git.oblomov.eu Git - linux-2.6/blob - kernel/posix-cpu-timers.c

   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
  12 /*
  13  * Called after updating RLIMIT_CPU to set timer expiration if necessary.
  14  */
  15 void update_rlimit_cpu(unsigned long rlim_new)
  16 {
  17         cputime_t cputime;
  18
  19         cputime = secs_to_cputime(rlim_new);
  20         if (cputime_eq(current->signal->it_prof_expires, cputime_zero) ||
  21             cputime_lt(current->signal->it_prof_expires, cputime)) {
  22                 spin_lock_irq(&current->sighand->siglock);
  23                 set_process_cpu_timer(current, CPUCLOCK_PROF, &cputime, NULL);
  24                 spin_unlock_irq(&current->sighand->siglock);
  25         }
  26 }
  27
  28 static 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         read_lock(&tasklist_lock);
  41         p = find_task_by_vpid(pid);
  42         if (!p || !(CPUCLOCK_PERTHREAD(which_clock) ?
  43                    same_thread_group(p, current) : thread_group_leader(p))) {
  44                 error = -EINVAL;
  45         }
  46         read_unlock(&tasklist_lock);
  47
  48         return error;
  49 }
  50
  51 static inline union cpu_time_count
  52 timespec_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
  64 static 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
  74 static 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 cputime_lt(now.cpu, then.cpu);
  82         }
  83 }
  84 static 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 = cputime_add(acc->cpu, val.cpu);
  92         }
  93 }
  94 static 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 = cputime_sub(a.cpu, b.cpu);
 102         }
 103         return a;
 104 }
 105
 106 /*
 107  * Divide and limit the result to res >= 1
 108  *
 109  * This is necessary to prevent signal delivery starvation, when the result of
 110  * the division would be rounded down to 0.
 111  */
 112 static inline cputime_t cputime_div_non_zero(cputime_t time, unsigned long div)
 113 {
 114         cputime_t res = cputime_div(time, div);
 115
 116         return max_t(cputime_t, res, 1);
 117 }
 118
 119 /*
 120  * Update expiry time from increment, and increase overrun count,
 121  * given the current clock sample.
 122  */
 123 static void bump_cpu_timer(struct k_itimer *timer,
 124                                   union cpu_time_count now)
 125 {
 126         int i;
 127
 128         if (timer->it.cpu.incr.sched == 0)
 129                 return;
 130
 131         if (CPUCLOCK_WHICH(timer->it_clock) == CPUCLOCK_SCHED) {
 132                 unsigned long long delta, incr;
 133
 134                 if (now.sched < timer->it.cpu.expires.sched)
 135                         return;
 136                 incr = timer->it.cpu.incr.sched;
 137                 delta = now.sched + incr - timer->it.cpu.expires.sched;
 138                 /* Don't use (incr*2 < delta), incr*2 might overflow. */
 139                 for (i = 0; incr < delta - incr; i++)
 140                         incr = incr << 1;
 141                 for (; i >= 0; incr >>= 1, i--) {
 142                         if (delta < incr)
 143                                 continue;
 144                         timer->it.cpu.expires.sched += incr;
 145                         timer->it_overrun += 1 << i;
 146                         delta -= incr;
 147                 }
 148         } else {
 149                 cputime_t delta, incr;
 150
 151                 if (cputime_lt(now.cpu, timer->it.cpu.expires.cpu))
 152                         return;
 153                 incr = timer->it.cpu.incr.cpu;
 154                 delta = cputime_sub(cputime_add(now.cpu, incr),
 155                                     timer->it.cpu.expires.cpu);
 156                 /* Don't use (incr*2 < delta), incr*2 might overflow. */
 157                 for (i = 0; cputime_lt(incr, cputime_sub(delta, incr)); i++)
 158                              incr = cputime_add(incr, incr);
 159                 for (; i >= 0; incr = cputime_halve(incr), i--) {
 160                         if (cputime_lt(delta, incr))
 161                                 continue;
 162                         timer->it.cpu.expires.cpu =
 163                                 cputime_add(timer->it.cpu.expires.cpu, incr);
 164                         timer->it_overrun += 1 << i;
 165                         delta = cputime_sub(delta, incr);
 166                 }
 167         }
 168 }
 169
 170 static inline cputime_t prof_ticks(struct task_struct *p)
 171 {
 172         return cputime_add(p->utime, p->stime);
 173 }
 174 static inline cputime_t virt_ticks(struct task_struct *p)
 175 {
 176         return p->utime;
 177 }
 178
 179 int posix_cpu_clock_getres(const clockid_t which_clock, struct timespec *tp)
 180 {
 181         int error = check_clock(which_clock);
 182         if (!error) {
 183                 tp->tv_sec = 0;
 184                 tp->tv_nsec = ((NSEC_PER_SEC + HZ - 1) / HZ);
 185                 if (CPUCLOCK_WHICH(which_clock) == CPUCLOCK_SCHED) {
 186                         /*
 187                          * If sched_clock is using a cycle counter, we
 188                          * don't have any idea of its true resolution
 189                          * exported, but it is much more than 1s/HZ.
 190                          */
 191                         tp->tv_nsec = 1;
 192                 }
 193         }
 194         return error;
 195 }
 196
 197 int posix_cpu_clock_set(const clockid_t which_clock, const struct timespec *tp)
 198 {
 199         /*
 200          * You can never reset a CPU clock, but we check for other errors
 201          * in the call before failing with EPERM.
 202          */
 203         int error = check_clock(which_clock);
 204         if (error == 0) {
 205                 error = -EPERM;
 206         }
 207         return error;
 208 }
 209
 210
 211 /*
 212  * Sample a per-thread clock for the given task.
 213  */
 214 static int cpu_clock_sample(const clockid_t which_clock, struct task_struct *p,
 215                             union cpu_time_count *cpu)
 216 {
 217         switch (CPUCLOCK_WHICH(which_clock)) {
 218         default:
 219                 return -EINVAL;
 220         case CPUCLOCK_PROF:
 221                 cpu->cpu = prof_ticks(p);
 222                 break;
 223         case CPUCLOCK_VIRT:
 224                 cpu->cpu = virt_ticks(p);
 225                 break;
 226         case CPUCLOCK_SCHED:
 227                 cpu->sched = p->se.sum_exec_runtime + task_delta_exec(p);
 228                 break;
 229         }
 230         return 0;
 231 }
 232
 233 void thread_group_cputime(struct task_struct *tsk, struct task_cputime *times)
 234 {
 235         struct sighand_struct *sighand;
 236         struct signal_struct *sig;
 237         struct task_struct *t;
 238
 239         *times = INIT_CPUTIME;
 240
 241         rcu_read_lock();
 242         sighand = rcu_dereference(tsk->sighand);
 243         if (!sighand)
 244                 goto out;
 245
 246         sig = tsk->signal;
 247
 248         t = tsk;
 249         do {
 250                 times->utime = cputime_add(times->utime, t->utime);
 251                 times->stime = cputime_add(times->stime, t->stime);
 252                 times->sum_exec_runtime += t->se.sum_exec_runtime;
 253
 254                 t = next_thread(t);
 255         } while (t != tsk);
 256
 257         times->utime = cputime_add(times->utime, sig->utime);
 258         times->stime = cputime_add(times->stime, sig->stime);
 259         times->sum_exec_runtime += sig->sum_sched_runtime;
 260 out:
 261         rcu_read_unlock();
 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  */
 268 static 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         thread_group_cputime(p, &cputime);
 275         switch (CPUCLOCK_WHICH(which_clock)) {
 276         default:
 277                 return -EINVAL;
 278         case CPUCLOCK_PROF:
 279                 cpu->cpu = cputime_add(cputime.utime, cputime.stime);
 280                 break;
 281         case CPUCLOCK_VIRT:
 282                 cpu->cpu = cputime.utime;
 283                 break;
 284         case CPUCLOCK_SCHED:
 285                 cpu->sched = cputime.sum_exec_runtime + task_delta_exec(p);
 286                 break;
 287         }
 288         return 0;
 289 }
 290
 291
 292 int posix_cpu_clock_get(const clockid_t which_clock, struct timespec *tp)
 293 {
 294         const pid_t pid = CPUCLOCK_PID(which_clock);
 295         int error = -EINVAL;
 296         union cpu_time_count rtn;
 297
 298         if (pid == 0) {
 299                 /*
 300                  * Special case constant value for our own clocks.
