/**
* @file coremutex.h
*
* 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) 1989-2004.
* 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.com/license/LICENSE.
*
* $Id$
*/
#ifndef __RTEMS_CORE_MUTEX_h
#define __RTEMS_CORE_MUTEX_h
/**
* @defgroup ScoreMutex Mutex Handler
*
* This group contains functionality which provides the foundation
* Mutex services used in all of the APIs supported by RTEMS.
*/
/**@{*/
#ifdef __cplusplus
extern "C" {
#endif
#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>
#include <rtems/score/sysstate.h>
/**
* The following type defines the callout which the API provides
* to support global/multiprocessor operations on mutexes.
*/
typedef void ( *CORE_mutex_API_mp_support_callout )(
Thread_Control *,
Objects_Id
);
/**
* Blocking disciplines for a mutex.
*/
typedef enum {
/** This specifies that threads will wait for the mutex in FIFO order. */
CORE_MUTEX_DISCIPLINES_FIFO,
/** This specifies that threads will wait for the mutex in priority order. */
CORE_MUTEX_DISCIPLINES_PRIORITY,
/** This specifies that threads will wait for the mutex in priority order.
* Additionally, the Priority Inheritance Protocol will be in effect.
*/
CORE_MUTEX_DISCIPLINES_PRIORITY_INHERIT,
/** This specifies that threads will wait for the mutex in priority order.
* Additionally, the Priority Ceiling Protocol will be in effect.
*/
CORE_MUTEX_DISCIPLINES_PRIORITY_CEILING
} CORE_mutex_Disciplines;
/**
* Mutex handler return statuses.
*/
typedef enum {
/** This status indicates that the operation completed successfully. */
CORE_MUTEX_STATUS_SUCCESSFUL,
/** This status indicates that the calling task did not want to block
* and the operation was unable to complete immediately because the
* resource was unavailable.
*/
CORE_MUTEX_STATUS_UNSATISFIED_NOWAIT,
/** This status indicates that an attempt was made to relock a mutex
* for which nesting is not configured.
*/
CORE_MUTEX_STATUS_NESTING_NOT_ALLOWED,
/** This status indicates that an attempt was made to release a mutex
* by a thread other than the thread which locked it.
*/
CORE_MUTEX_STATUS_NOT_OWNER_OF_RESOURCE,
/** This status indicates that the thread was blocked waiting for an
* operation to complete and the mutex was deleted.
*/
CORE_MUTEX_WAS_DELETED,
/** This status indicates that the calling task was willing to block
* but the operation was unable to complete within the time allotted
* because the resource never became available.
*/
CORE_MUTEX_TIMEOUT,
/** This status indicates that a thread of logically greater importance
* than the ceiling priority attempted to lock this mutex.
*/
CORE_MUTEX_STATUS_CEILING_VIOLATED
} CORE_mutex_Status;
/**
* Mutex lock nesting behavior
*
* + CORE_MUTEX_NESTING_ACQUIRES:
* This sequence has no blocking or errors:
*
* + lock(m)
* + lock(m)
* + unlock(m)
* + unlock(m)
*
* + CORE_MUTEX_NESTING_IS_ERROR
* This sequence returns an error at the indicated point:
*
* + lock(m)
* + lock(m) - already locked error
* + unlock(m)
*
* + CORE_MUTEX_NESTING_BLOCKS
* This sequence performs as indicated:
* + lock(m)
* + lock(m) - deadlocks or timeouts
* + unlock(m) - releases
*/
typedef enum {
CORE_MUTEX_NESTING_ACQUIRES,
CORE_MUTEX_NESTING_IS_ERROR,
CORE_MUTEX_NESTING_BLOCKS
} CORE_mutex_Nesting_behaviors;
/**
* This is the value of a mutex when it is unlocked.
*/
#define CORE_MUTEX_UNLOCKED 1
/**
* This is the value of a mutex when it is locked.
*/
#define CORE_MUTEX_LOCKED 0
/**
* 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;
/** When this field is TRUE, then only the thread that locked the mutex
* is allowed to unlock it.
*/
boolean only_owner_release;
/** This field indicates whether threads waiting on the mutex block in
* FIFO or priority order.
*/
CORE_mutex_Disciplines discipline;
/** This field contains the ceiling priority to be used if that protocol
* is selected.
*/
Priority_Control priority_ceiling;
} CORE_mutex_Attributes;
/**
* 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 current state of the mutex.
*/
uint32_t lock;
/** 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 is the number of waiting threads. */
uint32_t blocked_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;
/** This element contains the object Id of the holding thread. */
Objects_Id holder_id;
} CORE_mutex_Control;
/**
*
* This routine initializes the mutex based on the parameters passed.
