nptl/pthread_mutex_timedlock.c

   1 /* Copyright (C) 2002-2017 Free Software Foundation, Inc.
   2    This file is part of the GNU C Library.
   3    Contributed by Ulrich Drepper <drepper@redhat.com>, 2002.
   4
   5    The GNU C Library is free software; you can redistribute it and/or
   6    modify it under the terms of the GNU Lesser General Public
   7    License as published by the Free Software Foundation; either
   8    version 2.1 of the License, or (at your option) any later version.
   9
  10    The GNU C Library is distributed in the hope that it will be useful,
  11    but WITHOUT ANY WARRANTY; without even the implied warranty of
  12    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  13    Lesser General Public License for more details.
  14
  15    You should have received a copy of the GNU Lesser General Public
  16    License along with the GNU C Library; if not, see
  17    <http://www.gnu.org/licenses/>.  */
  18
  19 #include <assert.h>
  20 #include <errno.h>
  21 #include <time.h>
  22 #include <sys/param.h>
  23 #include <sys/time.h>
  24 #include "pthreadP.h"
  25 #include <atomic.h>
  26 #include <lowlevellock.h>
  27 #include <not-cancel.h>
  28
  29 #include <stap-probe.h>
  30
  31 #ifndef lll_timedlock_elision
  32 #define lll_timedlock_elision(a,dummy,b,c) lll_timedlock(a, b, c)
  33 #endif
  34
  35 #ifndef lll_trylock_elision
  36 #define lll_trylock_elision(a,t) lll_trylock(a)
  37 #endif
  38
  39 #ifndef FORCE_ELISION
  40 #define FORCE_ELISION(m, s)
  41 #endif
  42
  43 int
  44 __pthread_mutex_timedlock (pthread_mutex_t *mutex,
  45                            const struct timespec *abstime)
  46 {
  47   int oldval;
  48   pid_t id = THREAD_GETMEM (THREAD_SELF, tid);
  49   int result = 0;
  50
  51   LIBC_PROBE (mutex_timedlock_entry, 2, mutex, abstime);
  52
  53   /* We must not check ABSTIME here.  If the thread does not block
  54      abstime must not be checked for a valid value.  */
  55
  56   switch (__builtin_expect (PTHREAD_MUTEX_TYPE_ELISION (mutex),
  57                             PTHREAD_MUTEX_TIMED_NP))
  58     {
  59       /* Recursive mutex.  */
  60     case PTHREAD_MUTEX_RECURSIVE_NP|PTHREAD_MUTEX_ELISION_NP:
  61     case PTHREAD_MUTEX_RECURSIVE_NP:
  62       /* Check whether we already hold the mutex.  */
  63       if (mutex->__data.__owner == id)
  64         {
  65           /* Just bump the counter.  */
  66           if (__glibc_unlikely (mutex->__data.__count + 1 == 0))
  67             /* Overflow of the counter.  */
  68             return EAGAIN;
  69
  70           ++mutex->__data.__count;
  71
  72           goto out;
  73         }
  74
  75       /* We have to get the mutex.  */
  76       result = lll_timedlock (mutex->__data.__lock, abstime,
  77                               PTHREAD_MUTEX_PSHARED (mutex));
  78
  79       if (result != 0)
  80         goto out;
  81
  82       /* Only locked once so far.  */
  83       mutex->__data.__count = 1;
  84       break;
  85
  86       /* Error checking mutex.  */
  87     case PTHREAD_MUTEX_ERRORCHECK_NP:
  88       /* Check whether we already hold the mutex.  */
  89       if (__glibc_unlikely (mutex->__data.__owner == id))
  90         return EDEADLK;
  91
  92       /* Don't do lock elision on an error checking mutex.  */
  93       goto simple;
  94
  95     case PTHREAD_MUTEX_TIMED_NP:
  96       FORCE_ELISION (mutex, goto elision);
  97     simple:
  98       /* Normal mutex.  */
  99       result = lll_timedlock (mutex->__data.__lock, abstime,
 100                               PTHREAD_MUTEX_PSHARED (mutex));
