1 | /** |
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2 | * @file |
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3 | * |
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4 | * @ingroup ScoreMutex |
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5 | * |
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6 | * @brief CORE Mutex Implementation |
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7 | */ |
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8 | |
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9 | /* |
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10 | * COPYRIGHT (c) 1989-2009. |
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11 | * On-Line Applications Research Corporation (OAR). |
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12 | * |
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13 | * The license and distribution terms for this file may be |
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14 | * found in the file LICENSE in this distribution or at |
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15 | * http://www.rtems.org/license/LICENSE. |
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16 | */ |
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17 | |
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18 | #ifndef _RTEMS_SCORE_COREMUTEXIMPL_H |
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19 | #define _RTEMS_SCORE_COREMUTEXIMPL_H |
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20 | |
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21 | #include <rtems/score/coremutex.h> |
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22 | #include <rtems/score/chainimpl.h> |
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23 | #include <rtems/score/sysstate.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 | #ifdef __cplusplus |
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28 | extern "C" { |
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29 | #endif |
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30 | |
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31 | /** |
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32 | * @addtogroup ScoreMutex |
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33 | */ |
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34 | /**@{**/ |
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35 | |
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36 | /** |
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37 | * @brief Callout which provides to support global/multiprocessor operations. |
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38 | * |
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39 | * The following type defines the callout which the API provides |
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40 | * to support global/multiprocessor operations on mutexes. |
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41 | */ |
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42 | typedef void ( *CORE_mutex_API_mp_support_callout )( |
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43 | Thread_Control *, |
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44 | Objects_Id |
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45 | ); |
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46 | |
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47 | /** |
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48 | * @brief The possible Mutex handler return statuses. |
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49 | * |
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50 | * This enumerated type defines the possible Mutex handler return statuses. |
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51 | */ |
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52 | typedef enum { |
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53 | /** This status indicates that the operation completed successfully. */ |
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54 | CORE_MUTEX_STATUS_SUCCESSFUL, |
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55 | /** This status indicates that the calling task did not want to block |
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56 | * and the operation was unable to complete immediately because the |
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57 | * resource was unavailable. |
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58 | */ |
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59 | CORE_MUTEX_STATUS_UNSATISFIED_NOWAIT, |
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60 | #if defined(RTEMS_POSIX_API) |
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61 | /** This status indicates that an attempt was made to relock a mutex |
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62 | * for which nesting is not configured. |
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63 | */ |
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64 | CORE_MUTEX_STATUS_NESTING_NOT_ALLOWED, |
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65 | #endif |
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66 | /** This status indicates that an attempt was made to release a mutex |
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67 | * by a thread other than the thread which locked it. |
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68 | */ |
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69 | CORE_MUTEX_STATUS_NOT_OWNER_OF_RESOURCE, |
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70 | /** This status indicates that the thread was blocked waiting for an |
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71 | * operation to complete and the mutex was deleted. |
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72 | */ |
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73 | CORE_MUTEX_WAS_DELETED, |
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74 | /** This status indicates that the calling task was willing to block |
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75 | * but the operation was unable to complete within the time allotted |
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76 | * because the resource never became available. |
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77 | */ |
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78 | CORE_MUTEX_TIMEOUT, |
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79 | |
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80 | #if defined(__RTEMS_STRICT_ORDER_MUTEX__) |
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81 | /** This status indicates that a thread not release the mutex which has |
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82 | * the priority inheritance property in a right order. |
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83 | */ |
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84 | CORE_MUTEX_RELEASE_NOT_ORDER, |
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85 | #endif |
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86 | |
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87 | /** This status indicates that a thread of logically greater importance |
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88 | * than the ceiling priority attempted to lock this mutex. |
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89 | */ |
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90 | CORE_MUTEX_STATUS_CEILING_VIOLATED |
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91 | |
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92 | } CORE_mutex_Status; |
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93 | |
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94 | /** |
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95 | * @brief The last status value. |
