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
  13/*
  14 * Called after updating RLIMIT_CPU to run cpu timer and update
  15 * tsk->signal->cputime_expires expiration cache if necessary. Needs
  16 * siglock protection since other code may update expiration cache as
  17 * well.
  18 */
  19void update_rlimit_cpu(struct task_struct *task, unsigned long rlim_new)
  20{
  21        cputime_t cputime = secs_to_cputime(rlim_new);
  22
  23        spin_lock_irq(&task->sighand->siglock);
  24        set_process_cpu_timer(task, CPUCLOCK_PROF, &cputime, NULL);
  25        spin_unlock_irq(&task->sighand->siglock);
  26}
  27
  28static int check_clock(const clockid_t which_clock)
  29{
  30        int error = 0;
  31        struct task_struct *p;
  32        const pid_t pid = CPUCLOCK_PID(which_clock);
  33
  34        if (CPUCLOCK_WHICH(which_clock) >= CPUCLOCK_MAX)
  35                return -EINVAL;
  36
  37        if (pid == 0)
  38                return 0;
  39
  40        rcu_read_lock();
  41        p = find_task_by_vpid(pid);
  42        if (!p || !(CPUCLOCK_PERTHREAD(which_clock) ?
  43                   same_thread_group(p, current) : has_group_leader_pid(p))) {
  44                error = -EINVAL;
  45        }
  46        rcu_read_unlock();
  47
  48        return error;
  49}
  50
  51static inline union cpu_time_count
  52timespec_to_sample(const clockid_t which_clock, const struct timespec *tp)
  53{
  54        union cpu_time_count ret;
  55        ret.sched = 0;          /* high half always zero when .cpu used */
  56        if (CPUCLOCK_WHICH(which_clock) == CPUCLOCK_SCHED) {
  57                ret.sched = (unsigned long long)tp->tv_sec * NSEC_PER_SEC + tp->tv_nsec;
  58        } else {
  59                ret.cpu = timespec_to_cputime(tp);
  60        }
  61        return ret;
  62}
  63
  64static void sample_to_timespec(const clockid_t which_clock,
  65                               union cpu_time_count cpu,
  66                               struct timespec *tp)
  67{
  68        if (CPUCLOCK_WHICH(which_clock) == CPUCLOCK_SCHED)
  69                *tp = ns_to_timespec(cpu.sched);
  70        else
  71                cputime_to_timespec(cpu.cpu, tp);
  72}
  73
  74static inline int cpu_time_before(const clockid_t which_clock,
  75                                  union cpu_time_count now,
  76                                  union cpu_time_count then)
  77{
  78        if (CPUCLOCK_WHICH(which_clock) == CPUCLOCK_SCHED) {
  79                return now.sched < then.sched;
  80        }  else {
  81                return now.cpu < then.cpu;
  82        }
  83}
  84static inline void cpu_time_add(const clockid_t which_clock,
  85                                union cpu_time_count *acc,
  86                                union cpu_time_count val)
  87{
  88        if (CPUCLOCK_WHICH(which_clock) == CPUCLOCK_SCHED) {
  89                acc->sched += val.sched;
  90        }  else {
  91                acc->cpu += val.cpu;
  92        }
  93}
  94static inline union cpu_time_count cpu_time_sub(const clockid_t which_clock,
  95                                                union cpu_time_count a,
  96                                                union cpu_time_count b)
  97{
  98        if (CPUCLOCK_WHICH(which_clock) == CPUCLOCK_SCHED) {
  99                a.sched -= b.sched;
 100        }  else {
 101                a.cpu -= b.cpu;
 102        }
 103        return a;
 104}
 105
 106/*
 107 * Update expiry time from increment, and increase overrun count,
 108 * given the current clock sample.
 109 */
 110static void bump_cpu_timer(struct k_itimer *timer,
 111                                  union cpu_time_count now)
 112{
 113        int i;
 114
 115        if (timer->it.cpu.incr.sched == 0)
 116                return;
 117
 118        if (CPUCLOCK_WHICH(timer->it_clock) == CPUCLOCK_SCHED) {
 119                unsigned long long delta, incr;
 120
 121                if (now.sched < timer->it.cpu.expires.sched)
 122                        return;
 123                incr = timer->it.cpu.incr.sched;
 124                delta = now.sched + incr - timer->it.cpu.expires.sched;
 125                /* Don't use (incr*2 < delta), incr*2 might overflow. */
 126                for (i = 0; incr < delta - incr; i++)
 127                        incr = incr << 1;
 128                for (; i >= 0; incr >>= 1, i--) {
 129                        if (delta < incr)
 130                                continue;
 131                        timer->it.cpu.expires.sched += incr;
 132                        timer->it_overrun += 1 << i;
 133                        delta -= incr;
 134                }
 135        } else {
 136                cputime_t delta, incr;
 137
 138                if (now.cpu < timer->it.cpu.expires.cpu)
 139                        return;
 140                incr = timer->it.cpu.incr.cpu;
 141                delta = now.cpu + incr - timer->it.cpu.expires.cpu;
 142                /* Don't use (incr*2 < delta), incr*2 might overflow. */
 143                for (i = 0; incr < delta - incr; i++)
 144                             incr += incr;
 145                for (; i >= 0; incr = incr >> 1, i--) {
 146                        if (delta < incr)
 147                                continue;
 148                        timer->it.cpu.expires.cpu += incr;
 149                        timer->it_overrun += 1 << i;
 150                        delta -= incr;
 151                }
 152        }
 153}
 154
 155static inline cputime_t prof_ticks(struct task_struct *p)
 156{
 157        return p->utime + p->stime;
 158}
 159static inline cputime_t virt_ticks(struct task_struct *p)
 160{
 161        return p->utime;
 162}
 163
 164static int
 165posix_cpu_clock_getres(const clockid_t which_clock, struct timespec *tp)
 166{
 167        int error = check_clock(which_clock);
 168        if (!error) {
 169                tp->tv_sec = 0;
 170                tp->tv_nsec = ((NSEC_PER_SEC + HZ - 1) / HZ);
 171                if (CPUCLOCK_WHICH(which_clock) == CPUCLOCK_SCHED) {
 172                        /*
 173                         * If sched_clock is using a cycle counter, we
 174                         * don't have any idea of its true resolution
 175                         * exported, but it is much more than 1s/HZ.
 176                         */
 177                        tp->tv_nsec = 1;
 178                }
 179        }
 180        return error;
 181}
 182
 183static int
 184posix_cpu_clock_set(const clockid_t which_clock, const struct timespec *tp)
 185{
 186        /*
 187         * You can never reset a CPU clock, but we check for other errors
 188         * in the call before failing with EPERM.
 189         */
 190        int error = check_clock(which_clock);
 191        if (error == 0) {
 192                error = -EPERM;
 193        }
 194        return error;
 195}
 196
 197
 198/*
 199 * Sample a per-thread clock for the given task.