 101       break;
 102
 103     case PTHREAD_MUTEX_TIMED_ELISION_NP:
 104     elision: __attribute__((unused))
 105       /* Don't record ownership */
 106       return lll_timedlock_elision (mutex->__data.__lock,
 107                                     mutex->__data.__spins,
 108                                     abstime,
 109                                     PTHREAD_MUTEX_PSHARED (mutex));
 110
 111
 112     case PTHREAD_MUTEX_ADAPTIVE_NP:
 113       if (! __is_smp)
 114         goto simple;
 115
 116       if (lll_trylock (mutex->__data.__lock) != 0)
 117         {
 118           int cnt = 0;
 119           int max_cnt = MIN (MAX_ADAPTIVE_COUNT,
 120                              mutex->__data.__spins * 2 + 10);
 121           do
 122             {
 123               if (cnt++ >= max_cnt)
 124                 {
 125                   result = lll_timedlock (mutex->__data.__lock, abstime,
 126                                           PTHREAD_MUTEX_PSHARED (mutex));
 127                   break;
 128                 }
 129               atomic_spin_nop ();
 130             }
 131           while (lll_trylock (mutex->__data.__lock) != 0);
 132
 133           mutex->__data.__spins += (cnt - mutex->__data.__spins) / 8;
 134         }
 135       break;
 136
 137     case PTHREAD_MUTEX_ROBUST_RECURSIVE_NP:
 138     case PTHREAD_MUTEX_ROBUST_ERRORCHECK_NP:
 139     case PTHREAD_MUTEX_ROBUST_NORMAL_NP:
 140     case PTHREAD_MUTEX_ROBUST_ADAPTIVE_NP:
 141       THREAD_SETMEM (THREAD_SELF, robust_head.list_op_pending,
 142                      &mutex->__data.__list.__next);
 143       /* We need to set op_pending before starting the operation.  Also
 144          see comments at ENQUEUE_MUTEX.  */
 145       __asm ("" ::: "memory");
 146
 147       oldval = mutex->__data.__lock;
 148       /* This is set to FUTEX_WAITERS iff we might have shared the
 149          FUTEX_WAITERS flag with other threads, and therefore need to keep it
 150          set to avoid lost wake-ups.  We have the same requirement in the
 151          simple mutex algorithm.  */
 152       unsigned int assume_other_futex_waiters = 0;
 153       while (1)
 154         {
 155           /* Try to acquire the lock through a CAS from 0 (not acquired) to
 156              our TID | assume_other_futex_waiters.  */
 157           if (__glibc_likely ((oldval == 0)
 158                               && (atomic_compare_and_exchange_bool_acq
 159                                   (&mutex->__data.__lock,
 160                                    id | assume_other_futex_waiters, 0) == 0)))
 161               break;
 162
 163           if ((oldval & FUTEX_OWNER_DIED) != 0)
 164             {
 165               /* The previous owner died.  Try locking the mutex.  */
 166               int newval = id | (oldval & FUTEX_WAITERS)
 167                   | assume_other_futex_waiters;
 168
 169               newval
 170                 = atomic_compare_and_exchange_val_acq (&mutex->__data.__lock,
 171                                                        newval, oldval);
 172               if (newval != oldval)
 173                 {
 174                   oldval = newval;
 175                   continue;
 176                 }
 177
 178               /* We got the mutex.  */
 179               mutex->__data.__count = 1;
 180               /* But it is inconsistent unless marked otherwise.  */
 181               mutex->__data.__owner = PTHREAD_MUTEX_INCONSISTENT;
 182
 183               /* We must not enqueue the mutex before we have acquired it.
