1/*
2 * pthread_spin_destroy.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
41int
42pthread_spin_destroy (pthread_spinlock_t * lock)
43{
44  register pthread_spinlock_t s;
45  int result = 0;
46
47  if (lock == NULL || *lock == NULL)
48    {
49      return EINVAL;
50    }
51
52  if ((s = *lock) != PTHREAD_SPINLOCK_INITIALIZER)
53    {
54      if (s->interlock == PTW32_SPIN_USE_MUTEX)
55	{
56	  result = pthread_mutex_destroy (&(s->u.mutex));
57	}
58      else if ((PTW32_INTERLOCKED_LONG) PTW32_SPIN_UNLOCKED !=
59	       PTW32_INTERLOCKED_COMPARE_EXCHANGE_LONG ((PTW32_INTERLOCKED_LONGPTR) &s->interlock,
60						   (PTW32_INTERLOCKED_LONG) PTW32_SPIN_INVALID,
61						   (PTW32_INTERLOCKED_LONG) PTW32_SPIN_UNLOCKED))
62	{
63	  result = EINVAL;
64	}
65
66      if (0 == result)
67	{
68	  /*
69	   * We are relying on the application to ensure that all other threads
70	   * have finished with the spinlock before destroying it.
71	   */
72	  *lock = NULL;
73	  (void) free (s);
74	}
75    }
76  else
77    {
78      /*
79       * See notes in ptw32_spinlock_check_need_init() above also.
80       */
81      ptw32_mcs_local_node_t node;
82
83      ptw32_mcs_lock_acquire(&ptw32_spinlock_test_init_lock, &node);
84
85      /*
86       * Check again.
87       */
88      if (*lock == PTHREAD_SPINLOCK_INITIALIZER)
89	{
90	  /*
91	   * This is all we need to do to destroy a statically
92	   * initialised spinlock that has not yet been used (initialised).
93	   * If we get to here, another thread
94	   * waiting to initialise this mutex will get an EINVAL.
95	   */
96	  *lock = NULL;
97	}
98      else
99	{
100	  /*
101	   * The spinlock has been initialised while we were waiting
102	   * so assume it's in use.
103	   */
104	  result = EBUSY;
105	}
106
107       ptw32_mcs_lock_release(&node);
108    }
109
110  return (result);
111}
112