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96 | * |
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97 | * This is the last status value. |
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98 | */ |
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99 | #define CORE_MUTEX_STATUS_LAST CORE_MUTEX_STATUS_CEILING_VIOLATED |
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100 | |
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101 | /** |
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102 | * @brief Initializes the mutex based on the parameters passed. |
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103 | * |
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104 | * This routine initializes the mutex based on the parameters passed. |
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105 | * |
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106 | * @param[in,out] the_mutex is the mutex to initalize |
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107 | * @param[in,out] executing The currently executing thread. |
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108 | * @param[in] the_mutex_attributes is the attributes associated with this |
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109 | * mutex instance |
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110 | * @param[in] initially_locked If true, then the mutex is initially locked by |
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111 | * the executing thread. |
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112 | * |
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113 | * @retval This method returns CORE_MUTEX_STATUS_SUCCESSFUL if successful. |
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114 | */ |
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115 | CORE_mutex_Status _CORE_mutex_Initialize( |
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116 | CORE_mutex_Control *the_mutex, |
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117 | Thread_Control *executing, |
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118 | const CORE_mutex_Attributes *the_mutex_attributes, |
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119 | bool initially_locked |
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120 | ); |
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121 | |
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122 | /** |
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123 | * @brief Attempt to receive a unit from the_mutex. |
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124 | * |
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125 | * This routine attempts to receive a unit from the_mutex. |
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126 | * If a unit is available or if the wait flag is false, then the routine |
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127 | * returns. Otherwise, the calling task is blocked until a unit becomes |
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128 | * available. |
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129 | * |
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130 | * @param[in,out] executing The currently executing thread. |
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131 | * @param[in,out] the_mutex is the mutex to attempt to lock |
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132 | * @param[in] level is the interrupt level |
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133 | * |
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134 | * @retval This routine returns 0 if "trylock" can resolve whether or not |
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135 | * the mutex is immediately obtained or there was an error attempting to |
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136 | * get it. It returns 1 to indicate that the caller cannot obtain |
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137 | * the mutex and will have to block to do so. |
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138 | * |
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139 | * @note For performance reasons, this routine is implemented as |
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140 | * a macro that uses two support routines. |
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141 | */ |
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142 | |
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143 | RTEMS_INLINE_ROUTINE int _CORE_mutex_Seize_interrupt_trylock_body( |
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144 | CORE_mutex_Control *the_mutex, |
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145 | Thread_Control *executing, |
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146 | ISR_Level level |
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147 | ); |
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148 | |
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149 | #if defined(__RTEMS_DO_NOT_INLINE_CORE_MUTEX_SEIZE__) |
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150 | /** |
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151 | * @brief Interrupt trylock CORE mutex seize. |
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152 | * |
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153 | * When doing test coverage analysis or trying to minimize the code |
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154 | * space for RTEMS, it is often helpful to not inline this method |
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155 | * multiple times. It is fairly large and has a high branch complexity |
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156 | * which makes it harder to get full binary test coverage. |
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157 | * |
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158 | * @param[in] the_mutex will attempt to lock |
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159 | * @param[in] level_p is the interrupt level |
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160 | */ |
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161 | int _CORE_mutex_Seize_interrupt_trylock( |
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162 | CORE_mutex_Control *the_mutex, |
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163 | Thread_Control *executing, |
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164 | ISR_Level level |
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165 | ); |
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166 | #else |
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167 | /** |
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168 | * The default is to favor speed and inlining this definitely saves |
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169 | * a few instructions. This is very important for mutex performance. |
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170 | * |
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171 | * @param[in] _mutex will attempt to lock |
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172 | * @param[in] _level is the interrupt level |
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173 | */ |
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174 | #define _CORE_mutex_Seize_interrupt_trylock( _mutex, _executing, _level ) \ |
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175 | _CORE_mutex_Seize_interrupt_trylock_body( _mutex, _executing, _level ) |
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176 | #endif |
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177 | |
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178 | /** |
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179 | * @brief Performs the blocking portion of a mutex obtain. |
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180 | * |