*
* @param the_mutex (in) is the mutex to initalize
* @param the_mutex_attributes (in) is the attributes associated with this
* mutex instance
* @param initial_lock (in) is the initial value of the mutex
*/
void _CORE_mutex_Initialize(
CORE_mutex_Control *the_mutex,
CORE_mutex_Attributes *the_mutex_attributes,
uint32_t initial_lock
);
#ifndef __RTEMS_APPLICATION__
/**
* This routine attempts to receive a unit from the_mutex.
* If a unit is available or if the wait flag is FALSE, then the routine
* returns. Otherwise, the calling task is blocked until a unit becomes
* available.
*
* @param the_mutex (in) is the mutex to attempt to lock
* @param level_p (in) is the interrupt level holder
*
* @note For performance reasons, this routine is implemented as
* a macro that uses two support routines.
*/
RTEMS_INLINE_ROUTINE int _CORE_mutex_Seize_interrupt_trylock(
CORE_mutex_Control *the_mutex,
ISR_Level *level_p
);
/**
* This routine performs the blocking portion of a mutex obtain.
* It is an actual subroutine and is not implemented as something
* that may be inlined.
*
* @param the_mutex (in) is the mutex to attempt to lock
* @param timeout (in) is the maximum number of ticks to block
*/
void _CORE_mutex_Seize_interrupt_blocking(
CORE_mutex_Control *the_mutex,
Watchdog_Interval timeout
);
/**
* This routine attempts to obtain the mutex. If the mutex is available,
* then it will return immediately. Otherwise, it will invoke the
* support routine @a _Core_mutex_Seize_interrupt_blocking.
*
* @param _the_mutex (in) is the mutex to attempt to lock
* @param _id (in) is the Id of the owning API level Semaphore object
* @param _wait (in) is TRUE if the thread is willing to wait
* @param _timeout (in) is the maximum number of ticks to block
* @param _level (in) is a temporary variable used to contain the ISR
* disable level cookie
*/
#define _CORE_mutex_Seize( \
_the_mutex, _id, _wait, _timeout, _level ) \
do { \
if ( _Thread_Dispatch_disable_level \
&& (_wait) \
&& (_System_state_Get() >= SYSTEM_STATE_BEGIN_MULTITASKING ) \
) { \
_Internal_error_Occurred( \
INTERNAL_ERROR_CORE, \
FALSE, \
18 /* called from wrong environment */); \
} \
if ( _CORE_mutex_Seize_interrupt_trylock( _the_mutex, &_level ) ) { \
if ( !_wait ) { \
_ISR_Enable( _level ); \
_Thread_Executing->Wait.return_code = \
CORE_MUTEX_STATUS_UNSATISFIED_NOWAIT; \
} else { \
_Thread_queue_Enter_critical_section( &(_the_mutex)->Wait_queue ); \
_Thread_Executing->Wait.queue = &(_the_mutex)->Wait_queue; \
_Thread_Executing->Wait.id = _id; \
_Thread_Disable_dispatch(); \
_ISR_Enable( _level ); \
_CORE_mutex_Seize_interrupt_blocking( _the_mutex, _timeout ); \
} \
} \
} while (0)
/**
* This routine frees a unit to the mutex. If a task was blocked waiting for
* a unit from this mutex, then that task will be readied and the unit
* given to that task. Otherwise, the unit will be returned to the mutex.
*
* @param the_mutex (in) is the mutex to surrender
* @param id (in) is the id of the RTEMS Object associated with this mutex
* @param api_mutex_mp_support (in) is the routine that will be called when
* unblocking a remote mutex
*
* @return an indication of whether the routine succeeded or failed
*/
CORE_mutex_Status _CORE_mutex_Surrender(
CORE_mutex_Control *the_mutex,
Objects_Id id,
CORE_mutex_API_mp_support_callout api_mutex_mp_support
);
/**
* This routine assists in the deletion of a mutex by flushing the associated
* wait queue.
*
* @param the_mutex (in) is the mutex to flush
* @param remote_extract_callout (in) is the routine to invoke when a remote
* thread is extracted
* @param status (in) is the status value which each unblocked thread will
* return to its caller.
*/
void _CORE_mutex_Flush(
CORE_mutex_Control *the_mutex,
Thread_queue_Flush_callout remote_extract_callout,
uint32_t status
);
#include <rtems/score/coremutex.inl>
#endif
#ifdef __cplusplus
}
#endif
/**@}*/
#endif
/* end of include file */
