1 | /** |
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2 | * @file |
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3 | * |
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4 | * @brief Initialize a Mutex |
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5 | * @ingroup POSIXAPI |
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6 | */ |
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7 | |
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8 | /* |
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9 | * COPYRIGHT (c) 1989-2009. |
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10 | * On-Line Applications Research Corporation (OAR). |
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11 | * |
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12 | * The license and distribution terms for this file may be |
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13 | * found in the file LICENSE in this distribution or at |
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14 | * http://www.rtems.org/license/LICENSE. |
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15 | */ |
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16 | |
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17 | #if HAVE_CONFIG_H |
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18 | #include "config.h" |
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19 | #endif |
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20 | |
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21 | #include <rtems/posix/muteximpl.h> |
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22 | #include <rtems/posix/posixapi.h> |
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23 | #include <rtems/posix/priorityimpl.h> |
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24 | #include <rtems/score/schedulerimpl.h> |
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25 | |
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26 | #include <limits.h> |
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27 | |
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28 | RTEMS_STATIC_ASSERT( |
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29 | offsetof( POSIX_Mutex_Control, flags ) |
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30 | == offsetof( pthread_mutex_t, _flags ), |
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31 | POSIX_MUTEX_CONTROL_FLAGS |
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32 | ); |
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33 | |
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34 | RTEMS_STATIC_ASSERT( |
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35 | offsetof( POSIX_Mutex_Control, Recursive ) |
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36 | == offsetof( pthread_mutex_t, _Recursive ), |
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37 | POSIX_MUTEX_CONTROL_RECURSIVE |
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38 | ); |
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39 | |
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40 | RTEMS_STATIC_ASSERT( |
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41 | offsetof( POSIX_Mutex_Control, Priority_ceiling ) |
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42 | == offsetof( pthread_mutex_t, _Priority_ceiling ), |
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43 | POSIX_MUTEX_CONTROL_PRIORITY_CEILING |
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44 | ); |
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45 | |
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46 | RTEMS_STATIC_ASSERT( |
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47 | offsetof( POSIX_Mutex_Control, scheduler ) |
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48 | == offsetof( pthread_mutex_t, _scheduler ), |
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49 | POSIX_MUTEX_CONTROL_SCHEDULER |
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50 | ); |
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51 | |
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52 | RTEMS_STATIC_ASSERT( |
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53 | sizeof( POSIX_Mutex_Control ) == sizeof( pthread_mutex_t ), |
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54 | POSIX_MUTEX_CONTROL_SIZE |
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55 | ); |
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56 | |
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57 | const pthread_mutexattr_t _POSIX_Mutex_Default_attributes = { |
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58 | #if defined(_UNIX98_THREAD_MUTEX_ATTRIBUTES) |
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59 | .type = PTHREAD_MUTEX_DEFAULT, |
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60 | #endif |
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61 | .is_initialized = true, |
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62 | .process_shared = PTHREAD_PROCESS_PRIVATE, |
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63 | .prio_ceiling = INT_MAX, |
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64 | .protocol = PTHREAD_PRIO_NONE, |
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65 | .recursive = false |
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66 | }; |
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67 | |
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68 | /** |
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69 | * 11.3.2 Initializing and Destroying a Mutex, P1003.1c/Draft 10, p. 87 |
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70 | * |
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71 | * NOTE: XXX Could be optimized so all the attribute error checking |
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72 | * is not performed when attr is NULL. |
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73 | */ |
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74 | |
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75 | int pthread_mutex_init( |
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76 | pthread_mutex_t *mutex, |
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77 | const pthread_mutexattr_t *attr |
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78 | ) |
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79 | { |
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80 | POSIX_Mutex_Control *the_mutex; |
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81 | const pthread_mutexattr_t *the_attr; |
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82 | POSIX_Mutex_Protocol protocol; |
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83 | unsigned long flags; |
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84 | Priority_Control priority; |
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85 | const Scheduler_Control *scheduler; |
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86 | |
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87 | if ( attr ) the_attr = attr; |
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88 | else the_attr = &_POSIX_Mutex_Default_attributes; |
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89 | |
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90 | /* Check for NULL mutex */ |
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91 | if ( !mutex ) |
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92 | return EINVAL; |
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93 | |
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94 | /* |
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95 | * The POSIX specification says: |