 184                  Also see comments at ENQUEUE_MUTEX.  */
 185               __asm ("" ::: "memory");
 186               ENQUEUE_MUTEX (mutex);
 187               /* We need to clear op_pending after we enqueue the mutex.  */
 188               __asm ("" ::: "memory");
 189               THREAD_SETMEM (THREAD_SELF, robust_head.list_op_pending, NULL);
 190
 191               /* Note that we deliberately exit here.  If we fall
 192                  through to the end of the function __nusers would be
 193                  incremented which is not correct because the old
 194                  owner has to be discounted.  */
 195               return EOWNERDEAD;
 196             }
 197
 198           /* Check whether we already hold the mutex.  */
 199           if (__glibc_unlikely ((oldval & FUTEX_TID_MASK) == id))
 200             {
 201               int kind = PTHREAD_MUTEX_TYPE (mutex);
 202               if (kind == PTHREAD_MUTEX_ROBUST_ERRORCHECK_NP)
 203                 {
 204                   /* We do not need to ensure ordering wrt another memory
 205                      access.  Also see comments at ENQUEUE_MUTEX. */
 206                   THREAD_SETMEM (THREAD_SELF, robust_head.list_op_pending,
 207                                  NULL);
 208                   return EDEADLK;
 209                 }
 210
 211               if (kind == PTHREAD_MUTEX_ROBUST_RECURSIVE_NP)
 212                 {
 213                   /* We do not need to ensure ordering wrt another memory
 214                      access.  */
 215                   THREAD_SETMEM (THREAD_SELF, robust_head.list_op_pending,
 216                                  NULL);
 217
 218                   /* Just bump the counter.  */
 219                   if (__glibc_unlikely (mutex->__data.__count + 1 == 0))
 220                     /* Overflow of the counter.  */
 221                     return EAGAIN;
 222
 223                   ++mutex->__data.__count;
 224
 225                   LIBC_PROBE (mutex_timedlock_acquired, 1, mutex);
 226
 227                   return 0;
 228                 }
 229             }
 230
 231           /* We are about to block; check whether the timeout is invalid.  */
 232           if (abstime->tv_nsec < 0 || abstime->tv_nsec >= 1000000000)
 233             return EINVAL;
 234           /* Work around the fact that the kernel rejects negative timeout
 235              values despite them being valid.  */
 236           if (__glibc_unlikely (abstime->tv_sec < 0))
 237             return ETIMEDOUT;
 238 #if (!defined __ASSUME_FUTEX_CLOCK_REALTIME \
 239      || !defined lll_futex_timed_wait_bitset)
 240           struct timeval tv;
 241           struct timespec rt;
 242
 243           /* Get the current time.  */
 244           (void) __gettimeofday (&tv, NULL);
 245
 246           /* Compute relative timeout.  */
 247           rt.tv_sec = abstime->tv_sec - tv.tv_sec;
 248           rt.tv_nsec = abstime->tv_nsec - tv.tv_usec * 1000;
 249           if (rt.tv_nsec < 0)
 250             {
 251               rt.tv_nsec += 1000000000;
 252               --rt.tv_sec;
 253             }
 254
 255           /* Already timed out?  */
 256           if (rt.tv_sec < 0)
 257             return ETIMEDOUT;
 258 #endif
 259
 260           /* We cannot acquire the mutex nor has its owner died.  Thus, try
 261              to block using futexes.  Set FUTEX_WAITERS if necessary so that
 262              other threads are aware that there are potentially threads
 263              blocked on the futex.  Restart if oldval changed in the
 264              meantime.  */