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181 | * This routine performs the blocking portion of a mutex obtain. |
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182 | * It is an actual subroutine and is not implemented as something |
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183 | * that may be inlined. |
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184 | * |
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185 | * @param[in,out] the_mutex is the mutex to attempt to lock |
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186 | * @param[in,out] executing The currently executing thread. |
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187 | * @param[in] timeout is the maximum number of ticks to block |
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188 | */ |
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189 | void _CORE_mutex_Seize_interrupt_blocking( |
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190 | CORE_mutex_Control *the_mutex, |
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191 | Thread_Control *executing, |
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192 | Watchdog_Interval timeout |
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193 | ); |
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194 | /** |
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195 | * @brief Verifies that a mutex blocking seize is performed safely. |
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196 | * |
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197 | * This macro is to verify that a mutex blocking seize is |
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198 | * performed from a safe system state. For example, one |
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199 | * cannot block inside an isr. |
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200 | * |
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201 | * @retval this method returns true if dispatch is in an unsafe state. |
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202 | */ |
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203 | #ifdef RTEMS_SMP |
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204 | #define _CORE_mutex_Check_dispatch_for_seize(_wait) \ |
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205 | (_Thread_Dispatch_get_disable_level() != 1 \ |
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206 | && (_wait) \ |
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207 | && (_System_state_Get() >= SYSTEM_STATE_UP)) |
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208 | #else |
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209 | #define _CORE_mutex_Check_dispatch_for_seize(_wait) \ |
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210 | (!_Thread_Dispatch_is_enabled() \ |
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211 | && (_wait) \ |
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212 | && (_System_state_Get() >= SYSTEM_STATE_UP)) |
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213 | #endif |
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214 | |
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215 | /** |
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216 | * @brief Attempt to obtain the mutex. |
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217 | * |
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218 | * This routine attempts to obtain the mutex. If the mutex is available, |
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219 | * then it will return immediately. Otherwise, it will invoke the |
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220 | * support routine @a _Core_mutex_Seize_interrupt_blocking. |
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221 | * |
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222 | * @param[in] _the_mutex is the mutex to attempt to lock |
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223 | * @param[in] _id is the Id of the owning API level Semaphore object |
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224 | * @param[in] _wait is true if the thread is willing to wait |
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225 | * @param[in] _timeout is the maximum number of ticks to block |
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226 | * @param[in] _level is a temporary variable used to contain the ISR |
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227 | * disable level cookie |
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228 | * |
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229 | * @note If the mutex is called from an interrupt service routine, |
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230 | * with context switching disabled, or before multitasking, |
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231 | * then a fatal error is generated. |
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232 | * |
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233 | * The logic on this routine is as follows: |
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234 | * |
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235 | * * If incorrect system state |
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236 | * return an error |
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237 | * * If mutex is available without any contention or blocking |
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238 | * obtain it with interrupts disabled and returned |
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239 | * * If the caller is willing to wait |
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240 | * then they are blocked. |
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241 | */ |
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242 | RTEMS_INLINE_ROUTINE void _CORE_mutex_Seize_body( |
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243 | CORE_mutex_Control *the_mutex, |
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244 | Thread_Control *executing, |
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245 | Objects_Id id, |
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246 | bool wait, |
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247 | Watchdog_Interval timeout, |
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248 | ISR_Level level |
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249 | ) |
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250 | { |
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251 | if ( _CORE_mutex_Check_dispatch_for_seize( wait ) ) { |
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252 | _Terminate( |
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253 | INTERNAL_ERROR_CORE, |
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254 | false, |
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255 | INTERNAL_ERROR_MUTEX_OBTAIN_FROM_BAD_STATE |
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256 | ); |
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257 | } |
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258 | if ( _CORE_mutex_Seize_interrupt_trylock( the_mutex, executing, level ) ) { |
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259 | if ( !wait ) { |
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260 | _ISR_Enable( level ); |
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261 | executing->Wait.return_code = |
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262 | CORE_MUTEX_STATUS_UNSATISFIED_NOWAIT; |
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263 | } else { |
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264 | _Thread_queue_Enter_critical_section( &the_mutex->Wait_queue ); |
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265 | executing->Wait.queue = &the_mutex->Wait_queue; |
