nptl/pthread_create.c

   1 /* Copyright (C) 2002-2007,2008,2009 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 <errno.h>
  21 #include <stdbool.h>
  22 #include <stdlib.h>
  23 #include <string.h>
  24 #include "pthreadP.h"
  25 #include <hp-timing.h>
  26 #include <ldsodefs.h>
  27 #include <atomic.h>
  28 #include <libc-internal.h>
  29 #include <resolv.h>
  30 #include <kernel-features.h>
  31
  32 #include <shlib-compat.h>
  33
  34
  35 /* Local function to start thread and handle cleanup.  */
  36 static int start_thread (void *arg);
  37
  38
  39 /* Nozero if debugging mode is enabled.  */
  40 int __pthread_debug;
  41
  42 /* Globally enabled events.  */
  43 static td_thr_events_t __nptl_threads_events __attribute_used__;
  44
  45 /* Pointer to descriptor with the last event.  */
  46 static struct pthread *__nptl_last_event __attribute_used__;
  47
  48 /* Number of threads running.  */
  49 unsigned int __nptl_nthreads = 1;
  50
  51
  52 /* Code to allocate and deallocate a stack.  */
  53 #include "allocatestack.c"
  54
  55 /* Code to create the thread.  */
  56 #include <createthread.c>
  57
  58
  59 struct pthread *
  60 internal_function
  61 __find_in_stack_list (pd)
  62      struct pthread *pd;
  63 {
  64   list_t *entry;
  65   struct pthread *result = NULL;
  66
  67   lll_lock (stack_cache_lock, LLL_PRIVATE);
  68
  69   list_for_each (entry, &stack_used)
  70     {
  71       struct pthread *curp;
  72
  73       curp = list_entry (entry, struct pthread, list);
  74       if (curp == pd)
  75         {
  76           result = curp;
  77           break;
  78         }
  79     }
  80
  81   if (result == NULL)
  82     list_for_each (entry, &__stack_user)
  83       {
  84         struct pthread *curp;
  85
  86         curp = list_entry (entry, struct pthread, list);
  87         if (curp == pd)
  88           {
  89             result = curp;
  90             break;
  91           }
  92       }
  93
  94   lll_unlock (stack_cache_lock, LLL_PRIVATE);
  95
  96   return result;
  97 }
  98
  99
 100 /* Deallocate POSIX thread-local-storage.  */
 101 void
 102 attribute_hidden
 103 __nptl_deallocate_tsd (void)
 104 {
 105   struct pthread *self = THREAD_SELF;
 106
 107   /* Maybe no data was ever allocated.  This happens often so we have
 108      a flag for this.  */
 109   if (THREAD_GETMEM (self, specific_used))
 110     {
 111       size_t round;
 112       size_t cnt;
 113
 114       round = 0;
 115       do
 116         {
 117           size_t idx;
 118
 119           /* So far no new nonzero data entry.  */
 120           THREAD_SETMEM (self, specific_used, false);
 121
 122           for (cnt = idx = 0; cnt < PTHREAD_KEY_1STLEVEL_SIZE; ++cnt)
 123             {
 124               struct pthread_key_data *level2;
 125
 126               level2 = THREAD_GETMEM_NC (self, specific, cnt);
 127
 128               if (level2 != NULL)
 129                 {
 130                   size_t inner;
 131
 132                   for (inner = 0; inner < PTHREAD_KEY_2NDLEVEL_SIZE;
 133                        ++inner, ++idx)
 134                     {
 135                       void *data = level2[inner].data;
 136
 137                       if (data != NULL)
 138                         {
 139                           /* Always clear the data.  */
 140                           level2[inner].data = NULL;
 141
 142                           /* Make sure the data corresponds to a valid
 143                              key.  This test fails if the key was
 144                              deallocated and also if it was
 145                              re-allocated.  It is the user's
 146                              responsibility to free the memory in this
 147                              case.  */
 148                           if (level2[inner].seq
 149                               == __pthread_keys[idx].seq