 200 */
 201static int cpu_clock_sample(const clockid_t which_clock, struct task_struct *p,
 202                            union cpu_time_count *cpu)
 203{
 204        switch (CPUCLOCK_WHICH(which_clock)) {
 205        default:
 206                return -EINVAL;
 207        case CPUCLOCK_PROF:
 208                cpu->cpu = prof_ticks(p);
 209                break;
 210        case CPUCLOCK_VIRT:
 211                cpu->cpu = virt_ticks(p);
 212                break;
 213        case CPUCLOCK_SCHED:
 214                cpu->sched = task_sched_runtime(p);
 215                break;
 216        }
 217        return 0;
 218}
 219
 220void thread_group_cputime(struct task_struct *tsk, struct task_cputime *times)
 221{
 222        struct signal_struct *sig = tsk->signal;
 223        struct task_struct *t;
 224
 225        times->utime = sig->utime;
 226        times->stime = sig->stime;
 227        times->sum_exec_runtime = sig->sum_sched_runtime;
 228
 229        rcu_read_lock();
 230        /* make sure we can trust tsk->thread_group list */
 231        if (!likely(pid_alive(tsk)))
 232                goto out;
 233
 234        t = tsk;
 235        do {
 236                times->utime += t->utime;
 237                times->stime += t->stime;
 238                times->sum_exec_runtime += task_sched_runtime(t);
 239        } while_each_thread(tsk, t);
 240out:
 241        rcu_read_unlock();
 242}
 243
 244static void update_gt_cputime(struct task_cputime *a, struct task_cputime *b)
 245{
 246        if (b->utime > a->utime)
 247                a->utime = b->utime;
 248
 249        if (b->stime > a->stime)
 250                a->stime = b->stime;
 251
 252        if (b->sum_exec_runtime > a->sum_exec_runtime)
 253                a->sum_exec_runtime = b->sum_exec_runtime;
 254}
 255
 256void thread_group_cputimer(struct task_struct *tsk, struct task_cputime *times)
 257{
 258        struct thread_group_cputimer *cputimer = &tsk->signal->cputimer;
 259        struct task_cputime sum;
 260        unsigned long flags;
 261
 262        if (!cputimer->running) {
 263                /*
 264                 * The POSIX timer interface allows for absolute time expiry
 265                 * values through the TIMER_ABSTIME flag, therefore we have
 266                 * to synchronize the timer to the clock every time we start
 267                 * it.
 268                 */
 269                thread_group_cputime(tsk, &sum);
 270                raw_spin_lock_irqsave(&cputimer->lock, flags);
 271                cputimer->running = 1;
 272                update_gt_cputime(&cputimer->cputime, &sum);
 273        } else
 274                raw_spin_lock_irqsave(&cputimer->lock, flags);
 275        *times = cputimer->cputime;
 276        raw_spin_unlock_irqrestore(&cputimer->lock, flags);
 277}
 278
 279/*
 280 * Sample a process (thread group) clock for the given group_leader task.
 281 * Must be called with tasklist_lock held for reading.
 282 */
 283static int cpu_clock_sample_group(const clockid_t which_clock,
 284                                  struct task_struct *p,
 285                                  union cpu_time_count *cpu)
 286{
 287        struct task_cputime cputime;
 288
 289        switch (CPUCLOCK_WHICH(which_clock)) {
 290        default:
 291                return -EINVAL;
 292        case CPUCLOCK_PROF:
 293                thread_group_cputime(p, &cputime);
 294                cpu->cpu = cputime.utime + cputime.stime;
 295                break;
 296        case CPUCLOCK_VIRT:
 297                thread_group_cputime(p, &cputime);
 298                cpu->cpu = cputime.utime;
 299                break;
 300        case CPUCLOCK_SCHED:
 301                thread_group_cputime(p, &cputime);
 302                cpu->sched = cputime.sum_exec_runtime;
 303                break;
 304        }
 305        return 0;
 306}
 307
 308
 309static int posix_cpu_clock_get(const clockid_t which_clock, struct timespec *tp)
 310{
 311        const pid_t pid = CPUCLOCK_PID(which_clock);
 312        int error = -EINVAL;
 313        union cpu_time_count rtn;
 314
 315        if (pid == 0) {
 316                /*
 317                 * Special case constant value for our own clocks.
 318                 * We don't have to do any lookup to find ourselves.
 319                 */
 320                if (CPUCLOCK_PERTHREAD(which_clock)) {
 321                        /*
 322                         * Sampling just ourselves we can do with no locking.
 323                         */
 324                        error = cpu_clock_sample(which_clock,
 325                                                 current, &rtn);
 326                } else {
 327                        read_lock(&tasklist_lock);
 328                        error = cpu_clock_sample_group(which_clock,
 329                                                       current, &rtn);
 330                        read_unlock(&tasklist_lock);
 331                }
 332        } else {
 333                /*
 334                 * Find the given PID, and validate that the caller
 335                 * should be able to see it.
 336                 */
 337                struct task_struct *p;
 338                rcu_read_lock();
 339                p = find_task_by_vpid(pid);
 340                if (p) {
 341                        if (CPUCLOCK_PERTHREAD(which_clock)) {
 342                                if (same_thread_group(p, current)) {
 343                                        error = cpu_clock_sample(which_clock,
 344                                                                 p, &rtn);
 345                                }
 346                        } else {
 347                                read_lock(&tasklist_lock);
 348                                if (thread_group_leader(p) && p->sighand) {
 349                                        error =
 350                                            cpu_clock_sample_group(which_clock,
 351                                                                   p, &rtn);
 352                                }
 353                                read_unlock(&tasklist_lock);
 354                        }
 355                }
 356                rcu_read_unlock();
 357        }
 358
 359        if (error)
 360                return error;
 361        sample_to_timespec(which_clock, rtn, tp);
 362        return 0;
 363}
 364
 365
 366/*
 367 * Validate the clockid_t for a new CPU-clock timer, and initialize the timer.
 368 * This is called from sys_timer_create() and do_cpu_nanosleep() with the
 369 * new timer already all-zeros initialized.
 370 */
 371static int posix_cpu_timer_create(struct k_itimer *new_timer)
 372{
 373        int ret = 0;
 374        const pid_t pid = CPUCLOCK_PID(new_timer->it_clock);
 375        struct task_struct *p;
 376
 377        if (CPUCLOCK_WHICH(new_timer->it_clock) >= CPUCLOCK_MAX)
 378                return -EINVAL;
 379
 380        INIT_LIST_HEAD(&new_timer->it.cpu.entry);
 381
 382        rcu_read_lock();
 383        if (CPUCLOCK_PERTHREAD(new_timer->it_clock)) {
 384                if (pid == 0) {
 385                        p = current;
 386                } else {
 387                        p = find_task_by_vpid(pid);
 388                        if (p && !same_thread_group(p, current))
 389                                p = NULL;
 390                }
 391        } else {
 392                if (pid == 0) {
 393                        p = current->group_leader;
 394                } else {
 395                        p = find_task_by_vpid(pid);
 396                        if (p && !has_group_leader_pid(p))
 397                                p = NULL;
 398                }
 399        }
 400        new_timer->it.cpu.task = p;
 401        if (p) {
 402                get_task_struct(p);
 403        } else {
 404                ret = -EINVAL;
 405        }
 406        rcu_read_unlock();
 407
 408        return ret;
 409}
 410
 411/*
 412 * Clean up a CPU-clock timer that is about to be destroyed.
 413 * This is called from timer deletion with the timer already locked.
 414 * If we return TIMER_RETRY, it's necessary to release the timer's lock
 415 * and try again.  (This happens when the timer is in the middle of firing.)
 416 */
 417static int posix_cpu_timer_del(struct k_itimer *timer)
 418{
 419        struct task_struct *p = timer->it.cpu.task;
 420        int ret = 0;
 421
 422        if (likely(p != NULL)) {
 423                read_lock(&tasklist_lock);
 424                if (unlikely(p->sighand == NULL)) {
 425                        /*
 426                         * We raced with the reaping of the task.
