cputime_expires->virt_exp = expires_to_cputime(exp);
 526                        break;
 527                case CPUCLOCK_SCHED:
 528                        if (cputime_expires->sched_exp == 0 ||
 529                            cputime_expires->sched_exp > exp)
 530                                cputime_expires->sched_exp = exp;
 531                        break;
 532                }
 533        }
 534}
 535
 536/*
 537 * The timer is locked, fire it and arrange for its reload.
 538 */
 539static void cpu_timer_fire(struct k_itimer *timer)
 540{
 541        if ((timer->it_sigev_notify & ~SIGEV_THREAD_ID) == SIGEV_NONE) {
 542                /*
 543                 * User don't want any signal.
 544                 */
 545                timer->it.cpu.expires = 0;
 546        } else if (unlikely(timer->sigq == NULL)) {
 547                /*
 548                 * This a special case for clock_nanosleep,
 549                 * not a normal timer from sys_timer_create.
 550                 */
 551                wake_up_process(timer->it_process);
 552                timer->it.cpu.expires = 0;
 553        } else if (timer->it.cpu.incr == 0) {
 554                /*
 555                 * One-shot timer.  Clear it as soon as it's fired.
 556                 */
 557                posix_timer_event(timer, 0);
 558                timer->it.cpu.expires = 0;
 559        } else if (posix_timer_event(timer, ++timer->it_requeue_pending)) {
 560                /*
 561                 * The signal did not get queued because the signal
 562                 * was ignored, so we won't get any callback to
 563                 * reload the timer.  But we need to keep it
 564                 * ticking in case the signal is deliverable next time.
 565                 */
 566                posix_cpu_timer_schedule(timer);
 567        }
 568}
 569
 570/*
 571 * Sample a process (thread group) timer for the given group_leader task.
 572 * Must be called with tasklist_lock held for reading.
 573 */
 574static int cpu_timer_sample_group(const clockid_t which_clock,
 575                                  struct task_struct *p,
 576                                  unsigned long long *sample)
 577{
 578        struct task_cputime cputime;
 579
 580        thread_group_cputimer(p, &cputime);
 581        switch (CPUCLOCK_WHICH(which_clock)) {
 582        default:
 583                return -EINVAL;
 584        case CPUCLOCK_PROF:
 585                *sample = cputime_to_expires(cputime.utime + cputime.stime);
 586                break;
 587        case CPUCLOCK_VIRT:
 588                *sample = cputime_to_expires(cputime.utime);
 589                break;
 590        case CPUCLOCK_SCHED:
 591                *sample = cputime.sum_exec_runtime + task_delta_exec(p);
 592                break;
 593        }
 594        return 0;
 595}
 596
 597#ifdef CONFIG_NO_HZ_FULL
 598static void nohz_kick_work_fn(struct work_struct *work)
 599{
 600        tick_nohz_full_kick_all();
 601}
 602
 603static DECLARE_WORK(nohz_kick_work, nohz_kick_work_fn);
 604
 605/*
 606 * We need the IPIs to be sent from sane process context.
 607 * The posix cpu timers are always set with irqs disabled.
 608 */
 609static void posix_cpu_timer_kick_nohz(void)
 610{
 611        schedule_work(&nohz_kick_work);
 612}
 613
 614bool posix_cpu_timers_can_stop_tick(struct task_struct *tsk)
 615{
 616        if (!task_cputime_zero(&tsk->cputime_expires))
 617                return false;
 618
 619        if (tsk->signal->cputimer.running)
 620                return false;
 621
 622        return true;
 623}
 624#else
 625static inline void posix_cpu_timer_kick_nohz(void) { }
 626#endif
 627
 628/*
 629 * Guts of sys_timer_settime for CPU timers.
 630 * This is called with the timer locked and interrupts disabled.
 631 * If we return TIMER_RETRY, it's necessary to release the timer's lock
 632 * and try again.  (This happens when the timer is in the middle of firing.)
 633 */
 634static int posix_cpu_timer_set(struct k_itimer *timer, int flags,
 635                               struct itimerspec *new, struct itimerspec *old)
 636{
 637        struct task_struct *p = timer->it.cpu.task;
 638        unsigned long long old_expires, new_expires, old_incr, val;
 639        int ret;
 640
 641        if (unlikely(p == NULL)) {
 642                /*
 643                 * Timer refers to a dead task's clock.
 644                 */
 645                return -ESRCH;
 646        }
 647
 648        new_expires = timespec_to_sample(timer->it_clock, &new->it_value);
 649
 650        read_lock(&tasklist_lock);
 651        /*
 652         * We need the tasklist_lock to protect against reaping that
 653         * clears p->sighand.  If p has just been reaped, we can no
 654         * longer get any information about it at all.