 301                  * We don't have to do any lookup to find ourselves.
 302                  */
 303                 if (CPUCLOCK_PERTHREAD(which_clock)) {
 304                         /*
 305                          * Sampling just ourselves we can do with no locking.
 306                          */
 307                         error = cpu_clock_sample(which_clock,
 308                                                  current, &rtn);
 309                 } else {
 310                         read_lock(&tasklist_lock);
 311                         error = cpu_clock_sample_group(which_clock,
 312                                                        current, &rtn);
 313                         read_unlock(&tasklist_lock);
 314                 }
 315         } else {
 316                 /*
 317                  * Find the given PID, and validate that the caller
 318                  * should be able to see it.
 319                  */
 320                 struct task_struct *p;
 321                 rcu_read_lock();
 322                 p = find_task_by_vpid(pid);
 323                 if (p) {
 324                         if (CPUCLOCK_PERTHREAD(which_clock)) {
 325                                 if (same_thread_group(p, current)) {
 326                                         error = cpu_clock_sample(which_clock,
 327                                                                  p, &rtn);
 328                                 }
 329                         } else {
 330                                 read_lock(&tasklist_lock);
 331                                 if (thread_group_leader(p) && p->signal) {
 332                                         error =
 333                                             cpu_clock_sample_group(which_clock,
 334                                                                    p, &rtn);
 335                                 }
 336                                 read_unlock(&tasklist_lock);
 337                         }
 338                 }
 339                 rcu_read_unlock();
 340         }
 341
 342         if (error)
 343                 return error;
 344         sample_to_timespec(which_clock, rtn, tp);
 345         return 0;
 346 }
 347
 348
 349 /*
 350  * Validate the clockid_t for a new CPU-clock timer, and initialize the timer.
 351  * This is called from sys_timer_create with the new timer already locked.
 352  */
 353 int posix_cpu_timer_create(struct k_itimer *new_timer)
 354 {
 355         int ret = 0;
 356         const pid_t pid = CPUCLOCK_PID(new_timer->it_clock);
 357         struct task_struct *p;
 358
 359         if (CPUCLOCK_WHICH(new_timer->it_clock) >= CPUCLOCK_MAX)
 360                 return -EINVAL;
 361
 362         INIT_LIST_HEAD(&new_timer->it.cpu.entry);
 363         new_timer->it.cpu.incr.sched = 0;
 364         new_timer->it.cpu.expires.sched = 0;
 365
 366         read_lock(&tasklist_lock);
 367         if (CPUCLOCK_PERTHREAD(new_timer->it_clock)) {
 368                 if (pid == 0) {
 369                         p = current;
 370                 } else {
 371                         p = find_task_by_vpid(pid);
 372                         if (p && !same_thread_group(p, current))
 373                                 p = NULL;
 374                 }
 375         } else {
 376                 if (pid == 0) {
 377                         p = current->group_leader;
 378                 } else {
 379                         p = find_task_by_vpid(pid);
 380                         if (p && !thread_group_leader(p))
 381                                 p = NULL;
 382                 }
 383         }
 384         new_timer->it.cpu.task = p;
 385         if (p) {
 386                 get_task_struct(p);
 387         } else {
 388                 ret = -EINVAL;
 389         }
 390         read_unlock(&tasklist_lock);
 391
 392         return ret;
 393 }
 394
 395 /*
 396  * Clean up a CPU-clock timer that is about to be destroyed.
 397  * This is called from timer deletion with the timer already locked.
 398  * If we return TIMER_RETRY, it's necessary to release the timer's lock
 399  * and try again.  (This happens when the timer is in the middle of firing.)
 400  */
 401 int posix_cpu_timer_del(struct k_itimer *timer)
 402 {
 403         struct task_struct *p = timer->it.cpu.task;
 404         int ret = 0;
 405
 406         if (likely(p != NULL)) {
 407                 read_lock(&tasklist_lock);
 408                 if (unlikely(p->signal == NULL)) {
 409                         /*
 410                          * We raced with the reaping of the task.
 411                          * The deletion should have cleared us off the list.
 412                          */
 413                         BUG_ON(!list_empty(&timer->it.cpu.entry));
 414                 } else {
 415                         spin_lock(&p->sighand->siglock);
 416                         if (timer->it.cpu.firing)
 417                                 ret = TIMER_RETRY;
 418                         else
 419                                 list_del(&timer->it.cpu.entry);
 420                         spin_unlock(&p->sighand->siglock);
 421                 }
 422                 read_unlock(&tasklist_lock);
 423
 424                 if (!ret)
 425                         put_task_struct(p);
 426         }
 427
 428         return ret;
 429 }
 430
 431 /*
 432  * Clean out CPU timers still ticking when a thread exited.  The task
 433  * pointer is cleared, and the expiry time is replaced with the residual
 434  * time for later timer_gettime calls to return.
 435  * This must be called with the siglock held.
 436  */
 437 static void cleanup_timers(struct list_head *head,
 438                            cputime_t utime, cputime_t stime,
 439                            unsigned long long sum_exec_runtime)
 440 {
 441         struct cpu_timer_list *timer, *next;
 442         cputime_t ptime = cputime_add(utime, stime);
 443
 444         list_for_each_entry_safe(timer, next, head, entry) {
 445                 list_del_init(&timer->entry);
 446                 if (cputime_lt(timer->expires.cpu, ptime)) {
 447                         timer->expires.cpu = cputime_zero;
 448                 } else {
 449                         timer->expires.cpu = cputime_sub(timer->expires.cpu,
 450                                                          ptime);
 451                 }
 452         }
 453
 454         ++head;
 455         list_for_each_entry_safe(timer, next, head, entry) {
 456                 list_del_init(&timer->entry);
 457                 if (cputime_lt(timer->expires.cpu, utime)) {
 458                         timer->expires.cpu = cputime_zero;
 459                 } else {
 460                         timer->expires.cpu = cputime_sub(timer->expires.cpu,
 461                                                          utime);
 462                 }
 463         }
 464
 465         ++head;
 466         list_for_each_entry_safe(timer, next, head, entry) {
 467                 list_del_init(&timer->entry);
 468                 if (timer->expires.sched < sum_exec_runtime) {
 469                         timer->expires.sched = 0;
 470                 } else {
 471                         timer->expires.sched -= sum_exec_runtime;
 472                 }
 473         }
 474 }
 475
 476 /*
 477  * These are both called with the siglock held, when the current thread
 478  * is being reaped.  When the final (leader) thread in the group is reaped,
 479  * posix_cpu_timers_exit_group will be called after posix_cpu_timers_exit.
 480  */
 481 void posix_cpu_timers_exit(struct task_struct *tsk)
 482 {
 483         cleanup_timers(tsk->cpu_timers,
 484                        tsk->utime, tsk->stime, tsk->se.sum_exec_runtime);
 485
 486 }
 487 void posix_cpu_timers_exit_group(struct task_struct *tsk)
 488 {
 489         struct task_cputime cputime;
 490
 491         thread_group_cputime(tsk, &cputime);
 492         cleanup_timers(tsk->signal->cpu_timers,
 493                        cputime.utime, cputime.stime, cputime.sum_exec_runtime);
 494 }
 495
 496 static void clear_dead_task(struct k_itimer *timer, union cpu_time_count now)
 497 {
 498         /*
 499          * That's all for this thread or process.
 500          * We leave our residual in expires to be reported.
