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
  14/*
  15 * Called after updating RLIMIT_CPU to run cpu timer and update
  16 * tsk->signal->cputime_expires expiration cache if necessary. Needs
  17 * siglock protection since other code may update expiration cache as
  18 * well.
  19 */
  20void update_rlimit_cpu(struct task_struct *task, unsigned long rlim_new)
  21{
  22        cputime_t cputime = secs_to_cputime(rlim_new);
  23
  24        spin_lock_irq(&task->sighand->siglock);
  25        set_process_cpu_timer(task, CPUCLOCK_PROF, &cputime, NULL);
  26        spin_unlock_irq(&task->sighand->siglock);
  27}
  28
  29static int check_clock(const clockid_t which_clock)
  30{
  31        int error = 0;
  32        struct task_struct *p;
  33        const pid_t pid = CPUCLOCK_PID(which_clock);
  34
  35        if (CPUCLOCK_WHICH(which_clock) >= CPUCLOCK_MAX)
  36                return -EINVAL;
  37
  38        if (pid == 0)
  39                return 0;
  40
  41        rcu_read_lock();
  42        p = find_task_by_vpid(pid);
  43        if (!p || !(CPUCLOCK_PERTHREAD(which_clock) ?
  44                   same_thread_group(p, current) : has_group_leader_pid(p))) {
  45                error = -EINVAL;
  46        }
  47        rcu_read_unlock();
  48
  49        return error;
  50}
  51
  52static inline union cpu_time_count
  53timespec_to_sample(const clockid_t which_clock, const struct timespec *tp)
  54{
  55        union cpu_time_count ret;
  56        ret.sched = 0;          /* high half always zero when .cpu used */
  57        if (CPUCLOCK_WHICH(which_clock) == CPUCLOCK_SCHED) {
  58                ret.sched = (unsigned long long)tp->tv_sec * NSEC_PER_SEC + tp->tv_nsec;
  59        } else {
  60                ret.cpu = timespec_to_cputime(tp);
  61        }
  62        return ret;
  63}
  64
  65static void sample_to_timespec(const clockid_t which_clock,
  66                               union cpu_time_count cpu,
  67                               struct timespec *tp)
  68{
  69        if (CPUCLOCK_WHICH(which_clock) == CPUCLOCK_SCHED)
  70                *tp = ns_to_timespec(cpu.sched);
  71        else
  72                cputime_to_timespec(cpu.cpu, tp);
  73}
  74
  75static inline int cpu_time_before(const clockid_t which_clock,
  76                                  union cpu_time_count now,
  77                                  union cpu_time_count then)
  78{
  79        if (CPUCLOCK_WHICH(which_clock) == CPUCLOCK_SCHED) {
  80                return now.sched < then.sched;
  81        }  else {
  82                return now.cpu < then.cpu;
  83        }
  84}
  85static inline void cpu_time_add(const clockid_t which_clock,
  86                                union cpu_time_count *acc,
  87                                union cpu_time_count val)
  88{
  89        if (CPUCLOCK_WHICH(which_clock) == CPUCLOCK_SCHED) {
  90                acc->sched += val.sched;
  91        }  else {
  92                acc->cpu += val.cpu;
  93        }
  94}
  95static inline union cpu_time_count cpu_time_sub(const clockid_t which_clock,
  96                                                union cpu_time_count a,
  97                                                union cpu_time_count b)
  98{
  99        if (CPUCLOCK_WHICH(which_clock) == CPUCLOCK_SCHED) {
 100                a.sched -= b.sched;
 101        }  else {
 102                a.cpu -= b.cpu;
 103        }
 104        return a;
 105}
 106
 107/*
 108 * Update expiry time from increment, and increase overrun count,
 109 * given the current clock sample.
 110 */
 111static void bump_cpu_timer(struct k_itimer *timer,
 112                                  union cpu_time_count now)
 113{
 114        int i;
 115
 116        if (timer->it.cpu.incr.sched == 0)
 117                return;
 118
 119        if (CPUCLOCK_WHICH(timer->it_clock) == CPUCLOCK_SCHED) {
 120                unsigned long long delta, incr;
 121
 122                if (now.sched < timer->it.cpu.expires.sched)
 123                        return;
 124                incr = timer->it.cpu.incr.sched;
 125                delta = now.sched + incr - timer->it.cpu.expires.sched;
 126                /* Don't use (incr*2 < delta), incr*2 might overflow. */
 127                for (i = 0; incr < delta - incr; i++)
 128                        incr = incr << 1;
 129                for (; i >= 0; incr >>= 1, i--) {
 130                        if (delta < incr)
 131                                continue;
 132                        timer->it.cpu.expires.sched += incr;
 133                        timer->it_overrun += 1 << i;
 134                        delta -= incr;
 135                }
 136        } else {
 137                cputime_t delta, incr;
 138
 139                if (now.cpu < timer->it.cpu.expires.cpu)
 140                        return;
 141                incr = timer->it.cpu.incr.cpu;
 142                delta = now.cpu + incr - timer->it.cpu.expires.cpu;
 143                /* Don't use (incr*2 < delta), incr*2 might overflow. */
 144                for (i = 0; incr < delta - incr; i++)
 145                             incr += incr;
 146                for (; i >= 0; incr = incr >> 1, i--) {
 147                        if (delta < incr)
 148                                continue;
 149                        timer->it.cpu.expires.cpu += incr;
 150                        timer->it_overrun += 1 << i;
 151                        delta -= incr;
 152                }
 153        }
 154}
 155
 156static inline cputime_t prof_ticks(struct task_struct *p)
 157{
 158        cputime_t utime, stime;
 159
 160        task_cputime(p, &utime, &stime);
 161
 162        return utime + stime;
 163}
 164static inline cputime_t virt_ticks(struct task_struct *p)
 165{
 166        cputime_t utime;
 167
 168        task_cputime(p, &utime, NULL);
 169
 170        return utime;
 171}
 172
 173static int
 174posix_cpu_clock_getres(const clockid_t which_clock, struct timespec *tp)
 175{
 176        int error = check_clock(which_clock);
 177        if (!error) {
 178                tp->tv_sec = 0;
 179                tp->tv_nsec = ((NSEC_PER_SEC + HZ - 1) / HZ);
 180                if (CPUCLOCK_WHICH(which_clock) == CPUCLOCK_SCHED) {
 181                        /*
 182                         * If sched_clock is using a cycle counter, we
 183                         * don't have any idea of its true resolution
 184                         * exported, but it is much more than 1s/HZ.
 185                         */
 186                        tp->tv_nsec = 1;
 187                }
 188        }
 189        return error;
 190}
 191
 192static int
 193posix_cpu_clock_set(const clockid_t which_clock, const struct timespec *tp)
 194{
 195        /*
 196         * You can never reset a CPU clock, but we check for other errors
 197         * in the call before failing with EPERM.
 198         */
 199        int error = check_clock(which_clock);
 200        if (error == 0) {
 201                error = -EPERM;
 202        }
 203        return error;
 204}
 205
 206
 207/*
 208 * Sample a per-thread clock for the given task.
