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[glibc.git] / nptl / pthread_key_create.c
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1 /* Copyright (C) 2002-2015 Free Software Foundation, Inc.
2 This file is part of the GNU C Library.
3 Contributed by Ulrich Drepper <drepper@redhat.com>, 2002.
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.
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.
15 You should have received a copy of the GNU Lesser General Public
16 License along with the GNU C Library; if not, see
17 <http://www.gnu.org/licenses/>. */
19 #include <errno.h>
20 #include "pthreadP.h"
21 #include <atomic.h>
24 int
25 __pthread_key_create (key, destr)
26 pthread_key_t *key;
27 void (*destr) (void *);
29 /* Find a slot in __pthread_kyes which is unused. */
30 for (size_t cnt = 0; cnt < PTHREAD_KEYS_MAX; ++cnt)
32 uintptr_t seq = __pthread_keys[cnt].seq;
34 if (KEY_UNUSED (seq) && KEY_USABLE (seq)
35 /* We found an unused slot. Try to allocate it. */
36 && ! atomic_compare_and_exchange_bool_acq (&__pthread_keys[cnt].seq,
37 seq + 1, seq))
39 /* Remember the destructor. */
40 __pthread_keys[cnt].destr = destr;
42 /* Return the key to the caller. */
43 *key = cnt;
45 /* The call succeeded. */
46 return 0;
50 return EAGAIN;
52 strong_alias (__pthread_key_create, pthread_key_create)
53 hidden_def (__pthread_key_create)