 501          */
 502         put_task_struct(timer->it.cpu.task);
 503         timer->it.cpu.task = NULL;
 504         timer->it.cpu.expires = cpu_time_sub(timer->it_clock,
 505                                              timer->it.cpu.expires,
 506                                              now);
 507 }
 508
 509 /*
 510  * Enable the process wide cpu timer accounting.
 511  *
 512  * serialized using ->sighand->siglock
 513  */
 514 static void start_process_timers(struct task_struct *tsk)
 515 {
 516         tsk->signal->cputimer.running = 1;
 517         barrier();
 518 }
 519
 520 /*
 521  * Release the process wide timer accounting -- timer stops ticking when
 522  * nobody cares about it.
 523  *
 524  * serialized using ->sighand->siglock
 525  */
 526 static void stop_process_timers(struct task_struct *tsk)
 527 {
 528         tsk->signal->cputimer.running = 0;
 529         barrier();
 530 }
 531
 532 /*
 533  * Insert the timer on the appropriate list before any timers that
 534  * expire later.  This must be called with the tasklist_lock held
 535  * for reading, and interrupts disabled.
 536  */
 537 static void arm_timer(struct k_itimer *timer, union cpu_time_count now)
 538 {
 539         struct task_struct *p = timer->it.cpu.task;
 540         struct list_head *head, *listpos;
 541         struct cpu_timer_list *const nt = &timer->it.cpu;
 542         struct cpu_timer_list *next;
 543         unsigned long i;
 544
 545         head = (CPUCLOCK_PERTHREAD(timer->it_clock) ?
 546                 p->cpu_timers : p->signal->cpu_timers);
 547         head += CPUCLOCK_WHICH(timer->it_clock);
 548
 549         BUG_ON(!irqs_disabled());
 550         spin_lock(&p->sighand->siglock);
 551
 552         if (!CPUCLOCK_PERTHREAD(timer->it_clock))
 553                 start_process_timers(p);
 554
 555         listpos = head;
 556         if (CPUCLOCK_WHICH(timer->it_clock) == CPUCLOCK_SCHED) {
 557                 list_for_each_entry(next, head, entry) {
 558                         if (next->expires.sched > nt->expires.sched)
 559                                 break;
 560                         listpos = &next->entry;
 561                 }
 562         } else {
 563                 list_for_each_entry(next, head, entry) {
 564                         if (cputime_gt(next->expires.cpu, nt->expires.cpu))
 565                                 break;
 566                         listpos = &next->entry;
 567                 }
 568         }
 569         list_add(&nt->entry, listpos);
 570
 571         if (listpos == head) {
 572                 /*
 573                  * We are the new earliest-expiring timer.
 574                  * If we are a thread timer, there can always
 575                  * be a process timer telling us to stop earlier.
 576                  */
 577
 578                 if (CPUCLOCK_PERTHREAD(timer->it_clock)) {
 579                         switch (CPUCLOCK_WHICH(timer->it_clock)) {
 580                         default:
 581                                 BUG();
 582                         case CPUCLOCK_PROF:
 583                                 if (cputime_eq(p->cputime_expires.prof_exp,
 584                                                cputime_zero) ||
 585                                     cputime_gt(p->cputime_expires.prof_exp,
 586                                                nt->expires.cpu))
 587                                         p->cputime_expires.prof_exp =
 588                                                 nt->expires.cpu;
 589                                 break;
 590                         case CPUCLOCK_VIRT:
 591                                 if (cputime_eq(p->cputime_expires.virt_exp,
 592                                                cputime_zero) ||
 593                                     cputime_gt(p->cputime_expires.virt_exp,
 594                                                nt->expires.cpu))
 595                                         p->cputime_expires.virt_exp =
 596                                                 nt->expires.cpu;
 597                                 break;
 598                         case CPUCLOCK_SCHED:
 599                                 if (p->cputime_expires.sched_exp == 0 ||
 600                                     p->cputime_expires.sched_exp >
 601                                                         nt->expires.sched)
 602                                         p->cputime_expires.sched_exp =
 603                                                 nt->expires.sched;
 604                                 break;
 605                         }
 606                 } else {
 607                         /*
 608                          * For a process timer, set the cached expiration time.
 609                          */
 610                         switch (CPUCLOCK_WHICH(timer->it_clock)) {
 611                         default:
 612                                 BUG();
 613                         case CPUCLOCK_VIRT:
 614                                 if (!cputime_eq(p->signal->it_virt_expires,
 615                                                 cputime_zero) &&
 616                                     cputime_lt(p->signal->it_virt_expires,
 617                                                timer->it.cpu.expires.cpu))
 618                                         break;
 619                                 p->signal->cputime_expires.virt_exp =
 620                                         timer->it.cpu.expires.cpu;
 621                                 break;
 622                         case CPUCLOCK_PROF:
 623                                 if (!cputime_eq(p->signal->it_prof_expires,
 624                                                 cputime_zero) &&
 625                                     cputime_lt(p->signal->it_prof_expires,
 626                                                timer->it.cpu.expires.cpu))
 627                                         break;
 628                                 i = p->signal->rlim[RLIMIT_CPU].rlim_cur;
 629                                 if (i != RLIM_INFINITY &&
 630                                     i <= cputime_to_secs(timer->it.cpu.expires.cpu))
 631                                         break;
 632                                 p->signal->cputime_expires.prof_exp =
 633                                         timer->it.cpu.expires.cpu;
 634                                 break;
 635                         case CPUCLOCK_SCHED:
 636                                 p->signal->cputime_expires.sched_exp =
 637                                         timer->it.cpu.expires.sched;
 638                                 break;
 639                         }
 640                 }
 641         }
 642
 643         spin_unlock(&p->sighand->siglock);
 644 }
 645
 646 /*
 647  * The timer is locked, fire it and arrange for its reload.
 648  */
 649 static void cpu_timer_fire(struct k_itimer *timer)
 650 {
 651         if (unlikely(timer->sigq == NULL)) {
 652                 /*
 653                  * This a special case for clock_nanosleep,
 654                  * not a normal timer from sys_timer_create.
 655                  */
 656                 wake_up_process(timer->it_process);
 657                 timer->it.cpu.expires.sched = 0;
 658         } else if (timer->it.cpu.incr.sched == 0) {
 659                 /*
 660                  * One-shot timer.  Clear it as soon as it's fired.
 661                  */
 662                 posix_timer_event(timer, 0);
 663                 timer->it.cpu.expires.sched = 0;
 664         } else if (posix_timer_event(timer, ++timer->it_requeue_pending)) {
 665                 /*
 666                  * The signal did not get queued because the signal
 667                  * was ignored, so we won't get any callback to
 668                  * reload the timer.  But we need to keep it
 669                  * ticking in case the signal is deliverable next time.
 670                  */
 671                 posix_cpu_timer_schedule(timer);
 672         }
 673 }
 674
 675 /*
 676  * Guts of sys_timer_settime for CPU timers.
 677  * This is called with the timer locked and interrupts disabled.
 678  * If we return TIMER_RETRY, it's necessary to release the timer's lock
 679  * and try again.  (This happens when the timer is in the middle of firing.)
 680  */
 681 int posix_cpu_timer_set(struct k_itimer *timer, int flags,
 682                         struct itimerspec *new, struct itimerspec *old)
 683 {
 684         struct task_struct *p = timer->it.cpu.task;
 685         union cpu_time_count old_expires, new_expires, val;
 686         int ret;
 687
 688         if (unlikely(p == NULL)) {
 689                 /*
 690                  * Timer refers to a dead task's clock.
 691                  */
 692                 return -ESRCH;
 693         }
 694
 695         new_expires = timespec_to_sample(timer->it_clock, &new->it_value);
 696
 697         read_lock(&tasklist_lock);
 698         /*
 699          * We need the tasklist_lock to protect against reaping that
 700          * clears p->signal.  If p has just been reaped, we can no
 701          * longer get any information about it at all.