 209 */
 210static int cpu_clock_sample(const clockid_t which_clock, struct task_struct *p,
 211                            union cpu_time_count *cpu)
 212{
 213        switch (CPUCLOCK_WHICH(which_clock)) {
 214        default:
 215                return -EINVAL;
 216        case CPUCLOCK_PROF:
 217                cpu->cpu = prof_ticks(p);
 218                break;
 219        case CPUCLOCK_VIRT:
 220                cpu->cpu = virt_ticks(p);
 221                break;
 222        case CPUCLOCK_SCHED:
 223                cpu->sched = task_sched_runtime(p);
 224                break;
 225        }
 226        return 0;
 227}
 228
 229static void update_gt_cputime(struct task_cputime *a, struct task_cputime *b)
 230{
 231        if (b->utime > a->utime)
 232                a->utime = b->utime;
 233
 234        if (b->stime > a->stime)
 235                a->stime = b->stime;
 236
 237        if (b->sum_exec_runtime > a->sum_exec_runtime)
 238                a->sum_exec_runtime = b->sum_exec_runtime;
 239}
 240
 241void thread_group_cputimer(struct task_struct *tsk, struct task_cputime *times)
 242{
 243        struct thread_group_cputimer *cputimer = &tsk->signal->cputimer;
 244        struct task_cputime sum;
 245        unsigned long flags;
 246
 247        if (!cputimer->running) {
 248                /*
 249                 * The POSIX timer interface allows for absolute time expiry
 250                 * values through the TIMER_ABSTIME flag, therefore we have
 251                 * to synchronize the timer to the clock every time we start
 252                 * it.
 253                 */
 254                thread_group_cputime(tsk, &sum);
 255                raw_spin_lock_irqsave(&cputimer->lock, flags);
 256                cputimer->running = 1;
 257                update_gt_cputime(&cputimer->cputime, &sum);
 258        } else
 259                raw_spin_lock_irqsave(&cputimer->lock, flags);
 260        *times = cputimer->cputime;
 261        raw_spin_unlock_irqrestore(&cputimer->lock, flags);
 262}
 263
 264/*
 265 * Sample a process (thread group) clock for the given group_leader task.
 266 * Must be called with tasklist_lock held for reading.
 267 */
 268static int cpu_clock_sample_group(const clockid_t which_clock,
 269                                  struct task_struct *p,
 270                                  union cpu_time_count *cpu)
 271{
 272        struct task_cputime cputime;
 273
 274        switch (CPUCLOCK_WHICH(which_clock)) {
 275        default:
 276                return -EINVAL;
 277        case CPUCLOCK_PROF:
 278                thread_group_cputime(p, &cputime);
 279                cpu->cpu = cputime.utime + cputime.stime;
 280                break;
 281        case CPUCLOCK_VIRT:
 282                thread_group_cputime(p, &cputime);
 283                cpu->cpu = cputime.utime;
 284                break;
 285        case CPUCLOCK_SCHED:
 286                thread_group_cputime(p, &cputime);
 287                cpu->sched = cputime.sum_exec_runtime;
 288                break;
 289        }
 290        return 0;
 291}
 292
 293
 294static int posix_cpu_clock_get(const clockid_t which_clock, struct timespec *tp)
 295{
 296        const pid_t pid = CPUCLOCK_PID(which_clock);
 297        int error = -EINVAL;
 298        union cpu_time_count rtn;
 299
 300        if (pid == 0) {
 301                /*
 302                 * Special case constant value for our own clocks.
 303                 * We don't have to do any lookup to find ourselves.
 304                 */
 305                if (CPUCLOCK_PERTHREAD(which_clock)) {
 306                        /*
 307                         * Sampling just ourselves we can do with no locking.
 308                         */
 309                        error = cpu_clock_sample(which_clock,
 310                                                 current, &rtn);
 311                } else {
 312                        read_lock(&tasklist_lock);
 313                        error = cpu_clock_sample_group(which_clock,
 314                                                       current, &rtn);
 315                        read_unlock(&tasklist_lock);
 316                }
 317        } else {
 318                /*
 319                 * Find the given PID, and validate that the caller
 320                 * should be able to see it.
 321                 */
 322                struct task_struct *p;
 323                rcu_read_lock();
 324                p = find_task_by_vpid(pid);
 325                if (p) {
 326                        if (CPUCLOCK_PERTHREAD(which_clock)) {
 327                                if (same_thread_group(p, current)) {
 328                                        error = cpu_clock_sample(which_clock,
 329                                                                 p, &rtn);
 330                                }
 331                        } else {
 332                                read_lock(&tasklist_lock);
 333                                if (thread_group_leader(p) && p->sighand) {
 334                                        error =
 335                                            cpu_clock_sample_group(which_clock,
 336                                                                   p, &rtn);
 337                                }
 338                                read_unlock(&tasklist_lock);
 339                        }
 340                }
 341                rcu_read_unlock();
 342        }
 343
 344        if (error)
 345                return error;
 346        sample_to_timespec(which_clock, rtn, tp);
 347        return 0;
 348}
 349
 350
 351/*
 352 * Validate the clockid_t for a new CPU-clock timer, and initialize the timer.
 353 * This is called from sys_timer_create() and do_cpu_nanosleep() with the
 354 * new timer already all-zeros initialized.
 355 */
 356static int posix_cpu_timer_create(struct k_itimer *new_timer)
 357{
 358        int ret = 0;
 359        const pid_t pid = CPUCLOCK_PID(new_timer->it_clock);
 360        struct task_struct *p;
 361
 362        if (CPUCLOCK_WHICH(new_timer->it_clock) >= CPUCLOCK_MAX)
 363                return -EINVAL;
 364
 365        INIT_LIST_HEAD(&new_timer->it.cpu.entry);
 366
 367        rcu_read_lock();
 368        if (CPUCLOCK_PERTHREAD(new_timer->it_clock)) {
 369                if (pid == 0) {
 370                        p = current;
 371                } else {
 372                        p = find_task_by_vpid(pid);
 373                        if (p && !same_thread_group(p, current))
 374                                p = NULL;
 375                }
 376        } else {
 377                if (pid == 0) {
 378                        p = current->group_leader;
 379                } else {
 380                        p = find_task_by_vpid(pid);
 381                        if (p && !has_group_leader_pid(p))
 382                                p = NULL;
 383                }
 384        }
 385        new_timer->it.cpu.task = p;
 386        if (p) {
 387                get_task_struct(p);
 388        } else {
 389                ret = -EINVAL;
 390        }
 391        rcu_read_unlock();
 392
 393        return ret;
 394}
 395
 396/*
 397 * Clean up a CPU-clock timer that is about to be destroyed.
 398 * This is called from timer deletion with the timer already locked.
 399 * If we return TIMER_RETRY, it's necessary to release the timer's lock
 400 * and try again.  (This happens when the timer is in the middle of firing.)
 401 */
 402static int posix_cpu_timer_del(struct k_itimer *timer)
 403{
 404        struct task_struct *p = timer->it.cpu.task;
 405        int ret = 0;
 406
 407        if (likely(p != NULL)) {
 408                read_lock(&tasklist_lock);
 409                if (unlikely(p->sighand == NULL)) {
 410                        /*
 411                         * We raced with the reaping of the task.
 412                         * The deletion should have cleared us off the list.
 413                         */
 414                        BUG_ON(!list_empty(&timer->it.cpu.entry));
 415                } else {
 416                        spin_lock(&p->sighand->siglock);
 417                        if (timer->it.cpu.firing)
 418                                ret = TIMER_RETRY;
 419                        else
 420                                list_del(&timer->it.cpu.entry);
 421                        spin_unlock(&p->sighand->siglock);
 422                }
 423                read_unlock(&tasklist_lock);
 424
 425                if (!ret)
 426                        put_task_struct(p);
 427        }
 428
 429        return ret;
 430}
 431
 432/*
 433 * Clean out CPU timers still ticking when a thread exited.  The task
 434 * pointer is cleared, and the expiry time is replaced with the residual
 435 * time for later timer_gettime calls to return.
