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   /* Mark the memory of the stack as usable to the kernel.  We free
 381      everything except for the space used for the TCB itself.  */
 382   size_t pagesize_m1 = __getpagesize () - 1;
 383 #ifdef _STACK_GROWS_DOWN
 384   char *sp = CURRENT_STACK_FRAME;
 385   size_t freesize = (sp - (char *) pd->stackblock) & ~pagesize_m1;
 386 #else
 387 # error "to do"
 388 #endif
 389   assert (freesize < pd->stackblock_size);
 390   if (freesize > PTHREAD_STACK_MIN)
 391     madvise (pd->stackblock, freesize - PTHREAD_STACK_MIN, MADV_DONTNEED);
 392
 393   /* If the thread is detached free the TCB.  */
 394   if (IS_DETACHED (pd))
 395     /* Free the TCB.  */
 396     __free_tcb (pd);
 397   else if (__builtin_expect (pd->cancelhandling & SETXID_BITMASK, 0))
 398     {
 399       /* Some other thread might call any of the setXid functions and expect
 400          us to reply.  In this case wait until we did that.  */
 401       do
 402         lll_futex_wait (&pd->setxid_futex, 0, LLL_PRIVATE);
 403       while (pd->cancelhandling & SETXID_BITMASK);
 404
 405       /* Reset the value so that the stack can be reused.  */
 406       pd->setxid_futex = 0;
 407     }
 408
 409   /* We cannot call '_exit' here.  '_exit' will terminate the process.
 410
 411      The 'exit' implementation in the kernel will signal when the
 412      process is really dead since 'clone' got passed the CLONE_CLEARTID
 413      flag.  The 'tid' field in the TCB will be set to zero.
 414
 415      The exit code is zero since in case all threads exit by calling
 416      'pthread_exit' the exit status must be 0 (zero).  */
 417   __exit_thread_inline (0);
 418
 419   /* NOTREACHED */
 420   return 0;
 421 }
 422
 423
 424 /* Default thread attributes for the case when the user does not
 425    provide any.  */
 426 static const struct pthread_attr default_attr =
 427   {
 428     /* Just some value > 0 which gets rounded to the nearest page size.  */
 429     .guardsize = 1,
 430   };
 431
 432
 433 int
 434 __pthread_create_2_1 (newthread, attr, start_routine, arg)
 435      pthread_t *newthread;
 436      const pthread_attr_t *attr;
 437      void *(*start_routine) (void *);
 438      void *arg;
 439 {
 440   STACK_VARIABLES;
 441
 442   const struct pthread_attr *iattr = (struct pthread_attr *) attr;
 443   if (iattr == NULL)
 444     /* Is this the best idea?  On NUMA machines this could mean
 445        accessing far-away memory.  */
 446     iattr = &default_attr;
 447
 448   struct pthread *pd = NULL;
 449   int err = ALLOCATE_STACK (iattr, &pd);
 450   if (__builtin_expect (err != 0, 0))
 451     /* Something went wrong.  Maybe a parameter of the attributes is
 452        invalid or we could not allocate memory.  */
 453     return err;
 454
 455
 456   /* Initialize the TCB.  All initializations with zero should be
 457      performed in 'get_cached_stack'.  This way we avoid doing this if
 458      the stack freshly allocated with 'mmap'.  */
 459
 460 #ifdef TLS_TCB_AT_TP
 461   /* Reference to the TCB itself.  */
 462   pd->header.self = pd;
 463
 464   /* Self-reference for TLS.  */
 465   pd->header.tcb = pd;
 466 #endif
 467
 468   /* Store the address of the start routine and the parameter.  Since
 469      we do not start the function directly the stillborn thread will
 470      get the information from its thread descriptor.  */
 471   pd->start_routine = start_routine;
 472   pd->arg = arg;
 473
 474   /* Copy the thread attribute flags.  */
 475   struct pthread *self = THREAD_SELF;
 476   pd->flags = ((iattr->flags & ~(ATTR_FLAG_SCHED_SET | ATTR_FLAG_POLICY_SET))
 477                | (self->flags & (ATTR_FLAG_SCHED_SET | ATTR_FLAG_POLICY_SET)));
 478
 479   /* Initialize the field for the ID of the thread which is waiting
 480      for us.  This is a self-reference in case the thread is created
 481      detached.  */
 482   pd->joinid = iattr->flags & ATTR_FLAG_DETACHSTATE ? pd : NULL;
 483
 484   /* The debug events are inherited from the parent.  */
 485   pd->eventbuf = self->eventbuf;
 486
 487
 488   /* Copy the parent's scheduling parameters.  The flags will say what
 489      is valid and what is not.  */
 490   pd->schedpolicy = self->schedpolicy;
 491   pd->schedparam = self->schedparam;
 492
 493   /* Copy the stack guard canary.  */
 494 #ifdef THREAD_COPY_STACK_GUARD
 495   THREAD_COPY_STACK_GUARD (pd);
 496 #endif
 497
 498   /* Copy the pointer guard value.  */
 499 #ifdef THREAD_COPY_POINTER_GUARD
 500   THREAD_COPY_POINTER_GUARD (pd);
 501 #endif
 502