 702          */
 703         if (unlikely(p->signal == NULL)) {
 704                 read_unlock(&tasklist_lock);
 705                 put_task_struct(p);
 706                 timer->it.cpu.task = NULL;
 707                 return -ESRCH;
 708         }
 709
 710         /*
 711          * Disarm any old timer after extracting its expiry time.
 712          */
 713         BUG_ON(!irqs_disabled());
 714
 715         ret = 0;
 716         spin_lock(&p->sighand->siglock);
 717         old_expires = timer->it.cpu.expires;
 718         if (unlikely(timer->it.cpu.firing)) {
 719                 timer->it.cpu.firing = -1;
 720                 ret = TIMER_RETRY;
 721         } else
 722                 list_del_init(&timer->it.cpu.entry);
 723         spin_unlock(&p->sighand->siglock);
 724
 725         /*
 726          * We need to sample the current value to convert the new
 727          * value from to relative and absolute, and to convert the
 728          * old value from absolute to relative.  To set a process
 729          * timer, we need a sample to balance the thread expiry
 730          * times (in arm_timer).  With an absolute time, we must
 731          * check if it's already passed.  In short, we need a sample.
 732          */
 733         if (CPUCLOCK_PERTHREAD(timer->it_clock)) {
 734                 cpu_clock_sample(timer->it_clock, p, &val);
 735         } else {
 736                 cpu_clock_sample_group(timer->it_clock, p, &val);
 737         }
 738
 739         if (old) {
 740                 if (old_expires.sched == 0) {
 741                         old->it_value.tv_sec = 0;
 742                         old->it_value.tv_nsec = 0;
 743                 } else {
 744                         /*
 745                          * Update the timer in case it has
 746                          * overrun already.  If it has,
 747                          * we'll report it as having overrun
 748                          * and with the next reloaded timer
 749                          * already ticking, though we are
 750                          * swallowing that pending
 751                          * notification here to install the
 752                          * new setting.
 753                          */
 754                         bump_cpu_timer(timer, val);
 755                         if (cpu_time_before(timer->it_clock, val,
 756                                             timer->it.cpu.expires)) {
 757                                 old_expires = cpu_time_sub(
 758                                         timer->it_clock,
 759                                         timer->it.cpu.expires, val);
 760                                 sample_to_timespec(timer->it_clock,
 761                                                    old_expires,
 762                                                    &old->it_value);
 763                         } else {
 764                                 old->it_value.tv_nsec = 1;
 765                                 old->it_value.tv_sec = 0;
 766                         }
 767                 }
 768         }
 769
 770         if (unlikely(ret)) {
 771                 /*
 772                  * We are colliding with the timer actually firing.
 773                  * Punt after filling in the timer's old value, and
 774                  * disable this firing since we are already reporting
 775                  * it as an overrun (thanks to bump_cpu_timer above).
 776                  */
 777                 read_unlock(&tasklist_lock);
 778                 goto out;
 779         }
 780
 781         if (new_expires.sched != 0 && !(flags & TIMER_ABSTIME)) {
 782                 cpu_time_add(timer->it_clock, &new_expires, val);
 783         }
 784
 785         /*
 786          * Install the new expiry time (or zero).
 787          * For a timer with no notification action, we don't actually
 788          * arm the timer (we'll just fake it for timer_gettime).
 789          */
 790         timer->it.cpu.expires = new_expires;
 791         if (new_expires.sched != 0 &&
 792             (timer->it_sigev_notify & ~SIGEV_THREAD_ID) != SIGEV_NONE &&
 793             cpu_time_before(timer->it_clock, val, new_expires)) {
 794                 arm_timer(timer, val);
 795         }
 796
 797         read_unlock(&tasklist_lock);
 798
 799         /*
 800          * Install the new reload setting, and
 801          * set up the signal and overrun bookkeeping.
 802          */
 803         timer->it.cpu.incr = timespec_to_sample(timer->it_clock,
 804                                                 &new->it_interval);
 805
 806         /*
 807          * This acts as a modification timestamp for the timer,
 808          * so any automatic reload attempt will punt on seeing
 809          * that we have reset the timer manually.
 810          */
 811         timer->it_requeue_pending = (timer->it_requeue_pending + 2) &
 812                 ~REQUEUE_PENDING;
 813         timer->it_overrun_last = 0;
 814         timer->it_overrun = -1;
 815
 816         if (new_expires.sched != 0 &&
 817             (timer->it_sigev_notify & ~SIGEV_THREAD_ID) != SIGEV_NONE &&
 818             !cpu_time_before(timer->it_clock, val, new_expires)) {
 819                 /*
 820                  * The designated time already passed, so we notify
 821                  * immediately, even if the thread never runs to
 822                  * accumulate more time on this clock.
 823                  */
 824                 cpu_timer_fire(timer);
 825         }
 826
 827         ret = 0;
 828  out:
 829         if (old) {
 830                 sample_to_timespec(timer->it_clock,
 831                                    timer->it.cpu.incr, &old->it_interval);
 832         }
 833         return ret;
 834 }
 835
 836 void posix_cpu_timer_get(struct k_itimer *timer, struct itimerspec *itp)
 837 {
 838         union cpu_time_count now;
 839         struct task_struct *p = timer->it.cpu.task;
 840         int clear_dead;
 841
 842         /*
 843          * Easy part: convert the reload time.
 844          */
 845         sample_to_timespec(timer->it_clock,
 846                            timer->it.cpu.incr, &itp->it_interval);
 847
 848         if (timer->it.cpu.expires.sched == 0) { /* Timer not armed at all.  */
 849                 itp->it_value.tv_sec = itp->it_value.tv_nsec = 0;
 850                 return;
 851         }
 852
 853         if (unlikely(p == NULL)) {
 854                 /*
 855                  * This task already died and the timer will never fire.
 856                  * In this case, expires is actually the dead value.
 857                  */
 858         dead:
 859                 sample_to_timespec(timer->it_clock, timer->it.cpu.expires,
 860                                    &itp->it_value);
 861                 return;
 862         }
 863
 864         /*
 865          * Sample the clock to take the difference with the expiry time.
 866          */
 867         if (CPUCLOCK_PERTHREAD(timer->it_clock)) {
 868                 cpu_clock_sample(timer->it_clock, p, &now);
 869                 clear_dead = p->exit_state;
 870         } else {
 871                 read_lock(&tasklist_lock);
 872                 if (unlikely(p->signal == NULL)) {
 873                         /*
 874                          * The process has been reaped.
 875                          * We can't even collect a sample any more.
 876                          * Call the timer disarmed, nothing else to do.
 877                          */
 878                         put_task_struct(p);
 879                         timer->it.cpu.task = NULL;
 880                         timer->it.cpu.expires.sched = 0;
 881                         read_unlock(&tasklist_lock);
 882                         goto dead;
 883                 } else {
 884                         cpu_clock_sample_group(timer->it_clock, p, &now);
 885                         clear_dead = (unlikely(p->exit_state) &&
 886                                       thread_group_empty(p));
 887                 }
 888                 read_unlock(&tasklist_lock);
 889         }
 890
 891         if ((timer->it_sigev_notify & ~SIGEV_THREAD_ID) == SIGEV_NONE) {
 892                 if (timer->it.cpu.incr.sched == 0 &&
 893                     cpu_time_before(timer->it_clock,
 894                                     timer->it.cpu.expires, now)) {
 895                         /*
 896                          * Do-nothing timer expired and has no reload,
 897                          * so it's as if it was never set.
 898                          */
 899                         timer->it.cpu.expires.sched = 0;
 900                         itp->it_value.tv_sec = itp->it_value.tv_nsec = 0;
 901                         return;
 902                 }
 903                 /*
 904                  * Account for any expirations and reloads that should
 905                  * have happened.
 906                  */
 907                 bump_cpu_timer(timer, now);
 908         }
 909
 910         if (unlikely(clear_dead)) {
 911                 /*
 912                  * We've noticed that the thread is dead, but
 913                  * not yet reaped.  Take this opportunity to
 914                  * drop our task ref.