 265           if ((oldval & FUTEX_WAITERS) == 0)
 266             {
 267               if (atomic_compare_and_exchange_bool_acq (&mutex->__data.__lock,
 268                                                         oldval | FUTEX_WAITERS,
 269                                                         oldval)
 270                   != 0)
 271                 {
 272                   oldval = mutex->__data.__lock;
 273                   continue;
 274                 }
 275               oldval |= FUTEX_WAITERS;
 276             }
 277
 278           /* It is now possible that we share the FUTEX_WAITERS flag with
 279              another thread; therefore, update assume_other_futex_waiters so
 280              that we do not forget about this when handling other cases
 281              above and thus do not cause lost wake-ups.  */
 282           assume_other_futex_waiters |= FUTEX_WAITERS;
 283
 284           /* Block using the futex.  */
 285 #if (!defined __ASSUME_FUTEX_CLOCK_REALTIME \
 286      || !defined lll_futex_timed_wait_bitset)
 287           lll_futex_timed wait (&mutex->__data.__lock, oldval,
 288                                 &rt, PTHREAD_ROBUST_MUTEX_PSHARED (mutex));
 289 #else
 290           int err = lll_futex_timed_wait_bitset (&mutex->__data.__lock,
 291               oldval, abstime, FUTEX_CLOCK_REALTIME,
 292               PTHREAD_ROBUST_MUTEX_PSHARED (mutex));
 293           /* The futex call timed out.  */
 294           if (err == -ETIMEDOUT)
 295             return -err;
 296 #endif
 297           /* Reload current lock value.  */
 298           oldval = mutex->__data.__lock;
 299         }
 300
 301       /* We have acquired the mutex; check if it is still consistent.  */
 302       if (__builtin_expect (mutex->__data.__owner
 303                             == PTHREAD_MUTEX_NOTRECOVERABLE, 0))
 304         {
 305           /* This mutex is now not recoverable.  */
 306           mutex->__data.__count = 0;
 307           int private = PTHREAD_ROBUST_MUTEX_PSHARED (mutex);
 308           lll_unlock (mutex->__data.__lock, private);
 309           /* FIXME This violates the mutex destruction requirements.  See
 310              __pthread_mutex_unlock_full.  */
 311           THREAD_SETMEM (THREAD_SELF, robust_head.list_op_pending, NULL);
 312           return ENOTRECOVERABLE;
 313         }
 314
 315       mutex->__data.__count = 1;
 316       /* We must not enqueue the mutex before we have acquired it.
 317          Also see comments at ENQUEUE_MUTEX.  */
 318       __asm ("" ::: "memory");
 319       ENQUEUE_MUTEX (mutex);
 320       /* We need to clear op_pending after we enqueue the mutex.  */
 321       __asm ("" ::: "memory");
 322       THREAD_SETMEM (THREAD_SELF, robust_head.list_op_pending, NULL);
 323       break;
 324
 325     /* The PI support requires the Linux futex system call.  If that's not
 326        available, pthread_mutex_init should never have allowed the type to
 327        be set.  So it will get the default case for an invalid type.  */
 328 #ifdef __NR_futex
 329     case PTHREAD_MUTEX_PI_RECURSIVE_NP:
 330     case PTHREAD_MUTEX_PI_ERRORCHECK_NP:
 331     case PTHREAD_MUTEX_PI_NORMAL_NP:
 332     case PTHREAD_MUTEX_PI_ADAPTIVE_NP:
 333     case PTHREAD_MUTEX_PI_ROBUST_RECURSIVE_NP:
 334     case PTHREAD_MUTEX_PI_ROBUST_ERRORCHECK_NP:
 335     case PTHREAD_MUTEX_PI_ROBUST_NORMAL_NP:
 336     case PTHREAD_MUTEX_PI_ROBUST_ADAPTIVE_NP:
 337       {
 338         int kind = mutex->__data.__kind & PTHREAD_MUTEX_KIND_MASK_NP;
 339         int robust = mutex->__data.__kind & PTHREAD_MUTEX_ROBUST_NORMAL_NP;
 340
