[3a4ae6c] | 1 | /* |
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| 2 | * Mutex Handler |
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| 3 | * |
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| 4 | * DESCRIPTION: |
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| 5 | * |
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| 6 | * This package is the implementation of the Mutex Handler. |
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| 7 | * This handler provides synchronization and mutual exclusion capabilities. |
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| 8 | * |
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| 9 | * COPYRIGHT (c) 1989, 1990, 1991, 1992, 1993, 1994. |
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| 10 | * On-Line Applications Research Corporation (OAR). |
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| 11 | * All rights assigned to U.S. Government, 1994. |
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| 12 | * |
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| 13 | * This material may be reproduced by or for the U.S. Government pursuant |
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| 14 | * to the copyright license under the clause at DFARS 252.227-7013. This |
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| 15 | * notice must appear in all copies of this file and its derivatives. |
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| 16 | * |
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| 17 | * $Id$ |
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| 18 | */ |
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| 19 | |
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| 20 | #include <rtems/system.h> |
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| 21 | #include <rtems/core/isr.h> |
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| 22 | #include <rtems/core/coremutex.h> |
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| 23 | #include <rtems/core/states.h> |
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| 24 | #include <rtems/core/thread.h> |
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| 25 | #include <rtems/core/threadq.h> |
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| 26 | |
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| 27 | /*PAGE |
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| 28 | * |
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| 29 | * _CORE_mutex_Initialize |
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| 30 | * |
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| 31 | * This routine initializes a mutex at create time and set the control |
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| 32 | * structure according to the values passed. |
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| 33 | * |
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| 34 | * Input parameters: |
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| 35 | * the_mutex - the mutex control block to initialize |
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| 36 | * the_class - the API class of the object |
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| 37 | * the_mutex_attributes - the mutex attributes specified at create time |
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| 38 | * initial_lock - mutex initial lock or unlocked status |
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| 39 | * proxy_extract_callout - MP specific extract callout |
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| 40 | * |
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| 41 | * Output parameters: NONE |
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| 42 | */ |
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| 43 | |
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| 44 | void _CORE_mutex_Initialize( |
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| 45 | CORE_mutex_Control *the_mutex, |
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| 46 | Objects_Classes the_class, |
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| 47 | CORE_mutex_Attributes *the_mutex_attributes, |
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| 48 | unsigned32 initial_lock, |
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| 49 | Thread_queue_Extract_callout proxy_extract_callout |
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| 50 | ) |
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| 51 | { |
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| 52 | |
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| 53 | /* Add this to the RTEMS environment later ????????? |
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| 54 | rtems_assert( initial_lock == CORE_MUTEX_LOCKED || |
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| 55 | initial_lock == CORE_MUTEX_UNLOCKED ); |
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| 56 | */ |
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| 57 | |
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| 58 | the_mutex->Attributes = *the_mutex_attributes; |
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| 59 | the_mutex->lock = initial_lock; |
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| 60 | |
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| 61 | if ( initial_lock == CORE_MUTEX_LOCKED ) { |
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| 62 | the_mutex->nest_count = 1; |
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| 63 | the_mutex->holder = _Thread_Executing; |
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| 64 | the_mutex->holder_id = _Thread_Executing->Object.id; |
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| 65 | _Thread_Executing->resource_count++; |
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| 66 | } else { |
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| 67 | the_mutex->nest_count = 0; |
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| 68 | the_mutex->holder = NULL; |
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| 69 | the_mutex->holder_id = 0; |
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| 70 | } |
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| 71 | |
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| 72 | _Thread_queue_Initialize( |
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| 73 | &the_mutex->Wait_queue, |
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| 74 | the_class, |
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| 75 | _CORE_mutex_Is_priority( the_mutex_attributes ) ? |
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| 76 | THREAD_QUEUE_DISCIPLINE_PRIORITY : THREAD_QUEUE_DISCIPLINE_FIFO, |
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| 77 | STATES_WAITING_FOR_MUTEX, |
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| 78 | proxy_extract_callout, |
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| 79 | CORE_MUTEX_TIMEOUT |
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| 80 | ); |
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| 81 | } |
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| 82 | |
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| 83 | /*PAGE |
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| 84 | * |
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| 85 | * _CORE_mutex_Seize |
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| 86 | * |
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| 87 | * This routine attempts to allocate a mutex to the calling thread. |
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| 88 | * |
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| 89 | * Input parameters: |
