nptl/pthread_mutex_timedlock.c

   1 /* Copyright (C) 2002-2016 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
 144       oldval = mutex->__data.__lock;
 145       do
 146         {
 147         again:
 148           if ((oldval & FUTEX_OWNER_DIED) != 0)
 149             {
 150               /* The previous owner died.  Try locking the mutex.  */
 151               int newval = id | (oldval & FUTEX_WAITERS);
 152
 153               newval
 154                 = atomic_compare_and_exchange_val_acq (&mutex->__data.__lock,
 155                                                        newval, oldval);
 156               if (newval != oldval)
 157                 {
 158                   oldval = newval;
 159                   goto again;
 160                 }
 161
 162               /* We got the mutex.  */
 163               mutex->__data.__count = 1;
 164               /* But it is inconsistent unless marked otherwise.  */
 165               mutex->__data.__owner = PTHREAD_MUTEX_INCONSISTENT;
 166
 167               ENQUEUE_MUTEX (mutex);
 168               THREAD_SETMEM (THREAD_SELF, robust_head.list_op_pending, NULL);
 169
 170               /* Note that we deliberately exit here.  If we fall
 171                  through to the end of the function __nusers would be
 172                  incremented which is not correct because the old
 173                  owner has to be discounted.  */
 174               return EOWNERDEAD;
 175             }
 176
 177           /* Check whether we already hold the mutex.  */
 178           if (__glibc_unlikely ((oldval & FUTEX_TID_MASK) == id))
 179             {
 180               int kind = PTHREAD_MUTEX_TYPE (mutex);
 181               if (kind == PTHREAD_MUTEX_ROBUST_ERRORCHECK_NP)
 182                 {
 183                   THREAD_SETMEM (THREAD_SELF, robust_head.list_op_pending,
 184                                  NULL);
 185                   return EDEADLK;
 186                 }
 187
 188               if (kind == PTHREAD_MUTEX_ROBUST_RECURSIVE_NP)
 189                 {
 190                   THREAD_SETMEM (THREAD_SELF, robust_head.list_op_pending,
 191                                  NULL);
 192
 193                   /* Just bump the counter.  */
 194                   if (__glibc_unlikely (mutex->__data.__count + 1 == 0))
 195                     /* Overflow of the counter.  */
 196                     return EAGAIN;
 197
 198                   ++mutex->__data.__count;
 199
 200                   LIBC_PROBE (mutex_timedlock_acquired, 1, mutex);
 201
 202                   return 0;
 203                 }
 204             }
 205
 206           result = lll_robust_timedlock (mutex->__data.__lock, abstime, id,
 207                                          PTHREAD_ROBUST_MUTEX_PSHARED (mutex));
 208
 209           if (__builtin_expect (mutex->__data.__owner
 210                                 == PTHREAD_MUTEX_NOTRECOVERABLE, 0))
 211             {
 212               /* This mutex is now not recoverable.  */
 213               mutex->__data.__count = 0;
 214               lll_unlock (mutex->__data.__lock,
 215                           PTHREAD_ROBUST_MUTEX_PSHARED (mutex));
 216               THREAD_SETMEM (THREAD_SELF, robust_head.list_op_pending, NULL);
 217               return ENOTRECOVERABLE;
 218             }
 219
 220           if (result == ETIMEDOUT || result == EINVAL)
 221             goto out;
 222
 223           oldval = result;
 224         }
 225       while ((oldval & FUTEX_OWNER_DIED) != 0);
 226
 227       mutex->__data.__count = 1;
 228       ENQUEUE_MUTEX (mutex);
 229       THREAD_SETMEM (THREAD_SELF, robust_head.list_op_pending, NULL);
 230       break;
 231
 232     /* The PI support requires the Linux futex system call.  If that's not
 233        available, pthread_mutex_init should never have allowed the type to