 655         */
 656        if (unlikely(p->sighand == NULL)) {
 657                read_unlock(&tasklist_lock);
 658                put_task_struct(p);
 659                timer->it.cpu.task = NULL;
 660                return -ESRCH;
 661        }
 662
 663        /*
 664         * Disarm any old timer after extracting its expiry time.
 665         */
 666        BUG_ON(!irqs_disabled());
 667
 668        ret = 0;
 669        old_incr = timer->it.cpu.incr;
 670        spin_lock(&p->sighand->siglock);
 671        old_expires = timer->it.cpu.expires;
 672        if (unlikely(timer->it.cpu.firing)) {
 673                timer->it.cpu.firing = -1;
 674                ret = TIMER_RETRY;
 675        } else
 676                list_del_init(&timer->it.cpu.entry);
 677
 678        /*
 679         * We need to sample the current value to convert the new
 680         * value from to relative and absolute, and to convert the
 681         * old value from absolute to relative.  To set a process
 682         * timer, we need a sample to balance the thread expiry
 683         * times (in arm_timer).  With an absolute time, we must
 684         * check if it's already passed.  In short, we need a sample.
 685         */
 686        if (CPUCLOCK_PERTHREAD(timer->it_clock)) {
 687                cpu_clock_sample(timer->it_clock, p, &val);
 688        } else {
 689                cpu_timer_sample_group(timer->it_clock, p, &val);
 690        }
 691
 692        if (old) {
 693                if (old_expires == 0) {
 694                        old->it_value.tv_sec = 0;
 695                        old->it_value.tv_nsec = 0;
 696                } else {
 697                        /*
 698                         * Update the timer in case it has
 699                         * overrun already.  If it has,
 700                         * we'll report it as having overrun
 701                         * and with the next reloaded timer
 702                         * already ticking, though we are
 703                         * swallowing that pending
 704                         * notification here to install the
 705                         * new setting.
 706                         */
 707                        bump_cpu_timer(timer, val);
 708                        if (val < timer->it.cpu.expires) {
 709                                old_expires = timer->it.cpu.expires - val;
 710                                sample_to_timespec(timer->it_clock,
 711                                                   old_expires,
 712                                                   &old->it_value);
 713                        } else {
 714                                old->it_value.tv_nsec = 1;
 715                                old->it_value.tv_sec = 0;
 716                        }
 717                }
 718        }
 719
 720        if (unlikely(ret)) {
 721                /*
 722                 * We are colliding with the timer actually firing.
 723                 * Punt after filling in the timer's old value, and
 724                 * disable this firing since we are already reporting
 725                 * it as an overrun (thanks to bump_cpu_timer above).
 726                 */
 727                spin_unlock(&p->sighand->siglock);
 728                read_unlock(&tasklist_lock);
 729                goto out;
 730        }
 731
 732        if (new_expires != 0 && !(flags & TIMER_ABSTIME)) {
 733                new_expires += val;
 734        }
 735
 736        /*
 737         * Install the new expiry time (or zero).
 738         * For a timer with no notification action, we don't actually
 739         * arm the timer (we'll just fake it for timer_gettime).
 740         */
 741        timer->it.cpu.expires = new_expires;
 742        if (new_expires != 0 && val < new_expires) {
 743                arm_timer(timer);
 744        }
 745
 746        spin_unlock(&p->sighand->siglock);
 747        read_unlock(&tasklist_lock);
 748
 749        /*
 750         * Install the new reload setting, and
 751         * set up the signal and overrun bookkeeping.
 752         */
 753        timer->it.cpu.incr = timespec_to_sample(timer->it_clock,
 754                                                &new->it_interval);
 755
 756        /*
 757         * This acts as a modification timestamp for the timer,
 758         * so any automatic reload attempt will punt on seeing
 759         * that we have reset the timer manually.
 760         */
 761        timer->it_requeue_pending = (timer->it_requeue_pending + 2) &
 762                ~REQUEUE_PENDING;
 763        timer->it_overrun_last = 0;
 764        timer->it_overrun = -1;
 765
 766        if (new_expires != 0 && !(val < new_expires)) {
 767                /*
 768                 * The designated time already passed, so we notify
 769                 * immediately, even if the thread never runs to
 770                 * accumulate more time on this clock.
 771                 */
 772                cpu_timer_fire(timer);
 773        }
 774
 775        ret = 0;
 776 out:
 777        if (old) {
 778                sample_to_timespec(timer->it_clock,
 779                                   old_incr, &old->it_interval);
 780        }
 781        if (!ret)
 782                posix_cpu_timer_kick_nohz();
 783        return ret;
 784}
 785
 786static void posix_cpu_timer_get(struct k_itimer *timer, struct itimerspec *itp)
 787{
 788        unsigned long long now;
 789        struct task_struct *p = timer->it.cpu.task;
 790        int clear_dead;
 791
 792        /*
 793         * Easy part: convert the reload time.
