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