1 | /** |
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2 | * @file |
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3 | * |
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4 | * @brief POSIX Condition Variables Wait Support |
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5 | * @ingroup POSIX_COND_VARS |
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6 | */ |
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7 | |
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8 | /* |
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9 | * COPYRIGHT (c) 1989-2014. |
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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/condimpl.h> |
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22 | #include <rtems/posix/posixapi.h> |
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23 | #include <rtems/score/assert.h> |
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24 | #include <rtems/score/statesimpl.h> |
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25 | #include <rtems/score/status.h> |
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26 | #include <rtems/score/threaddispatch.h> |
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27 | |
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28 | static void _POSIX_Condition_variables_Enqueue_callout( |
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29 | Thread_queue_Queue *queue, |
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30 | Thread_Control *the_thread, |
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31 | Thread_queue_Context *queue_context |
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32 | ) |
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33 | { |
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34 | POSIX_Condition_variables_Control *the_cond; |
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35 | int mutex_error; |
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36 | |
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37 | the_cond = POSIX_CONDITION_VARIABLE_OF_THREAD_QUEUE_QUEUE( queue ); |
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38 | |
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39 | mutex_error = pthread_mutex_unlock( the_cond->mutex ); |
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40 | if ( mutex_error != 0 ) { |
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41 | /* |
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42 | * Historically, we ignored the unlock status since the behavior |
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43 | * is undefined by POSIX. But GNU/Linux returns EPERM in this |
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44 | * case, so we follow their lead. |
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45 | */ |
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46 | _Assert( mutex_error == EINVAL || mutex_error == EPERM ); |
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47 | _Thread_queue_Extract( the_thread ); |
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48 | the_thread->Wait.return_code= STATUS_NOT_OWNER; |
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49 | } |
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50 | } |
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51 | |
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52 | int _POSIX_Condition_variables_Wait_support( |
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53 | pthread_cond_t *cond, |
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54 | pthread_mutex_t *mutex, |
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55 | const struct timespec *abstime |
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56 | ) |
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57 | { |
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58 | POSIX_Condition_variables_Control *the_cond; |
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59 | unsigned long flags; |
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60 | Thread_queue_Context queue_context; |
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61 | int error; |
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62 | int mutex_error; |
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63 | Thread_Control *executing; |
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64 | Watchdog_Interval timeout; |
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65 | bool already_timedout; |
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66 | TOD_Absolute_timeout_conversion_results status; |
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67 | |
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68 | the_cond = _POSIX_Condition_variables_Get( cond ); |
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69 | POSIX_CONDITION_VARIABLES_VALIDATE_OBJECT( the_cond, flags ); |
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70 | |
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71 | _Thread_queue_Context_initialize( &queue_context ); |
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72 | already_timedout = false; |
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73 | |
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74 | if ( abstime != NULL ) { |
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75 | /* |
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76 | * POSIX requires that blocking calls with timeouts that take |
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77 | * an absolute timeout must ignore issues with the absolute |
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78 | * time provided if the operation would otherwise succeed. |
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79 | * So we check the abstime provided, and hold on to whether it |
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80 | * is valid or not. If it isn't correct and in the future, |
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81 | * then we do a polling operation and convert the UNSATISFIED |
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82 | * status into the appropriate error. |
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83 | */ |
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84 | status = _TOD_Absolute_timeout_to_ticks( |
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85 | abstime, |
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86 | _POSIX_Condition_variables_Get_clock( flags ), |
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87 | &timeout |
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88 | ); |
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89 | if ( status == TOD_ABSOLUTE_TIMEOUT_INVALID ) |
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90 | return EINVAL; |
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91 | |
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92 | if ( status == TOD_ABSOLUTE_TIMEOUT_IS_IN_PAST || |
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93 | status == TOD_ABSOLUTE_TIMEOUT_IS_NOW ) { |
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94 | already_timedout = true; |
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95 | } else { |
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96 | _Thread_queue_Context_set_relative_timeout( &queue_context, timeout ); |
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97 | } |
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98 | } else { |
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99 | _Thread_queue_Context_set_no_timeout( &queue_context ); |
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100 | } |
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101 | |
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102 | executing = _POSIX_Condition_variables_Acquire( the_cond, &queue_context ); |
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103 | |
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104 | if ( |
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105 | the_cond->mutex != POSIX_CONDITION_VARIABLES_NO_MUTEX |
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106 | && the_cond->mutex != mutex |
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107 | ) { |
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108 | _POSIX_Condition_variables_Release( the_cond, &queue_context ); |
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109 | return EINVAL; |
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110 | } |
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111 | |
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112 | the_cond->mutex = mutex; |
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113 | |
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114 | if ( !already_timedout ) { |
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115 | _Thread_queue_Context_set_thread_state( |
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116 | &queue_context, |
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117 | STATES_WAITING_FOR_CONDITION_VARIABLE |
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118 | ); |
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119 | _Thread_queue_Context_set_enqueue_callout( |
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120 | &queue_context, |
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121 | _POSIX_Condition_variables_Enqueue_callout |
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122 | ); |
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123 | _Thread_queue_Enqueue( |
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124 | &the_cond->Queue.Queue, |
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125 | POSIX_CONDITION_VARIABLES_TQ_OPERATIONS, |
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126 | executing, |
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127 | &queue_context |
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128 | ); |
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129 | error = _POSIX_Get_error_after_wait( executing ); |
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130 | } else { |
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131 | _POSIX_Condition_variables_Release( the_cond, &queue_context ); |
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132 | |
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133 | mutex_error = pthread_mutex_unlock( the_cond->mutex ); |
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134 | if ( mutex_error != 0 ) { |
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135 | error = EPERM; |
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136 | } else { |
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137 | error = ETIMEDOUT; |
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138 | } |
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139 | } |
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140 | |
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141 | /* |
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142 | * If the thread is interrupted, while in the thread queue, by |
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143 | * a POSIX signal, then pthread_cond_wait returns spuriously, |
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144 | * according to the POSIX standard. It means that pthread_cond_wait |
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145 | * returns a success status, except for the fact that it was not |
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146 | * woken up a pthread_cond_signal() or a pthread_cond_broadcast(). |
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147 | */ |
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148 | |
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149 | if ( error == EINTR ) { |
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150 | error = 0; |
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151 | } |
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152 | |
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153 | /* |
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154 | * When we get here the dispatch disable level is 0. |
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155 | */ |
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156 | |
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157 | if ( error != EPERM ) { |
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158 | mutex_error = pthread_mutex_lock( mutex ); |
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159 | if ( mutex_error != 0 ) { |
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160 | _Assert( mutex_error == EINVAL ); |
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161 | error = EINVAL; |
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162 | } |
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163 | } |
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164 | |
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165 | return error; |
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166 | } |
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