 503   /* Determine scheduling parameters for the thread.  */
 504   if (attr != NULL
 505       && __builtin_expect ((iattr->flags & ATTR_FLAG_NOTINHERITSCHED) != 0, 0)
 506       && (iattr->flags & (ATTR_FLAG_SCHED_SET | ATTR_FLAG_POLICY_SET)) != 0)
 507     {
 508       INTERNAL_SYSCALL_DECL (scerr);
 509
 510       /* Use the scheduling parameters the user provided.  */
 511       if (iattr->flags & ATTR_FLAG_POLICY_SET)
 512         pd->schedpolicy = iattr->schedpolicy;
 513       else if ((pd->flags & ATTR_FLAG_POLICY_SET) == 0)
 514         {
 515           pd->schedpolicy = INTERNAL_SYSCALL (sched_getscheduler, scerr, 1, 0);
 516           pd->flags |= ATTR_FLAG_POLICY_SET;
 517         }
 518
 519       if (iattr->flags & ATTR_FLAG_SCHED_SET)
 520         memcpy (&pd->schedparam, &iattr->schedparam,
 521                 sizeof (struct sched_param));
 522       else if ((pd->flags & ATTR_FLAG_SCHED_SET) == 0)
 523         {
 524           INTERNAL_SYSCALL (sched_getparam, scerr, 2, 0, &pd->schedparam);
 525           pd->flags |= ATTR_FLAG_SCHED_SET;
 526         }
 527
 528       /* Check for valid priorities.  */
 529       int minprio = INTERNAL_SYSCALL (sched_get_priority_min, scerr, 1,
 530                                       iattr->schedpolicy);
 531       int maxprio = INTERNAL_SYSCALL (sched_get_priority_max, scerr, 1,
 532                                       iattr->schedpolicy);
 533       if (pd->schedparam.sched_priority < minprio
 534           || pd->schedparam.sched_priority > maxprio)
 535         {
 536           err = EINVAL;
 537           goto errout;
 538         }
 539     }
 540
 541   /* Pass the descriptor to the caller.  */
 542   *newthread = (pthread_t) pd;
 543
 544   /* Remember whether the thread is detached or not.  In case of an
 545      error we have to free the stacks of non-detached stillborn
 546      threads.  */
 547   bool is_detached = IS_DETACHED (pd);
 548
 549   /* Start the thread.  */
 550   err = create_thread (pd, iattr, STACK_VARIABLES_ARGS);
 551   if (err != 0)
 552     {
 553       /* Something went wrong.  Free the resources.  */
 554       if (!is_detached)
 555         {
 556         errout:
 557           __deallocate_stack (pd);
 558         }
 559       return err;
 560     }
 561
 562   return 0;
 563 }
 564 versioned_symbol (libpthread, __pthread_create_2_1, pthread_create, GLIBC_2_1);
 565
 566
 567 #if SHLIB_COMPAT(libpthread, GLIBC_2_0, GLIBC_2_1)
 568 int
 569 __pthread_create_2_0 (newthread, attr, start_routine, arg)
 570      pthread_t *newthread;
 571      const pthread_attr_t *attr;
 572      void *(*start_routine) (void *);
 573      void *arg;
 574 {
 575   /* The ATTR attribute is not really of type `pthread_attr_t *'.  It has
 576      the old size and access to the new members might crash the program.
 577      We convert the struct now.  */
 578   struct pthread_attr new_attr;
 579
 580   if (attr != NULL)
 581     {
 582       struct pthread_attr *iattr = (struct pthread_attr *) attr;
 583       size_t ps = __getpagesize ();
 584
 585       /* Copy values from the user-provided attributes.  */
 586       new_attr.schedparam = iattr->schedparam;
 587       new_attr.schedpolicy = iattr->schedpolicy;
 588       new_attr.flags = iattr->flags;
 589
 590       /* Fill in default values for the fields not present in the old
 591          implementation.  */
 592       new_attr.guardsize = ps;
 593       new_attr.stackaddr = NULL;
 594       new_attr.stacksize = 0;
 595       new_attr.cpuset = NULL;
 596
 597       /* We will pass this value on to the real implementation.  */
 598       attr = (pthread_attr_t *) &new_attr;
 599     }
 600
 601   return __pthread_create_2_1 (newthread, attr, start_routine, arg);
 602 }
 603 compat_symbol (libpthread, __pthread_create_2_0, pthread_create,
 604                GLIBC_2_0);
 605 #endif
 606 \f
 607 /* Information for libthread_db.  */
 608
 609 #include "../nptl_db/db_info.c"
 610 \f
 611 /* If pthread_create is present, libgcc_eh.a and libsupc++.a expects some other POSIX thread
 612    functions to be present as well.  */
 613 PTHREAD_STATIC_FN_REQUIRE (pthread_mutex_lock)
 614 PTHREAD_STATIC_FN_REQUIRE (pthread_mutex_trylock)
 615 PTHREAD_STATIC_FN_REQUIRE (pthread_mutex_unlock)
 616
 617 PTHREAD_STATIC_FN_REQUIRE (pthread_once)
 618 PTHREAD_STATIC_FN_REQUIRE (pthread_cancel)
 619
 620 PTHREAD_STATIC_FN_REQUIRE (pthread_key_create)
 621 PTHREAD_STATIC_FN_REQUIRE (pthread_key_delete)
 622 PTHREAD_STATIC_FN_REQUIRE (pthread_setspecific)
 623 PTHREAD_STATIC_FN_REQUIRE (pthread_getspecific)