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96 | * |
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97 | * "Attempting to initialize an already initialized mutex results |
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98 | * in undefined behavior." |
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99 | * |
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100 | * Trying to keep the caller from doing the create when *mutex |
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101 | * is actually a valid ID causes grief. All it takes is the wrong |
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102 | * value in an uninitialized variable to make this fail. |
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103 | * |
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104 | * Thus, we do not look at *mutex. |
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105 | */ |
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106 | |
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107 | if ( !the_attr->is_initialized ) |
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108 | return EINVAL; |
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109 | |
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110 | if ( !_POSIX_Is_valid_pshared( the_attr->process_shared ) ) { |
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111 | return EINVAL; |
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112 | } |
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113 | |
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114 | /* |
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115 | * Determine the discipline of the mutex |
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116 | */ |
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117 | switch ( the_attr->protocol ) { |
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118 | case PTHREAD_PRIO_NONE: |
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119 | protocol = POSIX_MUTEX_NO_PROTOCOL; |
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120 | break; |
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121 | case PTHREAD_PRIO_INHERIT: |
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122 | protocol = POSIX_MUTEX_PRIORITY_INHERIT; |
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123 | break; |
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124 | case PTHREAD_PRIO_PROTECT: |
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125 | protocol = POSIX_MUTEX_PRIORITY_CEILING; |
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126 | break; |
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127 | default: |
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128 | return EINVAL; |
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129 | } |
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130 | |
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131 | #if defined(_UNIX98_THREAD_MUTEX_ATTRIBUTES) |
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132 | /* |
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133 | * Validate the mutex type and set appropriate SuperCore mutex |
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134 | * attributes. |
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135 | */ |
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136 | switch ( the_attr->type ) { |
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137 | case PTHREAD_MUTEX_NORMAL: |
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138 | case PTHREAD_MUTEX_RECURSIVE: |
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139 | case PTHREAD_MUTEX_ERRORCHECK: |
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140 | case PTHREAD_MUTEX_DEFAULT: |
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141 | break; |
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142 | |
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143 | default: |
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144 | return EINVAL; |
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145 | } |
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146 | #endif |
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147 | |
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148 | the_mutex = _POSIX_Mutex_Get( mutex ); |
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149 | |
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150 | flags = (uintptr_t) the_mutex ^ POSIX_MUTEX_MAGIC; |
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151 | flags &= ~POSIX_MUTEX_FLAGS_MASK; |
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152 | flags |= protocol; |
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153 | |
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154 | if ( the_attr->type == PTHREAD_MUTEX_RECURSIVE ) { |
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155 | flags |= POSIX_MUTEX_RECURSIVE; |
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156 | } |
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157 | |
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158 | the_mutex->flags = flags; |
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159 | |
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160 | if ( protocol == POSIX_MUTEX_PRIORITY_CEILING ) { |
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161 | int prio_ceiling; |
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162 | bool valid; |
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163 | |
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164 | scheduler = _Thread_Scheduler_get_home( _Thread_Get_executing() ); |
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165 | prio_ceiling = the_attr->prio_ceiling; |
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166 | |
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167 | if ( prio_ceiling == INT_MAX ) { |
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168 | prio_ceiling = _POSIX_Priority_Get_maximum( scheduler ); |
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169 | } |
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170 | |
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171 | priority = _POSIX_Priority_To_core( scheduler, prio_ceiling, &valid ); |
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172 | if ( !valid ) { |
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173 | return EINVAL; |
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174 | } |
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175 | } else { |
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176 | priority = 0; |
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177 | scheduler = NULL; |
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178 | } |
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179 | |
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180 | _Thread_queue_Queue_initialize( |
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181 | &the_mutex->Recursive.Mutex.Queue.Queue, |
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182 | NULL |
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183 | ); |
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184 | the_mutex->Recursive.nest_level = 0; |
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185 | _Priority_Node_initialize( &the_mutex->Priority_ceiling, priority ); |
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186 | the_mutex->scheduler = scheduler; |
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187 | return 0; |
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188 | } |
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