 915                  */
 916                 clear_dead_task(timer, now);
 917                 goto dead;
 918         }
 919
 920         if (cpu_time_before(timer->it_clock, now, timer->it.cpu.expires)) {
 921                 sample_to_timespec(timer->it_clock,
 922                                    cpu_time_sub(timer->it_clock,
 923                                                 timer->it.cpu.expires, now),
 924                                    &itp->it_value);
 925         } else {
 926                 /*
 927                  * The timer should have expired already, but the firing
 928                  * hasn't taken place yet.  Say it's just about to expire.
 929                  */
 930                 itp->it_value.tv_nsec = 1;
 931                 itp->it_value.tv_sec = 0;
 932         }
 933 }
 934
 935 /*
 936  * Check for any per-thread CPU timers that have fired and move them off
 937  * the tsk->cpu_timers[N] list onto the firing list.  Here we update the
 938  * tsk->it_*_expires values to reflect the remaining thread CPU timers.
 939  */
 940 static void check_thread_timers(struct task_struct *tsk,
 941                                 struct list_head *firing)
 942 {
 943         int maxfire;
 944         struct list_head *timers = tsk->cpu_timers;
 945         struct signal_struct *const sig = tsk->signal;
 946
 947         maxfire = 20;
 948         tsk->cputime_expires.prof_exp = cputime_zero;
 949         while (!list_empty(timers)) {
 950                 struct cpu_timer_list *t = list_first_entry(timers,
 951                                                       struct cpu_timer_list,
 952                                                       entry);
 953                 if (!--maxfire || cputime_lt(prof_ticks(tsk), t->expires.cpu)) {
 954                         tsk->cputime_expires.prof_exp = t->expires.cpu;
 955                         break;
 956                 }
 957                 t->firing = 1;
 958                 list_move_tail(&t->entry, firing);
 959         }
 960
 961         ++timers;
 962         maxfire = 20;
 963         tsk->cputime_expires.virt_exp = cputime_zero;
 964         while (!list_empty(timers)) {
 965                 struct cpu_timer_list *t = list_first_entry(timers,
 966                                                       struct cpu_timer_list,
 967                                                       entry);
 968                 if (!--maxfire || cputime_lt(virt_ticks(tsk), t->expires.cpu)) {
 969                         tsk->cputime_expires.virt_exp = t->expires.cpu;
 970                         break;
 971                 }
 972                 t->firing = 1;
 973                 list_move_tail(&t->entry, firing);
 974         }
 975
 976         ++timers;
 977         maxfire = 20;
 978         tsk->cputime_expires.sched_exp = 0;
 979         while (!list_empty(timers)) {
 980                 struct cpu_timer_list *t = list_first_entry(timers,
 981                                                       struct cpu_timer_list,
 982                                                       entry);
 983                 if (!--maxfire || tsk->se.sum_exec_runtime < t->expires.sched) {
 984                         tsk->cputime_expires.sched_exp = t->expires.sched;
 985                         break;
 986                 }
 987                 t->firing = 1;
 988                 list_move_tail(&t->entry, firing);
 989         }
 990
 991         /*
 992          * Check for the special case thread timers.
 993          */
 994         if (sig->rlim[RLIMIT_RTTIME].rlim_cur != RLIM_INFINITY) {
 995                 unsigned long hard = sig->rlim[RLIMIT_RTTIME].rlim_max;
 996                 unsigned long *soft = &sig->rlim[RLIMIT_RTTIME].rlim_cur;
 997
 998                 if (hard != RLIM_INFINITY &&
 999                     tsk->rt.timeout > DIV_ROUND_UP(hard, USEC_PER_SEC/HZ)) {
1000                         /*
1001                          * At the hard limit, we just die.
1002                          * No need to calculate anything else now.
1003                          */
1004                         __group_send_sig_info(SIGKILL, SEND_SIG_PRIV, tsk);
1005                         return;
1006                 }
1007                 if (tsk->rt.timeout > DIV_ROUND_UP(*soft, USEC_PER_SEC/HZ)) {
1008                         /*
1009                          * At the soft limit, send a SIGXCPU every second.
1010                          */
1011                         if (sig->rlim[RLIMIT_RTTIME].rlim_cur
1012                             < sig->rlim[RLIMIT_RTTIME].rlim_max) {
1013                                 sig->rlim[RLIMIT_RTTIME].rlim_cur +=
1014                                                                 USEC_PER_SEC;
1015                         }
1016                         printk(KERN_INFO
1017                                 "RT Watchdog Timeout: %s[%d]\n",
1018                                 tsk->comm, task_pid_nr(tsk));
1019                         __group_send_sig_info(SIGXCPU, SEND_SIG_PRIV, tsk);
1020                 }
1021         }
1022 }
1023
1024 /*
1025  * Check for any per-thread CPU timers that have fired and move them
1026  * off the tsk->*_timers list onto the firing list.  Per-thread timers
1027  * have already been taken off.
1028  */
1029 static void check_process_timers(struct task_struct *tsk,
1030                                  struct list_head *firing)
1031 {
1032         int maxfire;
1033         struct signal_struct *const sig = tsk->signal;
1034         cputime_t utime, ptime, virt_expires, prof_expires;
1035         unsigned long long sum_sched_runtime, sched_expires;
1036         struct list_head *timers = sig->cpu_timers;
1037         struct task_cputime cputime;
1038
1039         /*
1040          * Don't sample the current process CPU clocks if there are no timers.
1041          */
1042         if (list_empty(&timers[CPUCLOCK_PROF]) &&
1043             cputime_eq(sig->it_prof_expires, cputime_zero) &&
1044             sig->rlim[RLIMIT_CPU].rlim_cur == RLIM_INFINITY &&
1045             list_empty(&timers[CPUCLOCK_VIRT]) &&
1046             cputime_eq(sig->it_virt_expires, cputime_zero) &&
1047             list_empty(&timers[CPUCLOCK_SCHED])) {
1048                 stop_process_timers(tsk);
1049                 return;
1050         }
1051
1052         /*
1053          * Collect the current process totals.
1054          */
1055         thread_group_cputimer(tsk, &cputime);
1056         utime = cputime.utime;
1057         ptime = cputime_add(utime, cputime.stime);
1058         sum_sched_runtime = cputime.sum_exec_runtime;
1059         maxfire = 20;
1060         prof_expires = cputime_zero;
1061         while (!list_empty(timers)) {
1062                 struct cpu_timer_list *tl = list_first_entry(timers,
1063                                                       struct cpu_timer_list,
1064                                                       entry);
1065                 if (!--maxfire || cputime_lt(ptime, tl->expires.cpu)) {
1066                         prof_expires = tl->expires.cpu;
1067                         break;
1068                 }
1069                 tl->firing = 1;
1070                 list_move_tail(&tl->entry, firing);
1071         }
1072
1073         ++timers;
1074         maxfire = 20;
1075         virt_expires = cputime_zero;
1076         while (!list_empty(timers)) {
1077                 struct cpu_timer_list *tl = list_first_entry(timers,
1078                                                       struct cpu_timer_list,
1079                                                       entry);
1080                 if (!--maxfire || cputime_lt(utime, tl->expires.cpu)) {
1081                         virt_expires = tl->expires.cpu;
1082                         break;
1083                 }
1084                 tl->firing = 1;
1085                 list_move_tail(&tl->entry, firing);
1086         }
1087
1088         ++timers;
1089         maxfire = 20;
1090         sched_expires = 0;
1091         while (!list_empty(timers)) {
1092                 struct cpu_timer_list *tl = list_first_entry(timers,
1093                                                       struct cpu_timer_list,
1094                                                       entry);
1095                 if (!--maxfire || sum_sched_runtime < tl->expires.sched) {
1096                         sched_expires = tl->expires.sched;
1097                         break;
1098                 }
1099                 tl->firing = 1;
1100                 list_move_tail(&tl->entry, firing);
1101         }
1102
1103         /*
1104          * Check for the special case process timers.