 341         if (robust)
 342           {
 343             /* Note: robust PI futexes are signaled by setting bit 0.  */
 344             THREAD_SETMEM (THREAD_SELF, robust_head.list_op_pending,
 345                            (void *) (((uintptr_t) &mutex->__data.__list.__next)
 346                                      | 1));
 347             /* We need to set op_pending before starting the operation.  Also
 348                see comments at ENQUEUE_MUTEX.  */
 349             __asm ("" ::: "memory");
 350           }
 351
 352         oldval = mutex->__data.__lock;
 353
 354         /* Check whether we already hold the mutex.  */
 355         if (__glibc_unlikely ((oldval & FUTEX_TID_MASK) == id))
 356           {
 357             if (kind == PTHREAD_MUTEX_ERRORCHECK_NP)
 358               {
 359                 /* We do not need to ensure ordering wrt another memory
 360                    access.  */
 361                 THREAD_SETMEM (THREAD_SELF, robust_head.list_op_pending, NULL);
 362                 return EDEADLK;
 363               }
 364
 365             if (kind == PTHREAD_MUTEX_RECURSIVE_NP)
 366               {
 367                 /* We do not need to ensure ordering wrt another memory
 368                    access.  */
 369                 THREAD_SETMEM (THREAD_SELF, robust_head.list_op_pending, NULL);
 370
 371                 /* Just bump the counter.  */
 372                 if (__glibc_unlikely (mutex->__data.__count + 1 == 0))
 373                   /* Overflow of the counter.  */
 374                   return EAGAIN;
 375
 376                 ++mutex->__data.__count;
 377
 378                 LIBC_PROBE (mutex_timedlock_acquired, 1, mutex);
 379
 380                 return 0;
 381               }
 382           }
 383
 384         oldval = atomic_compare_and_exchange_val_acq (&mutex->__data.__lock,
 385                                                       id, 0);
 386
 387         if (oldval != 0)
 388           {
 389             /* The mutex is locked.  The kernel will now take care of
 390                everything.  The timeout value must be a relative value.
 391                Convert it.  */
 392             int private = (robust
 393                            ? PTHREAD_ROBUST_MUTEX_PSHARED (mutex)
 394                            : PTHREAD_MUTEX_PSHARED (mutex));
 395             INTERNAL_SYSCALL_DECL (__err);
 396
 397             int e = INTERNAL_SYSCALL (futex, __err, 4, &mutex->__data.__lock,
 398                                       __lll_private_flag (FUTEX_LOCK_PI,
 399                                                           private), 1,
 400                                       abstime);
 401             if (INTERNAL_SYSCALL_ERROR_P (e, __err))
 402               {
 403                 if (INTERNAL_SYSCALL_ERRNO (e, __err) == ETIMEDOUT)
 404                   return ETIMEDOUT;
 405
 406                 if (INTERNAL_SYSCALL_ERRNO (e, __err) == ESRCH
 407                     || INTERNAL_SYSCALL_ERRNO (e, __err) == EDEADLK)
 408                   {
 409                     assert (INTERNAL_SYSCALL_ERRNO (e, __err) != EDEADLK
 410                             || (kind != PTHREAD_MUTEX_ERRORCHECK_NP
 411                                 && kind != PTHREAD_MUTEX_RECURSIVE_NP));
 412                     /* ESRCH can happen only for non-robust PI mutexes where
 413                        the owner of the lock died.  */
 414                     assert (INTERNAL_SYSCALL_ERRNO (e, __err) != ESRCH
 415                             || !robust);
 416
 417                     /* Delay the thread until the timeout is reached.
