nptl/pthread_mutex_timedlock.c

   1 /* Copyright (C) 2002, 2003, 2004, 2005, 2006 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, write to the Free
  17    Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
  18    02111-1307 USA.  */
  19
  20 #include <assert.h>
  21 #include <errno.h>
  22 #include <time.h>
  23 #include "pthreadP.h"
  24 #include <lowlevellock.h>
  25 #include <not-cancel.h>
  26
  27
  28 int
  29 pthread_mutex_timedlock (mutex, abstime)
  30      pthread_mutex_t *mutex;
  31      const struct timespec *abstime;
  32 {
  33   int oldval;
  34   pid_t id = THREAD_GETMEM (THREAD_SELF, tid);
  35   int result = 0;
  36
  37   /* We must not check ABSTIME here.  If the thread does not block
  38      abstime must not be checked for a valid value.  */
  39
  40   switch (__builtin_expect (mutex->__data.__kind, 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_mutex_timedlock (mutex->__data.__lock, abstime);
  59
  60       if (result != 0)
  61         goto out;
  62
  63       /* Only locked once so far.  */
  64       mutex->__data.__count = 1;
  65       break;
  66
  67       /* Error checking mutex.  */
  68     case PTHREAD_MUTEX_ERRORCHECK_NP:
  69       /* Check whether we already hold the mutex.  */
  70       if (__builtin_expect (mutex->__data.__owner == id, 0))
  71         return EDEADLK;
  72
  73       /* FALLTHROUGH */
  74
  75     case PTHREAD_MUTEX_TIMED_NP:
  76     simple:
  77       /* Normal mutex.  */
  78       result = lll_mutex_timedlock (mutex->__data.__lock, abstime);
  79       break;
  80
  81     case PTHREAD_MUTEX_ADAPTIVE_NP:
  82       if (! __is_smp)
  83         goto simple;
  84
  85       if (lll_mutex_trylock (mutex->__data.__lock) != 0)
  86         {
  87           int cnt = 0;
  88           int max_cnt = MIN (MAX_ADAPTIVE_COUNT,
  89                              mutex->__data.__spins * 2 + 10);
  90           do
  91             {
  92               if (cnt++ >= max_cnt)
  93                 {
  94                   result = lll_mutex_timedlock (mutex->__data.__lock, abstime);
  95                   break;
  96                 }
  97
  98 #ifdef BUSY_WAIT_NOP
  99               BUSY_WAIT_NOP;
 100 #endif
 101             }
 102           while (lll_mutex_trylock (mutex->__data.__lock) != 0);
 103
 104           mutex->__data.__spins += (cnt - mutex->__data.__spins) / 8;
 105         }
 106       break;
 107
 108     case PTHREAD_MUTEX_ROBUST_RECURSIVE_NP:
 109     case PTHREAD_MUTEX_ROBUST_ERRORCHECK_NP:
 110     case PTHREAD_MUTEX_ROBUST_NORMAL_NP:
 111     case PTHREAD_MUTEX_ROBUST_ADAPTIVE_NP:
 112       THREAD_SETMEM (THREAD_SELF, robust_head.list_op_pending,
 113                      &mutex->__data.__list.__next);
 114
 115       oldval = mutex->__data.__lock;
 116       do
 117         {
 118         again:
 119           if ((oldval & FUTEX_OWNER_DIED) != 0)
 120             {
 121               /* The previous owner died.  Try locking the mutex.  */
 122               int newval
 123                 = atomic_compare_and_exchange_val_acq (&mutex->__data.__lock,
 124                                                        id, oldval);
 125               if (newval != oldval)
 126                 {
 127                   oldval = newval;
 128                   goto again;
 129                 }
 130
 131               /* We got the mutex.  */
 132               mutex->__data.__count = 1;
 133               /* But it is inconsistent unless marked otherwise.  */
 134               mutex->__data.__owner = PTHREAD_MUTEX_INCONSISTENT;
 135
 136               ENQUEUE_MUTEX (mutex);
 137               THREAD_SETMEM (THREAD_SELF, robust_head.list_op_pending, NULL);
 138
 139               /* Note that we deliberately exit here.  If we fall
 140                  through to the end of the function __nusers would be
 141                  incremented which is not correct because the old
 142                  owner has to be discounted.  */
 143               return EOWNERDEAD;
 144             }
 145
 146           /* Check whether we already hold the mutex.  */
 147           if (__builtin_expect ((oldval & FUTEX_TID_MASK) == id, 0))