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| 90 | * the_mutex - pointer to mutex control block |
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| 91 | * id - id of object to wait on |
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| 92 | * wait - TRUE if wait is allowed, FALSE otherwise |
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| 93 | * timeout - number of ticks to wait (0 means forever) |
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| 94 | * |
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| 95 | * Output parameters: NONE |
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| 96 | * |
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| 97 | * INTERRUPT LATENCY: |
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| 98 | * available |
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| 99 | * wait |
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| 100 | */ |
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| 101 | |
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| 102 | void _CORE_mutex_Seize( |
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| 103 | CORE_mutex_Control *the_mutex, |
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| 104 | Objects_Id id, |
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| 105 | boolean wait, |
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| 106 | Watchdog_Interval timeout |
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| 107 | ) |
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| 108 | { |
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| 109 | Thread_Control *executing; |
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| 110 | ISR_Level level; |
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| 111 | |
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| 112 | executing = _Thread_Executing; |
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| 113 | executing->Wait.return_code = CORE_MUTEX_STATUS_SUCCESSFUL; |
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| 114 | _ISR_Disable( level ); |
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| 115 | if ( ! _CORE_mutex_Is_locked( the_mutex ) ) { |
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| 116 | the_mutex->lock = CORE_MUTEX_LOCKED; |
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| 117 | the_mutex->holder = executing; |
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| 118 | the_mutex->holder_id = executing->Object.id; |
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| 119 | the_mutex->nest_count = 1; |
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| 120 | executing->resource_count++; |
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| 121 | _ISR_Enable( level ); |
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| 122 | return; |
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| 123 | } |
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| 124 | |
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| 125 | if ( !wait ) { |
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| 126 | _ISR_Enable( level ); |
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| 127 | executing->Wait.return_code = CORE_MUTEX_STATUS_UNSATISFIED_NOWAIT; |
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| 128 | return; |
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| 129 | } |
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| 130 | |
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| 131 | if ( _Objects_Are_ids_equal( |
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| 132 | _Thread_Executing->Object.id, the_mutex->holder_id ) ) { |
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| 133 | if ( _CORE_mutex_Is_nesting_allowed( &the_mutex->Attributes ) ) |
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| 134 | the_mutex->nest_count++; |
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| 135 | else |
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| 136 | executing->Wait.return_code = CORE_MUTEX_STATUS_NESTING_NOT_ALLOWED; |
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| 137 | |
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| 138 | _ISR_Enable( level ); |
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| 139 | return; |
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| 140 | } |
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| 141 | |
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| 142 | the_mutex->Wait_queue.sync = TRUE; |
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| 143 | executing->Wait.queue = &the_mutex->Wait_queue; |
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| 144 | executing->Wait.id = id; |
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| 145 | _ISR_Enable( level ); |
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| 146 | |
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| 147 | if ( _CORE_mutex_Is_inherit_priority( &the_mutex->Attributes ) && |
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| 148 | the_mutex->holder->current_priority > |
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| 149 | _Thread_Executing->current_priority ) { |
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| 150 | _Thread_Change_priority( |
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| 151 | the_mutex->holder, _Thread_Executing->current_priority ); |
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| 152 | } |
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| 153 | |
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| 154 | _Thread_queue_Enqueue( &the_mutex->Wait_queue, timeout ); |
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| 155 | } |
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| 156 | |
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| 157 | /* |
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| 158 | * _CORE_mutex_Surrender |
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| 159 | * |
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| 160 | * DESCRIPTION: |
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| 161 | * |
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| 162 | * This routine frees a unit to the mutex. If a task was blocked waiting for |
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| 163 | * a unit from this mutex, then that task will be readied and the unit |
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| 164 | * given to that task. Otherwise, the unit will be returned to the mutex. |
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| 165 | * |
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| 166 | * Input parameters: |
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| 167 | * the_mutex - the mutex to be flushed |
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| 168 | * id - id of parent mutex |
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| 169 | * api_mutex_mp_support - api dependent MP support actions |
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| 170 | * |
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| 171 | * Output parameters: |
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| 172 | * CORE_MUTEX_STATUS_SUCCESSFUL - if successful |
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| 173 | * core error code - if unsuccessful |
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| 174 | */ |
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| 175 | |
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| 176 | CORE_mutex_Status _CORE_mutex_Surrender( |
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| 177 | CORE_mutex_Control *the_mutex, |
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| 178 | Objects_Id id, |