 794         */
 795        sample_to_timespec(timer->it_clock,
 796                           timer->it.cpu.incr, &itp->it_interval);
 797
 798        if (timer->it.cpu.expires == 0) {       /* Timer not armed at all.  */
 799                itp->it_value.tv_sec = itp->it_value.tv_nsec = 0;
 800                return;
 801        }
 802
 803        if (unlikely(p == NULL)) {
 804                /*
 805                 * This task already died and the timer will never fire.
 806                 * In this case, expires is actually the dead value.
 807                 */
 808        dead:
 809                sample_to_timespec(timer->it_clock, timer->it.cpu.expires,
 810                                   &itp->it_value);
 811                return;
 812        }
 813
 814        /*
 815         * Sample the clock to take the difference with the expiry time.
 816         */
 817        if (CPUCLOCK_PERTHREAD(timer->it_clock)) {
 818                cpu_clock_sample(timer->it_clock, p, &now);
 819                clear_dead = p->exit_state;
 820        } else {
 821                read_lock(&tasklist_lock);
 822                if (unlikely(p->sighand == NULL)) {
 823                        /*
 824                         * The process has been reaped.
 825                         * We can't even collect a sample any more.
 826                         * Call the timer disarmed, nothing else to do.
 827                         */
 828                        put_task_struct(p);
 829                        timer->it.cpu.task = NULL;
 830                        timer->it.cpu.expires = 0;
 831                        read_unlock(&tasklist_lock);
 832                        goto dead;
 833                } else {
 834                        cpu_timer_sample_group(timer->it_clock, p, &now);
 835                        clear_dead = (unlikely(p->exit_state) &&
 836                                      thread_group_empty(p));
 837                }
 838                read_unlock(&tasklist_lock);
 839        }
 840
 841        if (unlikely(clear_dead)) {
 842                /*
 843                 * We've noticed that the thread is dead, but
 844                 * not yet reaped.  Take this opportunity to
 845                 * drop our task ref.
 846                 */
 847                clear_dead_task(timer, now);
 848                goto dead;
 849        }
 850
 851        if (now < timer->it.cpu.expires) {
 852                sample_to_timespec(timer->it_clock,
 853                                   timer->it.cpu.expires - now,
 854                                   &itp->it_value);
 855        } else {
 856                /*
 857                 * The timer should have expired already, but the firing
 858                 * hasn't taken place yet.  Say it's just about to expire.
 859                 */
 860                itp->it_value.tv_nsec = 1;
 861                itp->it_value.tv_sec = 0;
 862        }
 863}
 864
 865static unsigned long long
 866check_timers_list(struct list_head *timers,
 867                  struct list_head *firing,
 868                  unsigned long long curr)
 869{
 870        int maxfire = 20;
 871
 872        while (!list_empty(timers)) {
 873                struct cpu_timer_list *t;
 874
 875                t = list_first_entry(timers, struct cpu_timer_list, entry);
 876
 877                if (!--maxfire || curr < t->expires)
 878                        return t->expires;
 879
 880                t->firing = 1;
 881                list_move_tail(&t->entry, firing);
 882        }
 883
 884        return 0;
 885}
 886
 887/*
 888 * Check for any per-thread CPU timers that have fired and move them off
 889 * the tsk->cpu_timers[N] list onto the firing list.  Here we update the
 890 * tsk->it_*_expires values to reflect the remaining thread CPU timers.
 891 */
 892static void check_thread_timers(struct task_struct *tsk,
 893                                struct list_head *firing)
 894{
 895        struct list_head *timers = tsk->cpu_timers;
 896        struct signal_struct *const sig = tsk->signal;
 897        struct task_cputime *tsk_expires = &tsk->cputime_expires;
 898        unsigned long long expires;
 899        unsigned long soft;
 900
 901        expires = check_timers_list(timers, firing, prof_ticks(tsk));
 902        tsk_expires->prof_exp = expires_to_cputime(expires);
 903
 904        expires = check_timers_list(++timers, firing, virt_ticks(tsk));
 905        tsk_expires->virt_exp = expires_to_cputime(expires);
 906
 907        tsk_expires->sched_exp = check_timers_list(++timers, firing,
 908                                                   tsk->se.sum_exec_runtime);
 909
 910        /*
 911         * Check for the special case thread timers.
 912         */
 913        soft = ACCESS_ONCE(sig->rlim[RLIMIT_RTTIME].rlim_cur);
 914        if (soft != RLIM_INFINITY) {
 915                unsigned long hard =
 916                        ACCESS_ONCE(sig->rlim[RLIMIT_RTTIME].rlim_max);
 917
 918                if (hard != RLIM_INFINITY &&
 919                    tsk->rt.timeout > DIV_ROUND_UP(hard, USEC_PER_SEC/HZ)) {
 920                        /*
 921                         * At the hard limit, we just die.
 922                         * No need to calculate anything else now.