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266 | executing->Wait.id = id; |
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267 | _Thread_Disable_dispatch(); |
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268 | _ISR_Enable( level ); |
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269 | _CORE_mutex_Seize_interrupt_blocking( the_mutex, executing, timeout ); |
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270 | } |
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271 | } |
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272 | } |
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273 | |
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274 | /** |
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275 | * This method is used to obtain a core mutex. |
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276 | * |
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277 | * @param[in] _the_mutex is the mutex to attempt to lock |
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278 | * @param[in] _id is the Id of the owning API level Semaphore object |
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279 | * @param[in] _wait is true if the thread is willing to wait |
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280 | * @param[in] _timeout is the maximum number of ticks to block |
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281 | * @param[in] _level is a temporary variable used to contain the ISR |
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282 | * disable level cookie |
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283 | */ |
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284 | #if defined(__RTEMS_DO_NOT_INLINE_CORE_MUTEX_SEIZE__) |
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285 | void _CORE_mutex_Seize( |
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286 | CORE_mutex_Control *_the_mutex, |
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287 | Thread_Control *_executing, |
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288 | Objects_Id _id, |
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289 | bool _wait, |
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290 | Watchdog_Interval _timeout, |
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291 | ISR_Level _level |
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292 | ); |
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293 | #else |
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294 | #define _CORE_mutex_Seize( _executing, _mtx, _id, _wait, _timeout, _level ) \ |
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295 | _CORE_mutex_Seize_body( _executing, _mtx, _id, _wait, _timeout, _level ) |
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296 | #endif |
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297 | |
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298 | /** |
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299 | * @brief Frees a unit to the mutex. |
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300 | * |
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301 | * This routine frees a unit to the mutex. If a task was blocked waiting for |
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302 | * a unit from this mutex, then that task will be readied and the unit |
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303 | * given to that task. Otherwise, the unit will be returned to the mutex. |
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304 | * |
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305 | * @param[in] the_mutex is the mutex to surrender |
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306 | * @param[in] id is the id of the RTEMS Object associated with this mutex |
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307 | * @param[in] api_mutex_mp_support is the routine that will be called when |
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308 | * unblocking a remote mutex |
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309 | * |
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310 | * @retval an indication of whether the routine succeeded or failed |
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311 | */ |
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312 | CORE_mutex_Status _CORE_mutex_Surrender( |
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313 | CORE_mutex_Control *the_mutex, |
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314 | Objects_Id id, |
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315 | CORE_mutex_API_mp_support_callout api_mutex_mp_support |
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316 | ); |
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317 | |
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318 | /** |
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319 | * @brief Flush all waiting threads. |
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320 | * |
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321 | * This routine assists in the deletion of a mutex by flushing the associated |
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322 | * wait queue. |
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323 | * |
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324 | * @param[in] the_mutex is the mutex to flush |
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325 | * @param[in] remote_extract_callout is the routine to invoke when a remote |
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326 | * thread is extracted |
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327 | * @param[in] status is the status value which each unblocked thread will |
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328 | * return to its caller. |
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329 | */ |
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330 | void _CORE_mutex_Flush( |
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331 | CORE_mutex_Control *the_mutex, |
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332 | Thread_queue_Flush_callout remote_extract_callout, |
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333 | uint32_t status |
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334 | ); |
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335 | |
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336 | /** |
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337 | * @brief Is mutex locked. |
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338 | * |
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339 | * This routine returns true if the mutex specified is locked and false |
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340 | * otherwise. |
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341 | * |
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342 | * @param[in] the_mutex is the mutex to check. |
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343 | * |
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344 | * @retval true The mutex is locked. |
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345 | * @retval false The mutex is not locked. |
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346 | */ |
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347 | RTEMS_INLINE_ROUTINE bool _CORE_mutex_Is_locked( |
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348 | CORE_mutex_Control *the_mutex |
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349 | ) |
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350 | { |
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351 | return the_mutex->holder != NULL; |
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352 | } |
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353 | |
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354 | /** |
