1 /*
2 * pthread_spin_unlock.c
3 *
4 * Description:
5 * This translation unit implements spin lock primitives.
6 *
7 * --------------------------------------------------------------------------
8 *
9 * Pthreads-embedded (PTE) - POSIX Threads Library for embedded systems
10 * Copyright(C) 2008 Jason Schmidlapp
11 *
12 * Contact Email: jschmidlapp@users.sourceforge.net
13 *
14 *
15 * Based upon Pthreads-win32 - POSIX Threads Library for Win32
16 * Copyright(C) 1998 John E. Bossom
17 * Copyright(C) 1999,2005 Pthreads-win32 contributors
18 *
19 * Contact Email: rpj@callisto.canberra.edu.au
20 *
21 * The original list of contributors to the Pthreads-win32 project
22 * is contained in the file CONTRIBUTORS.ptw32 included with the
23 * source code distribution. The list can also be seen at the
24 * following World Wide Web location:
25 * http://sources.redhat.com/pthreads-win32/contributors.html
26 *
27 * This library is free software; you can redistribute it and/or
28 * modify it under the terms of the GNU Lesser General Public
29 * License as published by the Free Software Foundation; either
30 * version 2 of the License, or (at your option) any later version.
31 *
32 * This library is distributed in the hope that it will be useful,
33 * but WITHOUT ANY WARRANTY; without even the implied warranty of
34 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
35 * Lesser General Public License for more details.
36 *
37 * You should have received a copy of the GNU Lesser General Public
38 * License along with this library in the file COPYING.LIB;
39 * if not, write to the Free Software Foundation, Inc.,
40 * 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA
41 */
42
43 #include "pthread.h"
44 #include "implement.h"
45
46
47 int
pthread_spin_unlock(pthread_spinlock_t * lock)48 pthread_spin_unlock (pthread_spinlock_t * lock)
49 {
50 register pthread_spinlock_t s;
51
52 if (NULL == lock || NULL == *lock)
53 {
54 return (EINVAL);
55 }
56
57 s = *lock;
58
59 if (s == PTHREAD_SPINLOCK_INITIALIZER)
60 {
61 return EPERM;
62 }
63
64 switch ((long)
65 PTE_ATOMIC_COMPARE_EXCHANGE (&(s->interlock),
66 PTE_SPIN_UNLOCKED,
67 PTE_SPIN_LOCKED))
68 {
69 case PTE_SPIN_LOCKED:
70 return 0;
71 case PTE_SPIN_UNLOCKED:
72 return EPERM;
73 case PTE_SPIN_USE_MUTEX:
74 return pthread_mutex_unlock (&(s->u.mutex));
75 }
76
77 return EINVAL;
78 }
79