 150                               /* It is not necessary to register a destructor
 151                                  function.  */
 152                               && __pthread_keys[idx].destr != NULL)
 153                             /* Call the user-provided destructor.  */
 154                             __pthread_keys[idx].destr (data);
 155                         }
 156                     }
 157                 }
 158               else
 159                 idx += PTHREAD_KEY_1STLEVEL_SIZE;
 160             }
 161
 162           if (THREAD_GETMEM (self, specific_used) == 0)
 163             /* No data has been modified.  */
 164             goto just_free;
 165         }
 166       /* We only repeat the process a fixed number of times.  */
 167       while (__builtin_expect (++round < PTHREAD_DESTRUCTOR_ITERATIONS, 0));
 168
 169       /* Just clear the memory of the first block for reuse.  */
 170       memset (&THREAD_SELF->specific_1stblock, '\0',
 171               sizeof (self->specific_1stblock));
 172
 173     just_free:
 174       /* Free the memory for the other blocks.  */
 175       for (cnt = 1; cnt < PTHREAD_KEY_1STLEVEL_SIZE; ++cnt)
 176         {
 177           struct pthread_key_data *level2;
 178
 179           level2 = THREAD_GETMEM_NC (self, specific, cnt);
 180           if (level2 != NULL)
 181             {
 182               /* The first block is allocated as part of the thread
 183                  descriptor.  */
 184               free (level2);
 185               THREAD_SETMEM_NC (self, specific, cnt, NULL);
 186             }
 187         }
 188
 189       THREAD_SETMEM (self, specific_used, false);
 190     }
 191 }
 192
 193
 194 /* Deallocate a thread's stack after optionally making sure the thread
 195    descriptor is still valid.  */
 196 void
 197 internal_function
 198 __free_tcb (struct pthread *pd)
 199 {
 200   /* The thread is exiting now.  */
 201   if (__builtin_expect (atomic_bit_test_set (&pd->cancelhandling,
 202                                              TERMINATED_BIT) == 0, 1))
 203     {
 204       /* Remove the descriptor from the list.  */
 205       if (DEBUGGING_P && __find_in_stack_list (pd) == NULL)
 206         /* Something is really wrong.  The descriptor for a still
 207            running thread is gone.  */
 208         abort ();
 209
 210       /* Free TPP data.  */
 211       if (__builtin_expect (pd->tpp != NULL, 0))
 212         {
 213           struct priority_protection_data *tpp = pd->tpp;
 214
 215           pd->tpp = NULL;
 216           free (tpp);
 217         }
 218
 219       /* Queue the stack memory block for reuse and exit the process.  The
 220          kernel will signal via writing to the address returned by
 221          QUEUE-STACK when the stack is available.  */
 222       __deallocate_stack (pd);
 223     }
 224 }
 225
 226
 227 static int
 228 start_thread (void *arg)
 229 {
 230   struct pthread *pd = (struct pthread *) arg;
 231
 232 #if HP_TIMING_AVAIL
 233   /* Remember the time when the thread was started.  */
 234   hp_timing_t now;
 235   HP_TIMING_NOW (now);
 236   THREAD_SETMEM (pd, cpuclock_offset, now);
 237 #endif
 238
 239   /* Initialize resolver state pointer.  */
 240   __resp = &pd->res;
 241
 242 #ifdef __NR_set_robust_list
 243 # ifndef __ASSUME_SET_ROBUST_LIST
 244   if (__set_robust_list_avail >= 0)
 245 # endif
 246     {
 247       INTERNAL_SYSCALL_DECL (err);
 248       /* This call should never fail because the initial call in init.c
 249          succeeded.  */
 250       INTERNAL_SYSCALL (set_robust_list, err, 2, &pd->robust_head,
 251                         sizeof (struct robust_list_head));
 252     }
 253 #endif
 254
 255   /* If the parent was running cancellation handlers while creating
 256      the thread the new thread inherited the signal mask.  Reset the
 257      cancellation signal mask.  */
 258   if (__builtin_expect (pd->parent_cancelhandling & CANCELING_BITMASK, 0))