 427                         * The deletion should have cleared us off the list.
 428                         */
 429                        BUG_ON(!list_empty(&timer->it.cpu.entry));
 430                } else {
 431                        spin_lock(&p->sighand->siglock);
 432                        if (timer->it.cpu.firing)
 433                                ret = TIMER_RETRY;
 434                        else
 435                                list_del(&timer->it.cpu.entry);
 436                        spin_unlock(&p->sighand->siglock);
 437                }
 438                read_unlock(&tasklist_lock);
 439
 440                if (!ret)
 441                        put_task_struct(p);
 442        }
 443
 444        return ret;
 445}
 446
 447/*
 448 * Clean out CPU timers still ticking when a thread exited.  The task
 449 * pointer is cleared, and the expiry time is replaced with the residual
 450 * time for later timer_gettime calls to return.
 451 * This must be called with the siglock held.
 452 */
 453static void cleanup_timers(struct list_head *head,
 454                           cputime_t utime, cputime_t stime,
 455                           unsigned long long sum_exec_runtime)
 456{
 457        struct cpu_timer_list *timer, *next;
 458        cputime_t ptime = utime + stime;
 459
 460        list_for_each_entry_safe(timer, next, head, entry) {
 461                list_del_init(&timer->entry);
 462                if (timer->expires.cpu < ptime) {
 463                        timer->expires.cpu = 0;
 464                } else {
 465                        timer->expires.cpu -= ptime;
 466                }
 467        }
 468
 469        ++head;
 470        list_for_each_entry_safe(timer, next, head, entry) {
 471                list_del_init(&timer->entry);
 472                if (timer->expires.cpu < utime) {
 473                        timer->expires.cpu = 0;
 474                } else {
 475                        timer->expires.cpu -= utime;
 476                }
 477        }
 478
 479        ++head;
 480        list_for_each_entry_safe(timer, next, head, entry) {
 481                list_del_init(&timer->entry);
 482                if (timer->expires.sched < sum_exec_runtime) {
 483                        timer->expires.sched = 0;
 484                } else {
 485                        timer->expires.sched -= sum_exec_runtime;
 486                }
 487        }
 488}
 489
 490/*
 491 * These are both called with the siglock held, when the current thread
 492 * is being reaped.  When the final (leader) thread in the group is reaped,
 493 * posix_cpu_timers_exit_group will be called after posix_cpu_timers_exit.
 494 */
 495void posix_cpu_timers_exit(struct task_struct *tsk)
 496{
 497        cleanup_timers(tsk->cpu_timers,
 498                       tsk->utime, tsk->stime, tsk->se.sum_exec_runtime);
 499
 500}
 501void posix_cpu_timers_exit_group(struct task_struct *tsk)
 502{
 503        struct signal_struct *const sig = tsk->signal;
 504
 505        cleanup_timers(tsk->signal->cpu_timers,
 506                       tsk->utime + sig->utime, tsk->stime + sig->stime,
 507                       tsk->se.sum_exec_runtime + sig->sum_sched_runtime);
 508}
 509
 510static void clear_dead_task(struct k_itimer *timer, union cpu_time_count now)
 511{
 512        /*
 513         * That's all for this thread or process.
 514         * We leave our residual in expires to be reported.
 515         */
 516        put_task_struct(timer->it.cpu.task);
 517        timer->it.cpu.task = NULL;
 518        timer->it.cpu.expires = cpu_time_sub(timer->it_clock,
 519                                             timer->it.cpu.expires,
 520                                             now);
 521}
 522
 523static inline int expires_gt(cputime_t expires, cputime_t new_exp)
 524{
 525        return expires == 0 || expires > new_exp;
 526}
 527
 528/*
 529 * Insert the timer on the appropriate list before any timers that
 530 * expire later.  This must be called with the tasklist_lock held
 531 * for reading, interrupts disabled and p->sighand->siglock taken.
 532 */
 533static void arm_timer(struct k_itimer *timer)
 534{
 535        struct task_struct *p = timer->it.cpu.task;
 536        struct list_head *head, *listpos;
 537        struct task_cputime *cputime_expires;
 538        struct cpu_timer_list *const nt = &timer->it.cpu;
 539        struct cpu_timer_list *next;
 540
 541        if (CPUCLOCK_PERTHREAD(timer->it_clock)) {
 542                head = p->cpu_timers;
 543                cputime_expires = &p->cputime_expires;
 544        } else {
 545                head = p->signal->cpu_timers;
 546                cputime_expires = &p->signal->cputime_expires;
 547        }
 548        head += CPUCLOCK_WHICH(timer->it_clock);
 549
 550        listpos = head;
 551        list_for_each_entry(next, head, entry) {
 552                if (cpu_time_before(timer->it_clock, nt->expires, next->expires))
 553                        break;
 554                listpos = &next->entry;
 555        }
 556        list_add(&nt->entry, listpos);
 557
 558        if (listpos == head) {
 559                union cpu_time_count *exp = &nt->expires;
 560
 561                /*
 562                 * We are the new earliest-expiring POSIX 1.b timer, hence
 563                 * need to update expiration cache. Take into account that
 564                 * for process timers we share expiration cache with itimers
 565                 * and RLIMIT_CPU and for thread timers with RLIMIT_RTTIME.
 566                 */
 567
 568                switch (CPUCLOCK_WHICH(timer->it_clock)) {
 569                case CPUCLOCK_PROF:
 570                        if (expires_gt(cputime_expires->prof_exp, exp->cpu))
 571                                cputime_expires->prof_exp = exp->cpu;
 572                        break;
 573                case CPUCLOCK_VIRT:
 574                        if (expires_gt(cputime_expires->virt_exp, exp->cpu))
 575                                cputime_expires->virt_exp = exp->cpu;
 576                        break;
 577                case CPUCLOCK_SCHED:
 578                        if (cputime_expires->sched_exp == 0 ||
 579                            cputime_expires->sched_exp > exp->sched)
 580                                cputime_expires->sched_exp = exp->sched;
 581                        break;
 582                }
 583        }
 584}
 585
 586/*
 587 * The timer is locked, fire it and arrange for its reload.
 588 */
 589static void cpu_timer_fire(struct k_itimer *timer)
 590{
 591        if ((timer->it_sigev_notify & ~SIGEV_THREAD_ID) == SIGEV_NONE) {
 592                /*
 593                 * User don't want any signal.
 594                 */
 595                timer->it.cpu.expires.sched = 0;
 596        } else if (unlikely(timer->sigq == NULL)) {
 597                /*
 598                 * This a special case for clock_nanosleep,
 599                 * not a normal timer from sys_timer_create.
 600                 */
 601                wake_up_process(timer->it_process);
 602                timer->it.cpu.expires.sched = 0;
 603        } else if (timer->it.cpu.incr.sched == 0) {
 604                /*
 605                 * One-shot timer.  Clear it as soon as it's fired.
 606                 */
 607                posix_timer_event(timer, 0);
 608                timer->it.cpu.expires.sched = 0;
 609        } else if (posix_timer_event(timer, ++timer->it_requeue_pending)) {
 610                /*
 611                 * The signal did not get queued because the signal
 612                 * was ignored, so we won't get any callback to
 613                 * reload the timer.  But we need to keep it
 614                 * ticking in case the signal is deliverable next time.
 615                 */
 616                posix_cpu_timer_schedule(timer);
 617        }
 618}
 619
 620/*
 621 * Sample a process (thread group) timer for the given group_leader task.
