source: rtems/cpukit/posix/src/mutexinit.c @ 6601684f

Last change on this file since 6601684f was 6601684f, checked in by Joel Sherrill <joel@…>, on Apr 25, 2017 at 6:57:03 PM

posix/src/mutexinit.c: Fix used before initialized warning

  • Property mode set to 100644
File size: 3.8 KB
Line 
1/**
2 * @file
3 *
4 * @brief Initialize a Mutex
5 * @ingroup POSIXAPI
6 */
7
8/*
9 *  COPYRIGHT (c) 1989-2009.
10 *  On-Line Applications Research Corporation (OAR).
11 *
12 *  The license and distribution terms for this file may be
13 *  found in the file LICENSE in this distribution or at
14 *  http://www.rtems.org/license/LICENSE.
15 */
16
17#if HAVE_CONFIG_H
18#include "config.h"
19#endif
20
21#include <rtems/posix/muteximpl.h>
22#include <rtems/posix/priorityimpl.h>
23#include <rtems/score/schedulerimpl.h>
24
25/**
26 * 11.3.2 Initializing and Destroying a Mutex, P1003.1c/Draft 10, p. 87
27 *
28 * NOTE:  XXX Could be optimized so all the attribute error checking
29 *            is not performed when attr is NULL.
30 */
31
32int pthread_mutex_init(
33  pthread_mutex_t           *mutex,
34  const pthread_mutexattr_t *attr
35)
36{
37  POSIX_Mutex_Control       *the_mutex;
38  const pthread_mutexattr_t *the_attr;
39  POSIX_Mutex_Protocol       protocol;
40  const Scheduler_Control   *scheduler;
41  Priority_Control           priority;
42
43  /* initialize to avoid warning for used uninitialized */
44  priority = 0;
45
46  if ( attr ) the_attr = attr;
47  else        the_attr = &_POSIX_Mutex_Default_attributes;
48
49  /* Check for NULL mutex */
50  if ( !mutex )
51    return EINVAL;
52
53  /*
54   *  The POSIX specification says:
55   *
56   *  "Attempting to initialize an already initialized mutex results
57   *  in undefined behavior."
58   *
59   *  Trying to keep the caller from doing the create when *mutex
60   *  is actually a valid ID causes grief.  All it takes is the wrong
61   *  value in an uninitialized variable to make this fail.
62   *
63   *  Thus, we do not look at *mutex.
64   */
65
66  if ( !the_attr->is_initialized )
67    return EINVAL;
68
69  /*
70   *  We only support process private mutexes.
71   */
72  if ( the_attr->process_shared == PTHREAD_PROCESS_SHARED )
73    return ENOSYS;
74
75  if ( the_attr->process_shared != PTHREAD_PROCESS_PRIVATE )
76    return EINVAL;
77
78  /*
79   *  Determine the discipline of the mutex
80   */
81  switch ( the_attr->protocol ) {
82    case PTHREAD_PRIO_NONE:
83      protocol = POSIX_MUTEX_NO_PROTOCOL;
84      break;
85    case PTHREAD_PRIO_INHERIT:
86      protocol = POSIX_MUTEX_PRIORITY_INHERIT;
87      break;
88    case PTHREAD_PRIO_PROTECT:
89      protocol = POSIX_MUTEX_PRIORITY_CEILING;
90      break;
91    default:
92      return EINVAL;
93  }
94
95#if defined(_UNIX98_THREAD_MUTEX_ATTRIBUTES)
96  /*
97   *  Validate the mutex type and set appropriate SuperCore mutex
98   *  attributes.
99   */
100  switch ( the_attr->type ) {
101    case PTHREAD_MUTEX_NORMAL:
102    case PTHREAD_MUTEX_RECURSIVE:
103    case PTHREAD_MUTEX_ERRORCHECK:
104    case PTHREAD_MUTEX_DEFAULT:
105      break;
106
107    default:
108      return EINVAL;
109  }
110#endif
111
112  if ( protocol == POSIX_MUTEX_PRIORITY_CEILING ) {
113    int  prio_ceiling;
114    bool valid;
115
116    scheduler = _Thread_Scheduler_get_home( _Thread_Get_executing() );
117    prio_ceiling = the_attr->prio_ceiling;
118
119    if ( prio_ceiling == INT_MAX ) {
120      prio_ceiling = _POSIX_Priority_Get_maximum( scheduler );
121    }
122
123    priority = _POSIX_Priority_To_core( scheduler, prio_ceiling, &valid );
124    if ( !valid ) {
125      return EINVAL;
126    }
127  }
128
129  the_mutex = _POSIX_Mutex_Allocate();
130
131  if ( !the_mutex ) {
132    _Objects_Allocator_unlock();
133    return EAGAIN;
134  }
135
136  the_mutex->protocol = protocol;
137  the_mutex->is_recursive = ( the_attr->type == PTHREAD_MUTEX_RECURSIVE );
138
139  switch ( protocol ) {
140    case POSIX_MUTEX_PRIORITY_CEILING:
141      _CORE_ceiling_mutex_Initialize( &the_mutex->Mutex, scheduler, priority );
142      break;
143    default:
144      _Assert(
145        the_mutex->protocol == POSIX_MUTEX_NO_PROTOCOL
146          || the_mutex->protocol == POSIX_MUTEX_PRIORITY_INHERIT
147      );
148      _CORE_recursive_mutex_Initialize( &the_mutex->Mutex.Recursive );
149      break;
150  }
151
152  _Objects_Open_u32( &_POSIX_Mutex_Information, &the_mutex->Object, 0 );
153
154  *mutex = the_mutex->Object.id;
155
156  _Objects_Allocator_unlock();
157  return 0;
158}
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