 148             {
 149               if (mutex->__data.__kind
 150                   == PTHREAD_MUTEX_ROBUST_ERRORCHECK_NP)
 151                 {
 152                   THREAD_SETMEM (THREAD_SELF, robust_head.list_op_pending,
 153                                  NULL);
 154                   return EDEADLK;
 155                 }
 156
 157               if (mutex->__data.__kind
 158                   == PTHREAD_MUTEX_ROBUST_RECURSIVE_NP)
 159                 {
 160                   THREAD_SETMEM (THREAD_SELF, robust_head.list_op_pending,
 161                                  NULL);
 162
 163                   /* Just bump the counter.  */
 164                   if (__builtin_expect (mutex->__data.__count + 1 == 0, 0))
 165                     /* Overflow of the counter.  */
 166                     return EAGAIN;
 167
 168                   ++mutex->__data.__count;
 169
 170                   return 0;
 171                 }
 172             }
 173
 174           result = lll_robust_mutex_timedlock (mutex->__data.__lock, abstime,
 175                                                id);
 176
 177           if (__builtin_expect (mutex->__data.__owner
 178                                 == PTHREAD_MUTEX_NOTRECOVERABLE, 0))
 179             {
 180               /* This mutex is now not recoverable.  */
 181               mutex->__data.__count = 0;
 182               lll_mutex_unlock (mutex->__data.__lock);
 183               THREAD_SETMEM (THREAD_SELF, robust_head.list_op_pending, NULL);
 184               return ENOTRECOVERABLE;
 185             }
 186
 187           if (result == ETIMEDOUT || result == EINVAL)
 188             goto out;
 189
 190           oldval = result;
 191         }
 192       while ((oldval & FUTEX_OWNER_DIED) != 0);
 193
 194       mutex->__data.__count = 1;
 195       ENQUEUE_MUTEX (mutex);
 196       THREAD_SETMEM (THREAD_SELF, robust_head.list_op_pending, NULL);
 197       break;
 198
 199     case PTHREAD_MUTEX_PI_RECURSIVE_NP:
 200     case PTHREAD_MUTEX_PI_ERRORCHECK_NP:
 201     case PTHREAD_MUTEX_PI_NORMAL_NP:
 202     case PTHREAD_MUTEX_PI_ADAPTIVE_NP:
 203     case PTHREAD_MUTEX_PI_ROBUST_RECURSIVE_NP:
 204     case PTHREAD_MUTEX_PI_ROBUST_ERRORCHECK_NP:
 205     case PTHREAD_MUTEX_PI_ROBUST_NORMAL_NP:
 206     case PTHREAD_MUTEX_PI_ROBUST_ADAPTIVE_NP:
 207       {
 208         int kind = mutex->__data.__kind & PTHREAD_MUTEX_KIND_MASK_NP;
 209         int robust = mutex->__data.__kind & PTHREAD_MUTEX_ROBUST_NORMAL_NP;
 210
 211         if (robust)
 212           /* Note: robust PI futexes are signaled by setting bit 0.  */
 213           THREAD_SETMEM (THREAD_SELF, robust_head.list_op_pending,
 214                          (void *) (((uintptr_t) &mutex->__data.__list.__next)
 215                                    | 1));
 216
 217         oldval = mutex->__data.__lock;
 218
 219         /* Check whether we already hold the mutex.  */
 220         if (__builtin_expect ((oldval & FUTEX_TID_MASK) == id, 0))
 221           {
 222             if (kind == PTHREAD_MUTEX_ERRORCHECK_NP)
 223               {
 224                 THREAD_SETMEM (THREAD_SELF, robust_head.list_op_pending, NULL);
 225                 return EDEADLK;
 226               }
 227
 228             if (kind == PTHREAD_MUTEX_RECURSIVE_NP)
 229               {
 230                 THREAD_SETMEM (THREAD_SELF, robust_head.list_op_pending, NULL);
 231
 232                 /* Just bump the counter.  */
 233                 if (__builtin_expect (mutex->__data.__count + 1 == 0, 0))
 234                   /* Overflow of the counter.  */
 235                   return EAGAIN;
 236
 237                 ++mutex->__data.__count;
 238
 239                 return 0;
 240               }
 241           }
 242
 243         oldval = atomic_compare_and_exchange_val_acq (&mutex->__data.__lock,
 244                                                       id, 0);
 245
 246         if (oldval != 0)
 247           {
 248             /* The mutex is locked.  The kernel will now take care of
 249                everything.  The timeout value must be a relative value.
