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/*
* Copyright (c) 2014, 2016 embedded brains GmbH. All rights reserved.
*
* embedded brains GmbH
* Dornierstr. 4
* 82178 Puchheim
* Germany
* <rtems@embedded-brains.de>
*
* 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_MRSP_H
#define _RTEMS_SCORE_MRSP_H
#include <rtems/score/cpuopts.h>
#if defined(RTEMS_SMP)
#include <rtems/score/chain.h>
#include <rtems/score/scheduler.h>
#include <rtems/score/thread.h>
#include <rtems/score/threadq.h>
#ifdef __cplusplus
extern "C" {
#endif /* __cplusplus */
/**
* @defgroup ScoreMRSP Multiprocessor Resource Sharing Protocol Handler
*
* @ingroup Score
*
* @brief Multiprocessor Resource Sharing Protocol (MrsP).
*
* The Multiprocessor Resource Sharing Protocol (MrsP) is defined in A. Burns
* and A.J. Wellings, A Schedulability Compatible Multiprocessor Resource
* Sharing Protocol - MrsP, Proceedings of the 25th Euromicro Conference on
* Real-Time Systems (ECRTS 2013), July 2013. It is a generalization of the
* Priority Ceiling Protocol to SMP systems. Each MrsP semaphore uses a
* ceiling priority per scheduler instance. A task obtaining or owning a MrsP
* semaphore will execute with the ceiling priority for its scheduler instance
* as specified by the MrsP semaphore object. Tasks waiting to get ownership
* of a MrsP semaphore will not relinquish the processor voluntarily. In case
* the owner of a MrsP semaphore gets preempted it can ask all tasks waiting
* for this semaphore to help out and temporarily borrow the right to execute
* on one of their assigned processors.
*
* @{
*/
typedef struct MRSP_Control MRSP_Control;
/**
* @brief MrsP rival.
*
* The rivals are used by threads waiting for resource ownership. They are
* registered in the MrsP control block.
*/
typedef struct {
/**
* @brief The node for registration in the MrsP rival chain.
*
* The chain operations are protected by the MrsP control lock.
*
* @see MRSP_Control::Rivals.
*/
Chain_Node Node;
/**
* @brief The corresponding MrsP control block.
*/
MRSP_Control *resource;
/**
* @brief Identification of the rival thread.
*/
Thread_Control *thread;
/**
* @brief The ceiling priority used by the rival thread.
*/
Priority_Node Ceiling_priority;
/**
* @brief The initial help state of the thread at the begin of the resource
* obtain sequence.
*
* Used to restore this state after a timeout.
*/
Scheduler_Help_state initial_help_state;
/**
* @brief The rival status.
*
* Initially the status is set to MRSP_WAIT_FOR_OWNERSHIP. The rival will
* busy wait until a status change happens. This can be STATUS_SUCCESSFUL or
* STATUS_TIMEOUT. State changes are protected by the MrsP control lock.
*/
volatile int status;
/**
* @brief Watchdog for timeouts.
*/
Watchdog_Control Watchdog;
} MRSP_Rival;
/**
* @brief MrsP control block.
*/
struct MRSP_Control {
/**
* @brief Lock to protect the resource dependency tree.
*
* This is a thread queue since this simplifies the Classic semaphore
* implementation. Only the lock part of the thread queue is used.
*/
Thread_queue_Control Wait_queue;
/**
* @brief Basic resource control.
*/
Resource_Control Resource;
/**
* @brief A chain of MrsP rivals waiting for resource ownership.
*
* @see MRSP_Rival::Node.
*/
Chain_Control Rivals;
/**
* @brief The ceiling priority used by the owner thread.
*/
Priority_Node Ceiling_priority;
/**
* @brief One ceiling priority per scheduler instance.
*/
Priority_Control *ceiling_priorities;
};
/** @} */
#ifdef __cplusplus
}
#endif /* __cplusplus */
#endif /* RTEMS_SMP */
#endif /* _RTEMS_SCORE_MRSP_H */
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