1105          */
1106         if (!cputime_eq(sig->it_prof_expires, cputime_zero)) {
1107                 if (cputime_ge(ptime, sig->it_prof_expires)) {
1108                         /* ITIMER_PROF fires and reloads.  */
1109                         sig->it_prof_expires = sig->it_prof_incr;
1110                         if (!cputime_eq(sig->it_prof_expires, cputime_zero)) {
1111                                 sig->it_prof_expires = cputime_add(
1112                                         sig->it_prof_expires, ptime);
1113                         }
1114                         __group_send_sig_info(SIGPROF, SEND_SIG_PRIV, tsk);
1115                 }
1116                 if (!cputime_eq(sig->it_prof_expires, cputime_zero) &&
1117                     (cputime_eq(prof_expires, cputime_zero) ||
1118                      cputime_lt(sig->it_prof_expires, prof_expires))) {
1119                         prof_expires = sig->it_prof_expires;
1120                 }
1121         }
1122         if (!cputime_eq(sig->it_virt_expires, cputime_zero)) {
1123                 if (cputime_ge(utime, sig->it_virt_expires)) {
1124                         /* ITIMER_VIRTUAL fires and reloads.  */
1125                         sig->it_virt_expires = sig->it_virt_incr;
1126                         if (!cputime_eq(sig->it_virt_expires, cputime_zero)) {
1127                                 sig->it_virt_expires = cputime_add(
1128                                         sig->it_virt_expires, utime);
1129                         }
1130                         __group_send_sig_info(SIGVTALRM, SEND_SIG_PRIV, tsk);
1131                 }
1132                 if (!cputime_eq(sig->it_virt_expires, cputime_zero) &&
1133                     (cputime_eq(virt_expires, cputime_zero) ||
1134                      cputime_lt(sig->it_virt_expires, virt_expires))) {
1135                         virt_expires = sig->it_virt_expires;
1136                 }
1137         }
1138         if (sig->rlim[RLIMIT_CPU].rlim_cur != RLIM_INFINITY) {
1139                 unsigned long psecs = cputime_to_secs(ptime);
1140                 cputime_t x;
1141                 if (psecs >= sig->rlim[RLIMIT_CPU].rlim_max) {
1142                         /*
1143                          * At the hard limit, we just die.
1144                          * No need to calculate anything else now.
1145                          */
1146                         __group_send_sig_info(SIGKILL, SEND_SIG_PRIV, tsk);
1147                         return;
1148                 }
1149                 if (psecs >= sig->rlim[RLIMIT_CPU].rlim_cur) {
1150                         /*
1151                          * At the soft limit, send a SIGXCPU every second.
1152                          */
1153                         __group_send_sig_info(SIGXCPU, SEND_SIG_PRIV, tsk);
1154                         if (sig->rlim[RLIMIT_CPU].rlim_cur
1155                             < sig->rlim[RLIMIT_CPU].rlim_max) {
1156                                 sig->rlim[RLIMIT_CPU].rlim_cur++;
1157                         }
1158                 }
1159                 x = secs_to_cputime(sig->rlim[RLIMIT_CPU].rlim_cur);
1160                 if (cputime_eq(prof_expires, cputime_zero) ||
1161                     cputime_lt(x, prof_expires)) {
1162                         prof_expires = x;
1163                 }
1164         }
1165
1166         if (!cputime_eq(prof_expires, cputime_zero) &&
1167             (cputime_eq(sig->cputime_expires.prof_exp, cputime_zero) ||
1168              cputime_gt(sig->cputime_expires.prof_exp, prof_expires)))
1169                 sig->cputime_expires.prof_exp = prof_expires;
1170         if (!cputime_eq(virt_expires, cputime_zero) &&
1171             (cputime_eq(sig->cputime_expires.virt_exp, cputime_zero) ||
1172              cputime_gt(sig->cputime_expires.virt_exp, virt_expires)))
1173                 sig->cputime_expires.virt_exp = virt_expires;
1174         if (sched_expires != 0 &&
1175             (sig->cputime_expires.sched_exp == 0 ||
1176              sig->cputime_expires.sched_exp > sched_expires))
1177                 sig->cputime_expires.sched_exp = sched_expires;
1178 }
1179
1180 /*
1181  * This is called from the signal code (via do_schedule_next_timer)
1182  * when the last timer signal was delivered and we have to reload the timer.
1183  */
1184 void posix_cpu_timer_schedule(struct k_itimer *timer)
1185 {
1186         struct task_struct *p = timer->it.cpu.task;
1187         union cpu_time_count now;
1188
1189         if (unlikely(p == NULL))
1190                 /*
1191                  * The task was cleaned up already, no future firings.
1192                  */
1193                 goto out;
1194
1195         /*
1196          * Fetch the current sample and update the timer's expiry time.
1197          */
1198         if (CPUCLOCK_PERTHREAD(timer->it_clock)) {
1199                 cpu_clock_sample(timer->it_clock, p, &now);
1200                 bump_cpu_timer(timer, now);
1201                 if (unlikely(p->exit_state)) {
1202                         clear_dead_task(timer, now);
1203                         goto out;
1204                 }
1205                 read_lock(&tasklist_lock); /* arm_timer needs it.  */
1206         } else {
1207                 read_lock(&tasklist_lock);
1208                 if (unlikely(p->signal == NULL)) {
1209                         /*
1210                          * The process has been reaped.
1211                          * We can't even collect a sample any more.
1212                          */
1213                         put_task_struct(p);
1214                         timer->it.cpu.task = p = NULL;
1215                         timer->it.cpu.expires.sched = 0;
1216                         goto out_unlock;
1217                 } else if (unlikely(p->exit_state) && thread_group_empty(p)) {
1218                         /*
1219                          * We've noticed that the thread is dead, but
1220                          * not yet reaped.  Take this opportunity to
1221                          * drop our task ref.
1222                          */
1223                         clear_dead_task(timer, now);
1224                         goto out_unlock;
1225                 }
1226                 cpu_clock_sample_group(timer->it_clock, p, &now);
1227                 bump_cpu_timer(timer, now);
1228                 /* Leave the tasklist_lock locked for the call below.  */
1229         }
1230
1231         /*
1232          * Now re-arm for the new expiry time.
1233          */
1234         arm_timer(timer, now);
1235
1236 out_unlock:
1237         read_unlock(&tasklist_lock);
1238
1239 out:
1240         timer->it_overrun_last = timer->it_overrun;
1241         timer->it_overrun = -1;
1242         ++timer->it_requeue_pending;
1243 }
1244
1245 /**
1246  * task_cputime_zero - Check a task_cputime struct for all zero fields.
1247  *
1248  * @cputime:    The struct to compare.
1249  *
1250  * Checks @cputime to see if all fields are zero.  Returns true if all fields
1251  * are zero, false if any field is nonzero.
1252  */
1253 static inline int task_cputime_zero(const struct task_cputime *cputime)
1254 {
1255         if (cputime_eq(cputime->utime, cputime_zero) &&
1256             cputime_eq(cputime->stime, cputime_zero) &&
1257             cputime->sum_exec_runtime == 0)
1258                 return 1;
1259         return 0;
1260 }
1261
1262 /**
1263  * task_cputime_expired - Compare two task_cputime entities.
1264  *
1265  * @sample:     The task_cputime structure to be checked for expiration.
1266  * @expires:    Expiration times, against which @sample will be checked.
1267  *
1268  * Checks @sample against @expires to see if any field of @sample has expired.
1269  * Returns true if any field of the former is greater than the corresponding
1270  * field of the latter if the latter field is set.  Otherwise returns false.
1271  */
1272 static inline int task_cputime_expired(const struct task_cputime *sample,
1273                                         const struct task_cputime *expires)
1274 {
1275         if (!cputime_eq(expires->utime, cputime_zero) &&
1276             cputime_ge(sample->utime, expires->utime))
1277                 return 1;
1278         if (!cputime_eq(expires->stime, cputime_zero) &&
1279             cputime_ge(cputime_add(sample->utime, sample->stime),
1280                        expires->stime))
1281                 return 1;
1282         if (expires->sum_exec_runtime != 0 &&
1283             sample->sum_exec_runtime >= expires->sum_exec_runtime)
1284                 return 1;
1285         return 0;
1286 }
1287
1288 /**
1289  * fastpath_timer_check - POSIX CPU timers fast path.