 923                         */
 924                        __group_send_sig_info(SIGKILL, SEND_SIG_PRIV, tsk);
 925                        return;
 926                }
 927                if (tsk->rt.timeout > DIV_ROUND_UP(soft, USEC_PER_SEC/HZ)) {
 928                        /*
 929                         * At the soft limit, send a SIGXCPU every second.
 930                         */
 931                        if (soft < hard) {
 932                                soft += USEC_PER_SEC;
 933                                sig->rlim[RLIMIT_RTTIME].rlim_cur = soft;
 934                        }
 935                        printk(KERN_INFO
 936                                "RT Watchdog Timeout: %s[%d]\n",
 937                                tsk->comm, task_pid_nr(tsk));
 938                        __group_send_sig_info(SIGXCPU, SEND_SIG_PRIV, tsk);
 939                }
 940        }
 941}
 942
 943static void stop_process_timers(struct signal_struct *sig)
 944{
 945        struct thread_group_cputimer *cputimer = &sig->cputimer;
 946        unsigned long flags;
 947
 948        raw_spin_lock_irqsave(&cputimer->lock, flags);
 949        cputimer->running = 0;
 950        raw_spin_unlock_irqrestore(&cputimer->lock, flags);
 951}
 952
 953static u32 onecputick;
 954
 955static void check_cpu_itimer(struct task_struct *tsk, struct cpu_itimer *it,
 956                             unsigned long long *expires,
 957                             unsigned long long cur_time, int signo)
 958{
 959        if (!it->expires)
 960                return;
 961
 962        if (cur_time >= it->expires) {
 963                if (it->incr) {
 964                        it->expires += it->incr;
 965                        it->error += it->incr_error;
 966                        if (it->error >= onecputick) {
 967                                it->expires -= cputime_one_jiffy;
 968                                it->error -= onecputick;
 969                        }
 970                } else {
 971                        it->expires = 0;
 972                }
 973
 974                trace_itimer_expire(signo == SIGPROF ?
 975                                    ITIMER_PROF : ITIMER_VIRTUAL,
 976                                    tsk->signal->leader_pid, cur_time);
 977                __group_send_sig_info(signo, SEND_SIG_PRIV, tsk);
 978        }
 979
 980        if (it->expires && (!*expires || it->expires < *expires)) {
 981                *expires = it->expires;
 982        }
 983}
 984
 985/*
 986 * Check for any per-thread CPU timers that have fired and move them
 987 * off the tsk->*_timers list onto the firing list.  Per-thread timers
 988 * have already been taken off.
 989 */
 990static void check_process_timers(struct task_struct *tsk,
 991                                 struct list_head *firing)
 992{
 993        struct signal_struct *const sig = tsk->signal;
 994        unsigned long long utime, ptime, virt_expires, prof_expires;
 995        unsigned long long sum_sched_runtime, sched_expires;
 996        struct list_head *timers = sig->cpu_timers;
 997        struct task_cputime cputime;
 998        unsigned long soft;
 999
1000        /*
1001         * Collect the current process totals.
1002         */
1003        thread_group_cputimer(tsk, &cputime);
1004        utime = cputime_to_expires(cputime.utime);
1005        ptime = utime + cputime_to_expires(cputime.stime);
1006        sum_sched_runtime = cputime.sum_exec_runtime;
1007
1008        prof_expires = check_timers_list(timers, firing, ptime);
1009        virt_expires = check_timers_list(++timers, firing, utime);
1010        sched_expires = check_timers_list(++timers, firing, sum_sched_runtime);
1011
1012        /*
1013         * Check for the special case process timers.
1014         */
1015        check_cpu_itimer(tsk, &sig->it[CPUCLOCK_PROF], &prof_expires, ptime,
1016                         SIGPROF);
1017        check_cpu_itimer(tsk, &sig->it[CPUCLOCK_VIRT], &virt_expires, utime,
1018                         SIGVTALRM);
1019        soft = ACCESS_ONCE(sig->rlim[RLIMIT_CPU].rlim_cur);
1020        if (soft != RLIM_INFINITY) {
1021                unsigned long psecs = cputime_to_secs(ptime);
1022                unsigned long hard =
1023                        ACCESS_ONCE(sig->rlim[RLIMIT_CPU].rlim_max);
1024                cputime_t x;
1025                if (psecs >= hard) {
1026                        /*
1027                         * At the hard limit, we just die.
1028                         * No need to calculate anything else now.
1029                         */
1030                        __group_send_sig_info(SIGKILL, SEND_SIG_PRIV, tsk);
1031                        return;
1032                }
1033                if (psecs >= soft) {
1034                        /*
1035                         * At the soft limit, send a SIGXCPU every second.