 622 * Must be called with tasklist_lock held for reading.
 623 */
 624static int cpu_timer_sample_group(const clockid_t which_clock,
 625                                  struct task_struct *p,
 626                                  union cpu_time_count *cpu)
 627{
 628        struct task_cputime cputime;
 629
 630        thread_group_cputimer(p, &cputime);
 631        switch (CPUCLOCK_WHICH(which_clock)) {
 632        default:
 633                return -EINVAL;
 634        case CPUCLOCK_PROF:
 635                cpu->cpu = cputime.utime + cputime.stime;
 636                break;
 637        case CPUCLOCK_VIRT:
 638                cpu->cpu = cputime.utime;
 639                break;
 640        case CPUCLOCK_SCHED:
 641                cpu->sched = cputime.sum_exec_runtime + task_delta_exec(p);
 642                break;
 643        }
 644        return 0;
 645}
 646
 647/*
 648 * Guts of sys_timer_settime for CPU timers.
 649 * This is called with the timer locked and interrupts disabled.
 650 * If we return TIMER_RETRY, it's necessary to release the timer's lock
 651 * and try again.  (This happens when the timer is in the middle of firing.)
 652 */
 653static int posix_cpu_timer_set(struct k_itimer *timer, int flags,
 654                               struct itimerspec *new, struct itimerspec *old)
 655{
 656        struct task_struct *p = timer->it.cpu.task;
 657        union cpu_time_count old_expires, new_expires, old_incr, val;
 658        int ret;
 659
 660        if (unlikely(p == NULL)) {
 661                /*
 662                 * Timer refers to a dead task's clock.
 663                 */
 664                return -ESRCH;
 665        }
 666
 667        new_expires = timespec_to_sample(timer->it_clock, &new->it_value);
 668
 669        read_lock(&tasklist_lock);
 670        /*
 671         * We need the tasklist_lock to protect against reaping that
 672         * clears p->sighand.  If p has just been reaped, we can no
 673         * longer get any information about it at all.
 674         */
 675        if (unlikely(p->sighand == NULL)) {
 676                read_unlock(&tasklist_lock);
 677                put_task_struct(p);
 678                timer->it.cpu.task = NULL;
 679                return -ESRCH;
 680        }
 681
 682        /*
 683         * Disarm any old timer after extracting its expiry time.
 684         */
 685        BUG_ON(!irqs_disabled());
 686
 687        ret = 0;
 688        old_incr = timer->it.cpu.incr;
 689        spin_lock(&p->sighand->siglock);
 690        old_expires = timer->it.cpu.expires;
 691        if (unlikely(timer->it.cpu.firing)) {
 692                timer->it.cpu.firing = -1;
 693                ret = TIMER_RETRY;
 694        } else
 695                list_del_init(&timer->it.cpu.entry);
 696
 697        /*
 698         * We need to sample the current value to convert the new
 699         * value from to relative and absolute, and to convert the
 700         * old value from absolute to relative.  To set a process
 701         * timer, we need a sample to balance the thread expiry
 702         * times (in arm_timer).  With an absolute time, we must
 703         * check if it's already passed.  In short, we need a sample.
 704         */
 705        if (CPUCLOCK_PERTHREAD(timer->it_clock)) {
 706                cpu_clock_sample(timer->it_clock, p, &val);
 707        } else {
 708                cpu_timer_sample_group(timer->it_clock, p, &val);
 709        }
 710
 711        if (old) {
 712                if (old_expires.sched == 0) {
 713                        old->it_value.tv_sec = 0;
 714                        old->it_value.tv_nsec = 0;
 715                } else {
 716                        /*
 717                         * Update the timer in case it has
 718                         * overrun already.  If it has,
 719                         * we'll report it as having overrun
 720                         * and with the next reloaded timer
 721                         * already ticking, though we are
 722                         * swallowing that pending
 723                         * notification here to install the
 724                         * new setting.
 725                         */
 726                        bump_cpu_timer(timer, val);
 727                        if (cpu_time_before(timer->it_clock, val,
 728                                            timer->it.cpu.expires)) {
 729                                old_expires = cpu_time_sub(
 730                                        timer->it_clock,
 731                                        timer->it.cpu.expires, val);
 732                                sample_to_timespec(timer->it_clock,
 733                                                   old_expires,
 734                                                   &old->it_value);
 735                        } else {
 736                                old->it_value.tv_nsec = 1;
 737                                old->it_value.tv_sec = 0;
 738                        }
 739                }
 740        }
 741
 742        if (unlikely(ret)) {
 743                /*
 744                 * We are colliding with the timer actually firing.
 745                 * Punt after filling in the timer's old value, and
 746                 * disable this firing since we are already reporting
 747                 * it as an overrun (thanks to bump_cpu_timer above).
 748                 */
 749                spin_unlock(&p->sighand->siglock);
 750                read_unlock(&tasklist_lock);
 751                goto out;
 752        }
 753
 754        if (new_expires.sched != 0 && !(flags & TIMER_ABSTIME)) {
 755                cpu_time_add(timer->it_clock, &new_expires, val);
 756        }
 757
 758        /*
 759         * Install the new expiry time (or zero).
 760         * For a timer with no notification action, we don't actually
 761         * arm the timer (we'll just fake it for timer_gettime).
 762         */
 763        timer->it.cpu.expires = new_expires;
 764        if (new_expires.sched != 0 &&
 765            cpu_time_before(timer->it_clock, val, new_expires)) {
 766                arm_timer(timer);
 767        }
 768
 769        spin_unlock(&p->sighand->siglock);
 770        read_unlock(&tasklist_lock);
 771
 772        /*
 773         * Install the new reload setting, and
 774         * set up the signal and overrun bookkeeping.
 775         */
 776        timer->it.cpu.incr = timespec_to_sample(timer->it_clock,
 777                                                &new->it_interval);
 778
 779        /*
 780         * This acts as a modification timestamp for the timer,
 781         * so any automatic reload attempt will punt on seeing
 782         * that we have reset the timer manually.
 783         */
 784        timer->it_requeue_pending = (timer->it_requeue_pending + 2) &
 785                ~REQUEUE_PENDING;
 786        timer->it_overrun_last = 0;
 787        timer->it_overrun = -1;
 788
 789        if (new_expires.sched != 0 &&
 790            !cpu_time_before(timer->it_clock, val, new_expires)) {
 791                /*
 792                 * The designated time already passed, so we notify
 793                 * immediately, even if the thread never runs to
 794                 * accumulate more time on this clock.
 795                 */
 796                cpu_timer_fire(timer);
 797        }
 798
 799        ret = 0;
 800 out:
 801        if (old) {
 802                sample_to_timespec(timer->it_clock,
 803                                   old_incr, &old->it_interval);
 804        }
 805        return ret;
 806}
 807
 808static void posix_cpu_timer_get(struct k_itimer *timer, struct itimerspec *itp)
 809{
 810        union cpu_time_count now;
 811        struct task_struct *p = timer->it.cpu.task;
 812        int clear_dead;
 813
 814        /*
 815         * Easy part: convert the reload time.
 816         */
 817        sample_to_timespec(timer->it_clock,
 818                           timer->it.cpu.incr, &itp->it_interval);
 819
 820        if (timer->it.cpu.expires.sched == 0) { /* Timer not armed at all.  */
 821                itp->it_value.tv_sec = itp->it_value.tv_nsec = 0;
 822                return;
 823        }
 824
 825        if (unlikely(p == NULL)) {
 826                /*
 827                 * This task already died and the timer will never fire.