1290  *
1291  * @tsk:        The task (thread) being checked.
1292  *
1293  * Check the task and thread group timers.  If both are zero (there are no
1294  * timers set) return false.  Otherwise snapshot the task and thread group
1295  * timers and compare them with the corresponding expiration times.  Return
1296  * true if a timer has expired, else return false.
1297  */
1298 static inline int fastpath_timer_check(struct task_struct *tsk)
1299 {
1300         struct signal_struct *sig;
1301
1302         /* tsk == current, ensure it is safe to use ->signal/sighand */
1303         if (unlikely(tsk->exit_state))
1304                 return 0;
1305
1306         if (!task_cputime_zero(&tsk->cputime_expires)) {
1307                 struct task_cputime task_sample = {
1308                         .utime = tsk->utime,
1309                         .stime = tsk->stime,
1310                         .sum_exec_runtime = tsk->se.sum_exec_runtime
1311                 };
1312
1313                 if (task_cputime_expired(&task_sample, &tsk->cputime_expires))
1314                         return 1;
1315         }
1316
1317         sig = tsk->signal;
1318         if (!task_cputime_zero(&sig->cputime_expires)) {
1319                 struct task_cputime group_sample;
1320
1321                 thread_group_cputimer(tsk, &group_sample);
1322                 if (task_cputime_expired(&group_sample, &sig->cputime_expires))
1323                         return 1;
1324         }
1325         return 0;
1326 }
1327
1328 /*
1329  * This is called from the timer interrupt handler.  The irq handler has
1330  * already updated our counts.  We need to check if any timers fire now.
1331  * Interrupts are disabled.
1332  */
1333 void run_posix_cpu_timers(struct task_struct *tsk)
1334 {
1335         LIST_HEAD(firing);
1336         struct k_itimer *timer, *next;
1337
1338         BUG_ON(!irqs_disabled());
1339
1340         /*
1341          * The fast path checks that there are no expired thread or thread
1342          * group timers.  If that's so, just return.
1343          */
1344         if (!fastpath_timer_check(tsk))
1345                 return;
1346
1347         spin_lock(&tsk->sighand->siglock);
1348         /*
1349          * Here we take off tsk->signal->cpu_timers[N] and
1350          * tsk->cpu_timers[N] all the timers that are firing, and
1351          * put them on the firing list.
1352          */
1353         check_thread_timers(tsk, &firing);
1354         check_process_timers(tsk, &firing);
1355
1356         /*
1357          * We must release these locks before taking any timer's lock.
1358          * There is a potential race with timer deletion here, as the
1359          * siglock now protects our private firing list.  We have set
1360          * the firing flag in each timer, so that a deletion attempt
1361          * that gets the timer lock before we do will give it up and
1362          * spin until we've taken care of that timer below.
1363          */
1364         spin_unlock(&tsk->sighand->siglock);
1365
1366         /*
1367          * Now that all the timers on our list have the firing flag,
1368          * noone will touch their list entries but us.  We'll take
1369          * each timer's lock before clearing its firing flag, so no
1370          * timer call will interfere.
1371          */
1372         list_for_each_entry_safe(timer, next, &firing, it.cpu.entry) {
1373                 int firing;
1374                 spin_lock(&timer->it_lock);
1375                 list_del_init(&timer->it.cpu.entry);
1376                 firing = timer->it.cpu.firing;
1377                 timer->it.cpu.firing = 0;
1378                 /*
1379                  * The firing flag is -1 if we collided with a reset
1380                  * of the timer, which already reported this
1381                  * almost-firing as an overrun.  So don't generate an event.
1382                  */
1383                 if (likely(firing >= 0)) {
1384                         cpu_timer_fire(timer);
1385                 }
1386                 spin_unlock(&timer->it_lock);
1387         }
1388 }
1389
1390 /*
1391  * Sample a process (thread group) timer for the given group_leader task.
1392  * Must be called with tasklist_lock held for reading.
1393  */
1394 static int cpu_timer_sample_group(const clockid_t which_clock,
1395                                   struct task_struct *p,
1396                                   union cpu_time_count *cpu)
1397 {
1398         struct task_cputime cputime;
1399
1400         thread_group_cputimer(p, &cputime);
1401         switch (CPUCLOCK_WHICH(which_clock)) {
1402         default:
1403                 return -EINVAL;
1404         case CPUCLOCK_PROF:
1405                 cpu->cpu = cputime_add(cputime.utime, cputime.stime);
1406                 break;
1407         case CPUCLOCK_VIRT:
1408                 cpu->cpu = cputime.utime;
1409                 break;
1410         case CPUCLOCK_SCHED:
1411                 cpu->sched = cputime.sum_exec_runtime + task_delta_exec(p);
1412                 break;
1413         }
1414         return 0;
1415 }
1416
1417 /*
1418  * Set one of the process-wide special case CPU timers.
1419  * The tsk->sighand->siglock must be held by the caller.
1420  * The *newval argument is relative and we update it to be absolute, *oldval
1421  * is absolute and we update it to be relative.
1422  */
1423 void set_process_cpu_timer(struct task_struct *tsk, unsigned int clock_idx,
1424                            cputime_t *newval, cputime_t *oldval)
1425 {
1426         union cpu_time_count now;
1427         struct list_head *head;
1428
1429         BUG_ON(clock_idx == CPUCLOCK_SCHED);
1430         start_process_timers(tsk);
1431         cpu_timer_sample_group(clock_idx, tsk, &now);
1432
1433         if (oldval) {
1434                 if (!cputime_eq(*oldval, cputime_zero)) {
1435                         if (cputime_le(*oldval, now.cpu)) {
1436                                 /* Just about to fire. */
1437                                 *oldval = jiffies_to_cputime(1);
1438                         } else {
1439                                 *oldval = cputime_sub(*oldval, now.cpu);
1440                         }
1441                 }
1442
1443                 if (cputime_eq(*newval, cputime_zero))
1444                         return;
1445                 *newval = cputime_add(*newval, now.cpu);
1446
1447                 /*
1448                  * If the RLIMIT_CPU timer will expire before the
1449                  * ITIMER_PROF timer, we have nothing else to do.
1450                  */
1451                 if (tsk->signal->rlim[RLIMIT_CPU].rlim_cur
1452                     < cputime_to_secs(*newval))
1453                         return;
1454         }
1455
1456         /*
1457          * Check whether there are any process timers already set to fire
1458          * before this one.  If so, we don't have anything more to do.
1459          */
1460         head = &tsk->signal->cpu_timers[clock_idx];
1461         if (list_empty(head) ||
1462             cputime_ge(list_first_entry(head,
1463                                   struct cpu_timer_list, entry)->expires.cpu,
1464                        *newval)) {
1465                 switch (clock_idx) {
1466                 case CPUCLOCK_PROF:
1467                         tsk->signal->cputime_expires.prof_exp = *newval;
1468                         break;
1469                 case CPUCLOCK_VIRT:
1470                         tsk->signal->cputime_expires.virt_exp = *newval;
1471                         break;
1472                 }
1473         }
1474 }
1475
1476 static int do_cpu_nanosleep(const clockid_t which_clock, int flags,
1477                             struct timespec *rqtp, struct itimerspec *it)
1478 {
1479         struct k_itimer timer;
1480         int error;
1481
1482         /*
1483          * Set up a temporary timer and then wait for it to go off.