 436 * This must be called with the siglock held.
 437 */
 438static void cleanup_timers(struct list_head *head,
 439                           cputime_t utime, cputime_t stime,
 440                           unsigned long long sum_exec_runtime)
 441{
 442        struct cpu_timer_list *timer, *next;
 443        cputime_t ptime = utime + stime;
 444
 445        list_for_each_entry_safe(timer, next, head, entry) {
 446                list_del_init(&timer->entry);
 447                if (timer->expires.cpu < ptime) {
 448                        timer->expires.cpu = 0;
 449                } else {
 450                        timer->expires.cpu -= ptime;
 451                }
 452        }
 453
 454        ++head;
 455        list_for_each_entry_safe(timer, next, head, entry) {
 456                list_del_init(&timer->entry);
 457                if (timer->expires.cpu < utime) {
 458                        timer->expires.cpu = 0;
 459                } else {
 460                        timer->expires.cpu -= utime;
 461                }
 462        }
 463
 464        ++head;
 465        list_for_each_entry_safe(timer, next, head, entry) {
 466                list_del_init(&timer->entry);
 467                if (timer->expires.sched < sum_exec_runtime) {
 468                        timer->expires.sched = 0;
 469                } else {
 470                        timer->expires.sched -= sum_exec_runtime;
 471                }
 472        }
 473}
 474
 475/*
 476 * These are both called with the siglock held, when the current thread
 477 * is being reaped.  When the final (leader) thread in the group is reaped,
 478 * posix_cpu_timers_exit_group will be called after posix_cpu_timers_exit.
 479 */
 480void posix_cpu_timers_exit(struct task_struct *tsk)
 481{
 482        cputime_t utime, stime;
 483
 484        add_device_randomness((const void*) &tsk->se.sum_exec_runtime,
 485                                                sizeof(unsigned long long));
 486        task_cputime(tsk, &utime, &stime);
 487        cleanup_timers(tsk->cpu_timers,
 488                       utime, stime, tsk->se.sum_exec_runtime);
 489
 490}
 491void posix_cpu_timers_exit_group(struct task_struct *tsk)
 492{
 493        struct signal_struct *const sig = tsk->signal;
 494        cputime_t utime, stime;
 495
 496        task_cputime(tsk, &utime, &stime);
 497        cleanup_timers(tsk->signal->cpu_timers,
 498                       utime + sig->utime, stime + sig->stime,
 499                       tsk->se.sum_exec_runtime + sig->sum_sched_runtime);
 500}
 501
 502static void clear_dead_task(struct k_itimer *timer, union cpu_time_count now)
 503{
 504        /*
 505         * That's all for this thread or process.
 506         * We leave our residual in expires to be reported.
 507         */
 508        put_task_struct(timer->it.cpu.task);
 509        timer->it.cpu.task = NULL;
 510        timer->it.cpu.expires = cpu_time_sub(timer->it_clock,
 511                                             timer->it.cpu.expires,
 512                                             now);
 513}
 514
 515static inline int expires_gt(cputime_t expires, cputime_t new_exp)
 516{
 517        return expires == 0 || expires > new_exp;
 518}
 519
 520/*
 521 * Insert the timer on the appropriate list before any timers that
 522 * expire later.  This must be called with the tasklist_lock held
 523 * for reading, interrupts disabled and p->sighand->siglock taken.
 524 */
 525static void arm_timer(struct k_itimer *timer)
 526{
 527        struct task_struct *p = timer->it.cpu.task;
 528        struct list_head *head, *listpos;
 529        struct task_cputime *cputime_expires;
 530        struct cpu_timer_list *const nt = &timer->it.cpu;
 531        struct cpu_timer_list *next;
 532
 533        if (CPUCLOCK_PERTHREAD(timer->it_clock)) {
 534                head = p->cpu_timers;
 535                cputime_expires = &p->cputime_expires;
 536        } else {
 537                head = p->signal->cpu_timers;
 538                cputime_expires = &p->signal->cputime_expires;
 539        }
 540        head += CPUCLOCK_WHICH(timer->it_clock);
 541
 542        listpos = head;
 543        list_for_each_entry(next, head, entry) {
 544                if (cpu_time_before(timer->it_clock, nt->expires, next->expires))
 545                        break;
 546                listpos = &next->entry;
 547        }
 548        list_add(&nt->entry, listpos);
 549
 550        if (listpos == head) {
 551                union cpu_time_count *exp = &nt->expires;
 552
 553                /*
 554                 * We are the new earliest-expiring POSIX 1.b timer, hence
 555                 * need to update expiration cache. Take into account that
 556                 * for process timers we share expiration cache with itimers
 557                 * and RLIMIT_CPU and for thread timers with RLIMIT_RTTIME.
 558                 */
 559
 560                switch (CPUCLOCK_WHICH(timer->it_clock)) {
 561                case CPUCLOCK_PROF:
 562                        if (expires_gt(cputime_expires->prof_exp, exp->cpu))
 563                                cputime_expires->prof_exp = exp->cpu;
 564                        break;
 565                case CPUCLOCK_VIRT:
 566                        if (expires_gt(cputime_expires->virt_exp, exp->cpu))
 567                                cputime_expires->virt_exp = exp->cpu;
 568                        break;
 569                case CPUCLOCK_SCHED:
 570                        if (cputime_expires->sched_exp == 0 ||
 571                            cputime_expires->sched_exp > exp->sched)
 572                                cputime_expires->sched_exp = exp->sched;
 573                        break;
 574                }
 575        }
 576}
 577
 578/*
 579 * The timer is locked, fire it and arrange for its reload.
 580 */
 581static void cpu_timer_fire(struct k_itimer *timer)
 582{
 583        if ((timer->it_sigev_notify & ~SIGEV_THREAD_ID) == SIGEV_NONE) {
 584                /*
 585                 * User don't want any signal.
 586                 */
 587                timer->it.cpu.expires.sched = 0;
 588        } else if (unlikely(timer->sigq == NULL)) {
 589                /*
 590                 * This a special case for clock_nanosleep,
 591                 * not a normal timer from sys_timer_create.
 592                 */
 593                wake_up_process(timer->it_process);
 594                timer->it.cpu.expires.sched = 0;
 595        } else if (timer->it.cpu.incr.sched == 0) {
 596                /*
 597                 * One-shot timer.  Clear it as soon as it's fired.
 598                 */
 599                posix_timer_event(timer, 0);
 600                timer->it.cpu.expires.sched = 0;
 601        } else if (posix_timer_event(timer, ++timer->it_requeue_pending)) {
 602                /*
 603                 * The signal did not get queued because the signal
 604                 * was ignored, so we won't get any callback to
 605                 * reload the timer.  But we need to keep it
 606                 * ticking in case the signal is deliverable next time.
 607                 */
 608                posix_cpu_timer_schedule(timer);
 609        }
 610}
 611
 612/*
 613 * Sample a process (thread group) timer for the given group_leader task.
 614 * Must be called with tasklist_lock held for reading.
 615 */
 616static int cpu_timer_sample_group(const clockid_t which_clock,
 617                                  struct task_struct *p,
 618                                  union cpu_time_count *cpu)
 619{
 620        struct task_cputime cputime;
 621
 622        thread_group_cputimer(p, &cputime);
 623        switch (CPUCLOCK_WHICH(which_clock)) {
 624        default:
 625                return -EINVAL;
 626        case CPUCLOCK_PROF:
 627                cpu->cpu = cputime.utime + cputime.stime;
 628                break;
 629        case CPUCLOCK_VIRT:
 630                cpu->cpu = cputime.utime;
 631                break;
 632        case CPUCLOCK_SCHED:
 633                cpu->sched = cputime.sum_exec_runtime + task_delta_exec(p);
 634                break;
 635        }
 636        return 0;
 637}
 638
 639/*
 640 * Guts of sys_timer_settime for CPU timers.