 828                 * In this case, expires is actually the dead value.
 829                 */
 830        dead:
 831                sample_to_timespec(timer->it_clock, timer->it.cpu.expires,
 832                                   &itp->it_value);
 833                return;
 834        }
 835
 836        /*
 837         * Sample the clock to take the difference with the expiry time.
 838         */
 839        if (CPUCLOCK_PERTHREAD(timer->it_clock)) {
 840                cpu_clock_sample(timer->it_clock, p, &now);
 841                clear_dead = p->exit_state;
 842        } else {
 843                read_lock(&tasklist_lock);
 844                if (unlikely(p->sighand == NULL)) {
 845                        /*
 846                         * The process has been reaped.
 847                         * We can't even collect a sample any more.
 848                         * Call the timer disarmed, nothing else to do.
 849                         */
 850                        put_task_struct(p);
 851                        timer->it.cpu.task = NULL;
 852                        timer->it.cpu.expires.sched = 0;
 853                        read_unlock(&tasklist_lock);
 854                        goto dead;
 855                } else {
 856                        cpu_timer_sample_group(timer->it_clock, p, &now);
 857                        clear_dead = (unlikely(p->exit_state) &&
 858                                      thread_group_empty(p));
 859                }
 860                read_unlock(&tasklist_lock);
 861        }
 862
 863        if (unlikely(clear_dead)) {
 864                /*
 865                 * We've noticed that the thread is dead, but
 866                 * not yet reaped.  Take this opportunity to
 867                 * drop our task ref.
 868                 */
 869                clear_dead_task(timer, now);
 870                goto dead;
 871        }
 872
 873        if (cpu_time_before(timer->it_clock, now, timer->it.cpu.expires)) {
 874                sample_to_timespec(timer->it_clock,
 875                                   cpu_time_sub(timer->it_clock,
 876                                                timer->it.cpu.expires, now),
 877                                   &itp->it_value);
 878        } else {
 879                /*
 880                 * The timer should have expired already, but the firing
 881                 * hasn't taken place yet.  Say it's just about to expire.
 882                 */
 883                itp->it_value.tv_nsec = 1;
 884                itp->it_value.tv_sec = 0;
 885        }
 886}
 887
 888/*
 889 * Check for any per-thread CPU timers that have fired and move them off
 890 * the tsk->cpu_timers[N] list onto the firing list.  Here we update the
 891 * tsk->it_*_expires values to reflect the remaining thread CPU timers.
 892 */
 893static void check_thread_timers(struct task_struct *tsk,
 894                                struct list_head *firing)
 895{
 896        int maxfire;
 897        struct list_head *timers = tsk->cpu_timers;
 898        struct signal_struct *const sig = tsk->signal;
 899        unsigned long soft;
 900
 901        maxfire = 20;
 902        tsk->cputime_expires.prof_exp = 0;
 903        while (!list_empty(timers)) {
 904                struct cpu_timer_list *t = list_first_entry(timers,
 905                                                      struct cpu_timer_list,
 906                                                      entry);
 907                if (!--maxfire || prof_ticks(tsk) < t->expires.cpu) {
 908                        tsk->cputime_expires.prof_exp = t->expires.cpu;
 909                        break;
 910                }
 911                t->firing = 1;
 912                list_move_tail(&t->entry, firing);
 913        }
 914
 915        ++timers;
 916        maxfire = 20;
 917        tsk->cputime_expires.virt_exp = 0;
 918        while (!list_empty(timers)) {
 919                struct cpu_timer_list *t = list_first_entry(timers,
 920                                                      struct cpu_timer_list,
 921                                                      entry);
 922                if (!--maxfire || virt_ticks(tsk) < t->expires.cpu) {
 923                        tsk->cputime_expires.virt_exp = t->expires.cpu;
 924                        break;
 925                }
 926                t->firing = 1;
 927                list_move_tail(&t->entry, firing);
 928        }
 929
 930        ++timers;
 931        maxfire = 20;
 932        tsk->cputime_expires.sched_exp = 0;
 933        while (!list_empty(timers)) {
 934                struct cpu_timer_list *t = list_first_entry(timers,
 935                                                      struct cpu_timer_list,
 936                                                      entry);
 937                if (!--maxfire || tsk->se.sum_exec_runtime < t->expires.sched) {
 938                        tsk->cputime_expires.sched_exp = t->expires.sched;
 939                        break;
 940                }
 941                t->firing = 1;
 942                list_move_tail(&t->entry, firing);
 943        }
 944
 945        /*
 946         * Check for the special case thread timers.
 947         */
 948        soft = ACCESS_ONCE(sig->rlim[RLIMIT_RTTIME].rlim_cur);
 949        if (soft != RLIM_INFINITY) {
 950                unsigned long hard =
 951                        ACCESS_ONCE(sig->rlim[RLIMIT_RTTIME].rlim_max);
 952
 953                if (hard != RLIM_INFINITY &&
 954                    tsk->rt.timeout > DIV_ROUND_UP(hard, USEC_PER_SEC/HZ)) {
 955                        /*
 956                         * At the hard limit, we just die.
 957                         * No need to calculate anything else now.
 958                         */
 959                        __group_send_sig_info(SIGKILL, SEND_SIG_PRIV, tsk);
 960                        return;
 961                }
 962                if (tsk->rt.timeout > DIV_ROUND_UP(soft, USEC_PER_SEC/HZ)) {
 963                        /*
 964                         * At the soft limit, send a SIGXCPU every second.
 965                         */
 966                        if (soft < hard) {
 967                                soft += USEC_PER_SEC;
 968                                sig->rlim[RLIMIT_RTTIME].rlim_cur = soft;
 969                        }
 970                        printk(KERN_INFO
 971                                "RT Watchdog Timeout: %s[%d]\n",
 972                                tsk->comm, task_pid_nr(tsk));
 973                        __group_send_sig_info(SIGXCPU, SEND_SIG_PRIV, tsk);
 974                }
 975        }
 976}
 977
 978static void stop_process_timers(struct signal_struct *sig)
 979{
 980        struct thread_group_cputimer *cputimer = &sig->cputimer;
 981        unsigned long flags;
 982
 983        raw_spin_lock_irqsave(&cputimer->lock, flags);
 984        cputimer->running = 0;
 985        raw_spin_unlock_irqrestore(&cputimer->lock, flags);
 986}
 987
 988static u32 onecputick;
 989
 990static void check_cpu_itimer(struct task_struct *tsk, struct cpu_itimer *it,
 991                             cputime_t *expires, cputime_t cur_time, int signo)
 992{
 993        if (!it->expires)
 994                return;
 995
 996        if (cur_time >= it->expires) {
 997                if (it->incr) {
 998                        it->expires += it->incr;
 999                        it->error += it->incr_error;
1000                        if (it->error >= onecputick) {
1001                                it->expires -= cputime_one_jiffy;
1002                                it->error -= onecputick;
1003                        }
1004                } else {
1005                        it->expires = 0;
1006                }
1007
1008                trace_itimer_expire(signo == SIGPROF ?
1009                                    ITIMER_PROF : ITIMER_VIRTUAL,
1010                                    tsk->signal->leader_pid, cur_time);
1011                __group_send_sig_info(signo, SEND_SIG_PRIV, tsk);
1012        }
1013
1014        if (it->expires && (!*expires || it->expires < *expires)) {
1015                *expires = it->expires;
1016        }
1017}
1018
1019/**
1020 * task_cputime_zero - Check a task_cputime struct for all zero fields.