1484          */
1485         memset(&timer, 0, sizeof timer);
1486         spin_lock_init(&timer.it_lock);
1487         timer.it_clock = which_clock;
1488         timer.it_overrun = -1;
1489         error = posix_cpu_timer_create(&timer);
1490         timer.it_process = current;
1491         if (!error) {
1492                 static struct itimerspec zero_it;
1493
1494                 memset(it, 0, sizeof *it);
1495                 it->it_value = *rqtp;
1496
1497                 spin_lock_irq(&timer.it_lock);
1498                 error = posix_cpu_timer_set(&timer, flags, it, NULL);
1499                 if (error) {
1500                         spin_unlock_irq(&timer.it_lock);
1501                         return error;
1502                 }
1503
1504                 while (!signal_pending(current)) {
1505                         if (timer.it.cpu.expires.sched == 0) {
1506                                 /*
1507                                  * Our timer fired and was reset.
1508                                  */
1509                                 spin_unlock_irq(&timer.it_lock);
1510                                 return 0;
1511                         }
1512
1513                         /*
1514                          * Block until cpu_timer_fire (or a signal) wakes us.
1515                          */
1516                         __set_current_state(TASK_INTERRUPTIBLE);
1517                         spin_unlock_irq(&timer.it_lock);
1518                         schedule();
1519                         spin_lock_irq(&timer.it_lock);
1520                 }
1521
1522                 /*
1523                  * We were interrupted by a signal.
1524                  */
1525                 sample_to_timespec(which_clock, timer.it.cpu.expires, rqtp);
1526                 posix_cpu_timer_set(&timer, 0, &zero_it, it);
1527                 spin_unlock_irq(&timer.it_lock);
1528
1529                 if ((it->it_value.tv_sec | it->it_value.tv_nsec) == 0) {
1530                         /*
1531                          * It actually did fire already.
1532                          */
1533                         return 0;
1534                 }
1535
1536                 error = -ERESTART_RESTARTBLOCK;
1537         }
1538
1539         return error;
1540 }
1541
1542 int posix_cpu_nsleep(const clockid_t which_clock, int flags,
1543                      struct timespec *rqtp, struct timespec __user *rmtp)
1544 {
1545         struct restart_block *restart_block =
1546             &current_thread_info()->restart_block;
1547         struct itimerspec it;
1548         int error;
1549
1550         /*
1551          * Diagnose required errors first.
1552          */
1553         if (CPUCLOCK_PERTHREAD(which_clock) &&
1554             (CPUCLOCK_PID(which_clock) == 0 ||
1555              CPUCLOCK_PID(which_clock) == current->pid))
1556                 return -EINVAL;
1557
1558         error = do_cpu_nanosleep(which_clock, flags, rqtp, &it);
1559
1560         if (error == -ERESTART_RESTARTBLOCK) {
1561
1562                 if (flags & TIMER_ABSTIME)
1563                         return -ERESTARTNOHAND;
1564                 /*
1565                  * Report back to the user the time still remaining.
1566                  */
1567                 if (rmtp != NULL && copy_to_user(rmtp, &it.it_value, sizeof *rmtp))
1568                         return -EFAULT;
1569
1570                 restart_block->fn = posix_cpu_nsleep_restart;
1571                 restart_block->arg0 = which_clock;
1572                 restart_block->arg1 = (unsigned long) rmtp;
1573                 restart_block->arg2 = rqtp->tv_sec;
1574                 restart_block->arg3 = rqtp->tv_nsec;
1575         }
1576         return error;
1577 }
1578
1579 long posix_cpu_nsleep_restart(struct restart_block *restart_block)
1580 {
1581         clockid_t which_clock = restart_block->arg0;
1582         struct timespec __user *rmtp;
1583         struct timespec t;
1584         struct itimerspec it;
1585         int error;
1586
1587         rmtp = (struct timespec __user *) restart_block->arg1;
1588         t.tv_sec = restart_block->arg2;
1589         t.tv_nsec = restart_block->arg3;
1590
1591         restart_block->fn = do_no_restart_syscall;
1592         error = do_cpu_nanosleep(which_clock, TIMER_ABSTIME, &t, &it);
1593
1594         if (error == -ERESTART_RESTARTBLOCK) {
1595                 /*
1596                  * Report back to the user the time still remaining.
1597                  */
1598                 if (rmtp != NULL && copy_to_user(rmtp, &it.it_value, sizeof *rmtp))
1599                         return -EFAULT;
1600
1601                 restart_block->fn = posix_cpu_nsleep_restart;
1602                 restart_block->arg0 = which_clock;
1603                 restart_block->arg1 = (unsigned long) rmtp;
1604                 restart_block->arg2 = t.tv_sec;
1605                 restart_block->arg3 = t.tv_nsec;
1606         }
1607         return error;
1608
1609 }
1610
1611
1612 #define PROCESS_CLOCK   MAKE_PROCESS_CPUCLOCK(0, CPUCLOCK_SCHED)
1613 #define THREAD_CLOCK    MAKE_THREAD_CPUCLOCK(0, CPUCLOCK_SCHED)
1614
1615 static int process_cpu_clock_getres(const clockid_t which_clock,
1616                                     struct timespec *tp)
1617 {
1618         return posix_cpu_clock_getres(PROCESS_CLOCK, tp);
1619 }
1620 static int process_cpu_clock_get(const clockid_t which_clock,
1621                                  struct timespec *tp)
1622 {
1623         return posix_cpu_clock_get(PROCESS_CLOCK, tp);
1624 }
1625 static int process_cpu_timer_create(struct k_itimer *timer)
1626 {
1627         timer->it_clock = PROCESS_CLOCK;
1628         return posix_cpu_timer_create(timer);
1629 }
1630 static int process_cpu_nsleep(const clockid_t which_clock, int flags,
1631                               struct timespec *rqtp,
1632                               struct timespec __user *rmtp)
1633 {
1634         return posix_cpu_nsleep(PROCESS_CLOCK, flags, rqtp, rmtp);
1635 }
1636 static long process_cpu_nsleep_restart(struct restart_block *restart_block)
1637 {
1638         return -EINVAL;
1639 }
1640 static int thread_cpu_clock_getres(const clockid_t which_clock,
1641                                    struct timespec *tp)
1642 {
1643         return posix_cpu_clock_getres(THREAD_CLOCK, tp);
1644 }
1645 static int thread_cpu_clock_get(const clockid_t which_clock,
1646                                 struct timespec *tp)
1647 {
1648         return posix_cpu_clock_get(THREAD_CLOCK, tp);
1649 }
1650 static int thread_cpu_timer_create(struct k_itimer *timer)
1651 {
1652         timer->it_clock = THREAD_CLOCK;
1653         return posix_cpu_timer_create(timer);
1654 }
1655 static int thread_cpu_nsleep(const clockid_t which_clock, int flags,
1656                               struct timespec *rqtp, struct timespec __user *rmtp)
1657 {
1658         return -EINVAL;
1659 }
1660 static long thread_cpu_nsleep_restart(struct restart_block *restart_block)
1661 {
1662         return -EINVAL;
1663 }
1664
1665 static __init int init_posix_cpu_timers(void)
1666 {
1667         struct k_clock process = {
1668                 .clock_getres = process_cpu_clock_getres,
1669                 .clock_get = process_cpu_clock_get,
1670                 .clock_set = do_posix_clock_nosettime,
1671                 .timer_create = process_cpu_timer_create,
1672                 .nsleep = process_cpu_nsleep,
1673                 .nsleep_restart = process_cpu_nsleep_restart,
1674         };
1675         struct k_clock thread = {
1676                 .clock_getres = thread_cpu_clock_getres,
1677                 .clock_get = thread_cpu_clock_get,
1678                 .clock_set = do_posix_clock_nosettime,
1679                 .timer_create = thread_cpu_timer_create,
1680                 .nsleep = thread_cpu_nsleep,
1681                 .nsleep_restart = thread_cpu_nsleep_restart,
1682         };
1683
1684         register_posix_clock(CLOCK_PROCESS_CPUTIME_ID, &process);
1685         register_posix_clock(CLOCK_THREAD_CPUTIME_ID, &thread);
1686
1687         return 0;
1688 }
1689 __initcall(init_posix_cpu_timers);