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/**
* @file
*
* @brief CORE Mutex API
*
* This include file contains all the constants and structures associated with
* the Mutex Handler. A mutex is an enhanced version of the standard Dijkstra
* binary semaphore used to provide synchronization and mutual exclusion
* capabilities.
*/
/*
* COPYRIGHT (c) 1989-2011.
* On-Line Applications Research Corporation (OAR).
*
* The license and distribution terms for this file may be
* found in the file LICENSE in this distribution or at
* http://www.rtems.org/license/LICENSE.
*/
#ifndef _RTEMS_SCORE_COREMUTEX_H
#define _RTEMS_SCORE_COREMUTEX_H
#include <rtems/score/thread.h>
#include <rtems/score/threadq.h>
#include <rtems/score/priority.h>
#include <rtems/score/watchdog.h>
#include <rtems/score/interr.h>
#ifdef __cplusplus
extern "C" {
#endif
/**
* @defgroup ScoreMutex Mutex Handler
*
* @ingroup Score
*
* This handler encapsulates functionality which provides the foundation
* Mutex services used in all of the APIs supported by RTEMS.
*/
/**@{*/
/**
* @brief The possible behaviors for lock nesting.
*
* This enumerated type defines the possible behaviors for
* lock nesting.
*/
typedef enum {
/**
* This sequence has no blocking or errors:
*
* + lock(m)
* + lock(m)
* + unlock(m)
* + unlock(m)
*/
CORE_MUTEX_NESTING_ACQUIRES,
#if defined(RTEMS_POSIX_API)
/**
* This sequence returns an error at the indicated point:
*
* + lock(m)
* + lock(m) - already locked error
* + unlock(m)
*/
CORE_MUTEX_NESTING_IS_ERROR,
#endif
} CORE_mutex_Nesting_behaviors;
/**
* @brief The control block used to manage attributes of each mutex.
*
* The following defines the control block used to manage the
* attributes of each mutex.
*/
typedef struct {
/** This field determines what the behavior of this mutex instance will
* be when attempting to acquire the mutex when it is already locked.
*/
CORE_mutex_Nesting_behaviors lock_nesting_behavior;
} CORE_mutex_Attributes;
/**
* @brief Control block used to manage each mutex.
*
* The following defines the control block used to manage each mutex.
*/
typedef struct {
/** This field is the Waiting Queue used to manage the set of tasks
* which are blocked waiting to lock the mutex.
*/
Thread_queue_Control Wait_queue;
/** This element is the set of attributes which define this instance's
* behavior.
*/
CORE_mutex_Attributes Attributes;
/** This element contains the number of times the mutex has been acquired
* nested. This must be zero (0) before the mutex is actually unlocked.
*/
uint32_t nest_count;
/** This element points to the thread which is currently holding this mutex.
* The holder is the last thread to successfully lock the mutex and which
* has not unlocked it. If the thread is not locked, there is no holder.
*/
Thread_Control *holder;
} CORE_mutex_Control;
/**
* @brief The recursive mutex control.
*/
typedef struct {
/**
* @brief The plain non-recursive mutex.
*/
CORE_mutex_Control Mutex;
/**
* @brief The nest level in case of a recursive seize.
*/
unsigned int nest_level;
} CORE_recursive_mutex_Control;
/**
* @brief The recursive mutex control with priority ceiling protocol support.
*/
typedef struct {
/**
* @brief The plain recursive mutex.
*/
CORE_recursive_mutex_Control Recursive;
/**
* @brief The priority ceiling value for the mutex owner.
*/
Priority_Control priority_ceiling;
} CORE_ceiling_mutex_Control;
/**@}*/
#ifdef __cplusplus
}
#endif
#endif
/* end of include file */
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