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