nptl/pthread_mutex_timedlock.c

   1 /* Copyright (C) 2002-2007, 2008 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 "pthreadP.h"
  23 #include <lowlevellock.h>
  24 #include <not-cancel.h>
  25
  26
  27 int
  28 pthread_mutex_timedlock (mutex, abstime)
  29      pthread_mutex_t *mutex;
  30      const struct timespec *abstime;
  31 {
  32   int oldval;
  33   pid_t id = THREAD_GETMEM (THREAD_SELF, tid);
  34   int result = 0;
  35
  36   /* We must not check ABSTIME here.  If the thread does not block
  37      abstime must not be checked for a valid value.  */
  38
  39   switch (__builtin_expect (PTHREAD_MUTEX_TYPE (mutex),
  40                             PTHREAD_MUTEX_TIMED_NP))
  41     {
  42       /* Recursive mutex.  */
  43     case PTHREAD_MUTEX_RECURSIVE_NP:
  44       /* Check whether we already hold the mutex.  */
  45       if (mutex->__data.__owner == id)
  46         {
  47           /* Just bump the counter.  */
  48           if (__builtin_expect (mutex->__data.__count + 1 == 0, 0))
  49             /* Overflow of the counter.  */
  50             return EAGAIN;
  51
  52           ++mutex->__data.__count;
  53
  54           goto out;
  55         }
  56
  57       /* We have to get the mutex.  */
  58       result = lll_timedlock (mutex->__data.__lock, abstime,
  59                               PTHREAD_MUTEX_PSHARED (mutex));
  60
  61       if (result != 0)
  62         goto out;
  63
  64       /* Only locked once so far.  */
  65       mutex->__data.__count = 1;
  66       break;
  67
  68       /* Error checking mutex.  */
  69     case PTHREAD_MUTEX_ERRORCHECK_NP:
  70       /* Check whether we already hold the mutex.  */
  71       if (__builtin_expect (mutex->__data.__owner == id, 0))
  72         return EDEADLK;
  73
  74       /* FALLTHROUGH */
  75
  76     case PTHREAD_MUTEX_TIMED_NP:
  77     simple:
  78       /* Normal mutex.  */
  79       result = lll_timedlock (mutex->__data.__lock, abstime,
  80                               PTHREAD_MUTEX_PSHARED (mutex));
  81       break;
  82
  83     case PTHREAD_MUTEX_ADAPTIVE_NP:
  84       if (! __is_smp)
  85         goto simple;
  86
  87       if (lll_trylock (mutex->__data.__lock) != 0)
  88         {
  89           int cnt = 0;
  90           int max_cnt = MIN (MAX_ADAPTIVE_COUNT,
  91                              mutex->__data.__spins * 2 + 10);
  92           do
  93             {
  94               if (cnt++ >= max_cnt)
  95                 {
  96                   result = lll_timedlock (mutex->__data.__lock, abstime,
  97                                           PTHREAD_MUTEX_PSHARED (mutex));
  98                   break;
  99                 }
 100
 101 #ifdef BUSY_WAIT_NOP
 102               BUSY_WAIT_NOP;
 103 #endif
 104             }
 105           while (lll_trylock (mutex->__data.__lock) != 0);
 106
 107           mutex->__data.__spins += (cnt - mutex->__data.__spins) / 8;
 108         }
 109       break;
 110
 111     case PTHREAD_MUTEX_ROBUST_RECURSIVE_NP:
 112     case PTHREAD_MUTEX_ROBUST_ERRORCHECK_NP:
 113     case PTHREAD_MUTEX_ROBUST_NORMAL_NP:
 114     case PTHREAD_MUTEX_ROBUST_ADAPTIVE_NP:
 115       THREAD_SETMEM (THREAD_SELF, robust_head.list_op_pending,
 116                      &mutex->__data.__list.__next);
 117
 118       oldval = mutex->__data.__lock;
 119       do
 120         {
 121         again:
 122           if ((oldval & FUTEX_OWNER_DIED) != 0)
 123             {
 124               /* The previous owner died.  Try locking the mutex.  */
 125               int newval = id | (oldval & FUTEX_WAITERS);
 126
 127               newval
 128                 = atomic_compare_and_exchange_val_acq (&mutex->__data.__lock,
 129                                                        newval, oldval);
 130               if (newval != oldval)
 131                 {
 132                   oldval = newval;
 133                   goto again;
 134                 }
 135
 136               /* We got the mutex.  */
 137               mutex->__data.__count = 1;
 138               /* But it is inconsistent unless marked otherwise.  */
 139               mutex->__data.__owner = PTHREAD_MUTEX_INCONSISTENT;
 140
 141               ENQUEUE_MUTEX (mutex);
 142               THREAD_SETMEM (THREAD_SELF, robust_head.list_op_pending, NULL);
 143
 144               /* Note that we deliberately exit here.  If we fall
 145                  through to the end of the function __nusers would be
