nptl/pthread_create.c

   1 /* Copyright (C) 2002, 2003 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
  31 #include <shlib-compat.h>
  32
  33
  34 /* Local function to start thread and handle cleanup.  */
  35 static int start_thread (void *arg);
  36
  37
  38 /* Nozero if debugging mode is enabled.  */
  39 int __pthread_debug;
  40
  41 /* Globally enabled events.  */
  42 static td_thr_events_t __nptl_threads_events;
  43
  44 /* Pointer to descriptor with the last event.  */
  45 static struct pthread *__nptl_last_event;
  46
  47 /* Number of threads running.  */
  48 unsigned int __nptl_nthreads = 1;
  49
  50
  51 /* Code to allocate and deallocate a stack.  */
  52 #include "allocatestack.c"
  53
  54 /* Code to create the thread.  */
  55 #include "createthread.c"
  56
  57
  58 /* Table of the key information.  */
  59 struct pthread_key_struct __pthread_keys[PTHREAD_KEYS_MAX]
  60   __attribute__ ((nocommon));
  61 hidden_data_def (__pthread_keys)
  62
  63 /* This is for libthread_db only.  */
  64 const int __pthread_pthread_sizeof_descr = sizeof (struct pthread);
  65
  66 struct pthread *
  67 internal_function
  68 __find_in_stack_list (pd)
  69      struct pthread *pd;
  70 {
  71   list_t *entry;
  72   struct pthread *result = NULL;
  73
  74   lll_lock (stack_cache_lock);
  75
  76   list_for_each (entry, &stack_used)
  77     {
  78       struct pthread *curp;
  79
  80       curp = list_entry (entry, struct pthread, list);
  81       if (curp == pd)
  82         {
  83           result = curp;
  84           break;
  85         }
  86     }
  87
  88   if (result == NULL)
  89     list_for_each (entry, &__stack_user)
  90       {
  91         struct pthread *curp;
  92
  93         curp = list_entry (entry, struct pthread, list);
  94         if (curp == pd)
  95           {
  96             result = curp;
  97             break;
  98           }
  99       }
 100
 101   lll_unlock (stack_cache_lock);
 102
 103   return result;
 104 }
 105
 106
 107 /* Deallocate POSIX thread-local-storage.  */
 108 static void
 109 internal_function
 110 deallocate_tsd (void)
 111 {
 112   struct pthread *self = THREAD_SELF;
 113
 114   /* Maybe no data was ever allocated.  This happens often so we have
 115      a flag for this.  */
 116   if (THREAD_GETMEM (self, specific_used))
 117     {
 118       size_t round;
 119       size_t cnt;
 120
 121       round = 0;
 122       do
 123         {
 124           size_t idx;
 125
 126           /* So far no new nonzero data entry.  */
 127           THREAD_SETMEM (self, specific_used, false);
 128
 129           for (cnt = idx = 0; cnt < PTHREAD_KEY_1STLEVEL_SIZE; ++cnt)
 130             {
 131               struct pthread_key_data *level2;
 132
 133               level2 = THREAD_GETMEM_NC (self, specific, cnt);
 134
 135               if (level2 != NULL)
 136                 {
 137                   size_t inner;
 138
 139                   for (inner = 0; inner < PTHREAD_KEY_2NDLEVEL_SIZE;
 140                        ++inner, ++idx)
 141                     {
 142                       void *data = level2[inner].data;
 143
 144                       if (data != NULL)
 145                         {
 146                           /* Always clear the data.  */
 147                           level2[inner].data = NULL;
 148
 149                           /* Make sure the data corresponds to a valid
 150                              key.  This test fails if the key was
 151                              deallocated and also if it was
 152                              re-allocated.  It is the user's
 153                              responsibility to free the memory in this
 154                              case.  */
 155                           if (level2[inner].seq
 156                               == __pthread_keys[idx].seq