1036                         */
1037                        __group_send_sig_info(SIGXCPU, SEND_SIG_PRIV, tsk);
1038                        if (soft < hard) {
1039                                soft++;
1040                                sig->rlim[RLIMIT_CPU].rlim_cur = soft;
1041                        }
1042                }
1043                x = secs_to_cputime(soft);
1044                if (!prof_expires || x < prof_expires) {
1045                        prof_expires = x;
1046                }
1047        }
1048
1049        sig->cputime_expires.prof_exp = expires_to_cputime(prof_expires);
1050        sig->cputime_expires.virt_exp = expires_to_cputime(virt_expires);
1051        sig->cputime_expires.sched_exp = sched_expires;
1052        if (task_cputime_zero(&sig->cputime_expires))
1053                stop_process_timers(sig);
1054}
1055
1056/*
1057 * This is called from the signal code (via do_schedule_next_timer)
1058 * when the last timer signal was delivered and we have to reload the timer.
1059 */
1060void posix_cpu_timer_schedule(struct k_itimer *timer)
1061{
1062        struct task_struct *p = timer->it.cpu.task;
1063        unsigned long long now;
1064
1065        if (unlikely(p == NULL))
1066                /*
1067                 * The task was cleaned up already, no future firings.
1068                 */
1069                goto out;
1070
1071        /*
1072         * Fetch the current sample and update the timer's expiry time.
1073         */
1074        if (CPUCLOCK_PERTHREAD(timer->it_clock)) {
1075                cpu_clock_sample(timer->it_clock, p, &now);
1076                bump_cpu_timer(timer, now);
1077                if (unlikely(p->exit_state)) {
1078                        clear_dead_task(timer, now);
1079                        goto out;
1080                }
1081                read_lock(&tasklist_lock); /* arm_timer needs it.  */
1082                spin_lock(&p->sighand->siglock);
1083        } else {
1084                read_lock(&tasklist_lock);
1085                if (unlikely(p->sighand == NULL)) {
1086                        /*
1087                         * The process has been reaped.
1088                         * We can't even collect a sample any more.
1089                         */
1090                        put_task_struct(p);
1091                        timer->it.cpu.task = p = NULL;
1092                        timer->it.cpu.expires = 0;
1093                        goto out_unlock;
1094                } else if (unlikely(p->exit_state) && thread_group_empty(p)) {
1095                        /*
1096                         * We've noticed that the thread is dead, but
1097                         * not yet reaped.  Take this opportunity to
1098                         * drop our task ref.
1099                         */
1100                        cpu_timer_sample_group(timer->it_clock, p, &now);
1101                        clear_dead_task(timer, now);
1102                        goto out_unlock;
1103                }
1104                spin_lock(&p->sighand->siglock);
1105                cpu_timer_sample_group(timer->it_clock, p, &now);
1106                bump_cpu_timer(timer, now);
1107                /* Leave the tasklist_lock locked for the call below.  */
1108        }
1109
1110        /*
1111         * Now re-arm for the new expiry time.
1112         */
1113        BUG_ON(!irqs_disabled());
1114        arm_timer(timer);
1115        spin_unlock(&p->sighand->siglock);
1116
1117out_unlock:
1118        read_unlock(&tasklist_lock);
1119
1120out:
1121        timer->it_overrun_last = timer->it_overrun;
1122        timer->it_overrun = -1;
1123        ++timer->it_requeue_pending;
1124}
1125
1126/**
1127 * task_cputime_expired - Compare two task_cputime entities.
1128 *
1129 * @sample:     The task_cputime structure to be checked for expiration.
1130 * @expires:    Expiration times, against which @sample will be checked.
1131 *
1132 * Checks @sample against @expires to see if any field of @sample has expired.
1133 * Returns true if any field of the former is greater than the corresponding
1134 * field of the latter if the latter field is set.  Otherwise returns false.
1135 */
1136static inline int task_cputime_expired(const struct task_cputime *sample,
1137                                        const struct task_cputime *expires)
1138{
1139        if (expires->utime && sample->utime >= expires->utime)
1140                return 1;
1141        if (expires->stime && sample->utime + sample->stime >= expires->stime)
1142                return 1;
1143        if (expires->sum_exec_runtime != 0 &&
1144            sample->sum_exec_runtime >= expires->sum_exec_runtime)
1145                return 1;
1146        return 0;
1147}
1148
1149/**
1150 * fastpath_timer_check - POSIX CPU timers fast path.
1151 *
1152 * @tsk:        The task (thread) being checked.
1153 *
1154 * Check the task and thread group timers.  If both are zero (there are no
1155 * timers set) return false.  Otherwise snapshot the task and thread group
1156 * timers and compare them with the corresponding expiration times.  Return
1157 * true if a timer has expired, else return false.