 259     {
 260       INTERNAL_SYSCALL_DECL (err);
 261       sigset_t mask;
 262       __sigemptyset (&mask);
 263       __sigaddset (&mask, SIGCANCEL);
 264       (void) INTERNAL_SYSCALL (rt_sigprocmask, err, 4, SIG_UNBLOCK, &mask,
 265                                NULL, _NSIG / 8);
 266     }
 267
 268   /* This is where the try/finally block should be created.  For
 269      compilers without that support we do use setjmp.  */
 270   struct pthread_unwind_buf unwind_buf;
 271
 272   /* No previous handlers.  */
 273   unwind_buf.priv.data.prev = NULL;
 274   unwind_buf.priv.data.cleanup = NULL;
 275
 276   int not_first_call;
 277   not_first_call = setjmp ((struct __jmp_buf_tag *) unwind_buf.cancel_jmp_buf);
 278   if (__builtin_expect (! not_first_call, 1))
 279     {
 280       /* Store the new cleanup handler info.  */
 281       THREAD_SETMEM (pd, cleanup_jmp_buf, &unwind_buf);
 282
 283       if (__builtin_expect (pd->stopped_start, 0))
 284         {
 285           int oldtype = CANCEL_ASYNC ();
 286
 287           /* Get the lock the parent locked to force synchronization.  */
 288           lll_lock (pd->lock, LLL_PRIVATE);
 289           /* And give it up right away.  */
 290           lll_unlock (pd->lock, LLL_PRIVATE);
 291
 292           CANCEL_RESET (oldtype);
 293         }
 294
 295       /* Run the code the user provided.  */
 296 #ifdef CALL_THREAD_FCT
 297       THREAD_SETMEM (pd, result, CALL_THREAD_FCT (pd));
 298 #else
 299       THREAD_SETMEM (pd, result, pd->start_routine (pd->arg));
 300 #endif
 301     }
 302
 303   /* Run the destructor for the thread-local data.  */
 304   __nptl_deallocate_tsd ();
 305
 306   /* Clean up any state libc stored in thread-local variables.  */
 307   __libc_thread_freeres ();
 308
 309   /* If this is the last thread we terminate the process now.  We
 310      do not notify the debugger, it might just irritate it if there
 311      is no thread left.  */
 312   if (__builtin_expect (atomic_decrement_and_test (&__nptl_nthreads), 0))
 313     /* This was the last thread.  */
 314     exit (0);
 315
 316   /* Report the death of the thread if this is wanted.  */
 317   if (__builtin_expect (pd->report_events, 0))
 318     {
 319       /* See whether TD_DEATH is in any of the mask.  */
 320       const int idx = __td_eventword (TD_DEATH);
 321       const uint32_t mask = __td_eventmask (TD_DEATH);
 322
 323       if ((mask & (__nptl_threads_events.event_bits[idx]
 324                    | pd->eventbuf.eventmask.event_bits[idx])) != 0)
 325         {
 326           /* Yep, we have to signal the death.  Add the descriptor to
 327              the list but only if it is not already on it.  */
 328           if (pd->nextevent == NULL)
 329             {
 330               pd->eventbuf.eventnum = TD_DEATH;
 331               pd->eventbuf.eventdata = pd;
 332
 333               do
 334                 pd->nextevent = __nptl_last_event;
 335               while (atomic_compare_and_exchange_bool_acq (&__nptl_last_event,
 336                                                            pd, pd->nextevent));
 337             }
 338
 339           /* Now call the function to signal the event.  */
 340           __nptl_death_event ();
 341         }
 342     }
 343
 344   /* The thread is exiting now.  Don't set this bit until after we've hit
 345      the event-reporting breakpoint, so that td_thr_get_info on us while at
 346      the breakpoint reports TD_THR_RUN state rather than TD_THR_ZOMBIE.  */
 347   atomic_bit_set (&pd->cancelhandling, EXITING_BIT);
 348
 349 #ifndef __ASSUME_SET_ROBUST_LIST
 350   /* If this thread has any robust mutexes locked, handle them now.  */
 351 # if __WORDSIZE == 64
 352   void *robust = pd->robust_head.list;
 353 # else
 354   __pthread_slist_t *robust = pd->robust_list.__next;
 355 # endif
 356   /* We let the kernel do the notification if it is able to do so.