1021 *
1022 * @cputime:    The struct to compare.
1023 *
1024 * Checks @cputime to see if all fields are zero.  Returns true if all fields
1025 * are zero, false if any field is nonzero.
1026 */
1027static inline int task_cputime_zero(const struct task_cputime *cputime)
1028{
1029        if (!cputime->utime && !cputime->stime && !cputime->sum_exec_runtime)
1030                return 1;
1031        return 0;
1032}
1033
1034/*
1035 * Check for any per-thread CPU timers that have fired and move them
1036 * off the tsk->*_timers list onto the firing list.  Per-thread timers
1037 * have already been taken off.
1038 */
1039static void check_process_timers(struct task_struct *tsk,
1040                                 struct list_head *firing)
1041{
1042        int maxfire;
1043        struct signal_struct *const sig = tsk->signal;
1044        cputime_t utime, ptime, virt_expires, prof_expires;
1045        unsigned long long sum_sched_runtime, sched_expires;
1046        struct list_head *timers = sig->cpu_timers;
1047        struct task_cputime cputime;
1048        unsigned long soft;
1049
1050        /*
1051         * Collect the current process totals.
1052         */
1053        thread_group_cputimer(tsk, &cputime);
1054        utime = cputime.utime;
1055        ptime = utime + cputime.stime;
1056        sum_sched_runtime = cputime.sum_exec_runtime;
1057        maxfire = 20;
1058        prof_expires = 0;
1059        while (!list_empty(timers)) {
1060                struct cpu_timer_list *tl = list_first_entry(timers,
1061                                                      struct cpu_timer_list,
1062                                                      entry);
1063                if (!--maxfire || ptime < tl->expires.cpu) {
1064                        prof_expires = tl->expires.cpu;
1065                        break;
1066                }
1067                tl->firing = 1;
1068                list_move_tail(&tl->entry, firing);
1069        }
1070
1071        ++timers;
1072        maxfire = 20;
1073        virt_expires = 0;
1074        while (!list_empty(timers)) {
1075                struct cpu_timer_list *tl = list_first_entry(timers,
1076                                                      struct cpu_timer_list,
1077                                                      entry);
1078                if (!--maxfire || utime < tl->expires.cpu) {
1079                        virt_expires = tl->expires.cpu;
1080                        break;
1081                }
1082                tl->firing = 1;
1083                list_move_tail(&tl->entry, firing);
1084        }
1085
1086        ++timers;
1087        maxfire = 20;
1088        sched_expires = 0;
1089        while (!list_empty(timers)) {
1090                struct cpu_timer_list *tl = list_first_entry(timers,
1091                                                      struct cpu_timer_list,
1092                                                      entry);
1093                if (!--maxfire || sum_sched_runtime < tl->expires.sched) {
1094                        sched_expires = tl->expires.sched;
1095                        break;
1096                }
1097                tl->firing = 1;
1098                list_move_tail(&tl->entry, firing);
1099        }
1100
1101        /*
1102         * Check for the special case process timers.
1103         */
1104        check_cpu_itimer(tsk, &sig->it[CPUCLOCK_PROF], &prof_expires, ptime,
1105                         SIGPROF);
1106        check_cpu_itimer(tsk, &sig->it[CPUCLOCK_VIRT], &virt_expires, utime,
1107                         SIGVTALRM);
1108        soft = ACCESS_ONCE(sig->rlim[RLIMIT_CPU].rlim_cur);
1109        if (soft != RLIM_INFINITY) {
1110                unsigned long psecs = cputime_to_secs(ptime);
1111                unsigned long hard =
1112                        ACCESS_ONCE(sig->rlim[RLIMIT_CPU].rlim_max);
1113                cputime_t x;
1114                if (psecs >= hard) {
1115                        /*
1116                         * At the hard limit, we just die.
1117                         * No need to calculate anything else now.
1118                         */
1119                        __group_send_sig_info(SIGKILL, SEND_SIG_PRIV, tsk);
1120                        return;
1121                }
1122                if (psecs >= soft) {
1123                        /*
1124                         * At the soft limit, send a SIGXCPU every second.
1125                         */
1126                        __group_send_sig_info(SIGXCPU, SEND_SIG_PRIV, tsk);
1127                        if (soft < hard) {
1128                                soft++;
1129                                sig->rlim[RLIMIT_CPU].rlim_cur = soft;
1130                        }
1131                }
1132                x = secs_to_cputime(soft);
1133                if (!prof_expires || x < prof_expires) {
1134                        prof_expires = x;
1135                }
1136        }
1137
1138        sig->cputime_expires.prof_exp = prof_expires;
1139        sig->cputime_expires.virt_exp = virt_expires;
1140        sig->cputime_expires.sched_exp = sched_expires;
1141        if (task_cputime_zero(&sig->cputime_expires))
1142                stop_process_timers(sig);
1143}
1144
1145/*
1146 * This is called from the signal code (via do_schedule_next_timer)
1147 * when the last timer signal was delivered and we have to reload the timer.
1148 */
1149void posix_cpu_timer_schedule(struct k_itimer *timer)
1150{
1151        struct task_struct *p = timer->it.cpu.task;
1152        union cpu_time_count now;
1153
1154        if (unlikely(p == NULL))
1155                /*
1156                 * The task was cleaned up already, no future firings.
1157                 */
1158                goto out;
1159
1160        /*
1161         * Fetch the current sample and update the timer's expiry time.
1162         */
1163        if (CPUCLOCK_PERTHREAD(timer->it_clock)) {
1164                cpu_clock_sample(timer->it_clock, p, &now);
1165                bump_cpu_timer(timer, now);
1166                if (unlikely(p->exit_state)) {
1167                        clear_dead_task(timer, now);
1168                        goto out;
1169                }
1170                read_lock(&tasklist_lock); /* arm_timer needs it.  */
1171                spin_lock(&p->sighand->siglock);
1172        } else {
1173                read_lock(&tasklist_lock);
1174                if (unlikely(p->sighand == NULL)) {
1175                        /*
1176                         * The process has been reaped.
1177                         * We can't even collect a sample any more.
1178                         */
1179                        put_task_struct(p);
1180                        timer->it.cpu.task = p = NULL;
1181                        timer->it.cpu.expires.sched = 0;
1182                        goto out_unlock;
1183                } else if (unlikely(p->exit_state) && thread_group_empty(p)) {
1184                        /*
1185                         * We've noticed that the thread is dead, but
1186                         * not yet reaped.  Take this opportunity to
1187                         * drop our task ref.
1188                         */
1189                        clear_dead_task(timer, now);
1190                        goto out_unlock;
1191                }
1192                spin_lock(&p->sighand->siglock);
1193                cpu_timer_sample_group(timer->it_clock, p, &now);
1194                bump_cpu_timer(timer, now);
1195                /* Leave the tasklist_lock locked for the call below.  */
1196        }
1197
1198        /*
1199         * Now re-arm for the new expiry time.
1200         */
1201        BUG_ON(!irqs_disabled());
1202        arm_timer(timer);
1203        spin_unlock(&p->sighand->siglock);
1204
1205out_unlock:
1206        read_unlock(&tasklist_lock);
1207
1208out:
1209        timer->it_overrun_last = timer->it_overrun;
1210        timer->it_overrun = -1;
1211        ++timer->it_requeue_pending;
1212}
1213
1214/**
1215 * task_cputime_expired - Compare two task_cputime entities.
