source: rtems/cpukit/posix/src/mutexinit.c @ c16d45a5

Last change on this file since c16d45a5 was c16d45a5, checked in by Joel Sherrill <joel@…>, on Apr 26, 2017 at 8:42:09 PM

posix/src/mutexinit.c: Reorder to make priority a scoped variable

  • 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
42  if ( attr ) the_attr = attr;
43  else        the_attr = &_POSIX_Mutex_Default_attributes;
44
45  /* Check for NULL mutex */
46  if ( !mutex )
47    return EINVAL;
48
49  /*
50   *  The POSIX specification says:
51   *
52   *  "Attempting to initialize an already initialized mutex results
53   *  in undefined behavior."
54   *
55   *  Trying to keep the caller from doing the create when *mutex
56   *  is actually a valid ID causes grief.  All it takes is the wrong
57   *  value in an uninitialized variable to make this fail.
58   *
59   *  Thus, we do not look at *mutex.
60   */
61
62  if ( !the_attr->is_initialized )
63    return EINVAL;
64
65  /*
66   *  We only support process private mutexes.
67   */
68  if ( the_attr->process_shared == PTHREAD_PROCESS_SHARED )
69    return ENOSYS;
70
71  if ( the_attr->process_shared != PTHREAD_PROCESS_PRIVATE )
72    return EINVAL;
73
74  /*
75   *  Determine the discipline of the mutex
76   */
77  switch ( the_attr->protocol ) {
78    case PTHREAD_PRIO_NONE:
79      protocol = POSIX_MUTEX_NO_PROTOCOL;
80      break;
81    case PTHREAD_PRIO_INHERIT:
82      protocol = POSIX_MUTEX_PRIORITY_INHERIT;
83      break;
84    case PTHREAD_PRIO_PROTECT:
85      protocol = POSIX_MUTEX_PRIORITY_CEILING;
86      break;
87    default:
88      return EINVAL;
89  }
90
91#if defined(_UNIX98_THREAD_MUTEX_ATTRIBUTES)
92  /*
93   *  Validate the mutex type and set appropriate SuperCore mutex
94   *  attributes.
95   */
96  switch ( the_attr->type ) {
97    case PTHREAD_MUTEX_NORMAL:
98    case PTHREAD_MUTEX_RECURSIVE:
99    case PTHREAD_MUTEX_ERRORCHECK:
100    case PTHREAD_MUTEX_DEFAULT:
101      break;
102
103    default:
104      return EINVAL;
105  }
106#endif
107
108  the_mutex = _POSIX_Mutex_Allocate();
109
110  if ( !the_mutex ) {
111    _Objects_Allocator_unlock();
112    return EAGAIN;
113  }
114
115  the_mutex->protocol = protocol;
116  the_mutex->is_recursive = ( the_attr->type == PTHREAD_MUTEX_RECURSIVE );
117
118  switch ( protocol ) {
119    case POSIX_MUTEX_PRIORITY_CEILING: {
120      int               prio_ceiling;
121      bool              valid;
122      Priority_Control  priority;
123
124      scheduler = _Thread_Scheduler_get_home( _Thread_Get_executing() );
125      prio_ceiling = the_attr->prio_ceiling;
126
127      if ( prio_ceiling == INT_MAX ) {
128        prio_ceiling = _POSIX_Priority_Get_maximum( scheduler );
129      }
130
131      priority = _POSIX_Priority_To_core( scheduler, prio_ceiling, &valid );
132      if ( !valid ) {
133        _POSIX_Mutex_Free(the_mutex);
134        _Objects_Allocator_unlock();
135        return EINVAL;
136      }
137      _CORE_ceiling_mutex_Initialize( &the_mutex->Mutex, scheduler, priority );
138      break;
139    }
140    default:
141      _Assert(
142        the_mutex->protocol == POSIX_MUTEX_NO_PROTOCOL
143          || the_mutex->protocol == POSIX_MUTEX_PRIORITY_INHERIT
144      );
145      _CORE_recursive_mutex_Initialize( &the_mutex->Mutex.Recursive );
146      break;
147  }
148
149  _Objects_Open_u32( &_POSIX_Mutex_Information, &the_mutex->Object, 0 );
150
151  *mutex = the_mutex->Object.id;
152
153  _Objects_Allocator_unlock();
154  return 0;
155}
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