1158 */
1159static inline int fastpath_timer_check(struct task_struct *tsk)
1160{
1161        struct signal_struct *sig;
1162        cputime_t utime, stime;
1163
1164        task_cputime(tsk, &utime, &stime);
1165
1166        if (!task_cputime_zero(&tsk->cputime_expires)) {
1167                struct task_cputime task_sample = {
1168                        .utime = utime,
1169                        .stime = stime,
1170                        .sum_exec_runtime = tsk->se.sum_exec_runtime
1171                };
1172
1173                if (task_cputime_expired(&task_sample, &tsk->cputime_expires))
1174                        return 1;
1175        }
1176
1177        sig = tsk->signal;
1178        if (sig->cputimer.running) {
1179                struct task_cputime group_sample;
1180
1181                raw_spin_lock(&sig->cputimer.lock);
1182                group_sample = sig->cputimer.cputime;
1183                raw_spin_unlock(&sig->cputimer.lock);
1184
1185                if (task_cputime_expired(&group_sample, &sig->cputime_expires))
1186                        return 1;
1187        }
1188
1189        return 0;
1190}
1191
1192/*
1193 * This is called from the timer interrupt handler.  The irq handler has
1194 * already updated our counts.  We need to check if any timers fire now.
1195 * Interrupts are disabled.
1196 */
1197void run_posix_cpu_timers(struct task_struct *tsk)
1198{
1199        LIST_HEAD(firing);
1200        struct k_itimer *timer, *next;
1201        unsigned long flags;
1202
1203        BUG_ON(!irqs_disabled());
1204
1205        /*
1206         * The fast path checks that there are no expired thread or thread
1207         * group timers.  If that's so, just return.
1208         */
1209        if (!fastpath_timer_check(tsk))
1210                return;
1211
1212        if (!lock_task_sighand(tsk, &flags))
1213                return;
1214        /*
1215         * Here we take off tsk->signal->cpu_timers[N] and
1216         * tsk->cpu_timers[N] all the timers that are firing, and
1217         * put them on the firing list.
1218         */
1219        check_thread_timers(tsk, &firing);
1220        /*
1221         * If there are any active process wide timers (POSIX 1.b, itimers,
1222         * RLIMIT_CPU) cputimer must be running.
1223         */
1224        if (tsk->signal->cputimer.running)
1225                check_process_timers(tsk, &firing);
1226
1227        /*
1228         * We must release these locks before taking any timer's lock.
1229         * There is a potential race with timer deletion here, as the
1230         * siglock now protects our private firing list.  We have set
1231         * the firing flag in each timer, so that a deletion attempt
1232         * that gets the timer lock before we do will give it up and
1233         * spin until we've taken care of that timer below.
1234         */
1235        unlock_task_sighand(tsk, &flags);
1236
1237        /*
1238         * Now that all the timers on our list have the firing flag,
1239         * no one will touch their list entries but us.  We'll take
1240         * each timer's lock before clearing its firing flag, so no
1241         * timer call will interfere.
1242         */
1243        list_for_each_entry_safe(timer, next, &firing, it.cpu.entry) {
1244                int cpu_firing;
1245
1246                spin_lock(&timer->it_lock);
1247                list_del_init(&timer->it.cpu.entry);
1248                cpu_firing = timer->it.cpu.firing;
1249                timer->it.cpu.firing = 0;
1250                /*
1251                 * The firing flag is -1 if we collided with a reset
1252                 * of the timer, which already reported this
1253                 * almost-firing as an overrun.  So don't generate an event.
1254                 */
1255                if (likely(cpu_firing >= 0))
1256                        cpu_timer_fire(timer);
1257                spin_unlock(&timer->it_lock);
1258        }
1259
1260        /*
1261         * In case some timers were rescheduled after the queue got emptied,
1262         * wake up full dynticks CPUs.
1263         */
1264        if (tsk->signal->cputimer.running)
1265                posix_cpu_timer_kick_nohz();
1266}
1267
1268/*
1269 * Set one of the process-wide special case CPU timers or RLIMIT_CPU.
1270 * The tsk->sighand->siglock must be held by the caller.
1271 */
1272void set_process_cpu_timer(struct task_struct *tsk, unsigned int clock_idx,
1273                           cputime_t *newval, cputime_t *oldval)
1274{
1275        unsigned long long now;
1276
1277        BUG_ON(clock_idx == CPUCLOCK_SCHED);
1278        cpu_timer_sample_group(clock_idx, tsk, &now);
1279
1280        if (oldval) {
1281                /*
1282                 * We are setting itimer. The *oldval is absolute and we update
1283                 * it to be relative, *newval argument is relative and we update
1284                 * it to be absolute.
1285                 */
1286                if (*oldval) {
1287                        if (*oldval <= now) {
1288                                /* Just about to fire. */
1289                                *oldval = cputime_one_jiffy;
1290                        } else {
1291                                *oldval -= now;
1292                        }
1293                }
1294
1295                if (!*newval)
1296                        goto out;
1297                *newval += now;
1298        }
1299
1300        /*
1301         * Update expiration cache if we are the earliest timer, or eventually
1302         * RLIMIT_CPU limit is earlier than prof_exp cpu timer expire.
