1 /*
2 * ptw32_spinlock_check_need_init.c
3 *
4 * Description:
5 * This translation unit implements spin 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 "pthread.h"
38 #include "implement.h"
39
40
41 INLINE int
ptw32_spinlock_check_need_init(pthread_spinlock_t * lock)42 ptw32_spinlock_check_need_init (pthread_spinlock_t * lock)
43 {
44 int result = 0;
45 ptw32_mcs_local_node_t node;
46
47 /*
48 * The following guarded test is specifically for statically
49 * initialised spinlocks (via PTHREAD_SPINLOCK_INITIALIZER).
50 */
51 ptw32_mcs_lock_acquire(&ptw32_spinlock_test_init_lock, &node);
52
53 /*
54 * We got here possibly under race
55 * conditions. Check again inside the critical section
56 * and only initialise if the spinlock is valid (not been destroyed).
57 * If a static spinlock has been destroyed, the application can
58 * re-initialise it only by calling pthread_spin_init()
59 * explicitly.
60 */
61 if (*lock == PTHREAD_SPINLOCK_INITIALIZER)
62 {
63 result = pthread_spin_init (lock, PTHREAD_PROCESS_PRIVATE);
64 }
65 else if (*lock == NULL)
66 {
67 /*
68 * The spinlock has been destroyed while we were waiting to
69 * initialise it, so the operation that caused the
70 * auto-initialisation should fail.
71 */
72 result = EINVAL;
73 }
74
75 ptw32_mcs_lock_release(&node);
76
77 return (result);
78 }
79