 641 * This is called with the timer locked and interrupts disabled.
 642 * If we return TIMER_RETRY, it's necessary to release the timer's lock
 643 * and try again.  (This happens when the timer is in the middle of firing.)
 644 */
 645static int posix_cpu_timer_set(struct k_itimer *timer, int flags,
 646                               struct itimerspec *new, struct itimerspec *old)
 647{
 648        struct task_struct *p = timer->it.cpu.task;
 649        union cpu_time_count old_expires, new_expires, old_incr, val;
 650        int ret;
 651
 652        if (unlikely(p == NULL)) {
 653                /*
 654                 * Timer refers to a dead task's clock.
 655                 */
 656                return -ESRCH;
 657        }
 658
 659        new_expires = timespec_to_sample(timer->it_clock, &new->it_value);
 660
 661        read_lock(&tasklist_lock);
 662        /*
 663         * We need the tasklist_lock to protect against reaping that
 664         * clears p->sighand.  If p has just been reaped, we can no
 665         * longer get any information about it at all.
 666         */
 667        if (unlikely(p->sighand == NULL)) {
 668                read_unlock(&tasklist_lock);
 669                put_task_struct(p);
 670                timer->it.cpu.task = NULL;
 671                return -ESRCH;
 672        }
 673
 674        /*
 675         * Disarm any old timer after extracting its expiry time.
 676         */
 677        BUG_ON(!irqs_disabled());
 678
 679        ret = 0;
 680        old_incr = timer->it.cpu.incr;
 681        spin_lock(&p->sighand->siglock);
 682        old_expires = timer->it.cpu.expires;
 683        if (unlikely(timer->it.cpu.firing)) {
 684                timer->it.cpu.firing = -1;
 685                ret = TIMER_RETRY;
 686        } else
 687                list_del_init(&timer->it.cpu.entry);
 688
 689        /*
 690         * We need to sample the current value to convert the new
 691         * value from to relative and absolute, and to convert the
 692         * old value from absolute to relative.  To set a process
 693         * timer, we need a sample to balance the thread expiry
 694         * times (in arm_timer).  With an absolute time, we must
 695         * check if it's already passed.  In short, we need a sample.
 696         */
 697        if (CPUCLOCK_PERTHREAD(timer->it_clock)) {
 698                cpu_clock_sample(timer->it_clock, p, &val);
 699        } else {
 700                cpu_timer_sample_group(timer->it_clock, p, &val);
 701        }
 702
 703        if (old) {
 704                if (old_expires.sched == 0) {
 705                        old->it_value.tv_sec = 0;
 706                        old->it_value.tv_nsec = 0;
 707                } else {
 708                        /*
 709                         * Update the timer in case it has
 710                         * overrun already.  If it has,
 711                         * we'll report it as having overrun
 712                         * and with the next reloaded timer
 713                         * already ticking, though we are
 714                         * swallowing that pending
 715                         * notification here to install the
 716                         * new setting.
 717                         */
 718                        bump_cpu_timer(timer, val);
 719                        if (cpu_time_before(timer->it_clock, val,
 720                                            timer->it.cpu.expires)) {
 721                                old_expires = cpu_time_sub(
 722                                        timer->it_clock,
 723                                        timer->it.cpu.expires, val);
 724                                sample_to_timespec(timer->it_clock,
 725                                                   old_expires,
 726                                                   &old->it_value);
 727                        } else {
 728                                old->it_value.tv_nsec = 1;
 729                                old->it_value.tv_sec = 0;
 730                        }
 731                }
 732        }
 733
 734        if (unlikely(ret)) {
 735                /*
 736                 * We are colliding with the timer actually firing.
 737                 * Punt after filling in the timer's old value, and
 738                 * disable this firing since we are already reporting
 739                 * it as an overrun (thanks to bump_cpu_timer above).
 740                 */
 741                spin_unlock(&p->sighand->siglock);
 742                read_unlock(&tasklist_lock);
 743                goto out;
 744        }
 745
 746        if (new_expires.sched != 0 && !(flags & TIMER_ABSTIME)) {
 747                cpu_time_add(timer->it_clock, &new_expires, val);
 748        }
 749
 750        /*
 751         * Install the new expiry time (or zero).
 752         * For a timer with no notification action, we don't actually
 753         * arm the timer (we'll just fake it for timer_gettime).
 754         */
 755        timer->it.cpu.expires = new_expires;
 756        if (new_expires.sched != 0 &&
 757            cpu_time_before(timer->it_clock, val, new_expires)) {
 758                arm_timer(timer);
 759        }
 760
 761        spin_unlock(&p->sighand->siglock);
 762        read_unlock(&tasklist_lock);
 763
 764        /*
 765         * Install the new reload setting, and
 766         * set up the signal and overrun bookkeeping.
 767         */
 768        timer->it.cpu.incr = timespec_to_sample(timer->it_clock,
 769                                                &new->it_interval);
 770
 771        /*
 772         * This acts as a modification timestamp for the timer,
 773         * so any automatic reload attempt will punt on seeing
 774         * that we have reset the timer manually.
 775         */
 776        timer->it_requeue_pending = (timer->it_requeue_pending + 2) &
 777                ~REQUEUE_PENDING;
 778        timer->it_overrun_last = 0;
 779        timer->it_overrun = -1;
 780
 781        if (new_expires.sched != 0 &&
 782            !cpu_time_before(timer->it_clock, val, new_expires)) {
 783                /*
 784                 * The designated time already passed, so we notify
 785                 * immediately, even if the thread never runs to
 786                 * accumulate more time on this clock.
 787                 */
 788                cpu_timer_fire(timer);
 789        }
 790
 791        ret = 0;
 792 out:
 793        if (old) {
 794                sample_to_timespec(timer->it_clock,
 795                                   old_incr, &old->it_interval);
 796        }
 797        return ret;
 798}
 799
 800static void posix_cpu_timer_get(struct k_itimer *timer, struct itimerspec *itp)
 801{
 802        union cpu_time_count now;
 803        struct task_struct *p = timer->it.cpu.task;
 804        int clear_dead;
 805
 806        /*
 807         * Easy part: convert the reload time.
 808         */
 809        sample_to_timespec(timer->it_clock,
 810                           timer->it.cpu.incr, &itp->it_interval);
 811
 812        if (timer->it.cpu.expires.sched == 0) { /* Timer not armed at all.  */
 813                itp->it_value.tv_sec = itp->it_value.tv_nsec = 0;
 814                return;
 815        }
 816
 817        if (unlikely(p == NULL)) {
 818                /*
 819                 * This task already died and the timer will never fire.
 820                 * In this case, expires is actually the dead value.
 821                 */
 822        dead:
 823                sample_to_timespec(timer->it_clock, timer->it.cpu.expires,
 824                                   &itp->it_value);
 825                return;
 826        }
 827
 828        /*
 829         * Sample the clock to take the difference with the expiry time.
 830         */
 831        if (CPUCLOCK_PERTHREAD(timer->it_clock)) {
 832                cpu_clock_sample(timer->it_clock, p, &now);
 833                clear_dead = p->exit_state;
 834        } else {
 835                read_lock(&tasklist_lock);
 836                if (unlikely(p->sighand == NULL)) {
 837                        /*
 838                         * The process has been reaped.