 157                               /* It is not necessary to register a destructor
 158                                  function.  */
 159                               && __pthread_keys[idx].destr != NULL)
 160                             /* Call the user-provided destructor.  */
 161                             __pthread_keys[idx].destr (data);
 162                         }
 163                     }
 164                 }
 165               else
 166                 idx += PTHREAD_KEY_1STLEVEL_SIZE;
 167             }
 168
 169           if (THREAD_GETMEM (self, specific_used) == 0)
 170             /* No data has been modified.  */
 171             goto just_free;
 172         }
 173       /* We only repeat the process a fixed number of times.  */
 174       while (__builtin_expect (++round < PTHREAD_DESTRUCTOR_ITERATIONS, 0));
 175
 176       /* Just clear the memory of the first block for reuse.  */
 177       memset (&THREAD_SELF->specific_1stblock, '\0',
 178               sizeof (self->specific_1stblock));
 179
 180     just_free:
 181       /* Free the memory for the other blocks.  */
 182       for (cnt = 1; cnt < PTHREAD_KEY_1STLEVEL_SIZE; ++cnt)
 183         {
 184           struct pthread_key_data *level2;
 185
 186           level2 = THREAD_GETMEM_NC (self, specific, cnt);
 187           if (level2 != NULL)
 188             {
 189               /* The first block is allocated as part of the thread
 190                  descriptor.  */
 191               free (level2);
 192               THREAD_SETMEM_NC (self, specific, cnt, NULL);
 193             }
 194         }
 195
 196       THREAD_SETMEM (self, specific_used, false);
 197     }
 198 }
 199
 200
 201 /* Deallocate a thread's stack after optionally making sure the thread
 202    descriptor is still valid.  */
 203 void
 204 internal_function
 205 __free_tcb (struct pthread *pd)
 206 {
 207   /* The thread is exiting now.  */
 208   if (__builtin_expect (atomic_bit_test_set (&pd->cancelhandling,
 209                                              TERMINATED_BIT) == 0, 1))
 210     {
 211       /* Remove the descriptor from the list.  */
 212       if (DEBUGGING_P && __find_in_stack_list (pd) == NULL)
 213         /* Something is really wrong.  The descriptor for a still
 214            running thread is gone.  */
 215         abort ();
 216
 217       /* Queue the stack memory block for reuse and exit the process.  The
 218          kernel will signal via writing to the address returned by
 219          QUEUE-STACK when the stack is available.  */
 220       __deallocate_stack (pd);
 221     }
 222 }
 223
 224
 225 static int
 226 start_thread (void *arg)
 227 {
 228   /* One more thread.  */
 229   atomic_increment (&__nptl_nthreads);
 230
 231   struct pthread *pd = (struct pthread *) arg;
 232
 233 #ifndef __ASSUME_CLONE_STOPPED
 234   /* Get the lock the parent locked to force synchronization.  */
 235   lll_lock (pd->lock);
 236   /* And give it up right away.  */
 237   lll_unlock (pd->lock);
 238 #endif
 239
 240 #if HP_TIMING_AVAIL
 241   /* Remember the time when the thread was started.  */
 242   hp_timing_t now;
 243   HP_TIMING_NOW (now);
 244   THREAD_SETMEM (pd, cpuclock_offset, now);
 245 #endif
 246
 247   /* Initialize resolver state pointer.  */
 248   __resp = &pd->res;
 249
 250   /* This is where the try/finally block should be created.  For
 251      compilers without that support we do use setjmp.  */
 252   struct pthread_unwind_buf unwind_buf;
 253
 254   /* No previous handlers.  */
 255   unwind_buf.priv.data.prev = NULL;
 256   unwind_buf.priv.data.cleanup = NULL;
 257
 258   int not_first_call;
 259   not_first_call = setjmp ((struct __jmp_buf_tag *) unwind_buf.cancel_jmp_buf);
 260   if (__builtin_expect (! not_first_call, 1))
 261     {
 262       /* Store the new cleanup handler info.  */
 263       THREAD_SETMEM (pd, cleanup_jmp_buf, &unwind_buf);