 357      If we have to do it here there for sure are no PI mutexes involved
 358      since the kernel support for them is even more recent.  */
 359   if (__set_robust_list_avail < 0
 360       && __builtin_expect (robust != (void *) &pd->robust_head, 0))
 361     {
 362       do
 363         {
 364           struct __pthread_mutex_s *this = (struct __pthread_mutex_s *)
 365             ((char *) robust - offsetof (struct __pthread_mutex_s,
 366                                          __list.__next));
 367           robust = *((void **) robust);
 368
 369 # ifdef __PTHREAD_MUTEX_HAVE_PREV
 370           this->__list.__prev = NULL;
 371 # endif
 372           this->__list.__next = NULL;
 373
 374           lll_robust_dead (this->__lock, /* XYZ */ LLL_SHARED);
 375         }
 376       while (robust != (void *) &pd->robust_head);
 377     }
 378 #endif
 379
 380   /* If the thread is detached free the TCB.  */
 381   if (IS_DETACHED (pd))
 382     /* Free the TCB.  */
 383     __free_tcb (pd);
 384   else if (__builtin_expect (pd->cancelhandling & SETXID_BITMASK, 0))
 385     {
 386       /* Some other thread might call any of the setXid functions and expect
 387          us to reply.  In this case wait until we did that.  */
 388       do
 389         lll_futex_wait (&pd->setxid_futex, 0, LLL_PRIVATE);
 390       while (pd->cancelhandling & SETXID_BITMASK);
 391
 392       /* Reset the value so that the stack can be reused.  */
 393       pd->setxid_futex = 0;
 394     }
 395
 396   /* We cannot call '_exit' here.  '_exit' will terminate the process.
 397
 398      The 'exit' implementation in the kernel will signal when the
 399      process is really dead since 'clone' got passed the CLONE_CLEARTID
 400      flag.  The 'tid' field in the TCB will be set to zero.
 401
 402      The exit code is zero since in case all threads exit by calling
 403      'pthread_exit' the exit status must be 0 (zero).  */
 404   __exit_thread_inline (0);
 405
 406   /* NOTREACHED */
 407   return 0;
 408 }
 409
 410
 411 /* Default thread attributes for the case when the user does not
 412    provide any.  */
 413 static const struct pthread_attr default_attr =
 414   {
 415     /* Just some value > 0 which gets rounded to the nearest page size.  */
 416     .guardsize = 1,
 417   };
 418
 419
 420 int
 421 __pthread_create_2_1 (newthread, attr, start_routine, arg)
 422      pthread_t *newthread;
 423      const pthread_attr_t *attr;
 424      void *(*start_routine) (void *);
 425      void *arg;
 426 {
 427   STACK_VARIABLES;
 428
 429   const struct pthread_attr *iattr = (struct pthread_attr *) attr;
 430   if (iattr == NULL)
 431     /* Is this the best idea?  On NUMA machines this could mean
 432        accessing far-away memory.  */
 433     iattr = &default_attr;
 434
 435   struct pthread *pd = NULL;
 436   int err = ALLOCATE_STACK (iattr, &pd);
 437   if (__builtin_expect (err != 0, 0))
 438     /* Something went wrong.  Maybe a parameter of the attributes is
 439        invalid or we could not allocate memory.  */
 440     return err;
 441
 442
 443   /* Initialize the TCB.  All initializations with zero should be