1216 *
1217 * @sample:     The task_cputime structure to be checked for expiration.
1218 * @expires:    Expiration times, against which @sample will be checked.
1219 *
1220 * Checks @sample against @expires to see if any field of @sample has expired.
1221 * Returns true if any field of the former is greater than the corresponding
1222 * field of the latter if the latter field is set.  Otherwise returns false.
1223 */
1224static inline int task_cputime_expired(const struct task_cputime *sample,
1225                                        const struct task_cputime *expires)
1226{
1227        if (expires->utime && sample->utime >= expires->utime)
1228                return 1;
1229        if (expires->stime && sample->utime + sample->stime >= expires->stime)
1230                return 1;
1231        if (expires->sum_exec_runtime != 0 &&
1232            sample->sum_exec_runtime >= expires->sum_exec_runtime)
1233                return 1;
1234        return 0;
1235}
1236
1237/**
1238 * fastpath_timer_check - POSIX CPU timers fast path.
1239 *
1240 * @tsk:        The task (thread) being checked.
1241 *
1242 * Check the task and thread group timers.  If both are zero (there are no
1243 * timers set) return false.  Otherwise snapshot the task and thread group
1244 * timers and compare them with the corresponding expiration times.  Return
1245 * true if a timer has expired, else return false.
1246 */
1247static inline int fastpath_timer_check(struct task_struct *tsk)
1248{
1249        struct signal_struct *sig;
1250
1251        if (!task_cputime_zero(&tsk->cputime_expires)) {
1252                struct task_cputime task_sample = {
1253                        .utime = tsk->utime,
1254                        .stime = tsk->stime,
1255                        .sum_exec_runtime = tsk->se.sum_exec_runtime
1256                };
1257
1258                if (task_cputime_expired(&task_sample, &tsk->cputime_expires))
1259                        return 1;
1260        }
1261
1262        sig = tsk->signal;
1263        if (sig->cputimer.running) {
1264                struct task_cputime group_sample;
1265
1266                raw_spin_lock(&sig->cputimer.lock);
1267                group_sample = sig->cputimer.cputime;
1268                raw_spin_unlock(&sig->cputimer.lock);
1269
1270                if (task_cputime_expired(&group_sample, &sig->cputime_expires))
1271                        return 1;
1272        }
1273
1274        return 0;
1275}
1276
1277/*
1278 * This is called from the timer interrupt handler.  The irq handler has
1279 * already updated our counts.  We need to check if any timers fire now.
1280 * Interrupts are disabled.
1281 */
1282void run_posix_cpu_timers(struct task_struct *tsk)
1283{
1284        LIST_HEAD(firing);
1285        struct k_itimer *timer, *next;
1286        unsigned long flags;
1287
1288        BUG_ON(!irqs_disabled());
1289
1290        /*
1291         * The fast path checks that there are no expired thread or thread
1292         * group timers.  If that's so, just return.
1293         */
1294        if (!fastpath_timer_check(tsk))
1295                return;
1296
1297        if (!lock_task_sighand(tsk, &flags))
1298                return;
1299        /*
1300         * Here we take off tsk->signal->cpu_timers[N] and
1301         * tsk->cpu_timers[N] all the timers that are firing, and
1302         * put them on the firing list.
1303         */
1304        check_thread_timers(tsk, &firing);
1305        /*
1306         * If there are any active process wide timers (POSIX 1.b, itimers,
1307         * RLIMIT_CPU) cputimer must be running.
1308         */
1309        if (tsk->signal->cputimer.running)
1310                check_process_timers(tsk, &firing);
1311
1312        /*
1313         * We must release these locks before taking any timer's lock.
1314         * There is a potential race with timer deletion here, as the
1315         * siglock now protects our private firing list.  We have set
1316         * the firing flag in each timer, so that a deletion attempt
1317         * that gets the timer lock before we do will give it up and
1318         * spin until we've taken care of that timer below.
1319         */
1320        unlock_task_sighand(tsk, &flags);
1321
1322        /*
1323         * Now that all the timers on our list have the firing flag,
1324         * no one will touch their list entries but us.  We'll take
1325         * each timer's lock before clearing its firing flag, so no
1326         * timer call will interfere.
1327         */
1328        list_for_each_entry_safe(timer, next, &firing, it.cpu.entry) {
1329                int cpu_firing;
1330
1331                spin_lock(&timer->it_lock);
1332                list_del_init(&timer->it.cpu.entry);
1333                cpu_firing = timer->it.cpu.firing;
1334                timer->it.cpu.firing = 0;
1335                /*
1336                 * The firing flag is -1 if we collided with a reset
1337                 * of the timer, which already reported this
1338                 * almost-firing as an overrun.  So don't generate an event.
1339                 */
1340                if (likely(cpu_firing >= 0))
1341                        cpu_timer_fire(timer);
1342                spin_unlock(&timer->it_lock);
1343        }
1344}
1345
1346/*
1347 * Set one of the process-wide special case CPU timers or RLIMIT_CPU.
1348 * The tsk->sighand->siglock must be held by the caller.
1349 */
1350void set_process_cpu_timer(struct task_struct *tsk, unsigned int clock_idx,
1351                           cputime_t *newval, cputime_t *oldval)
1352{
1353        union cpu_time_count now;
1354
1355        BUG_ON(clock_idx == CPUCLOCK_SCHED);
1356        cpu_timer_sample_group(clock_idx, tsk, &now);
1357
1358        if (oldval) {
1359                /*
1360                 * We are setting itimer. The *oldval is absolute and we update
1361                 * it to be relative, *newval argument is relative and we update
1362                 * it to be absolute.
1363                 */
1364                if (*oldval) {
1365                        if (*oldval <= now.cpu) {
1366                                /* Just about to fire. */
1367                                *oldval = cputime_one_jiffy;
1368                        } else {
1369                                *oldval -= now.cpu;
1370                        }
1371                }
1372
1373                if (!*newval)
1374                        return;
1375                *newval += now.cpu;
1376        }
1377
1378        /*
1379         * Update expiration cache if we are the earliest timer, or eventually
1380         * RLIMIT_CPU limit is earlier than prof_exp cpu timer expire.
1381         */
1382        switch (clock_idx) {
1383        case CPUCLOCK_PROF:
1384                if (expires_gt(tsk->signal->cputime_expires.prof_exp, *newval))
1385                        tsk->signal->cputime_expires.prof_exp = *newval;
1386                break;
1387        case CPUCLOCK_VIRT:
1388                if (expires_gt(tsk->signal->cputime_expires.virt_exp, *newval))
1389                        tsk->signal->cputime_expires.virt_exp = *newval;
1390                break;
1391        }
1392}
1393
1394static int do_cpu_nanosleep(const clockid_t which_clock, int flags,
1395                            struct timespec *rqtp, struct itimerspec *it)
1396{
1397        struct k_itimer timer;
1398        int error;
1399
1400        /*
1401         * Set up a temporary timer and then wait for it to go off.
1402         */
1403        memset(&timer, 0, sizeof timer);
1404        spin_lock_init(&timer.it_lock);
1405        timer.it_clock = which_clock;
1406        timer.it_overrun = -1;
1407        error = posix_cpu_timer_create(&timer);
1408        timer.it_process = current;
1409        if (!error) {
1410                static struct itimerspec zero_it;
1411
1412                memset(it, 0, sizeof *it);
1413                it->it_value = *rqtp;
1414
1415                spin_lock_irq(&timer.it_lock);
1416                error = posix_cpu_timer_set(&timer, flags, it, NULL);
1417                if (error) {
1418                        spin_unlock_irq(&timer.it_lock);
1419                        return error;
1420                }
1421
1422                while (!signal_pending(current)) {
1423                        if (timer.it.cpu.expires.sched == 0) {
1424                                /*
1425                                 * Our timer fired and was reset.