 418                        Then return ETIMEDOUT.  */
 419                     struct timespec reltime;
 420                     struct timespec now;
 421
 422                     INTERNAL_SYSCALL (clock_gettime, __err, 2, CLOCK_REALTIME,
 423                                       &now);
 424                     reltime.tv_sec = abstime->tv_sec - now.tv_sec;
 425                     reltime.tv_nsec = abstime->tv_nsec - now.tv_nsec;
 426                     if (reltime.tv_nsec < 0)
 427                       {
 428                         reltime.tv_nsec += 1000000000;
 429                         --reltime.tv_sec;
 430                       }
 431                     if (reltime.tv_sec >= 0)
 432                       while (nanosleep_not_cancel (&reltime, &reltime) != 0)
 433                         continue;
 434
 435                     return ETIMEDOUT;
 436                   }
 437
 438                 return INTERNAL_SYSCALL_ERRNO (e, __err);
 439               }
 440
 441             oldval = mutex->__data.__lock;
 442
 443             assert (robust || (oldval & FUTEX_OWNER_DIED) == 0);
 444           }
 445
 446         if (__glibc_unlikely (oldval & FUTEX_OWNER_DIED))
 447           {
 448             atomic_and (&mutex->__data.__lock, ~FUTEX_OWNER_DIED);
 449
 450             /* We got the mutex.  */
 451             mutex->__data.__count = 1;
 452             /* But it is inconsistent unless marked otherwise.  */
 453             mutex->__data.__owner = PTHREAD_MUTEX_INCONSISTENT;
 454
 455             /* We must not enqueue the mutex before we have acquired it.
 456                Also see comments at ENQUEUE_MUTEX.  */
 457             __asm ("" ::: "memory");
 458             ENQUEUE_MUTEX_PI (mutex);
 459             /* We need to clear op_pending after we enqueue the mutex.  */
 460             __asm ("" ::: "memory");
 461             THREAD_SETMEM (THREAD_SELF, robust_head.list_op_pending, NULL);
 462
 463             /* Note that we deliberately exit here.  If we fall
 464                through to the end of the function __nusers would be
 465                incremented which is not correct because the old owner
 466                has to be discounted.  */
 467             return EOWNERDEAD;
 468           }
 469
 470         if (robust
 471             && __builtin_expect (mutex->__data.__owner
 472                                  == PTHREAD_MUTEX_NOTRECOVERABLE, 0))
 473           {
 474             /* This mutex is now not recoverable.  */
 475             mutex->__data.__count = 0;
 476
 477             INTERNAL_SYSCALL_DECL (__err);
 478             INTERNAL_SYSCALL (futex, __err, 4, &mutex->__data.__lock,
 479                               __lll_private_flag (FUTEX_UNLOCK_PI,
 480                                                   PTHREAD_ROBUST_MUTEX_PSHARED (mutex)),
 481                               0, 0);
 482
 483             /* To the kernel, this will be visible after the kernel has
 484                acquired the mutex in the syscall.  */
 485             THREAD_SETMEM (THREAD_SELF, robust_head.list_op_pending, NULL);
 486             return ENOTRECOVERABLE;
 487           }
 488
 489         mutex->__data.__count = 1;
 490         if (robust)
 491           {
 492             /* We must not enqueue the mutex before we have acquired it.
 493                Also see comments at ENQUEUE_MUTEX.  */
 494             __asm ("" ::: "memory");
 495             ENQUEUE_MUTEX_PI (mutex);
 496             /* We need to clear op_pending after we enqueue the mutex.  */
 497             __asm ("" ::: "memory");
 498             THREAD_SETMEM (THREAD_SELF, robust_head.list_op_pending, NULL);
 499           }
 500         }
 501       break;
 502 #endif  /* __NR_futex.  */
 503
 504     case PTHREAD_MUTEX_PP_RECURSIVE_NP:
 505     case PTHREAD_MUTEX_PP_ERRORCHECK_NP:
 506     case PTHREAD_MUTEX_PP_NORMAL_NP:
 507     case PTHREAD_MUTEX_PP_ADAPTIVE_NP:
 508       {
 509         int kind = mutex->__data.__kind & PTHREAD_MUTEX_KIND_MASK_NP;
 510
 511         oldval = mutex->__data.__lock;
 512
 513         /* Check whether we already hold the mutex.  */
 514         if (mutex->__data.__owner == id)
 515           {
 516             if (kind == PTHREAD_MUTEX_ERRORCHECK_NP)
 517               return EDEADLK;
 518