 839                         * We can't even collect a sample any more.
 840                         * Call the timer disarmed, nothing else to do.
 841                         */
 842                        put_task_struct(p);
 843                        timer->it.cpu.task = NULL;
 844                        timer->it.cpu.expires.sched = 0;
 845                        read_unlock(&tasklist_lock);
 846                        goto dead;
 847                } else {
 848                        cpu_timer_sample_group(timer->it_clock, p, &now);
 849                        clear_dead = (unlikely(p->exit_state) &&
 850                                      thread_group_empty(p));
 851                }
 852                read_unlock(&tasklist_lock);
 853        }
 854
 855        if (unlikely(clear_dead)) {
 856                /*
 857                 * We've noticed that the thread is dead, but
 858                 * not yet reaped.  Take this opportunity to
 859                 * drop our task ref.
 860                 */
 861                clear_dead_task(timer, now);
 862                goto dead;
 863        }
 864
 865        if (cpu_time_before(timer->it_clock, now, timer->it.cpu.expires)) {
 866                sample_to_timespec(timer->it_clock,
 867                                   cpu_time_sub(timer->it_clock,
 868                                                timer->it.cpu.expires, now),
 869                                   &itp->it_value);
 870        } else {
 871                /*
 872                 * The timer should have expired already, but the firing
 873                 * hasn't taken place yet.  Say it's just about to expire.
 874                 */
 875                itp->it_value.tv_nsec = 1;
 876                itp->it_value.tv_sec = 0;
 877        }
 878}
 879
 880/*
 881 * Check for any per-thread CPU timers that have fired and move them off
 882 * the tsk->cpu_timers[N] list onto the firing list.  Here we update the
 883 * tsk->it_*_expires values to reflect the remaining thread CPU timers.
 884 */
 885static void check_thread_timers(struct task_struct *tsk,
 886                                struct list_head *firing)
 887{
 888        int maxfire;
 889        struct list_head *timers = tsk->cpu_timers;
 890        struct signal_struct *const sig = tsk->signal;
 891        unsigned long soft;
 892
 893        maxfire = 20;
 894        tsk->cputime_expires.prof_exp = 0;
 895        while (!list_empty(timers)) {
 896                struct cpu_timer_list *t = list_first_entry(timers,
 897                                                      struct cpu_timer_list,
 898                                                      entry);
 899                if (!--maxfire || prof_ticks(tsk) < t->expires.cpu) {
 900                        tsk->cputime_expires.prof_exp = t->expires.cpu;
 901                        break;
 902                }
 903                t->firing = 1;
 904                list_move_tail(&t->entry, firing);
 905        }
 906
 907        ++timers;
 908        maxfire = 20;
 909        tsk->cputime_expires.virt_exp = 0;
 910        while (!list_empty(timers)) {
 911                struct cpu_timer_list *t = list_first_entry(timers,
 912                                                      struct cpu_timer_list,
 913                                                      entry);
 914                if (!--maxfire || virt_ticks(tsk) < t->expires.cpu) {
 915                        tsk->cputime_expires.virt_exp = t->expires.cpu;
 916                        break;
 917                }
 918                t->firing = 1;
 919                list_move_tail(&t->entry, firing);
 920        }
 921
 922        ++timers;
 923        maxfire = 20;
 924        tsk->cputime_expires.sched_exp = 0;
 925        while (!list_empty(timers)) {
 926                struct cpu_timer_list *t = list_first_entry(timers,
 927                                                      struct cpu_timer_list,
 928                                                      entry);
 929                if (!--maxfire || tsk->se.sum_exec_runtime < t->expires.sched) {
 930                        tsk->cputime_expires.sched_exp = t->expires.sched;
 931                        break;
 932                }
 933                t->firing = 1;
 934                list_move_tail(&t->entry, firing);
 935        }
 936
 937        /*
 938         * Check for the special case thread timers.
 939         */
 940        soft = ACCESS_ONCE(sig->rlim[RLIMIT_RTTIME].rlim_cur);
 941        if (soft != RLIM_INFINITY) {
 942                unsigned long hard =
 943                        ACCESS_ONCE(sig->rlim[RLIMIT_RTTIME].rlim_max);
 944
 945                if (hard != RLIM_INFINITY &&
 946                    tsk->rt.timeout > DIV_ROUND_UP(hard, USEC_PER_SEC/HZ)) {
 947                        /*
 948                         * At the hard limit, we just die.
 949                         * No need to calculate anything else now.
 950                         */
 951                        __group_send_sig_info(SIGKILL, SEND_SIG_PRIV, tsk);
 952                        return;
 953                }
 954                if (tsk->rt.timeout > DIV_ROUND_UP(soft, USEC_PER_SEC/HZ)) {
 955                        /*
 956                         * At the soft limit, send a SIGXCPU every second.
 957                         */
 958                        if (soft < hard) {
 959                                soft += USEC_PER_SEC;
 960                                sig->rlim[RLIMIT_RTTIME].rlim_cur = soft;
 961                        }
 962                        printk(KERN_INFO
 963                                "RT Watchdog Timeout: %s[%d]\n",
 964                                tsk->comm, task_pid_nr(tsk));
 965                        __group_send_sig_info(SIGXCPU, SEND_SIG_PRIV, tsk);
 966                }
 967        }
 968}
 969
 970static void stop_process_timers(struct signal_struct *sig)
 971{
 972        struct thread_group_cputimer *cputimer = &sig->cputimer;
 973        unsigned long flags;
 974
 975        raw_spin_lock_irqsave(&cputimer->lock, flags);
 976        cputimer->running = 0;
 977        raw_spin_unlock_irqrestore(&cputimer->lock, flags);
 978}
 979
 980static u32 onecputick;
 981
 982static void check_cpu_itimer(struct task_struct *tsk, struct cpu_itimer *it,
 983                             cputime_t *expires, cputime_t cur_time, int signo)
 984{
 985        if (!it->expires)
 986                return;
 987
 988        if (cur_time >= it->expires) {
 989                if (it->incr) {
 990                        it->expires += it->incr;
 991                        it->error += it->incr_error;
 992                        if (it->error >= onecputick) {
 993                                it->expires -= cputime_one_jiffy;
 994                                it->error -= onecputick;
 995                        }
 996                } else {
 997                        it->expires = 0;
 998                }
 999
1000                trace_itimer_expire(signo == SIGPROF ?
1001                                    ITIMER_PROF : ITIMER_VIRTUAL,
1002                                    tsk->signal->leader_pid, cur_time);
1003                __group_send_sig_info(signo, SEND_SIG_PRIV, tsk);
1004        }
1005
1006        if (it->expires && (!*expires || it->expires < *expires)) {
1007                *expires = it->expires;
1008        }
1009}
1010
1011/**
1012 * task_cputime_zero - Check a task_cputime struct for all zero fields.
1013 *
1014 * @cputime:    The struct to compare.
1015 *
1016 * Checks @cputime to see if all fields are zero.  Returns true if all fields
1017 * are zero, false if any field is nonzero.
1018 */
1019static inline int task_cputime_zero(const struct task_cputime *cputime)
1020{
1021        if (!cputime->utime && !cputime->stime && !cputime->sum_exec_runtime)
1022                return 1;
1023        return 0;
1024}
1025
1026/*
1027 * Check for any per-thread CPU timers that have fired and move them
1028 * off the tsk->*_timers list onto the firing list.  Per-thread timers
1029 * have already been taken off.