 234        be set.  So it will get the default case for an invalid type.  */
 235 #ifdef __NR_futex
 236     case PTHREAD_MUTEX_PI_RECURSIVE_NP:
 237     case PTHREAD_MUTEX_PI_ERRORCHECK_NP:
 238     case PTHREAD_MUTEX_PI_NORMAL_NP:
 239     case PTHREAD_MUTEX_PI_ADAPTIVE_NP:
 240     case PTHREAD_MUTEX_PI_ROBUST_RECURSIVE_NP:
 241     case PTHREAD_MUTEX_PI_ROBUST_ERRORCHECK_NP:
 242     case PTHREAD_MUTEX_PI_ROBUST_NORMAL_NP:
 243     case PTHREAD_MUTEX_PI_ROBUST_ADAPTIVE_NP:
 244       {
 245         int kind = mutex->__data.__kind & PTHREAD_MUTEX_KIND_MASK_NP;
 246         int robust = mutex->__data.__kind & PTHREAD_MUTEX_ROBUST_NORMAL_NP;
 247
 248         if (robust)
 249           /* Note: robust PI futexes are signaled by setting bit 0.  */
 250           THREAD_SETMEM (THREAD_SELF, robust_head.list_op_pending,
 251                          (void *) (((uintptr_t) &mutex->__data.__list.__next)
 252                                    | 1));
 253
 254         oldval = mutex->__data.__lock;
 255
 256         /* Check whether we already hold the mutex.  */
 257         if (__glibc_unlikely ((oldval & FUTEX_TID_MASK) == id))
 258           {
 259             if (kind == PTHREAD_MUTEX_ERRORCHECK_NP)
 260               {
 261                 THREAD_SETMEM (THREAD_SELF, robust_head.list_op_pending, NULL);
 262                 return EDEADLK;
 263               }
 264
 265             if (kind == PTHREAD_MUTEX_RECURSIVE_NP)
 266               {
 267                 THREAD_SETMEM (THREAD_SELF, robust_head.list_op_pending, NULL);
 268
 269                 /* Just bump the counter.  */
 270                 if (__glibc_unlikely (mutex->__data.__count + 1 == 0))
 271                   /* Overflow of the counter.  */
 272                   return EAGAIN;
 273
 274                 ++mutex->__data.__count;
 275
 276                 LIBC_PROBE (mutex_timedlock_acquired, 1, mutex);
 277
 278                 return 0;
 279               }
 280           }
 281
 282         oldval = atomic_compare_and_exchange_val_acq (&mutex->__data.__lock,
 283                                                       id, 0);
 284
 285         if (oldval != 0)
 286           {
 287             /* The mutex is locked.  The kernel will now take care of
 288                everything.  The timeout value must be a relative value.
 289                Convert it.  */
 290             int private = (robust
 291                            ? PTHREAD_ROBUST_MUTEX_PSHARED (mutex)
 292                            : PTHREAD_MUTEX_PSHARED (mutex));
 293             INTERNAL_SYSCALL_DECL (__err);
 294
 295             int e = INTERNAL_SYSCALL (futex, __err, 4, &mutex->__data.__lock,
 296                                       __lll_private_flag (FUTEX_LOCK_PI,
 297                                                           private), 1,
 298                                       abstime);
 299             if (INTERNAL_SYSCALL_ERROR_P (e, __err))
 300               {
 301                 if (INTERNAL_SYSCALL_ERRNO (e, __err) == ETIMEDOUT)
 302                   return ETIMEDOUT;
 303
 304                 if (INTERNAL_SYSCALL_ERRNO (e, __err) == ESRCH
 305                     || INTERNAL_SYSCALL_ERRNO (e, __err) == EDEADLK)
 306                   {
 307                     assert (INTERNAL_SYSCALL_ERRNO (e, __err) != EDEADLK
 308                             || (kind != PTHREAD_MUTEX_ERRORCHECK_NP
 309                                 && kind != PTHREAD_MUTEX_RECURSIVE_NP));
 310                     /* ESRCH can happen only for non-robust PI mutexes where
 311                        the owner of the lock died.  */
 312                     assert (INTERNAL_SYSCALL_ERRNO (e, __err) != ESRCH
 313                             || !robust);
 314
 315                     /* Delay the thread until the timeout is reached.
