source: mainline/kernel/generic/src/synch/mutex.c@ c7fbb90

lfn serial ticket/834-toolchain-update topic/msim-upgrade topic/simplify-dev-export
Last change on this file since c7fbb90 was d7da4284, checked in by Jakub Jermar <jakub@…>, 15 years ago

Add interface for testing the state of a mutex.

  • Property mode set to 100644
File size: 3.0 KB
Line 
1/*
2 * Copyright (c) 2001-2004 Jakub Jermar
3 * All rights reserved.
4 *
5 * Redistribution and use in source and binary forms, with or without
6 * modification, are permitted provided that the following conditions
7 * are met:
8 *
9 * - Redistributions of source code must retain the above copyright
10 * notice, this list of conditions and the following disclaimer.
11 * - Redistributions in binary form must reproduce the above copyright
12 * notice, this list of conditions and the following disclaimer in the
13 * documentation and/or other materials provided with the distribution.
14 * - The name of the author may not be used to endorse or promote products
15 * derived from this software without specific prior written permission.
16 *
17 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
18 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
19 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
20 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
21 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
22 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
23 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
24 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
25 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
26 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
27 */
28
29/** @addtogroup sync
30 * @{
31 */
32
33/**
34 * @file
35 * @brief Mutexes.
36 */
37
38#include <synch/mutex.h>
39#include <synch/semaphore.h>
40#include <synch/synch.h>
41#include <debug.h>
42#include <arch.h>
43
44/** Initialize mutex.
45 *
46 * @param mtx Mutex.
47 * @param type Type of the mutex.
48 */
49void mutex_initialize(mutex_t *mtx, mutex_type_t type)
50{
51 mtx->type = type;
52 semaphore_initialize(&mtx->sem, 1);
53}
54
55/** Find out whether the mutex is currently locked.
56 *
57 * @param mtx Mutex.
58 * @return True if the mutex is locked, false otherwise.
59 */
60bool mutex_locked(mutex_t *mtx)
61{
62 return semaphore_count_get(&mtx->sem) <= 0;
63}
64
65/** Acquire mutex.
66 *
67 * Timeout mode and non-blocking mode can be requested.
68 *
69 * @param mtx Mutex.
70 * @param usec Timeout in microseconds.
71 * @param flags Specify mode of operation.
72 *
73 * For exact description of possible combinations of
74 * usec and flags, see comment for waitq_sleep_timeout().
75 *
76 * @return See comment for waitq_sleep_timeout().
77 *
78 */
79int _mutex_lock_timeout(mutex_t *mtx, uint32_t usec, unsigned int flags)
80{
81 int rc;
82
83 if ((mtx->type == MUTEX_PASSIVE) && (THREAD)) {
84 rc = _semaphore_down_timeout(&mtx->sem, usec, flags);
85 } else {
86 ASSERT((mtx->type == MUTEX_ACTIVE) || (!THREAD));
87 ASSERT(usec == SYNCH_NO_TIMEOUT);
88 ASSERT(!(flags & SYNCH_FLAGS_INTERRUPTIBLE));
89
90 do {
91 rc = semaphore_trydown(&mtx->sem);
92 } while (SYNCH_FAILED(rc) &&
93 !(flags & SYNCH_FLAGS_NON_BLOCKING));
94 }
95
96 return rc;
97}
98
99/** Release mutex.
100 *
101 * @param mtx Mutex.
102 */
103void mutex_unlock(mutex_t *mtx)
104{
105 semaphore_up(&mtx->sem);
106}
107
108/** @}
109 */
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