 519             if (kind == PTHREAD_MUTEX_RECURSIVE_NP)
 520               {
 521                 /* Just bump the counter.  */
 522                 if (__glibc_unlikely (mutex->__data.__count + 1 == 0))
 523                   /* Overflow of the counter.  */
 524                   return EAGAIN;
 525
 526                 ++mutex->__data.__count;
 527
 528                 LIBC_PROBE (mutex_timedlock_acquired, 1, mutex);
 529
 530                 return 0;
 531               }
 532           }
 533
 534         int oldprio = -1, ceilval;
 535         do
 536           {
 537             int ceiling = (oldval & PTHREAD_MUTEX_PRIO_CEILING_MASK)
 538                           >> PTHREAD_MUTEX_PRIO_CEILING_SHIFT;
 539
 540             if (__pthread_current_priority () > ceiling)
 541               {
 542                 result = EINVAL;
 543               failpp:
 544                 if (oldprio != -1)
 545                   __pthread_tpp_change_priority (oldprio, -1);
 546                 return result;
 547               }
 548
 549             result = __pthread_tpp_change_priority (oldprio, ceiling);
 550             if (result)
 551               return result;
 552
 553             ceilval = ceiling << PTHREAD_MUTEX_PRIO_CEILING_SHIFT;
 554             oldprio = ceiling;
 555
 556             oldval
 557               = atomic_compare_and_exchange_val_acq (&mutex->__data.__lock,
 558                                                      ceilval | 1, ceilval);
 559
 560             if (oldval == ceilval)
 561               break;
 562
 563             do
 564               {
 565                 oldval
 566                   = atomic_compare_and_exchange_val_acq (&mutex->__data.__lock,
 567                                                          ceilval | 2,
 568                                                          ceilval | 1);
 569
 570                 if ((oldval & PTHREAD_MUTEX_PRIO_CEILING_MASK) != ceilval)
 571                   break;
 572
 573                 if (oldval != ceilval)
 574                   {
 575                     /* Reject invalid timeouts.  */
 576                     if (abstime->tv_nsec < 0 || abstime->tv_nsec >= 1000000000)
 577                       {
 578                         result = EINVAL;
 579                         goto failpp;
 580                       }
 581
 582                     struct timeval tv;
 583                     struct timespec rt;
 584
 585                     /* Get the current time.  */
 586                     (void) __gettimeofday (&tv, NULL);
 587
 588                     /* Compute relative timeout.  */
 589                     rt.tv_sec = abstime->tv_sec - tv.tv_sec;
 590                     rt.tv_nsec = abstime->tv_nsec - tv.tv_usec * 1000;
 591                     if (rt.tv_nsec < 0)
 592                       {
 593                         rt.tv_nsec += 1000000000;
 594                         --rt.tv_sec;
 595                       }
 596
 597                     /* Already timed out?  */
 598                     if (rt.tv_sec < 0)
 599                       {
 600                         result = ETIMEDOUT;
 601                         goto failpp;
 602                       }
 603
 604                     lll_futex_timed_wait (&mutex->__data.__lock,
 605                                           ceilval | 2, &rt,
 606                                           PTHREAD_MUTEX_PSHARED (mutex));
 607                   }
 608               }
 609             while (atomic_compare_and_exchange_val_acq (&mutex->__data.__lock,
 610                                                         ceilval | 2, ceilval)
 611                    != ceilval);
 612           }
 613         while ((oldval & PTHREAD_MUTEX_PRIO_CEILING_MASK) != ceilval);
 614
 615         assert (mutex->__data.__owner == 0);
 616         mutex->__data.__count = 1;
 617       }
 618       break;
 619
 620     default:
 621       /* Correct code cannot set any other type.  */
 622       return EINVAL;
 623     }
 624
 625   if (result == 0)
 626     {
 627       /* Record the ownership.  */
 628       mutex->__data.__owner = id;
 629       ++mutex->__data.__nusers;
 630
 631       LIBC_PROBE (mutex_timedlock_acquired, 1, mutex);
 632     }
 633
 634  out:
 635   return result;
 636 }
 637 weak_alias (__pthread_mutex_timedlock, pthread_mutex_timedlock)