 316                        Then return ETIMEDOUT.  */
 317                     struct timespec reltime;
 318                     struct timespec now;
 319
 320                     INTERNAL_SYSCALL (clock_gettime, __err, 2, CLOCK_REALTIME,
 321                                       &now);
 322                     reltime.tv_sec = abstime->tv_sec - now.tv_sec;
 323                     reltime.tv_nsec = abstime->tv_nsec - now.tv_nsec;
 324                     if (reltime.tv_nsec < 0)
 325                       {
 326                         reltime.tv_nsec += 1000000000;
 327                         --reltime.tv_sec;
 328                       }
 329                     if (reltime.tv_sec >= 0)
 330                       while (nanosleep_not_cancel (&reltime, &reltime) != 0)
 331                         continue;
 332
 333                     return ETIMEDOUT;
 334                   }
 335
 336                 return INTERNAL_SYSCALL_ERRNO (e, __err);
 337               }
 338
 339             oldval = mutex->__data.__lock;
 340
 341             assert (robust || (oldval & FUTEX_OWNER_DIED) == 0);
 342           }
 343
 344         if (__glibc_unlikely (oldval & FUTEX_OWNER_DIED))
 345           {
 346             atomic_and (&mutex->__data.__lock, ~FUTEX_OWNER_DIED);
 347
 348             /* We got the mutex.  */
 349             mutex->__data.__count = 1;
 350             /* But it is inconsistent unless marked otherwise.  */
 351             mutex->__data.__owner = PTHREAD_MUTEX_INCONSISTENT;
 352
 353             ENQUEUE_MUTEX_PI (mutex);
 354             THREAD_SETMEM (THREAD_SELF, robust_head.list_op_pending, NULL);
 355
 356             /* Note that we deliberately exit here.  If we fall
 357                through to the end of the function __nusers would be
 358                incremented which is not correct because the old owner
 359                has to be discounted.  */
 360             return EOWNERDEAD;
 361           }
 362
 363         if (robust
 364             && __builtin_expect (mutex->__data.__owner
 365                                  == PTHREAD_MUTEX_NOTRECOVERABLE, 0))
 366           {
 367             /* This mutex is now not recoverable.  */
 368             mutex->__data.__count = 0;
 369
 370             INTERNAL_SYSCALL_DECL (__err);
 371             INTERNAL_SYSCALL (futex, __err, 4, &mutex->__data.__lock,
 372                               __lll_private_flag (FUTEX_UNLOCK_PI,
 373                                                   PTHREAD_ROBUST_MUTEX_PSHARED (mutex)),
 374                               0, 0);
 375
 376             THREAD_SETMEM (THREAD_SELF, robust_head.list_op_pending, NULL);
 377             return ENOTRECOVERABLE;
 378           }
 379
 380         mutex->__data.__count = 1;
 381         if (robust)
 382           {
 383             ENQUEUE_MUTEX_PI (mutex);
 384             THREAD_SETMEM (THREAD_SELF, robust_head.list_op_pending, NULL);
 385           }
 386         }
 387       break;
 388 #endif  /* __NR_futex.  */
 389
 390     case PTHREAD_MUTEX_PP_RECURSIVE_NP:
 391     case PTHREAD_MUTEX_PP_ERRORCHECK_NP:
 392     case PTHREAD_MUTEX_PP_NORMAL_NP:
 393     case PTHREAD_MUTEX_PP_ADAPTIVE_NP:
 394       {
 395         int kind = mutex->__data.__kind & PTHREAD_MUTEX_KIND_MASK_NP;
 396
 397         oldval = mutex->__data.__lock;
 398
 399         /* Check whether we already hold the mutex.  */
 400         if (mutex->__data.__owner == id)
 401           {
 402             if (kind == PTHREAD_MUTEX_ERRORCHECK_NP)
 403               return EDEADLK;
 404
 405             if (kind == PTHREAD_MUTEX_RECURSIVE_NP)
 406               {
 407                 /* Just bump the counter.  */
 408                 if (__glibc_unlikely (mutex->__data.__count + 1 == 0))
 409                   /* Overflow of the counter.  */
 410                   return EAGAIN;
 411
 412                 ++mutex->__data.__count;
 413