 264
 265       /* Run the code the user provided.  */
 266 #ifdef CALL_THREAD_FCT
 267       THREAD_SETMEM (pd, result, CALL_THREAD_FCT (pd));
 268 #else
 269       THREAD_SETMEM (pd, result, pd->start_routine (pd->arg));
 270 #endif
 271     }
 272
 273   /* Run the destructor for the thread-local data.  */
 274   deallocate_tsd ();
 275
 276   /* Clean up any state libc stored in thread-local variables.  */
 277   __libc_thread_freeres ();
 278
 279   /* If this is the last thread we terminate the process now.  We
 280      do not notify the debugger, it might just irritate it if there
 281      is no thread left.  */
 282   if (__builtin_expect (atomic_decrement_and_test (&__nptl_nthreads), 0))
 283     /* This was the last thread.  */
 284     exit (0);
 285
 286   /* Report the death of the thread if this is wanted.  */
 287   if (__builtin_expect (pd->report_events, 0))
 288     {
 289       /* See whether TD_DEATH is in any of the mask.  */
 290       const int idx = __td_eventword (TD_DEATH);
 291       const uint32_t mask = __td_eventmask (TD_DEATH);
 292
 293       if ((mask & (__nptl_threads_events.event_bits[idx]
 294                    | pd->eventbuf.eventmask.event_bits[idx])) != 0)
 295         {
 296           /* Yep, we have to signal the death.  Add the descriptor to
 297              the list but only if it is not already on it.  */
 298           if (pd->nextevent == NULL)
 299             {
 300               pd->eventbuf.eventnum = TD_DEATH;
 301               pd->eventbuf.eventdata = pd;
 302
 303               do
 304                 pd->nextevent = __nptl_last_event;
 305               while (atomic_compare_and_exchange_bool_acq (&__nptl_last_event,
 306                                                            pd, pd->nextevent));
 307             }
 308
 309           /* Now call the function to signal the event.  */
 310           __nptl_death_event ();
 311         }
 312     }
 313
 314   /* The thread is exiting now.  Don't set this bit until after we've hit
 315      the event-reporting breakpoint, so that td_thr_get_info on us while at
 316      the breakpoint reports TD_THR_RUN state rather than TD_THR_ZOMBIE.  */
 317   atomic_bit_set (&pd->cancelhandling, EXITING_BIT);
 318
 319   /* If the thread is detached free the TCB.  */
 320   if (IS_DETACHED (pd))
 321     /* Free the TCB.  */
 322     __free_tcb (pd);
 323
 324   /* We cannot call '_exit' here.  '_exit' will terminate the process.
 325
 326      The 'exit' implementation in the kernel will signal when the
 327      process is really dead since 'clone' got passed the CLONE_CLEARTID
 328      flag.  The 'tid' field in the TCB will be set to zero.
 329
 330      The exit code is zero since in case all threads exit by calling
 331      'pthread_exit' the exit status must be 0 (zero).  */
 332   __exit_thread_inline (0);
 333
 334   /* NOTREACHED */
 335   return 0;
 336 }
 337
 338
 339 /* Default thread attributes for the case when the user does not
 340    provide any.  */
 341 static const struct pthread_attr default_attr =
 342   {
 343     /* Just some value > 0 which gets rounded to the nearest page size.  */
 344     .guardsize = 1,
 345   };
 346
 347
 348 int
 349 __pthread_create_2_1 (newthread, attr, start_routine, arg)
 350      pthread_t *newthread;
 351      const pthread_attr_t *attr;
 352      void *(*start_routine) (void *);
 353      void *arg;
 354 {
 355   STACK_VARIABLES;
 356   const struct pthread_attr *iattr;
 357   struct pthread *pd;
 358   int err;
 359
 360   iattr = (struct pthread_attr *) attr;
 361   if (iattr == NULL)
 362     /* Is this the best idea?  On NUMA machines this could mean
 363        accessing far-away memory.  */
 364     iattr = &default_attr;
 365
 366   err = ALLOCATE_STACK (iattr, &pd);
 367   if (__builtin_expect (err != 0, 0))
 368     /* Something went wrong.  Maybe a parameter of the attributes is
