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 *      59 Temple Place - Suite 330, Boston, MA 02111-1307, USA
35 */
36
37#include "pthread.h"
38#include "implement.h"
39
40
41INLINE int
42ptw32_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