1030 */
1031static void check_process_timers(struct task_struct *tsk,
1032                                 struct list_head *firing)
1033{
1034        int maxfire;
1035        struct signal_struct *const sig = tsk->signal;
1036        cputime_t utime, ptime, virt_expires, prof_expires;
1037        unsigned long long sum_sched_runtime, sched_expires;
1038        struct list_head *timers = sig->cpu_timers;
1039        struct task_cputime cputime;
1040        unsigned long soft;
1041
1042        /*
1043         * Collect the current process totals.
1044         */
1045        thread_group_cputimer(tsk, &cputime);
1046        utime = cputime.utime;
1047        ptime = utime + cputime.stime;
1048        sum_sched_runtime = cputime.sum_exec_runtime;
1049        maxfire = 20;
1050        prof_expires = 0;
1051        while (!list_empty(timers)) {
1052                struct cpu_timer_list *tl = list_first_entry(timers,
1053                                                      struct cpu_timer_list,
1054                                                      entry);
1055                if (!--maxfire || ptime < tl->expires.cpu) {
1056                        prof_expires = tl->expires.cpu;
1057                        break;
1058                }
1059                tl->firing = 1;
1060                list_move_tail(&tl->entry, firing);
1061        }
1062
1063        ++timers;
1064        maxfire = 20;
1065        virt_expires = 0;
1066        while (!list_empty(timers)) {
1067                struct cpu_timer_list *tl = list_first_entry(timers,
1068                                                      struct cpu_timer_list,
1069                                                      entry);
1070                if (!--maxfire || utime < tl->expires.cpu) {
1071                        virt_expires = tl->expires.cpu;
1072                        break;
1073                }
1074                tl->firing = 1;
1075                list_move_tail(&tl->entry, firing);
1076        }
1077
1078        ++timers;
1079        maxfire = 20;
1080        sched_expires = 0;
1081        while (!list_empty(timers)) {
1082                struct cpu_timer_list *tl = list_first_entry(timers,
1083                                                      struct cpu_timer_list,
1084                                                      entry);
1085                if (!--maxfire || sum_sched_runtime < tl->expires.sched) {
1086                        sched_expires = tl->expires.sched;
1087                        break;
1088                }
1089                tl->firing = 1;
1090                list_move_tail(&tl->entry, firing);
1091        }
1092
1093        /*
1094         * Check for the special case process timers.
1095         */
1096        check_cpu_itimer(tsk, &sig->it[CPUCLOCK_PROF], &prof_expires, ptime,
1097                         SIGPROF);
1098        check_cpu_itimer(tsk, &sig->it[CPUCLOCK_VIRT], &virt_expires, utime,
1099                         SIGVTALRM);
1100        soft = ACCESS_ONCE(sig->rlim[RLIMIT_CPU].rlim_cur);
1101        if (soft != RLIM_INFINITY) {
1102                unsigned long psecs = cputime_to_secs(ptime);
1103                unsigned long hard =
1104                        ACCESS_ONCE(sig->rlim[RLIMIT_CPU].rlim_max);
1105                cputime_t x;
1106                if (psecs >= hard) {
1107                        /*
1108                         * At the hard limit, we just die.
1109                         * No need to calculate anything else now.
1110                         */
1111                        __group_send_sig_info(SIGKILL, SEND_SIG_PRIV, tsk);
1112                        return;
1113                }
1114                if (psecs >= soft) {
1115                        /*
1116                         * At the soft limit, send a SIGXCPU every second.
1117                         */
1118                        __group_send_sig_info(SIGXCPU, SEND_SIG_PRIV, tsk);
1119                        if (soft < hard) {
1120                                soft++;
1121                                sig->rlim[RLIMIT_CPU].rlim_cur = soft;
1122                        }
1123                }
1124                x = secs_to_cputime(soft);
1125                if (!prof_expires || x < prof_expires) {
1126                        prof_expires = x;
1127                }
1128        }
1129
1130        sig->cputime_expires.prof_exp = prof_expires;
1131        sig->cputime_expires.virt_exp = virt_expires;
1132        sig->cputime_expires.sched_exp = sched_expires;
1133        if (task_cputime_zero(&sig->cputime_expires))
1134                stop_process_timers(sig);
1135}
1136
1137/*
1138 * This is called from the signal code (via do_schedule_next_timer)
1139 * when the last timer signal was delivered and we have to reload the timer.
1140 */
1141void posix_cpu_timer_schedule(struct k_itimer *timer)
1142{
1143        struct task_struct *p = timer->it.cpu.task;
1144        union cpu_time_count now;
1145
1146        if (unlikely(p == NULL))
1147                /*
1148                 * The task was cleaned up already, no future firings.
1149                 */
1150                goto out;
1151
1152        /*
1153         * Fetch the current sample and update the timer's expiry time.
1154         */
1155        if (CPUCLOCK_PERTHREAD(timer->it_clock)) {
1156                cpu_clock_sample(timer->it_clock, p, &now);
1157                bump_cpu_timer(timer, now);
1158                if (unlikely(p->exit_state)) {
1159                        clear_dead_task(timer, now);
1160                        goto out;
1161                }
1162                read_lock(&tasklist_lock); /* arm_timer needs it.  */
1163                spin_lock(&p->sighand->siglock);
1164        } else {
1165                read_lock(&tasklist_lock);
1166                if (unlikely(p->sighand == NULL)) {
1167                        /*
1168                         * The process has been reaped.
1169                         * We can't even collect a sample any more.
1170                         */
1171                        put_task_struct(p);
1172                        timer->it.cpu.task = p = NULL;
1173                        timer->it.cpu.expires.sched = 0;
1174                        goto out_unlock;
1175                } else if (unlikely(p->exit_state) && thread_group_empty(p)) {
1176                        /*
1177                         * We've noticed that the thread is dead, but
1178                         * not yet reaped.  Take this opportunity to
1179                         * drop our task ref.
1180                         */
1181                        clear_dead_task(timer, now);
1182                        goto out_unlock;
1183                }
1184                spin_lock(&p->sighand->siglock);
1185                cpu_timer_sample_group(timer->it_clock, p, &now);
1186                bump_cpu_timer(timer, now);
1187                /* Leave the tasklist_lock locked for the call below.  */
1188        }
1189
1190        /*
1191         * Now re-arm for the new expiry time.
1192         */
1193        BUG_ON(!irqs_disabled());
1194        arm_timer(timer);
1195        spin_unlock(&p->sighand->siglock);
1196
1197out_unlock:
1198        read_unlock(&tasklist_lock);
1199
1200out:
1201        timer->it_overrun_last = timer->it_overrun;
1202        timer->it_overrun = -1;
1203        ++timer->it_requeue_pending;
1204}
1205
1206/**
1207 * task_cputime_expired - Compare two task_cputime entities.
1208 *
1209 * @sample:     The task_cputime structure to be checked for expiration.
1210 * @expires:    Expiration times, against which @sample will be checked.
1211 *
1212 * Checks @sample against @expires to see if any field of @sample has expired.
1213 * Returns true if any field of the former is greater than the corresponding
1214 * field of the latter if the latter field is set.  Otherwise returns false.
1215 */
1216static inline int task_cputime_expired(const struct task_cputime *sample,
1217                                        const struct task_cputime *expires)
1218{
1219        if (expires->utime && sample->utime >= expires->utime)
1220                return 1;
1221        if (expires->stime && sample->utime + sample->stime >= expires->stime)
1222                return 1;
1223        if (expires->sum_exec_runtime != 0 &&
1224            sample->sum_exec_runtime >= expires->sum_exec_runtime)
1225                return 1;
1226        return 0;
1227}
1228
1229/**
1230 * fastpath_timer_check - POSIX CPU timers fast path.