 369        invalid or we could not allocate memory.  */
 370     return err;
 371
 372
 373   /* Initialize the TCB.  All initializations with zero should be
 374      performed in 'get_cached_stack'.  This way we avoid doing this if
 375      the stack freshly allocated with 'mmap'.  */
 376
 377 #ifdef TLS_TCB_AT_TP
 378   /* Reference to the TCB itself.  */
 379   pd->header.self = pd;
 380
 381   /* Self-reference for TLS.  */
 382   pd->header.tcb = pd;
 383 #endif
 384
 385   /* Store the address of the start routine and the parameter.  Since
 386      we do not start the function directly the stillborn thread will
 387      get the information from its thread descriptor.  */
 388   pd->start_routine = start_routine;
 389   pd->arg = arg;
 390
 391   /* Copy the thread attribute flags.  */
 392   pd->flags = iattr->flags;
 393
 394   /* Initialize the field for the ID of the thread which is waiting
 395      for us.  This is a self-reference in case the thread is created
 396      detached.  */
 397   pd->joinid = iattr->flags & ATTR_FLAG_DETACHSTATE ? pd : NULL;
 398
 399   /* The debug events are inherited from the parent.  */
 400   pd->eventbuf = THREAD_SELF->eventbuf;
 401
 402
 403   /* Determine scheduling parameters for the thread.
 404      XXX How to determine whether scheduling handling is needed?  */
 405   if (0 && attr != NULL)
 406     {
 407       if (iattr->flags & ATTR_FLAG_NOTINHERITSCHED)
 408         {
 409           /* Use the scheduling parameters the user provided.  */
 410           pd->schedpolicy = iattr->schedpolicy;
 411           memcpy (&pd->schedparam, &iattr->schedparam,
 412                   sizeof (struct sched_param));
 413         }
 414       else
 415         {
 416           /* Just store the scheduling attributes of the parent.  */
 417           pd->schedpolicy = __sched_getscheduler (0);
 418           __sched_getparam (0, &pd->schedparam);
 419         }
 420     }
 421
 422   /* Pass the descriptor to the caller.  */
 423   *newthread = (pthread_t) pd;
 424
 425   /* Start the thread.  */
 426   err = create_thread (pd, iattr, STACK_VARIABLES_ARGS);
 427   if (err != 0)
 428     {
 429       /* Something went wrong.  Free the resources.  */
 430       __deallocate_stack (pd);
 431       return err;
 432     }
 433
 434   return 0;
 435 }
 436 versioned_symbol (libpthread, __pthread_create_2_1, pthread_create, GLIBC_2_1);
 437
 438
 439 #if SHLIB_COMPAT(libpthread, GLIBC_2_0, GLIBC_2_1)
 440 int
 441 __pthread_create_2_0 (newthread, attr, start_routine, arg)
 442      pthread_t *newthread;
 443      const pthread_attr_t *attr;
 444      void *(*start_routine) (void *);
 445      void *arg;
 446 {
 447   /* The ATTR attribute is not really of type `pthread_attr_t *'.  It has
 448      the old size and access to the new members might crash the program.
 449      We convert the struct now.  */
 450   struct pthread_attr new_attr;
 451
 452   if (attr != NULL)
 453     {
 454       struct pthread_attr *iattr = (struct pthread_attr *) attr;
 455       size_t ps = __getpagesize ();
 456
 457       /* Copy values from the user-provided attributes.  */
 458       new_attr.schedparam = iattr->schedparam;
 459       new_attr.schedpolicy = iattr->schedpolicy;
 460       new_attr.flags = iattr->flags;
 461
 462       /* Fill in default values for the fields not present in the old
 463          implementation.  */
 464       new_attr.guardsize = ps;
 465       new_attr.stackaddr = NULL;
 466       new_attr.stacksize = 0;
 467
 468       /* We will pass this value on to the real implementation.  */
 469       attr = (pthread_attr_t *) &new_attr;
 470     }
 471
 472   return __pthread_create_2_1 (newthread, attr, start_routine, arg);
 473 }
 474 compat_symbol (libpthread, __pthread_create_2_0, pthread_create,
 475                GLIBC_2_0);
 476 #endif