1 /*
2 * pthread_rwlock_destroy.c
3 *
4 * Description:
5 * This translation unit implements read/write lock primitives.
6 *
7 * --------------------------------------------------------------------------
8 *
9 * Pthreads-win32 - POSIX Threads Library for Win32
10 * Copyright(C) 1998 John E. Bossom
11 * Copyright(C) 1999,2005 Pthreads-win32 contributors
12 *
13 * Contact Email: rpj@callisto.canberra.edu.au
14 *
15 * The current list of contributors is contained
16 * in the file CONTRIBUTORS included with the source
17 * code distribution. The list can also be seen at the
18 * following World Wide Web location:
19 * http://sources.redhat.com/pthreads-win32/contributors.html
20 *
21 * This library is free software; you can redistribute it and/or
22 * modify it under the terms of the GNU Lesser General Public
23 * License as published by the Free Software Foundation; either
24 * version 2 of the License, or (at your option) any later version.
25 *
26 * This library is distributed in the hope that it will be useful,
27 * but WITHOUT ANY WARRANTY; without even the implied warranty of
28 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
29 * Lesser General Public License for more details.
30 *
31 * You should have received a copy of the GNU Lesser General Public
32 * License along with this library in the file COPYING.LIB;
33 * if not, write to the Free Software Foundation, Inc.,
34 * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA
35 */
36
37 #include <limits.h>
38
39 #include "pthread.h"
40 #include "implement.h"
41
42 int
pthread_rwlock_destroy(pthread_rwlock_t * rwlock)43 pthread_rwlock_destroy (pthread_rwlock_t * rwlock)
44 {
45 pthread_rwlock_t rwl;
46 int result = 0, result1 = 0, result2 = 0;
47
48 if (rwlock == NULL || *rwlock == NULL)
49 {
50 return EINVAL;
51 }
52
53 if (*rwlock != PTHREAD_RWLOCK_INITIALIZER)
54 {
55 rwl = *rwlock;
56
57 if (rwl->nMagic != PTW32_RWLOCK_MAGIC)
58 {
59 return EINVAL;
60 }
61
62 if ((result = pthread_mutex_lock (&(rwl->mtxExclusiveAccess))) != 0)
63 {
64 return result;
65 }
66
67 if ((result =
68 pthread_mutex_lock (&(rwl->mtxSharedAccessCompleted))) != 0)
69 {
70 (void) pthread_mutex_unlock (&(rwl->mtxExclusiveAccess));
71 return result;
72 }
73
74 /*
75 * Check whether any threads own/wait for the lock (wait for ex.access);
76 * report "BUSY" if so.
77 */
78 if (rwl->nExclusiveAccessCount > 0
79 || rwl->nSharedAccessCount > rwl->nCompletedSharedAccessCount)
80 {
81 result = pthread_mutex_unlock (&(rwl->mtxSharedAccessCompleted));
82 result1 = pthread_mutex_unlock (&(rwl->mtxExclusiveAccess));
83 result2 = EBUSY;
84 }
85 else
86 {
87 rwl->nMagic = 0;
88
89 if ((result =
90 pthread_mutex_unlock (&(rwl->mtxSharedAccessCompleted))) != 0)
91 {
92 pthread_mutex_unlock (&rwl->mtxExclusiveAccess);
93 return result;
94 }
95
96 if ((result =
97 pthread_mutex_unlock (&(rwl->mtxExclusiveAccess))) != 0)
98 {
99 return result;
100 }
101
102 *rwlock = NULL; /* Invalidate rwlock before anything else */
103 result = pthread_cond_destroy (&(rwl->cndSharedAccessCompleted));
104 result1 = pthread_mutex_destroy (&(rwl->mtxSharedAccessCompleted));
105 result2 = pthread_mutex_destroy (&(rwl->mtxExclusiveAccess));
106 (void) free (rwl);
107 }
108 }
109 else
110 {
111 ptw32_mcs_local_node_t node;
112 /*
113 * See notes in ptw32_rwlock_check_need_init() above also.
114 */
115 ptw32_mcs_lock_acquire(&ptw32_rwlock_test_init_lock, &node);
116
117 /*
118 * Check again.
119 */
120 if (*rwlock == PTHREAD_RWLOCK_INITIALIZER)
121 {
122 /*
123 * This is all we need to do to destroy a statically
124 * initialised rwlock that has not yet been used (initialised).
125 * If we get to here, another thread
126 * waiting to initialise this rwlock will get an EINVAL.
127 */
128 *rwlock = NULL;
129 }
130 else
131 {
132 /*
133 * The rwlock has been initialised while we were waiting
134 * so assume it's in use.
135 */
136 result = EBUSY;
137 }
138
139 ptw32_mcs_lock_release(&node);
140 }
141
142 return ((result != 0) ? result : ((result1 != 0) ? result1 : result2));
143 }
144