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| 179 | CORE_mutex_API_mp_support_callout api_mutex_mp_support |
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| 180 | ) |
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| 181 | { |
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| 182 | Thread_Control *the_thread; |
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| 183 | |
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| 184 | if ( !_Objects_Are_ids_equal( |
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| 185 | _Thread_Executing->Object.id, the_mutex->holder_id ) ) |
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| 186 | return( CORE_MUTEX_STATUS_NOT_OWNER_OF_RESOURCE ); |
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| 187 | |
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| 188 | the_mutex->nest_count--; |
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| 189 | |
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| 190 | if ( the_mutex->nest_count != 0 ) |
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| 191 | return( CORE_MUTEX_STATUS_SUCCESSFUL ); |
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| 192 | |
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| 193 | _Thread_Executing->resource_count--; |
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| 194 | the_mutex->holder = NULL; |
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| 195 | the_mutex->holder_id = 0; |
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| 196 | |
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| 197 | /* |
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| 198 | * Whether or not someone is waiting for the mutex, an |
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| 199 | * inherited priority must be lowered if this is the last |
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| 200 | * mutex (i.e. resource) this task has. |
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| 201 | */ |
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| 202 | |
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| 203 | if ( _CORE_mutex_Is_inherit_priority( &the_mutex->Attributes ) && |
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| 204 | _Thread_Executing->resource_count == 0 && |
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| 205 | _Thread_Executing->real_priority != |
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| 206 | _Thread_Executing->current_priority ) { |
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| 207 | _Thread_Change_priority( |
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| 208 | _Thread_Executing, |
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| 209 | _Thread_Executing->real_priority |
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| 210 | ); |
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| 211 | } |
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| 212 | |
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| 213 | if ( ( the_thread = _Thread_queue_Dequeue( &the_mutex->Wait_queue ) ) ) { |
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| 214 | |
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| 215 | if ( !_Objects_Is_local_id( the_thread->Object.id ) ) { |
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| 216 | |
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| 217 | the_mutex->holder = NULL; |
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| 218 | the_mutex->holder_id = the_thread->Object.id; |
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| 219 | the_mutex->nest_count = 1; |
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| 220 | |
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| 221 | ( *api_mutex_mp_support)( the_thread, id ); |
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| 222 | |
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| 223 | } else { |
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| 224 | |
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| 225 | the_mutex->holder = the_thread; |
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| 226 | the_mutex->holder_id = the_thread->Object.id; |
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| 227 | the_thread->resource_count++; |
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| 228 | the_mutex->nest_count = 1; |
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| 229 | |
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| 230 | /* |
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| 231 | * No special action for priority inheritance because the_thread |
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| 232 | * is guaranteed to be the highest priority thread waiting for |
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| 233 | * the mutex. |
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| 234 | */ |
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| 235 | } |
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| 236 | } else |
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| 237 | the_mutex->lock = CORE_MUTEX_UNLOCKED; |
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| 238 | |
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| 239 | return( CORE_MUTEX_STATUS_SUCCESSFUL ); |
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| 240 | } |
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| 241 | |
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| 242 | /*PAGE |
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| 243 | * |
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| 244 | * _CORE_mutex_Flush |
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| 245 | * |
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| 246 | * This function a flushes the mutex's task wait queue. |
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| 247 | * |
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| 248 | * Input parameters: |
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| 249 | * the_mutex - the mutex to be flushed |
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| 250 | * remote_extract_callout - function to invoke remotely |
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| 251 | * status - status to pass to thread |
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| 252 | * |
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| 253 | * Output parameters: NONE |
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| 254 | */ |
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| 255 | |
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| 256 | void _CORE_mutex_Flush( |
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| 257 | CORE_mutex_Control *the_mutex, |
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| 258 | Thread_queue_Flush_callout remote_extract_callout, |
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| 259 | unsigned32 status |
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| 260 | ) |
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| 261 | { |
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| 262 | |
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| 263 | _Thread_queue_Flush( |
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| 264 | &the_mutex->Wait_queue, |
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| 265 | remote_extract_callout, |
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| 266 | status |
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| 267 | ); |
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| 268 | |
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| 269 | } |
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