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355 | * @brief Does core mutex use FIFO blocking. |
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356 | * |
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357 | * This routine returns true if the mutex's wait discipline is FIFO and false |
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358 | * otherwise. |
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359 | * |
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360 | * @param[in] the_attribute is the attribute set of the mutex. |
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361 | * |
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362 | * @retval true The mutex is using FIFO blocking order. |
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363 | * @retval false The mutex is not using FIFO blocking order. |
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364 | */ |
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365 | RTEMS_INLINE_ROUTINE bool _CORE_mutex_Is_fifo( |
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366 | const CORE_mutex_Attributes *the_attribute |
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367 | ) |
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368 | { |
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369 | return the_attribute->discipline == CORE_MUTEX_DISCIPLINES_FIFO; |
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370 | } |
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371 | |
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372 | /** |
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373 | * @brief Doex core mutex use priority blocking. |
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374 | * |
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375 | * This routine returns true if the mutex's wait discipline is PRIORITY and |
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376 | * false otherwise. |
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377 | * |
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378 | * @param[in] the_attribute is the attribute set of the mutex. |
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379 | * |
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380 | * @retval true The mutex is using priority blocking order. |
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381 | * @retval false The mutex is not using priority blocking order. |
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382 | * |
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383 | */ |
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384 | RTEMS_INLINE_ROUTINE bool _CORE_mutex_Is_priority( |
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385 | CORE_mutex_Attributes *the_attribute |
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386 | ) |
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387 | { |
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388 | return the_attribute->discipline == CORE_MUTEX_DISCIPLINES_PRIORITY; |
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389 | } |
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390 | |
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391 | /** |
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392 | * @brief Does mutex use priority inheritance. |
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393 | * |
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394 | * This routine returns true if the mutex's wait discipline is |
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395 | * INHERIT_PRIORITY and false otherwise. |
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396 | * |
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397 | * @param[in] the_attribute is the attribute set of the mutex. |
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398 | * |
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399 | * @retval true The mutex is using priority inheritance. |
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400 | * @retval false The mutex is not using priority inheritance. |
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401 | */ |
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402 | RTEMS_INLINE_ROUTINE bool _CORE_mutex_Is_inherit_priority( |
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403 | CORE_mutex_Attributes *the_attribute |
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404 | ) |
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405 | { |
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406 | return the_attribute->discipline == CORE_MUTEX_DISCIPLINES_PRIORITY_INHERIT; |
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407 | } |
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408 | |
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409 | /** |
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410 | * @brief Does mutex use priority ceiling. |
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411 | * |
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412 | * This routine returns true if the mutex's wait discipline is |
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413 | * PRIORITY_CEILING and false otherwise. |
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414 | * |
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415 | * @param[in] the_attribute is the attribute set of the mutex. |
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416 | * |
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417 | * @retval true The mutex is using priority ceiling. |
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418 | * @retval false The mutex is not using priority ceiling. |
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419 | */ |
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420 | RTEMS_INLINE_ROUTINE bool _CORE_mutex_Is_priority_ceiling( |
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421 | CORE_mutex_Attributes *the_attribute |
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422 | ) |
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423 | { |
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424 | return the_attribute->discipline == CORE_MUTEX_DISCIPLINES_PRIORITY_CEILING; |
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425 | } |
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426 | |
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427 | /* |
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428 | * Seize Mutex with Quick Success Path |
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429 | * |
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430 | * NOTE: There is no MACRO version of this routine. A body is in |
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431 | * coremutexseize.c that is duplicated from the .inl by hand. |
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432 | * |
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433 | * NOTE: The Doxygen for this routine is in the .h file. |
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434 | */ |
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435 | |
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436 | RTEMS_INLINE_ROUTINE int _CORE_mutex_Seize_interrupt_trylock_body( |
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437 | CORE_mutex_Control *the_mutex, |
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438 | Thread_Control *executing, |
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439 | ISR_Level level |
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440 | ) |
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441 | { |
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442 | /* disabled when you get here */ |
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443 | |
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444 | executing->Wait.return_code = CORE_MUTEX_STATUS_SUCCESSFUL; |
