1 | /* |
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2 | * Copyright (c) 2015, 2016 embedded brains GmbH. All rights reserved. |
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3 | * |
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4 | * embedded brains GmbH |
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5 | * Dornierstr. 4 |
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6 | * 82178 Puchheim |
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7 | * Germany |
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8 | * <rtems@embedded-brains.de> |
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9 | * |
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10 | * The license and distribution terms for this file may be |
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11 | * found in the file LICENSE in this distribution or at |
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12 | * http://www.rtems.org/license/LICENSE. |
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13 | */ |
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14 | |
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15 | #if HAVE_CONFIG_H |
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16 | #include "config.h" |
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17 | #endif |
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18 | |
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19 | #include <sys/lock.h> |
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20 | #include <errno.h> |
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21 | |
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22 | #include <rtems/score/atomic.h> |
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23 | #include <rtems/score/chainimpl.h> |
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24 | #include <rtems/score/threadimpl.h> |
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25 | #include <rtems/score/threadqimpl.h> |
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26 | |
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27 | #define FUTEX_TQ_OPERATIONS &_Thread_queue_Operations_FIFO |
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28 | |
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29 | typedef struct { |
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30 | Thread_queue_Syslock_queue Queue; |
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31 | } Futex_Control; |
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32 | |
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33 | RTEMS_STATIC_ASSERT( |
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34 | offsetof( Futex_Control, Queue ) |
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35 | == offsetof( struct _Futex_Control, _Queue ), |
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36 | FUTEX_CONTROL_QUEUE |
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37 | ); |
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38 | |
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39 | RTEMS_STATIC_ASSERT( |
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40 | sizeof( Futex_Control ) == sizeof( struct _Futex_Control ), |
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41 | FUTEX_CONTROL_SIZE |
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42 | ); |
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43 | |
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44 | static Futex_Control *_Futex_Get( struct _Futex_Control *_futex ) |
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45 | { |
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46 | return (Futex_Control *) _futex; |
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47 | } |
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48 | |
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49 | static Thread_Control *_Futex_Queue_acquire_critical( |
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50 | Futex_Control *futex, |
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51 | Thread_queue_Context *queue_context |
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52 | ) |
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53 | { |
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54 | Thread_Control *executing; |
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55 | |
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56 | executing = _Thread_Executing; |
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57 | _Thread_queue_Queue_acquire_critical( |
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58 | &futex->Queue.Queue, |
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59 | &executing->Potpourri_stats, |
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60 | &queue_context->Lock_context.Lock_context |
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61 | ); |
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62 | |
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63 | return executing; |
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64 | } |
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65 | |
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66 | static void _Futex_Queue_release( |
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67 | Futex_Control *futex, |
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68 | ISR_Level level, |
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69 | Thread_queue_Context *queue_context |
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70 | ) |
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71 | { |
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72 | _Thread_queue_Queue_release_critical( |
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73 | &futex->Queue.Queue, |
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74 | &queue_context->Lock_context.Lock_context |
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75 | ); |
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76 | _ISR_Local_enable( level ); |
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77 | } |
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78 | |
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79 | int _Futex_Wait( struct _Futex_Control *_futex, int *uaddr, int val ) |
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80 | { |
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81 | Futex_Control *futex; |
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82 | ISR_Level level; |
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83 | Thread_queue_Context queue_context; |
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84 | Thread_Control *executing; |
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85 | int eno; |
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86 | |
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87 | futex = _Futex_Get( _futex ); |
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88 | _Thread_queue_Context_initialize( &queue_context ); |
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89 | _Thread_queue_Context_ISR_disable( &queue_context, level ); |
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90 | executing = _Futex_Queue_acquire_critical( futex, &queue_context ); |
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91 | |
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92 | if ( *uaddr == val ) { |
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93 | _Thread_queue_Context_set_thread_state( |
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94 | &queue_context, |
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95 | STATES_WAITING_FOR_FUTEX |
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96 | ); |
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97 | _Thread_queue_Context_set_enqueue_do_nothing_extra( &queue_context ); |
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98 | _Thread_queue_Context_set_ISR_level( &queue_context, level ); |
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99 | _Thread_queue_Enqueue( |
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100 | &futex->Queue.Queue, |
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101 | FUTEX_TQ_OPERATIONS, |
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102 | executing, |
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103 | &queue_context |
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104 | ); |
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105 | eno = 0; |
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106 | } else { |
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107 | _Futex_Queue_release( futex, level, &queue_context ); |
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108 | eno = EWOULDBLOCK; |
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109 | } |
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110 | |
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111 | return eno; |
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112 | } |
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113 | |
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114 | typedef struct { |
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115 | Thread_queue_Context Base; |
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116 | int count; |
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117 | } Futex_Context; |
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118 | |
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119 | static Thread_Control *_Futex_Flush_filter( |
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120 | Thread_Control *the_thread, |
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121 | Thread_queue_Queue *queue, |
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122 | Thread_queue_Context *queue_context |
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123 | ) |
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124 | { |
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125 | Futex_Context *context; |
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126 | |
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127 | context = (Futex_Context *) queue_context; |
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128 | |
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129 | if ( context->count <= 0 ) { |
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130 | return NULL; |
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131 | } |
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132 | |
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133 | --context->count; |
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134 | |
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135 | return the_thread; |
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136 | } |
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137 | |
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138 | int _Futex_Wake( struct _Futex_Control *_futex, int count ) |
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139 | { |
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140 | Futex_Control *futex; |
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141 | ISR_Level level; |
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142 | Futex_Context context; |
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143 | |
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144 | futex = _Futex_Get( _futex ); |
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145 | _Thread_queue_Context_initialize( &context.Base ); |
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146 | _Thread_queue_Context_ISR_disable( &context.Base, level ); |
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147 | _Futex_Queue_acquire_critical( futex, &context.Base ); |
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148 | |
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149 | /* |
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150 | * For some synchronization objects like barriers the _Futex_Wake() must be |
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151 | * called in the fast path. Normally there are no threads on the queue, so |
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152 | * check this condition early. |
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153 | */ |
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154 | if ( __predict_true( _Thread_queue_Is_empty( &futex->Queue.Queue ) ) ) { |
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155 | _Futex_Queue_release( futex, level, &context.Base ); |
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156 | return 0; |
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157 | } |
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158 | |
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159 | context.count = count; |
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160 | _Thread_queue_Context_set_ISR_level( &context.Base, level ); |
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161 | return (int) _Thread_queue_Flush_critical( |
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162 | &futex->Queue.Queue, |
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163 | FUTEX_TQ_OPERATIONS, |
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164 | _Futex_Flush_filter, |
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165 | &context.Base |
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166 | ); |
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167 | } |
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