1231 *
1232 * @tsk:        The task (thread) being checked.
1233 *
1234 * Check the task and thread group timers.  If both are zero (there are no
1235 * timers set) return false.  Otherwise snapshot the task and thread group
1236 * timers and compare them with the corresponding expiration times.  Return
1237 * true if a timer has expired, else return false.
1238 */
1239static inline int fastpath_timer_check(struct task_struct *tsk)
1240{
1241        struct signal_struct *sig;
1242        cputime_t utime, stime;
1243
1244        task_cputime(tsk, &utime, &stime);
1245
1246        if (!task_cputime_zero(&tsk->cputime_expires)) {
1247                struct task_cputime task_sample = {
1248                        .utime = utime,
1249                        .stime = stime,
1250                        .sum_exec_runtime = tsk->se.sum_exec_runtime
1251                };
1252
1253                if (task_cputime_expired(&task_sample, &tsk->cputime_expires))
1254                        return 1;
1255        }
1256
1257        sig = tsk->signal;
1258        if (sig->cputimer.running) {
1259                struct task_cputime group_sample;
1260
1261                raw_spin_lock(&sig->cputimer.lock);
1262                group_sample = sig->cputimer.cputime;
1263                raw_spin_unlock(&sig->cputimer.lock);
1264
1265                if (task_cputime_expired(&group_sample, &sig->cputime_expires))
1266                        return 1;
1267        }
1268
1269        return 0;
1270}
1271
1272/*
1273 * This is called from the timer interrupt handler.  The irq handler has
1274 * already updated our counts.  We need to check if any timers fire now.
1275 * Interrupts are disabled.
1276 */
1277void run_posix_cpu_timers(struct task_struct *tsk)
1278{
1279        LIST_HEAD(firing);
1280        struct k_itimer *timer, *next;
1281        unsigned long flags;
1282
1283        BUG_ON(!irqs_disabled());
1284
1285        /*
1286         * The fast path checks that there are no expired thread or thread
1287         * group timers.  If that's so, just return.
1288         */
1289        if (!fastpath_timer_check(tsk))
1290                return;
1291
1292        if (!lock_task_sighand(tsk, &flags))
1293                return;
1294        /*
1295         * Here we take off tsk->signal->cpu_timers[N] and
1296         * tsk->cpu_timers[N] all the timers that are firing, and
1297         * put them on the firing list.
1298         */
1299        check_thread_timers(tsk, &firing);
1300        /*
1301         * If there are any active process wide timers (POSIX 1.b, itimers,
1302         * RLIMIT_CPU) cputimer must be running.
1303         */
1304        if (tsk->signal->cputimer.running)
1305                check_process_timers(tsk, &firing);
1306
1307        /*
1308         * We must release these locks before taking any timer's lock.
1309         * There is a potential race with timer deletion here, as the
1310         * siglock now protects our private firing list.  We have set
1311         * the firing flag in each timer, so that a deletion attempt
1312         * that gets the timer lock before we do will give it up and
1313         * spin until we've taken care of that timer below.
1314         */
1315        unlock_task_sighand(tsk, &flags);
1316
1317        /*
1318         * Now that all the timers on our list have the firing flag,
1319         * no one will touch their list entries but us.  We'll take
1320         * each timer's lock before clearing its firing flag, so no
1321         * timer call will interfere.
1322         */
1323        list_for_each_entry_safe(timer, next, &firing, it.cpu.entry) {
1324                int cpu_firing;
1325
1326                spin_lock(&timer->it_lock);
1327                list_del_init(&timer->it.cpu.entry);
1328                cpu_firing = timer->it.cpu.firing;
1329                timer->it.cpu.firing = 0;
1330                /*
1331                 * The firing flag is -1 if we collided with a reset
1332                 * of the timer, which already reported this
1333                 * almost-firing as an overrun.  So don't generate an event.
1334                 */
1335                if (likely(cpu_firing >= 0))
1336                        cpu_timer_fire(timer);
1337                spin_unlock(&timer->it_lock);
1338        }
1339}
1340
1341/*
1342 * Set one of the process-wide special case CPU timers or RLIMIT_CPU.
1343 * The tsk->sighand->siglock must be held by the caller.
1344 */
1345void set_process_cpu_timer(struct task_struct *tsk, unsigned int clock_idx,
1346                           cputime_t *newval, cputime_t *oldval)
1347{
1348        union cpu_time_count now;
1349
1350        BUG_ON(clock_idx == CPUCLOCK_SCHED);
1351        cpu_timer_sample_group(clock_idx, tsk, &now);
1352
1353        if (oldval) {
1354                /*
1355                 * We are setting itimer. The *oldval is absolute and we update
1356                 * it to be relative, *newval argument is relative and we update
1357                 * it to be absolute.
1358                 */
1359                if (*oldval) {
1360                        if (*oldval <= now.cpu) {
1361                                /* Just about to fire. */
1362                                *oldval = cputime_one_jiffy;
1363                        } else {
1364                                *oldval -= now.cpu;
1365                        }
1366                }
1367
1368                if (!*newval)
1369                        return;
1370                *newval += now.cpu;
1371        }
1372
1373        /*
1374         * Update expiration cache if we are the earliest timer, or eventually
1375         * RLIMIT_CPU limit is earlier than prof_exp cpu timer expire.
1376         */
1377        switch (clock_idx) {
1378        case CPUCLOCK_PROF:
1379                if (expires_gt(tsk->signal->cputime_expires.prof_exp, *newval))
1380                        tsk->signal->cputime_expires.prof_exp = *newval;
1381                break;
1382        case CPUCLOCK_VIRT:
1383                if (expires_gt(tsk->signal->cputime_expires.virt_exp, *newval))
1384                        tsk->signal->cputime_expires.virt_exp = *newval;
1385                break;
1386        }
1387}
1388
1389static int do_cpu_nanosleep(const clockid_t which_clock, int flags,
1390                            struct timespec *rqtp, struct itimerspec *it)
1391{
1392        struct k_itimer timer;
1393        int error;
1394
1395        /*
1396         * Set up a temporary timer and then wait for it to go off.
1397         */
1398        memset(&timer, 0, sizeof timer);
1399        spin_lock_init(&timer.it_lock);
1400        timer.it_clock = which_clock;
1401        timer.it_overrun = -1;
1402        error = posix_cpu_timer_create(&timer);
1403        timer.it_process = current;
1404        if (!error) {
1405                static struct itimerspec zero_it;
1406
1407                memset(it, 0, sizeof *it);
1408                it->it_value = *rqtp;
1409
1410                spin_lock_irq(&timer.it_lock);
1411                error = posix_cpu_timer_set(&timer, flags, it, NULL);
1412                if (error) {
1413                        spin_unlock_irq(&timer.it_lock);
1414                        return error;
1415                }
1416
1417                while (!signal_pending(current)) {
1418                        if (timer.it.cpu.expires.sched == 0) {
1419                                /*
1420                                 * Our timer fired and was reset, below
1421                                 * deletion can not fail.
1422                                 */
1423                                posix_cpu_timer_del(&timer);
1424                                spin_unlock_irq(&timer.it_lock);
1425                                return 0;
1426                        }
1427
1428                        /*
1429                         * Block until cpu_timer_fire (or a signal) wakes us.
