1/*
2 * pthread_mutex_consistent.c
3 *
4 * Description:
5 * This translation unit implements mutual exclusion (mutex) 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/*
38 * From the Sun Multi-threaded Programming Guide
39 *
40 * robustness defines the behavior when the owner of the mutex terminates without unlocking the
41 * mutex, usually because its process terminated abnormally. The value of robustness that is
42 * defined in pthread.h is PTHREAD_MUTEX_ROBUST or PTHREAD_MUTEX_STALLED. The
43 * default value is PTHREAD_MUTEX_STALLED .
44 * ■ PTHREAD_MUTEX_STALLED
45 * When the owner of the mutex terminates without unlocking the mutex, all subsequent calls
46 * to pthread_mutex_lock() are blocked from progress in an unspecified manner.
47 * ■ PTHREAD_MUTEX_ROBUST
48 * When the owner of the mutex terminates without unlocking the mutex, the mutex is
49 * unlocked. The next owner of this mutex acquires the mutex with an error return of
50 * EOWNERDEAD.
51 * Note – Your application must always check the return code from pthread_mutex_lock() for
52 * a mutex initialized with the PTHREAD_MUTEX_ROBUST attribute.
53 * ■ The new owner of this mutex should make the state protected by the mutex consistent.
54 * This state might have been left inconsistent when the previous owner terminated.
55 * ■ If the new owner is able to make the state consistent, call
56 * pthread_mutex_consistent() for the mutex before unlocking the mutex. This
57 * marks the mutex as consistent and subsequent calls to pthread_mutex_lock() and
58 * pthread_mutex_unlock() will behave in the normal manner.
59 * ■ If the new owner is not able to make the state consistent, do not call
60 * pthread_mutex_consistent() for the mutex, but unlock the mutex.
61 * All waiters are woken up and all subsequent calls to pthread_mutex_lock() fail to
62 * acquire the mutex. The return code is ENOTRECOVERABLE. The mutex can be made
63 * consistent by calling pthread_mutex_destroy() to uninitialize the mutex, and calling
64 * pthread_mutex_int() to reinitialize the mutex.However, the state that was protected
65 * by the mutex remains inconsistent and some form of application recovery is required.
66 * ■ If the thread that acquires the lock with EOWNERDEAD terminates without unlocking the
67 * mutex, the next owner acquires the lock with an EOWNERDEAD return code.
68 */
69#if !defined(_UWIN)
70/*#   include <process.h> */
71#endif
72#include "pthread.h"
73#include "implement.h"
74
75INLINE
76int
77ptw32_robust_mutex_inherit(pthread_mutex_t * mutex)
78{
79  int result;
80  pthread_mutex_t mx = *mutex;
81  ptw32_robust_node_t* robust = mx->robustNode;
82
83  switch ((LONG)PTW32_INTERLOCKED_COMPARE_EXCHANGE_LONG(
84            (PTW32_INTERLOCKED_LONGPTR)&robust->stateInconsistent,
85            (PTW32_INTERLOCKED_LONG)PTW32_ROBUST_INCONSISTENT,
86            (PTW32_INTERLOCKED_LONG)-1 /* The terminating thread sets this */))
87    {
88      case -1L:
89          result = EOWNERDEAD;
90          break;
91      case (LONG)PTW32_ROBUST_NOTRECOVERABLE:
92          result = ENOTRECOVERABLE;
93          break;
94      default:
95          result = 0;
96          break;
97    }
98
99  return result;
100}
101
102/*
103 * The next two internal support functions depend on only being
104 * called by the thread that owns the robust mutex. This enables
105 * us to avoid additional locks.
106 * Any mutex currently in the thread's robust mutex list is held
107 * by the thread, again eliminating the need for locks.
108 * The forward/backward links allow the thread to unlock mutexes
109 * in any order, not necessarily the reverse locking order.
110 * This is all possible because it is an error if a thread that
111 * does not own the [robust] mutex attempts to unlock it.
112 */
113
114INLINE
115void
116ptw32_robust_mutex_add(pthread_mutex_t* mutex, pthread_t self)
117{
118  ptw32_robust_node_t** list;
119  pthread_mutex_t mx = *mutex;
120  ptw32_thread_t* tp = (ptw32_thread_t*)self.p;
121  ptw32_robust_node_t* robust = mx->robustNode;
122
123  list = &tp->robustMxList;
124  mx->ownerThread = self;
125  if (NULL == *list)
126    {
127      robust->prev = NULL;
128      robust->next = NULL;
129      *list = robust;
130    }
131  else
132    {
133      robust->prev = NULL;
134      robust->next = *list;
135      (*list)->prev = robust;
136      *list = robust;
137    }
138}
139
140INLINE
141void
142ptw32_robust_mutex_remove(pthread_mutex_t* mutex, ptw32_thread_t* otp)
143{
144  ptw32_robust_node_t** list;
145  pthread_mutex_t mx = *mutex;
146  ptw32_robust_node_t* robust = mx->robustNode;
147
148  list = &(((ptw32_thread_t*)mx->ownerThread.p)->robustMxList);
149  mx->ownerThread.p = otp;
150  if (robust->next != NULL)
151    {
152      robust->next->prev = robust->prev;
153    }
154  if (robust->prev != NULL)
155    {
156      robust->prev->next = robust->next;
157    }
158  if (*list == robust)
159    {
160      *list = robust->next;
161    }
162}
163
164
165int
166pthread_mutex_consistent (pthread_mutex_t* mutex)
167{
168  pthread_mutex_t mx = *mutex;
169  int result = 0;
170
171  /*
172   * Let the system deal with invalid pointers.
173   */
174  if (mx == NULL)
175    {
176      return EINVAL;
177    }
178
179  if (mx->kind >= 0
180        || (PTW32_INTERLOCKED_LONG)PTW32_ROBUST_INCONSISTENT != PTW32_INTERLOCKED_COMPARE_EXCHANGE_LONG(
181                                                (PTW32_INTERLOCKED_LONGPTR)&mx->robustNode->stateInconsistent,
182                                                (PTW32_INTERLOCKED_LONG)PTW32_ROBUST_CONSISTENT,
183                                                (PTW32_INTERLOCKED_LONG)PTW32_ROBUST_INCONSISTENT))
184    {
185      result = EINVAL;
186    }
187
188  return (result);
189}
190
191