 444      performed in 'get_cached_stack'.  This way we avoid doing this if
 445      the stack freshly allocated with 'mmap'.  */
 446
 447 #ifdef TLS_TCB_AT_TP
 448   /* Reference to the TCB itself.  */
 449   pd->header.self = pd;
 450
 451   /* Self-reference for TLS.  */
 452   pd->header.tcb = pd;
 453 #endif
 454
 455   /* Store the address of the start routine and the parameter.  Since
 456      we do not start the function directly the stillborn thread will
 457      get the information from its thread descriptor.  */
 458   pd->start_routine = start_routine;
 459   pd->arg = arg;
 460
 461   /* Copy the thread attribute flags.  */
 462   struct pthread *self = THREAD_SELF;
 463   pd->flags = ((iattr->flags & ~(ATTR_FLAG_SCHED_SET | ATTR_FLAG_POLICY_SET))
 464                | (self->flags & (ATTR_FLAG_SCHED_SET | ATTR_FLAG_POLICY_SET)));
 465
 466   /* Initialize the field for the ID of the thread which is waiting
 467      for us.  This is a self-reference in case the thread is created
 468      detached.  */
 469   pd->joinid = iattr->flags & ATTR_FLAG_DETACHSTATE ? pd : NULL;
 470
 471   /* The debug events are inherited from the parent.  */
 472   pd->eventbuf = self->eventbuf;
 473
 474
 475   /* Copy the parent's scheduling parameters.  The flags will say what
 476      is valid and what is not.  */
 477   pd->schedpolicy = self->schedpolicy;
 478   pd->schedparam = self->schedparam;
 479
 480   /* Copy the stack guard canary.  */
 481 #ifdef THREAD_COPY_STACK_GUARD
 482   THREAD_COPY_STACK_GUARD (pd);
 483 #endif
 484
 485   /* Copy the pointer guard value.  */
 486 #ifdef THREAD_COPY_POINTER_GUARD
 487   THREAD_COPY_POINTER_GUARD (pd);
 488 #endif
 489
 490   /* Determine scheduling parameters for the thread.  */
 491   if (attr != NULL
 492       && __builtin_expect ((iattr->flags & ATTR_FLAG_NOTINHERITSCHED) != 0, 0)
 493       && (iattr->flags & (ATTR_FLAG_SCHED_SET | ATTR_FLAG_POLICY_SET)) != 0)
 494     {
 495       INTERNAL_SYSCALL_DECL (scerr);
 496
 497       /* Use the scheduling parameters the user provided.  */
 498       if (iattr->flags & ATTR_FLAG_POLICY_SET)
 499         pd->schedpolicy = iattr->schedpolicy;
 500       else if ((pd->flags & ATTR_FLAG_POLICY_SET) == 0)
 501         {
 502           pd->schedpolicy = INTERNAL_SYSCALL (sched_getscheduler, scerr, 1, 0);
 503           pd->flags |= ATTR_FLAG_POLICY_SET;
 504         }
 505
 506       if (iattr->flags & ATTR_FLAG_SCHED_SET)
 507         memcpy (&pd->schedparam, &iattr->schedparam,
 508                 sizeof (struct sched_param));
 509       else if ((pd->flags & ATTR_FLAG_SCHED_SET) == 0)
 510         {
 511           INTERNAL_SYSCALL (sched_getparam, scerr, 2, 0, &pd->schedparam);
 512           pd->flags |= ATTR_FLAG_SCHED_SET;
 513         }
 514
 515       /* Check for valid priorities.  */
 516       int minprio = INTERNAL_SYSCALL (sched_get_priority_min, scerr, 1,
 517                                       iattr->schedpolicy);
 518       int maxprio = INTERNAL_SYSCALL (sched_get_priority_max, scerr, 1,
 519                                       iattr->schedpolicy);