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445 | if ( !_CORE_mutex_Is_locked( the_mutex ) ) { |
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446 | the_mutex->holder = executing; |
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447 | the_mutex->nest_count = 1; |
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448 | if ( _CORE_mutex_Is_inherit_priority( &the_mutex->Attributes ) || |
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449 | _CORE_mutex_Is_priority_ceiling( &the_mutex->Attributes ) ){ |
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450 | |
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451 | #ifdef __RTEMS_STRICT_ORDER_MUTEX__ |
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452 | _Chain_Prepend_unprotected( &executing->lock_mutex, |
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453 | &the_mutex->queue.lock_queue ); |
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454 | the_mutex->queue.priority_before = executing->current_priority; |
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455 | #endif |
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456 | |
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457 | executing->resource_count++; |
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458 | } |
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459 | |
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460 | if ( !_CORE_mutex_Is_priority_ceiling( &the_mutex->Attributes ) ) { |
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461 | _ISR_Enable( level ); |
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462 | return 0; |
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463 | } /* else must be CORE_MUTEX_DISCIPLINES_PRIORITY_CEILING |
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464 | * |
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465 | * we possibly bump the priority of the current holder -- which |
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466 | * happens to be _Thread_Executing. |
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467 | */ |
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468 | { |
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469 | Priority_Control ceiling; |
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470 | Priority_Control current; |
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471 | |
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472 | ceiling = the_mutex->Attributes.priority_ceiling; |
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473 | current = executing->current_priority; |
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474 | if ( current == ceiling ) { |
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475 | _ISR_Enable( level ); |
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476 | return 0; |
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477 | } |
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478 | |
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479 | if ( current > ceiling ) { |
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480 | _Thread_Disable_dispatch(); |
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481 | _ISR_Enable( level ); |
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482 | _Thread_Change_priority( |
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483 | executing, |
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484 | ceiling, |
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485 | false |
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486 | ); |
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487 | _Thread_Enable_dispatch(); |
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488 | return 0; |
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489 | } |
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490 | /* if ( current < ceiling ) */ { |
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491 | executing->Wait.return_code = CORE_MUTEX_STATUS_CEILING_VIOLATED; |
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492 | the_mutex->holder = NULL; |
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493 | the_mutex->nest_count = 0; /* undo locking above */ |
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494 | executing->resource_count--; /* undo locking above */ |
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495 | _ISR_Enable( level ); |
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496 | return 0; |
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497 | } |
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498 | } |
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499 | return 0; |
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500 | } |
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501 | |
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502 | /* |
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503 | * At this point, we know the mutex was not available. If this thread |
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504 | * is the thread that has locked the mutex, let's see if we are allowed |
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505 | * to nest access. |
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506 | */ |
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507 | if ( _Thread_Is_executing( the_mutex->holder ) ) { |
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508 | switch ( the_mutex->Attributes.lock_nesting_behavior ) { |
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509 | case CORE_MUTEX_NESTING_ACQUIRES: |
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510 | the_mutex->nest_count++; |
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511 | _ISR_Enable( level ); |
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512 | return 0; |
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513 | #if defined(RTEMS_POSIX_API) |
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514 | case CORE_MUTEX_NESTING_IS_ERROR: |
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515 | executing->Wait.return_code = CORE_MUTEX_STATUS_NESTING_NOT_ALLOWED; |
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516 | _ISR_Enable( level ); |
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517 | return 0; |
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518 | #endif |
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519 | case CORE_MUTEX_NESTING_BLOCKS: |
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520 | break; |
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521 | } |
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522 | } |
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523 | |
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524 | /* |
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525 | * The mutex is not available and the caller must deal with the possibility |
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526 | * of blocking. |
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527 | */ |
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528 | return 1; |
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529 | } |
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530 | |
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531 | /** @} */ |
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532 | |
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533 | #ifdef __cplusplus |
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534 | } |
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535 | #endif |
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536 | |
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537 | #endif |
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538 | /* end of include file */ |
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