 250                Convert it.  */
 251             INTERNAL_SYSCALL_DECL (__err);
 252
 253             int e = INTERNAL_SYSCALL (futex, __err, 4, &mutex->__data.__lock,
 254                                       FUTEX_LOCK_PI, 1, abstime);
 255             if (INTERNAL_SYSCALL_ERROR_P (e, __err))
 256               {
 257                 if (INTERNAL_SYSCALL_ERRNO (e, __err) == ETIMEDOUT)
 258                   return ETIMEDOUT;
 259
 260                 if (INTERNAL_SYSCALL_ERRNO (e, __err) == ESRCH
 261                     || INTERNAL_SYSCALL_ERRNO (e, __err) == EDEADLK)
 262                   {
 263                     assert (INTERNAL_SYSCALL_ERRNO (e, __err) != EDEADLK
 264                             || (kind != PTHREAD_MUTEX_ERRORCHECK_NP
 265                                 && kind != PTHREAD_MUTEX_RECURSIVE_NP));
 266                     /* ESRCH can happen only for non-robust PI mutexes where
 267                        the owner of the lock died.  */
 268                     assert (INTERNAL_SYSCALL_ERRNO (e, __err) != ESRCH
 269                             || !robust);
 270
 271                     /* Delay the thread until the timeout is reached.
 272                        Then return ETIMEDOUT.  */
 273                     struct timespec reltime;
 274                     struct timespec now;
 275
 276                     INTERNAL_SYSCALL (clock_gettime, __err, 2, CLOCK_REALTIME,
 277                                       &now);
 278                     reltime.tv_sec = abstime->tv_sec - now.tv_sec;
 279                     reltime.tv_nsec = abstime->tv_nsec - now.tv_nsec;
 280                     if (reltime.tv_nsec < 0)
 281                       {
 282                         reltime.tv_nsec += 1000000000;
 283                         --reltime.tv_sec;
 284                       }
 285                     if (reltime.tv_sec >= 0)
 286                       while (nanosleep_not_cancel (&reltime, &reltime) != 0)
 287                         continue;
 288
 289                     return ETIMEDOUT;
 290                   }
 291
 292                 return INTERNAL_SYSCALL_ERRNO (e, __err);
 293               }
 294
 295             oldval = mutex->__data.__lock;
 296
 297             assert (robust || (oldval & FUTEX_OWNER_DIED) == 0);
 298           }
 299
 300         if (__builtin_expect (oldval & FUTEX_OWNER_DIED, 0))
 301           {
 302             atomic_and (&mutex->__data.__lock, ~FUTEX_OWNER_DIED);
 303
 304             /* We got the mutex.  */
 305             mutex->__data.__count = 1;
 306             /* But it is inconsistent unless marked otherwise.  */
 307             mutex->__data.__owner = PTHREAD_MUTEX_INCONSISTENT;
 308
 309             ENQUEUE_MUTEX_PI (mutex);
 310             THREAD_SETMEM (THREAD_SELF, robust_head.list_op_pending, NULL);
 311
 312             /* Note that we deliberately exit here.  If we fall
 313                through to the end of the function __nusers would be
 314                incremented which is not correct because the old owner
 315                has to be discounted.  */
 316             return EOWNERDEAD;
 317           }
 318
 319         if (robust
 320             && __builtin_expect (mutex->__data.__owner
 321                                  == PTHREAD_MUTEX_NOTRECOVERABLE, 0))
 322           {
 323             /* This mutex is now not recoverable.  */
 324             mutex->__data.__count = 0;
 325
 326             INTERNAL_SYSCALL_DECL (__err);
 327             INTERNAL_SYSCALL (futex, __err, 4, &mutex->__data.__lock,
 328                               FUTEX_UNLOCK_PI, 0, 0);
 329
 330             THREAD_SETMEM (THREAD_SELF, robust_head.list_op_pending, NULL);
 331             return ENOTRECOVERABLE;
 332           }
 333
 334         mutex->__data.__count = 1;
 335         if (robust)
 336           {
 337             ENQUEUE_MUTEX_PI (mutex);
 338             THREAD_SETMEM (THREAD_SELF, robust_head.list_op_pending, NULL);
 339           }
 340         }
 341       break;
 342
 343     case PTHREAD_MUTEX_PP_RECURSIVE_NP:
 344     case PTHREAD_MUTEX_PP_ERRORCHECK_NP:
 345     case PTHREAD_MUTEX_PP_NORMAL_NP:
 346     case PTHREAD_MUTEX_PP_ADAPTIVE_NP:
 347       {
 348         int kind = mutex->__data.__kind & PTHREAD_MUTEX_KIND_MASK_NP;
 349