 414                 LIBC_PROBE (mutex_timedlock_acquired, 1, mutex);
 415
 416                 return 0;
 417               }
 418           }
 419
 420         int oldprio = -1, ceilval;
 421         do
 422           {
 423             int ceiling = (oldval & PTHREAD_MUTEX_PRIO_CEILING_MASK)
 424                           >> PTHREAD_MUTEX_PRIO_CEILING_SHIFT;
 425
 426             if (__pthread_current_priority () > ceiling)
 427               {
 428                 result = EINVAL;
 429               failpp:
 430                 if (oldprio != -1)
 431                   __pthread_tpp_change_priority (oldprio, -1);
 432                 return result;
 433               }
 434
 435             result = __pthread_tpp_change_priority (oldprio, ceiling);
 436             if (result)
 437               return result;
 438
 439             ceilval = ceiling << PTHREAD_MUTEX_PRIO_CEILING_SHIFT;
 440             oldprio = ceiling;
 441
 442             oldval
 443               = atomic_compare_and_exchange_val_acq (&mutex->__data.__lock,
 444                                                      ceilval | 1, ceilval);
 445
 446             if (oldval == ceilval)
 447               break;
 448
 449             do
 450               {
 451                 oldval
 452                   = atomic_compare_and_exchange_val_acq (&mutex->__data.__lock,
 453                                                          ceilval | 2,
 454                                                          ceilval | 1);
 455
 456                 if ((oldval & PTHREAD_MUTEX_PRIO_CEILING_MASK) != ceilval)
 457                   break;
 458
 459                 if (oldval != ceilval)
 460                   {
 461                     /* Reject invalid timeouts.  */
 462                     if (abstime->tv_nsec < 0 || abstime->tv_nsec >= 1000000000)
 463                       {
 464                         result = EINVAL;
 465                         goto failpp;
 466                       }
 467
 468                     struct timeval tv;
 469                     struct timespec rt;
 470
 471                     /* Get the current time.  */
 472                     (void) __gettimeofday (&tv, NULL);
 473
 474                     /* Compute relative timeout.  */
 475                     rt.tv_sec = abstime->tv_sec - tv.tv_sec;
 476                     rt.tv_nsec = abstime->tv_nsec - tv.tv_usec * 1000;
 477                     if (rt.tv_nsec < 0)
 478                       {
 479                         rt.tv_nsec += 1000000000;
 480                         --rt.tv_sec;
 481                       }
 482
 483                     /* Already timed out?  */
 484                     if (rt.tv_sec < 0)
 485                       {
 486                         result = ETIMEDOUT;
 487                         goto failpp;
 488                       }
 489
 490                     lll_futex_timed_wait (&mutex->__data.__lock,
 491                                           ceilval | 2, &rt,
 492                                           PTHREAD_MUTEX_PSHARED (mutex));
 493                   }
 494               }
 495             while (atomic_compare_and_exchange_val_acq (&mutex->__data.__lock,
 496                                                         ceilval | 2, ceilval)
 497                    != ceilval);
 498           }
 499         while ((oldval & PTHREAD_MUTEX_PRIO_CEILING_MASK) != ceilval);
 500
 501         assert (mutex->__data.__owner == 0);
 502         mutex->__data.__count = 1;
 503       }
 504       break;
 505
 506     default:
 507       /* Correct code cannot set any other type.  */
 508       return EINVAL;
 509     }
 510
 511   if (result == 0)
 512     {
 513       /* Record the ownership.  */
 514       mutex->__data.__owner = id;
 515       ++mutex->__data.__nusers;
 516
 517       LIBC_PROBE (mutex_timedlock_acquired, 1, mutex);
 518     }
 519
 520  out:
 521   return result;
 522 }