1426                                 */
1427                                spin_unlock_irq(&timer.it_lock);
1428                                return 0;
1429                        }
1430
1431                        /*
1432                         * Block until cpu_timer_fire (or a signal) wakes us.
1433                         */
1434                        __set_current_state(TASK_INTERRUPTIBLE);
1435                        spin_unlock_irq(&timer.it_lock);
1436                        schedule();
1437                        spin_lock_irq(&timer.it_lock);
1438                }
1439
1440                /*
1441                 * We were interrupted by a signal.
1442                 */
1443                sample_to_timespec(which_clock, timer.it.cpu.expires, rqtp);
1444                posix_cpu_timer_set(&timer, 0, &zero_it, it);
1445                spin_unlock_irq(&timer.it_lock);
1446
1447                if ((it->it_value.tv_sec | it->it_value.tv_nsec) == 0) {
1448                        /*
1449                         * It actually did fire already.
1450                         */
1451                        return 0;
1452                }
1453
1454                error = -ERESTART_RESTARTBLOCK;
1455        }
1456
1457        return error;
1458}
1459
1460static long posix_cpu_nsleep_restart(struct restart_block *restart_block);
1461
1462static int posix_cpu_nsleep(const clockid_t which_clock, int flags,
1463                            struct timespec *rqtp, struct timespec __user *rmtp)
1464{
1465        struct restart_block *restart_block =
1466                &current_thread_info()->restart_block;
1467        struct itimerspec it;
1468        int error;
1469
1470        /*
1471         * Diagnose required errors first.
1472         */
1473        if (CPUCLOCK_PERTHREAD(which_clock) &&
1474            (CPUCLOCK_PID(which_clock) == 0 ||
1475             CPUCLOCK_PID(which_clock) == current->pid))
1476                return -EINVAL;
1477
1478        error = do_cpu_nanosleep(which_clock, flags, rqtp, &it);
1479
1480        if (error == -ERESTART_RESTARTBLOCK) {
1481
1482                if (flags & TIMER_ABSTIME)
1483                        return -ERESTARTNOHAND;
1484                /*
1485                 * Report back to the user the time still remaining.
1486                 */
1487                if (rmtp && copy_to_user(rmtp, &it.it_value, sizeof *rmtp))
1488                        return -EFAULT;
1489
1490                restart_block->fn = posix_cpu_nsleep_restart;
1491                restart_block->nanosleep.clockid = which_clock;
1492                restart_block->nanosleep.rmtp = rmtp;
1493                restart_block->nanosleep.expires = timespec_to_ns(rqtp);
1494        }
1495        return error;
1496}
1497
1498static long posix_cpu_nsleep_restart(struct restart_block *restart_block)
1499{
1500        clockid_t which_clock = restart_block->nanosleep.clockid;
1501        struct timespec t;
1502        struct itimerspec it;
1503        int error;
1504
1505        t = ns_to_timespec(restart_block->nanosleep.expires);
1506
1507        error = do_cpu_nanosleep(which_clock, TIMER_ABSTIME, &t, &it);
1508
1509        if (error == -ERESTART_RESTARTBLOCK) {
1510                struct timespec __user *rmtp = restart_block->nanosleep.rmtp;
1511                /*
1512                 * Report back to the user the time still remaining.
1513                 */
1514                if (rmtp && copy_to_user(rmtp, &it.it_value, sizeof *rmtp))
1515                        return -EFAULT;
1516
1517                restart_block->nanosleep.expires = timespec_to_ns(&t);
1518        }
1519        return error;
1520
1521}
1522
1523#define PROCESS_CLOCK   MAKE_PROCESS_CPUCLOCK(0, CPUCLOCK_SCHED)
1524#define THREAD_CLOCK    MAKE_THREAD_CPUCLOCK(0, CPUCLOCK_SCHED)
1525
1526static int process_cpu_clock_getres(const clockid_t which_clock,
1527                                    struct timespec *tp)
1528{
1529        return posix_cpu_clock_getres(PROCESS_CLOCK, tp);
1530}
1531static int process_cpu_clock_get(const clockid_t which_clock,
1532                                 struct timespec *tp)
1533{
1534        return posix_cpu_clock_get(PROCESS_CLOCK, tp);
1535}
1536static int process_cpu_timer_create(struct k_itimer *timer)
1537{
1538        timer->it_clock = PROCESS_CLOCK;
1539        return posix_cpu_timer_create(timer);
1540}
1541static int process_cpu_nsleep(const clockid_t which_clock, int flags,
1542                              struct timespec *rqtp,
1543                              struct timespec __user *rmtp)
1544{
1545        return posix_cpu_nsleep(PROCESS_CLOCK, flags, rqtp, rmtp);
1546}
1547static long process_cpu_nsleep_restart(struct restart_block *restart_block)
1548{
1549        return -EINVAL;
1550}
1551static int thread_cpu_clock_getres(const clockid_t which_clock,
1552                                   struct timespec *tp)
1553{
1554        return posix_cpu_clock_getres(THREAD_CLOCK, tp);
1555}
1556static int thread_cpu_clock_get(const clockid_t which_clock,
1557                                struct timespec *tp)
1558{
1559        return posix_cpu_clock_get(THREAD_CLOCK, tp);
1560}
1561static int thread_cpu_timer_create(struct k_itimer *timer)
1562{
1563        timer->it_clock = THREAD_CLOCK;
1564        return posix_cpu_timer_create(timer);
1565}
1566
1567struct k_clock clock_posix_cpu = {
1568        .clock_getres   = posix_cpu_clock_getres,
1569        .clock_set      = posix_cpu_clock_set,
1570        .clock_get      = posix_cpu_clock_get,
1571        .timer_create   = posix_cpu_timer_create,
1572        .nsleep         = posix_cpu_nsleep,
1573        .nsleep_restart = posix_cpu_nsleep_restart,
1574        .timer_set      = posix_cpu_timer_set,
1575        .timer_del      = posix_cpu_timer_del,
1576        .timer_get      = posix_cpu_timer_get,
1577};
1578
1579static __init int init_posix_cpu_timers(void)
1580{
1581        struct k_clock process = {
1582                .clock_getres   = process_cpu_clock_getres,
1583                .clock_get      = process_cpu_clock_get,
1584                .timer_create   = process_cpu_timer_create,
1585                .nsleep         = process_cpu_nsleep,
1586                .nsleep_restart = process_cpu_nsleep_restart,
1587        };
1588        struct k_clock thread = {
1589                .clock_getres   = thread_cpu_clock_getres,
1590                .clock_get      = thread_cpu_clock_get,
1591                .timer_create   = thread_cpu_timer_create,
1592        };
1593        struct timespec ts;
1594
1595        posix_timers_register_clock(CLOCK_PROCESS_CPUTIME_ID, &process);
1596        posix_timers_register_clock(CLOCK_THREAD_CPUTIME_ID, &thread);
1597
1598        cputime_to_timespec(cputime_one_jiffy, &ts);
1599        onecputick = ts.tv_nsec;
1600        WARN_ON(ts.tv_sec != 0);
1601
1602        return 0;
1603}
1604__initcall(init_posix_cpu_timers);
1605
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