1430                         */
1431                        __set_current_state(TASK_INTERRUPTIBLE);
1432                        spin_unlock_irq(&timer.it_lock);
1433                        schedule();
1434                        spin_lock_irq(&timer.it_lock);
1435                }
1436
1437                /*
1438                 * We were interrupted by a signal.
1439                 */
1440                sample_to_timespec(which_clock, timer.it.cpu.expires, rqtp);
1441                error = posix_cpu_timer_set(&timer, 0, &zero_it, it);
1442                if (!error) {
1443                        /*
1444                         * Timer is now unarmed, deletion can not fail.
1445                         */
1446                        posix_cpu_timer_del(&timer);
1447                }
1448                spin_unlock_irq(&timer.it_lock);
1449
1450                while (error == TIMER_RETRY) {
1451                        /*
1452                         * We need to handle case when timer was or is in the
1453                         * middle of firing. In other cases we already freed
1454                         * resources.
1455                         */
1456                        spin_lock_irq(&timer.it_lock);
1457                        error = posix_cpu_timer_del(&timer);
1458                        spin_unlock_irq(&timer.it_lock);
1459                }
1460
1461                if ((it->it_value.tv_sec | it->it_value.tv_nsec) == 0) {
1462                        /*
1463                         * It actually did fire already.
1464                         */
1465                        return 0;
1466                }
1467
1468                error = -ERESTART_RESTARTBLOCK;
1469        }
1470
1471        return error;
1472}
1473
1474static long posix_cpu_nsleep_restart(struct restart_block *restart_block);
1475
1476static int posix_cpu_nsleep(const clockid_t which_clock, int flags,
1477                            struct timespec *rqtp, struct timespec __user *rmtp)
1478{
1479        struct restart_block *restart_block =
1480                &current_thread_info()->restart_block;
1481        struct itimerspec it;
1482        int error;
1483
1484        /*
1485         * Diagnose required errors first.
1486         */
1487        if (CPUCLOCK_PERTHREAD(which_clock) &&
1488            (CPUCLOCK_PID(which_clock) == 0 ||
1489             CPUCLOCK_PID(which_clock) == current->pid))
1490                return -EINVAL;
1491
1492        error = do_cpu_nanosleep(which_clock, flags, rqtp, &it);
1493
1494        if (error == -ERESTART_RESTARTBLOCK) {
1495
1496                if (flags & TIMER_ABSTIME)
1497                        return -ERESTARTNOHAND;
1498                /*
1499                 * Report back to the user the time still remaining.
1500                 */
1501                if (rmtp && copy_to_user(rmtp, &it.it_value, sizeof *rmtp))
1502                        return -EFAULT;
1503
1504                restart_block->fn = posix_cpu_nsleep_restart;
1505                restart_block->nanosleep.clockid = which_clock;
1506                restart_block->nanosleep.rmtp = rmtp;
1507                restart_block->nanosleep.expires = timespec_to_ns(rqtp);
1508        }
1509        return error;
1510}
1511
1512static long posix_cpu_nsleep_restart(struct restart_block *restart_block)
1513{
1514        clockid_t which_clock = restart_block->nanosleep.clockid;
1515        struct timespec t;
1516        struct itimerspec it;
1517        int error;
1518
1519        t = ns_to_timespec(restart_block->nanosleep.expires);
1520
1521        error = do_cpu_nanosleep(which_clock, TIMER_ABSTIME, &t, &it);
1522
1523        if (error == -ERESTART_RESTARTBLOCK) {
1524                struct timespec __user *rmtp = restart_block->nanosleep.rmtp;
1525                /*
1526                 * Report back to the user the time still remaining.
1527                 */
1528                if (rmtp && copy_to_user(rmtp, &it.it_value, sizeof *rmtp))
1529                        return -EFAULT;
1530
1531                restart_block->nanosleep.expires = timespec_to_ns(&t);
1532        }
1533        return error;
1534
1535}
1536
1537#define PROCESS_CLOCK   MAKE_PROCESS_CPUCLOCK(0, CPUCLOCK_SCHED)
1538#define THREAD_CLOCK    MAKE_THREAD_CPUCLOCK(0, CPUCLOCK_SCHED)
1539
1540static int process_cpu_clock_getres(const clockid_t which_clock,
1541                                    struct timespec *tp)
1542{
1543        return posix_cpu_clock_getres(PROCESS_CLOCK, tp);
1544}
1545static int process_cpu_clock_get(const clockid_t which_clock,
1546                                 struct timespec *tp)
1547{
1548        return posix_cpu_clock_get(PROCESS_CLOCK, tp);
1549}
1550static int process_cpu_timer_create(struct k_itimer *timer)
1551{
1552        timer->it_clock = PROCESS_CLOCK;
1553        return posix_cpu_timer_create(timer);
1554}
1555static int process_cpu_nsleep(const clockid_t which_clock, int flags,
1556                              struct timespec *rqtp,
1557                              struct timespec __user *rmtp)
1558{
1559        return posix_cpu_nsleep(PROCESS_CLOCK, flags, rqtp, rmtp);
1560}
1561static long process_cpu_nsleep_restart(struct restart_block *restart_block)
1562{
1563        return -EINVAL;
1564}
1565static int thread_cpu_clock_getres(const clockid_t which_clock,
1566                                   struct timespec *tp)
1567{
1568        return posix_cpu_clock_getres(THREAD_CLOCK, tp);
1569}
1570static int thread_cpu_clock_get(const clockid_t which_clock,
1571                                struct timespec *tp)
1572{
1573        return posix_cpu_clock_get(THREAD_CLOCK, tp);
1574}
1575static int thread_cpu_timer_create(struct k_itimer *timer)
1576{
1577        timer->it_clock = THREAD_CLOCK;
1578        return posix_cpu_timer_create(timer);
1579}
1580
1581struct k_clock clock_posix_cpu = {
1582        .clock_getres   = posix_cpu_clock_getres,
1583        .clock_set      = posix_cpu_clock_set,
1584        .clock_get      = posix_cpu_clock_get,
1585        .timer_create   = posix_cpu_timer_create,
1586        .nsleep         = posix_cpu_nsleep,
1587        .nsleep_restart = posix_cpu_nsleep_restart,
1588        .timer_set      = posix_cpu_timer_set,
1589        .timer_del      = posix_cpu_timer_del,
1590        .timer_get      = posix_cpu_timer_get,
1591};
1592
1593static __init int init_posix_cpu_timers(void)
1594{
1595        struct k_clock process = {
1596                .clock_getres   = process_cpu_clock_getres,
1597                .clock_get      = process_cpu_clock_get,
1598                .timer_create   = process_cpu_timer_create,
1599                .nsleep         = process_cpu_nsleep,
1600                .nsleep_restart = process_cpu_nsleep_restart,
1601        };
1602        struct k_clock thread = {
1603                .clock_getres   = thread_cpu_clock_getres,
1604                .clock_get      = thread_cpu_clock_get,
1605                .timer_create   = thread_cpu_timer_create,
1606        };
1607        struct timespec ts;
1608
1609        posix_timers_register_clock(CLOCK_PROCESS_CPUTIME_ID, &process);
1610        posix_timers_register_clock(CLOCK_THREAD_CPUTIME_ID, &thread);
1611
1612        cputime_to_timespec(cputime_one_jiffy, &ts);
1613        onecputick = ts.tv_nsec;
1614        WARN_ON(ts.tv_sec != 0);
1615
1616        return 0;
1617}
1618__initcall(init_posix_cpu_timers);
1619
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