nptl/pthread_key_create.c

   1 /* Copyright (C) 2002, 2003, 2006 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 "pthreadP.h"
  22 #include <atomic.h>
  23
  24
  25 int
  26 __pthread_key_create (key, destr)
  27      pthread_key_t *key;
  28      void (*destr) (void *);
  29 {
  30   /* Find a slot in __pthread_kyes which is unused.  */
  31   for (size_t cnt = 0; cnt < PTHREAD_KEYS_MAX; ++cnt)
  32     {
  33       uintptr_t seq = __pthread_keys[cnt].seq;
  34
  35       if (KEY_UNUSED (seq) && KEY_USABLE (seq)
  36           /* We found an unused slot.  Try to allocate it.  */
  37           && ! atomic_compare_and_exchange_bool_acq (&__pthread_keys[cnt].seq,
  38                                                      seq + 1, seq))
  39         {
  40           /* Remember the destructor.  */
  41           __pthread_keys[cnt].destr = destr;
  42
  43           /* Return the key to the caller.  */
  44           *key = cnt;
  45
  46           /* The call succeeded.  */
  47           return 0;
  48         }
  49     }
  50
  51   return EAGAIN;
  52 }
  53 strong_alias (__pthread_key_create, pthread_key_create)
  54 strong_alias (__pthread_key_create, __pthread_key_create_internal)