1303         */
1304        switch (clock_idx) {
1305        case CPUCLOCK_PROF:
1306                if (expires_gt(tsk->signal->cputime_expires.prof_exp, *newval))
1307                        tsk->signal->cputime_expires.prof_exp = *newval;
1308                break;
1309        case CPUCLOCK_VIRT:
1310                if (expires_gt(tsk->signal->cputime_expires.virt_exp, *newval))
1311                        tsk->signal->cputime_expires.virt_exp = *newval;
1312                break;
1313        }
1314out:
1315        posix_cpu_timer_kick_nohz();
1316}
1317
1318static int do_cpu_nanosleep(const clockid_t which_clock, int flags,
1319                            struct timespec *rqtp, struct itimerspec *it)
1320{
1321        struct k_itimer timer;
1322        int error;
1323
1324        /*
1325         * Set up a temporary timer and then wait for it to go off.
1326         */
1327        memset(&timer, 0, sizeof timer);
1328        spin_lock_init(&timer.it_lock);
1329        timer.it_clock = which_clock;
1330        timer.it_overrun = -1;
1331        error = posix_cpu_timer_create(&timer);
1332        timer.it_process = current;
1333        if (!error) {
1334                static struct itimerspec zero_it;
1335
1336                memset(it, 0, sizeof *it);
1337                it->it_value = *rqtp;
1338
1339                spin_lock_irq(&timer.it_lock);
1340                error = posix_cpu_timer_set(&timer, flags, it, NULL);
1341                if (error) {
1342                        spin_unlock_irq(&timer.it_lock);
1343                        return error;
1344                }
1345
1346                while (!signal_pending(current)) {
1347                        if (timer.it.cpu.expires == 0) {
1348                                /*
1349                                 * Our timer fired and was reset, below
1350                                 * deletion can not fail.
1351                                 */
1352                                posix_cpu_timer_del(&timer);
1353                                spin_unlock_irq(&timer.it_lock);
1354                                return 0;
1355                        }
1356
1357                        /*
1358                         * Block until cpu_timer_fire (or a signal) wakes us.
1359                         */
1360                        __set_current_state(TASK_INTERRUPTIBLE);
1361                        spin_unlock_irq(&timer.it_lock);
1362                        schedule();
1363                        spin_lock_irq(&timer.it_lock);
1364                }
1365
1366                /*
1367                 * We were interrupted by a signal.
1368                 */
1369                sample_to_timespec(which_clock, timer.it.cpu.expires, rqtp);
1370                error = posix_cpu_timer_set(&timer, 0, &zero_it, it);
1371                if (!error) {
1372                        /*
1373                         * Timer is now unarmed, deletion can not fail.
1374                         */
1375                        posix_cpu_timer_del(&timer);
1376                }
1377                spin_unlock_irq(&timer.it_lock);
1378
1379                while (error == TIMER_RETRY) {
1380                        /*
1381                         * We need to handle case when timer was or is in the
1382                         * middle of firing. In other cases we already freed
1383                         * resources.
1384                         */
1385                        spin_lock_irq(&timer.it_lock);
1386                        error = posix_cpu_timer_del(&timer);
1387                        spin_unlock_irq(&timer.it_lock);
1388                }
1389
1390                if ((it->it_value.tv_sec | it->it_value.tv_nsec) == 0) {
1391                        /*
1392                         * It actually did fire already.
1393                         */
1394                        return 0;
1395                }
1396
1397                error = -ERESTART_RESTARTBLOCK;
1398        }
1399
1400        return error;
1401}
1402
1403static long posix_cpu_nsleep_restart(struct restart_block *restart_block);
1404
1405static int posix_cpu_nsleep(const clockid_t which_clock, int flags,
1406                            struct timespec *rqtp, struct timespec __user *rmtp)
1407{
1408        struct restart_block *restart_block =
1409                &current_thread_info()->restart_block;
1410        struct itimerspec it;
1411        int error;
1412
1413        /*
1414         * Diagnose required errors first.
1415         */
1416        if (CPUCLOCK_PERTHREAD(which_clock) &&
1417            (CPUCLOCK_PID(which_clock) == 0 ||
1418             CPUCLOCK_PID(which_clock) == current->pid))
1419                return -EINVAL;
1420
1421        error = do_cpu_nanosleep(which_clock, flags, rqtp, &it);
1422
1423        if (error == -ERESTART_RESTARTBLOCK) {
1424
1425                if (flags & TIMER_ABSTIME)
1426                        return -ERESTARTNOHAND;
1427                /*
1428                 * Report back to the user the time still remaining.