 520       if (pd->schedparam.sched_priority < minprio
 521           || pd->schedparam.sched_priority > maxprio)
 522         {
 523           err = EINVAL;
 524           goto errout;
 525         }
 526     }
 527
 528   /* Pass the descriptor to the caller.  */
 529   *newthread = (pthread_t) pd;
 530
 531   /* Remember whether the thread is detached or not.  In case of an
 532      error we have to free the stacks of non-detached stillborn
 533      threads.  */
 534   bool is_detached = IS_DETACHED (pd);
 535
 536   /* Start the thread.  */
 537   err = create_thread (pd, iattr, STACK_VARIABLES_ARGS);
 538   if (err != 0)
 539     {
 540       /* Something went wrong.  Free the resources.  */
 541       if (!is_detached)
 542         {
 543         errout:
 544           __deallocate_stack (pd);
 545         }
 546       return err;
 547     }
 548
 549   return 0;
 550 }
 551 versioned_symbol (libpthread, __pthread_create_2_1, pthread_create, GLIBC_2_1);
 552
 553
 554 #if SHLIB_COMPAT(libpthread, GLIBC_2_0, GLIBC_2_1)
 555 int
 556 __pthread_create_2_0 (newthread, attr, start_routine, arg)
 557      pthread_t *newthread;
 558      const pthread_attr_t *attr;
 559      void *(*start_routine) (void *);
 560      void *arg;
 561 {
 562   /* The ATTR attribute is not really of type `pthread_attr_t *'.  It has
 563      the old size and access to the new members might crash the program.
 564      We convert the struct now.  */
 565   struct pthread_attr new_attr;
 566
 567   if (attr != NULL)
 568     {
 569       struct pthread_attr *iattr = (struct pthread_attr *) attr;
 570       size_t ps = __getpagesize ();
 571
 572       /* Copy values from the user-provided attributes.  */
 573       new_attr.schedparam = iattr->schedparam;
 574       new_attr.schedpolicy = iattr->schedpolicy;
 575       new_attr.flags = iattr->flags;
 576
 577       /* Fill in default values for the fields not present in the old
 578          implementation.  */
 579       new_attr.guardsize = ps;
 580       new_attr.stackaddr = NULL;
 581       new_attr.stacksize = 0;
 582       new_attr.cpuset = NULL;
 583
 584       /* We will pass this value on to the real implementation.  */
 585       attr = (pthread_attr_t *) &new_attr;
 586     }
 587
 588   return __pthread_create_2_1 (newthread, attr, start_routine, arg);
 589 }
 590 compat_symbol (libpthread, __pthread_create_2_0, pthread_create,
 591                GLIBC_2_0);
 592 #endif
 593 \f
 594 /* Information for libthread_db.  */
 595
 596 #include "../nptl_db/db_info.c"
 597 \f
 598 /* If pthread_create is present, libgcc_eh.a and libsupc++.a expects some other POSIX thread
 599    functions to be present as well.  */
 600 PTHREAD_STATIC_FN_REQUIRE (pthread_mutex_lock)
 601 PTHREAD_STATIC_FN_REQUIRE (pthread_mutex_trylock)
 602 PTHREAD_STATIC_FN_REQUIRE (pthread_mutex_unlock)
 603
 604 PTHREAD_STATIC_FN_REQUIRE (pthread_once)
 605 PTHREAD_STATIC_FN_REQUIRE (pthread_cancel)
 606
 607 PTHREAD_STATIC_FN_REQUIRE (pthread_key_create)
 608 PTHREAD_STATIC_FN_REQUIRE (pthread_key_delete)
 609 PTHREAD_STATIC_FN_REQUIRE (pthread_setspecific)
 610 PTHREAD_STATIC_FN_REQUIRE (pthread_getspecific)