 146                  incremented which is not correct because the old
 147                  owner has to be discounted.  */
 148               return EOWNERDEAD;
 149             }
 150
 151           /* Check whether we already hold the mutex.  */
 152           if (__builtin_expect ((oldval & FUTEX_TID_MASK) == id, 0))
 153             {
 154               int kind = PTHREAD_MUTEX_TYPE (mutex);
 155               if (kind == PTHREAD_MUTEX_ROBUST_ERRORCHECK_NP)
 156                 {
 157                   THREAD_SETMEM (THREAD_SELF, robust_head.list_op_pending,
 158                                  NULL);
 159                   return EDEADLK;
 160                 }
 161
 162               if (kind == PTHREAD_MUTEX_ROBUST_RECURSIVE_NP)
 163                 {
 164                   THREAD_SETMEM (THREAD_SELF, robust_head.list_op_pending,
 165                                  NULL);
 166
 167                   /* Just bump the counter.  */
 168                   if (__builtin_expect (mutex->__data.__count + 1 == 0, 0))
 169                     /* Overflow of the counter.  */
 170                     return EAGAIN;
 171
 172                   ++mutex->__data.__count;
 173
 174                   return 0;
 175                 }
 176             }
 177
 178           result = lll_robust_timedlock (mutex->__data.__lock, abstime, id,
 179                                          PTHREAD_ROBUST_MUTEX_PSHARED (mutex));
 180
 181           if (__builtin_expect (mutex->__data.__owner
 182                                 == PTHREAD_MUTEX_NOTRECOVERABLE, 0))
 183             {
 184               /* This mutex is now not recoverable.  */
 185               mutex->__data.__count = 0;
 186               lll_unlock (mutex->__data.__lock,
 187                           PTHREAD_ROBUST_MUTEX_PSHARED (mutex));
 188               THREAD_SETMEM (THREAD_SELF, robust_head.list_op_pending, NULL);
 189               return ENOTRECOVERABLE;
 190             }
 191
 192           if (result == ETIMEDOUT || result == EINVAL)
 193             goto out;
 194
 195           oldval = result;
 196         }
 197       while ((oldval & FUTEX_OWNER_DIED) != 0);
 198
 199       mutex->__data.__count = 1;
 200       ENQUEUE_MUTEX (mutex);
 201       THREAD_SETMEM (THREAD_SELF, robust_head.list_op_pending, NULL);
 202       break;
 203
 204     case PTHREAD_MUTEX_PI_RECURSIVE_NP:
 205     case PTHREAD_MUTEX_PI_ERRORCHECK_NP:
 206     case PTHREAD_MUTEX_PI_NORMAL_NP:
 207     case PTHREAD_MUTEX_PI_ADAPTIVE_NP:
 208     case PTHREAD_MUTEX_PI_ROBUST_RECURSIVE_NP:
 209     case PTHREAD_MUTEX_PI_ROBUST_ERRORCHECK_NP:
 210     case PTHREAD_MUTEX_PI_ROBUST_NORMAL_NP:
 211     case PTHREAD_MUTEX_PI_ROBUST_ADAPTIVE_NP:
 212       {
 213         int kind = mutex->__data.__kind & PTHREAD_MUTEX_KIND_MASK_NP;
 214         int robust = mutex->__data.__kind & PTHREAD_MUTEX_ROBUST_NORMAL_NP;
 215
 216         if (robust)
 217           /* Note: robust PI futexes are signaled by setting bit 0.  */
 218           THREAD_SETMEM (THREAD_SELF, robust_head.list_op_pending,
 219                          (void *) (((uintptr_t) &mutex->__data.__list.__next)
 220                                    | 1));
 221
 222         oldval = mutex->__data.__lock;
 223
 224         /* Check whether we already hold the mutex.  */
 225         if (__builtin_expect ((oldval & FUTEX_TID_MASK) == id, 0))
 226           {
 227             if (kind == PTHREAD_MUTEX_ERRORCHECK_NP)
 228               {
 229                 THREAD_SETMEM (THREAD_SELF, robust_head.list_op_pending, NULL);
 230                 return EDEADLK;
 231               }
 232
 233             if (kind == PTHREAD_MUTEX_RECURSIVE_NP)
 234               {
 235                 THREAD_SETMEM (THREAD_SELF, robust_head.list_op_pending, NULL);
 236
 237                 /* Just bump the counter.  */
 238                 if (__builtin_expect (mutex->__data.__count + 1 == 0, 0))
 239                   /* Overflow of the counter.  */
 240                   return EAGAIN;
 241
 242                 ++mutex->__data.__count;
 243
 244                 return 0;
 245               }
 246           }
 247
 248         oldval = atomic_compare_and_exchange_val_acq (&mutex->__data.__lock,
 249                                                       id, 0);
 250
 251         if (oldval != 0)
 252           {
 253             /* The mutex is locked.  The kernel will now take care of
 254                everything.  The timeout value must be a relative value.