1429                 */
1430                if (rmtp && copy_to_user(rmtp, &it.it_value, sizeof *rmtp))
1431                        return -EFAULT;
1432
1433                restart_block->fn = posix_cpu_nsleep_restart;
1434                restart_block->nanosleep.clockid = which_clock;
1435                restart_block->nanosleep.rmtp = rmtp;
1436                restart_block->nanosleep.expires = timespec_to_ns(rqtp);
1437        }
1438        return error;
1439}
1440
1441static long posix_cpu_nsleep_restart(struct restart_block *restart_block)
1442{
1443        clockid_t which_clock = restart_block->nanosleep.clockid;
1444        struct timespec t;
1445        struct itimerspec it;
1446        int error;
1447
1448        t = ns_to_timespec(restart_block->nanosleep.expires);
1449
1450        error = do_cpu_nanosleep(which_clock, TIMER_ABSTIME, &t, &it);
1451
1452        if (error == -ERESTART_RESTARTBLOCK) {
1453                struct timespec __user *rmtp = restart_block->nanosleep.rmtp;
1454                /*
1455                 * Report back to the user the time still remaining.
1456                 */
1457                if (rmtp && copy_to_user(rmtp, &it.it_value, sizeof *rmtp))
1458                        return -EFAULT;
1459
1460                restart_block->nanosleep.expires = timespec_to_ns(&t);
1461        }
1462        return error;
1463
1464}
1465
1466#define PROCESS_CLOCK   MAKE_PROCESS_CPUCLOCK(0, CPUCLOCK_SCHED)
1467#define THREAD_CLOCK    MAKE_THREAD_CPUCLOCK(0, CPUCLOCK_SCHED)
1468
1469static int process_cpu_clock_getres(const clockid_t which_clock,
1470                                    struct timespec *tp)
1471{
1472        return posix_cpu_clock_getres(PROCESS_CLOCK, tp);
1473}
1474static int process_cpu_clock_get(const clockid_t which_clock,
1475                                 struct timespec *tp)
1476{
1477        return posix_cpu_clock_get(PROCESS_CLOCK, tp);
1478}
1479static int process_cpu_timer_create(struct k_itimer *timer)
1480{
1481        timer->it_clock = PROCESS_CLOCK;
1482        return posix_cpu_timer_create(timer);
1483}
1484static int process_cpu_nsleep(const clockid_t which_clock, int flags,
1485                              struct timespec *rqtp,
1486                              struct timespec __user *rmtp)
1487{
1488        return posix_cpu_nsleep(PROCESS_CLOCK, flags, rqtp, rmtp);
1489}
1490static long process_cpu_nsleep_restart(struct restart_block *restart_block)
1491{
1492        return -EINVAL;
1493}
1494static int thread_cpu_clock_getres(const clockid_t which_clock,
1495                                   struct timespec *tp)
1496{
1497        return posix_cpu_clock_getres(THREAD_CLOCK, tp);
1498}
1499static int thread_cpu_clock_get(const clockid_t which_clock,
1500                                struct timespec *tp)
1501{
1502        return posix_cpu_clock_get(THREAD_CLOCK, tp);
1503}
1504static int thread_cpu_timer_create(struct k_itimer *timer)
1505{
1506        timer->it_clock = THREAD_CLOCK;
1507        return posix_cpu_timer_create(timer);
1508}
1509
1510struct k_clock clock_posix_cpu = {
1511        .clock_getres   = posix_cpu_clock_getres,
1512        .clock_set      = posix_cpu_clock_set,
1513        .clock_get      = posix_cpu_clock_get,
1514        .timer_create   = posix_cpu_timer_create,
1515        .nsleep         = posix_cpu_nsleep,
1516        .nsleep_restart = posix_cpu_nsleep_restart,
1517        .timer_set      = posix_cpu_timer_set,
1518        .timer_del      = posix_cpu_timer_del,
1519        .timer_get      = posix_cpu_timer_get,
1520};
1521
1522static __init int init_posix_cpu_timers(void)
1523{
1524        struct k_clock process = {
1525                .clock_getres   = process_cpu_clock_getres,
1526                .clock_get      = process_cpu_clock_get,
1527                .timer_create   = process_cpu_timer_create,
1528                .nsleep         = process_cpu_nsleep,
1529                .nsleep_restart = process_cpu_nsleep_restart,
1530        };
1531        struct k_clock thread = {
1532                .clock_getres   = thread_cpu_clock_getres,
1533                .clock_get      = thread_cpu_clock_get,
1534                .timer_create   = thread_cpu_timer_create,
1535        };
1536        struct timespec ts;
1537
1538        posix_timers_register_clock(CLOCK_PROCESS_CPUTIME_ID, &process);
1539        posix_timers_register_clock(CLOCK_THREAD_CPUTIME_ID, &thread);
1540
1541        cputime_to_timespec(cputime_one_jiffy, &ts);
1542        onecputick = ts.tv_nsec;
1543        WARN_ON(ts.tv_sec != 0);
1544
1545        return 0;
1546}
1547__initcall(init_posix_cpu_timers);
1548
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