 350         oldval = mutex->__data.__lock;
 351
 352         /* Check whether we already hold the mutex.  */
 353         if (mutex->__data.__owner == id)
 354           {
 355             if (kind == PTHREAD_MUTEX_ERRORCHECK_NP)
 356               return EDEADLK;
 357
 358             if (kind == PTHREAD_MUTEX_RECURSIVE_NP)
 359               {
 360                 /* Just bump the counter.  */
 361                 if (__builtin_expect (mutex->__data.__count + 1 == 0, 0))
 362                   /* Overflow of the counter.  */
 363                   return EAGAIN;
 364
 365                 ++mutex->__data.__count;
 366
 367                 return 0;
 368               }
 369           }
 370
 371         int oldprio = -1, ceilval;
 372         do
 373           {
 374             int ceiling = (oldval & PTHREAD_MUTEX_PRIO_CEILING_MASK)
 375                           >> PTHREAD_MUTEX_PRIO_CEILING_SHIFT;
 376
 377             if (__pthread_current_priority () > ceiling)
 378               {
 379                 result = EINVAL;
 380               failpp:
 381                 if (oldprio != -1)
 382                   __pthread_tpp_change_priority (oldprio, -1);
 383                 return result;
 384               }
 385
 386             result = __pthread_tpp_change_priority (oldprio, ceiling);
 387             if (result)
 388               return result;
 389
 390             ceilval = ceiling << PTHREAD_MUTEX_PRIO_CEILING_SHIFT;
 391             oldprio = ceiling;
 392
 393             oldval
 394               = atomic_compare_and_exchange_val_acq (&mutex->__data.__lock,
 395                                                      ceilval | 1, ceilval);
 396
 397             if (oldval == ceilval)
 398               break;
 399
 400             do
 401               {
 402                 oldval
 403                   = atomic_compare_and_exchange_val_acq (&mutex->__data.__lock,
 404                                                          ceilval | 2,
 405                                                          ceilval | 1);
 406
 407                 if ((oldval & PTHREAD_MUTEX_PRIO_CEILING_MASK) != ceilval)
 408                   break;
 409
 410                 if (oldval != ceilval)
 411                   {
 412                     /* Reject invalid timeouts.  */
 413                     if (abstime->tv_nsec < 0 || abstime->tv_nsec >= 1000000000)
 414                       {
 415                         result = EINVAL;
 416                         goto failpp;
 417                       }
 418
 419                     struct timeval tv;
 420                     struct timespec rt;
 421
 422                     /* Get the current time.  */
 423                     (void) __gettimeofday (&tv, NULL);
 424
 425                     /* Compute relative timeout.  */
 426                     rt.tv_sec = abstime->tv_sec - tv.tv_sec;
 427                     rt.tv_nsec = abstime->tv_nsec - tv.tv_usec * 1000;
 428                     if (rt.tv_nsec < 0)
 429                       {
 430                         rt.tv_nsec += 1000000000;
 431                         --rt.tv_sec;
 432                       }
 433
 434                     /* Already timed out?  */
 435                     if (rt.tv_sec < 0)
 436                       {
 437                         result = ETIMEDOUT;
 438                         goto failpp;
 439                       }
 440
 441                     lll_futex_timed_wait (&mutex->__data.__lock,
 442                                           ceilval | 2, &rt);
 443                   }
 444               }
 445             while (atomic_compare_and_exchange_val_acq (&mutex->__data.__lock,
 446                                                         ceilval | 2, ceilval)
 447                    != ceilval);
 448           }
 449         while ((oldval & PTHREAD_MUTEX_PRIO_CEILING_MASK) != ceilval);
 450
 451         assert (mutex->__data.__owner == 0);
 452         mutex->__data.__count = 1;
 453       }
 454       break;
 455
 456     default:
 457       /* Correct code cannot set any other type.  */
 458       return EINVAL;
 459     }
 460
 461   if (result == 0)
 462     {
 463       /* Record the ownership.  */
 464       mutex->__data.__owner = id;
 465       ++mutex->__data.__nusers;
 466     }
 467
 468  out:
 469   return result;
 470 }