 255                Convert it.  */
 256             int private = (robust
 257                            ? PTHREAD_ROBUST_MUTEX_PSHARED (mutex)
 258                            : PTHREAD_MUTEX_PSHARED (mutex));
 259             INTERNAL_SYSCALL_DECL (__err);
 260
 261             int e = INTERNAL_SYSCALL (futex, __err, 4, &mutex->__data.__lock,
 262                                       __lll_private_flag (FUTEX_LOCK_PI,
 263                                                           private), 1,
 264                                       abstime);
 265             if (INTERNAL_SYSCALL_ERROR_P (e, __err))
 266               {
 267                 if (INTERNAL_SYSCALL_ERRNO (e, __err) == ETIMEDOUT)
 268                   return ETIMEDOUT;
 269
 270                 if (INTERNAL_SYSCALL_ERRNO (e, __err) == ESRCH
 271                     || INTERNAL_SYSCALL_ERRNO (e, __err) == EDEADLK)
 272                   {
 273                     assert (INTERNAL_SYSCALL_ERRNO (e, __err) != EDEADLK
 274                             || (kind != PTHREAD_MUTEX_ERRORCHECK_NP
 275                                 && kind != PTHREAD_MUTEX_RECURSIVE_NP));
 276                     /* ESRCH can happen only for non-robust PI mutexes where
 277                        the owner of the lock died.  */
 278                     assert (INTERNAL_SYSCALL_ERRNO (e, __err) != ESRCH
 279                             || !robust);
 280
 281                     /* Delay the thread until the timeout is reached.
 282                        Then return ETIMEDOUT.  */
 283                     struct timespec reltime;
 284                     struct timespec now;
 285
 286                     INTERNAL_SYSCALL (clock_gettime, __err, 2, CLOCK_REALTIME,
 287                                       &now);
 288                     reltime.tv_sec = abstime->tv_sec - now.tv_sec;
 289                     reltime.tv_nsec = abstime->tv_nsec - now.tv_nsec;
 290                     if (reltime.tv_nsec < 0)
 291                       {
 292                         reltime.tv_nsec += 1000000000;
 293                         --reltime.tv_sec;
 294                       }
 295                     if (reltime.tv_sec >= 0)
 296                       while (nanosleep_not_cancel (&reltime, &reltime) != 0)
 297                         continue;
 298
 299                     return ETIMEDOUT;
 300                   }
 301
 302                 return INTERNAL_SYSCALL_ERRNO (e, __err);
 303               }
 304
 305             oldval = mutex->__data.__lock;
 306
 307             assert (robust || (oldval & FUTEX_OWNER_DIED) == 0);
 308           }
 309
 310         if (__builtin_expect (oldval & FUTEX_OWNER_DIED, 0))
 311           {
 312             atomic_and (&mutex->__data.__lock, ~FUTEX_OWNER_DIED);
 313
 314             /* We got the mutex.  */
 315             mutex->__data.__count = 1;
 316             /* But it is inconsistent unless marked otherwise.  */
 317             mutex->__data.__owner = PTHREAD_MUTEX_INCONSISTENT;
 318
 319             ENQUEUE_MUTEX_PI (mutex);
 320             THREAD_SETMEM (THREAD_SELF, robust_head.list_op_pending, NULL);
 321
 322             /* Note that we deliberately exit here.  If we fall
 323                through to the end of the function __nusers would be
 324                incremented which is not correct because the old owner
 325                has to be discounted.  */
 326             return EOWNERDEAD;
 327           }
 328
 329         if (robust
 330             && __builtin_expect (mutex->__data.__owner
 331                                  == PTHREAD_MUTEX_NOTRECOVERABLE, 0))
 332           {
 333             /* This mutex is now not recoverable.  */
 334             mutex->__data.__count = 0;
 335
 336             INTERNAL_SYSCALL_DECL (__err);
 337             INTERNAL_SYSCALL (futex, __err, 4, &mutex->__data.__lock,
 338                               __lll_private_flag (FUTEX_UNLOCK_PI,
 339                                                   PTHREAD_ROBUST_MUTEX_PSHARED (mutex)),
 340                               0, 0);
 341
 342             THREAD_SETMEM (THREAD_SELF, robust_head.list_op_pending, NULL);
 343             return ENOTRECOVERABLE;
 344           }
 345
 346         mutex->__data.__count = 1;
 347         if (robust)
 348           {
 349             ENQUEUE_MUTEX_PI (mutex);
 350             THREAD_SETMEM (THREAD_SELF, robust_head.list_op_pending, NULL);
 351           }
 352         }
 353       break;
 354
 355     case PTHREAD_MUTEX_PP_RECURSIVE_NP:
 356     case PTHREAD_MUTEX_PP_ERRORCHECK_NP:
