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