 357     case PTHREAD_MUTEX_PP_NORMAL_NP:
 358     case PTHREAD_MUTEX_PP_ADAPTIVE_NP:
 359       {
 360         int kind = mutex->__data.__kind & PTHREAD_MUTEX_KIND_MASK_NP;
 361
 362         oldval = mutex->__data.__lock;
 363
 364         /* Check whether we already hold the mutex.  */
 365         if (mutex->__data.__owner == id)
 366           {
 367             if (kind == PTHREAD_MUTEX_ERRORCHECK_NP)
 368               return EDEADLK;
 369
 370             if (kind == PTHREAD_MUTEX_RECURSIVE_NP)
 371               {
 372                 /* Just bump the counter.  */
 373                 if (__builtin_expect (mutex->__data.__count + 1 == 0, 0))
 374                   /* Overflow of the counter.  */
 375                   return EAGAIN;
 376
 377                 ++mutex->__data.__count;
 378
 379                 return 0;
 380               }
 381           }
 382
 383         int oldprio = -1, ceilval;
 384         do
 385           {
 386             int ceiling = (oldval & PTHREAD_MUTEX_PRIO_CEILING_MASK)
 387                           >> PTHREAD_MUTEX_PRIO_CEILING_SHIFT;
 388
 389             if (__pthread_current_priority () > ceiling)
 390               {
 391                 result = EINVAL;
 392               failpp:
 393                 if (oldprio != -1)
 394                   __pthread_tpp_change_priority (oldprio, -1);
 395                 return result;
 396               }
 397
 398             result = __pthread_tpp_change_priority (oldprio, ceiling);
 399             if (result)
 400               return result;
 401
 402             ceilval = ceiling << PTHREAD_MUTEX_PRIO_CEILING_SHIFT;
 403             oldprio = ceiling;
 404
 405             oldval
 406               = atomic_compare_and_exchange_val_acq (&mutex->__data.__lock,
 407                                                      ceilval | 1, ceilval);
 408
 409             if (oldval == ceilval)
 410               break;
 411
 412             do
 413               {
 414                 oldval
 415                   = atomic_compare_and_exchange_val_acq (&mutex->__data.__lock,
 416                                                          ceilval | 2,
 417                                                          ceilval | 1);
 418
 419                 if ((oldval & PTHREAD_MUTEX_PRIO_CEILING_MASK) != ceilval)
 420                   break;
 421
 422                 if (oldval != ceilval)
 423                   {
 424                     /* Reject invalid timeouts.  */
 425                     if (abstime->tv_nsec < 0 || abstime->tv_nsec >= 1000000000)
 426                       {
 427                         result = EINVAL;
 428                         goto failpp;
 429                       }
 430
 431                     struct timeval tv;
 432                     struct timespec rt;
 433
 434                     /* Get the current time.  */
 435                     (void) __gettimeofday (&tv, NULL);
 436
 437                     /* Compute relative timeout.  */
 438                     rt.tv_sec = abstime->tv_sec - tv.tv_sec;
 439                     rt.tv_nsec = abstime->tv_nsec - tv.tv_usec * 1000;
 440                     if (rt.tv_nsec < 0)
 441                       {
 442                         rt.tv_nsec += 1000000000;
 443                         --rt.tv_sec;
 444                       }
 445
 446                     /* Already timed out?  */
 447                     if (rt.tv_sec < 0)
 448                       {
 449                         result = ETIMEDOUT;
 450                         goto failpp;
 451                       }
 452
 453                     lll_futex_timed_wait (&mutex->__data.__lock,
 454                                           ceilval | 2, &rt,
 455                                           PTHREAD_MUTEX_PSHARED (mutex));
 456                   }
 457               }
 458             while (atomic_compare_and_exchange_val_acq (&mutex->__data.__lock,
 459                                                         ceilval | 2, ceilval)
 460                    != ceilval);
 461           }
 462         while ((oldval & PTHREAD_MUTEX_PRIO_CEILING_MASK) != ceilval);
 463
 464         assert (mutex->__data.__owner == 0);
 465         mutex->__data.__count = 1;
 466       }
 467       break;
 468
 469     default:
 470       /* Correct code cannot set any other type.  */
 471       return EINVAL;
 472     }
 473
 474   if (result == 0)
 475     {
 476       /* Record the ownership.  */
 477       mutex->__data.__owner = id;
 478       ++mutex->__data.__nusers;
 479     }
 480
 481  out:
 482   return result;
 483 }