/**
* @file
*
* @ingroup ScoreMutex
*
* @brief CORE Mutex Implementation
*/
/*
* COPYRIGHT (c) 1989-2009.
* 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_COREMUTEXIMPL_H
#define _RTEMS_SCORE_COREMUTEXIMPL_H
#include <rtems/score/coremutex.h>
#include <rtems/score/chainimpl.h>
#include <rtems/score/status.h>
#include <rtems/score/sysstate.h>
#include <rtems/score/threadimpl.h>
#include <rtems/score/threadqimpl.h>
#ifdef __cplusplus
extern "C" {
#endif
/**
* @addtogroup ScoreMutex
*/
/**@{**/
/**
* @brief Initializes the mutex based on the parameters passed.
*
* This routine initializes the mutex based on the parameters passed.
*
* @param[in,out] the_mutex is the mutex to initalize
* @param[in,out] executing The currently executing thread.
* @param[in] the_mutex_attributes is the attributes associated with this
* mutex instance
* @param[in] initially_locked If true, then the mutex is initially locked by
* the executing thread.
*
* @retval This method returns STATUS_SUCCESSFUL if successful.
*/
Status_Control _CORE_mutex_Initialize(
CORE_mutex_Control *the_mutex,
Thread_Control *executing,
const CORE_mutex_Attributes *the_mutex_attributes,
bool initially_locked
);
RTEMS_INLINE_ROUTINE void _CORE_mutex_Destroy( CORE_mutex_Control *the_mutex )
{
_Thread_queue_Destroy( &the_mutex->Wait_queue );
}
RTEMS_INLINE_ROUTINE void _CORE_mutex_Acquire_critical(
CORE_mutex_Control *the_mutex,
Thread_queue_Context *queue_context
)
{
_Thread_queue_Acquire_critical(
&the_mutex->Wait_queue,
&queue_context->Lock_context
);
}
RTEMS_INLINE_ROUTINE void _CORE_mutex_Release(
CORE_mutex_Control *the_mutex,
Thread_queue_Context *queue_context
)
{
_Thread_queue_Release(
&the_mutex->Wait_queue,
&queue_context->Lock_context
);
}
/**
* @brief Performs the blocking portion of a mutex obtain.
*
* 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[in,out] the_mutex is the mutex to attempt to lock
* @param[in,out] executing The currently executing thread.
* @param[in] timeout is the maximum number of ticks to block
* @param[in] lock_context is the interrupt level
*/
Status_Control _CORE_mutex_Seize_interrupt_blocking(
CORE_mutex_Control *the_mutex,
Thread_Control *executing,
Watchdog_Interval timeout,
ISR_lock_Context *lock_context
);
/**
* @brief Verifies that a mutex blocking seize is performed safely.
*
* This macro is to verify that a mutex blocking seize is
* performed from a safe system state. For example, one
* cannot block inside an isr.
*
* @retval this method returns true if dispatch is in an unsafe state.
*/
#define _CORE_mutex_Check_dispatch_for_seize(_wait) \
(!_Thread_Dispatch_is_enabled() \
&& (_wait) \
&& (_System_state_Get() >= SYSTEM_STATE_UP))
/**
* @brief Is mutex locked.
*
* This routine returns true if the mutex specified is locked and false
* otherwise.
*
* @param[in] the_mutex is the mutex to check.
*
* @retval true The mutex is locked.
* @retval false The mutex is not locked.
*/
RTEMS_INLINE_ROUTINE bool _CORE_mutex_Is_locked(
const CORE_mutex_Control *the_mutex
)
{
return the_mutex->holder != NULL;
}
/**
* @brief Does mutex use priority inheritance.
*
* This routine returns true if the mutex's wait discipline is
* INHERIT_PRIORITY and false otherwise.
*
* @param[in] the_attribute is the attribute set of the mutex.
*
* @retval true The mutex is using priority inheritance.
* @retval false The mutex is not using priority inheritance.
*/
RTEMS_INLINE_ROUTINE bool _CORE_mutex_Is_inherit_priority(
const CORE_mutex_Attributes *the_attribute
)
{
return the_attribute->discipline == CORE_MUTEX_DISCIPLINES_PRIORITY_INHERIT;
}
/**
* @brief Does mutex use priority ceiling.
*
* This routine returns true if the mutex's wait discipline is
* PRIORITY_CEILING and false otherwise.
*
* @param[in] the_attribute is the attribute set of the mutex.
*
* @retval true The mutex is using priority ceiling.
* @retval false The mutex is not using priority ceiling.
*/
RTEMS_INLINE_ROUTINE bool _CORE_mutex_Is_priority_ceiling(
const CORE_mutex_Attributes *the_attribute
)
{
return the_attribute->discipline == CORE_MUTEX_DISCIPLINES_PRIORITY_CEILING;
}
/**
* @brief Attempt to receive a unit from the_mutex.
*
* 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[in,out] executing The currently executing thread.
* @param[in,out] the_mutex is the mutex to attempt to lock
* @param[in] queue_context is the interrupt level
*
* @retval STATUS_UNAVAILABLE The mutex is already locked.
* @retval other Otherwise.
*/
RTEMS_INLINE_ROUTINE Status_Control _CORE_mutex_Seize_interrupt_trylock(
CORE_mutex_Control *the_mutex,
Thread_Control *executing,
Thread_queue_Context *queue_context
)
{
/* disabled when you get here */
if ( !_CORE_mutex_Is_locked( the_mutex ) ) {
the_mutex->holder = executing;
the_mutex->nest_count = 1;
if ( _CORE_mutex_Is_inherit_priority( &the_mutex->Attributes ) ||
_CORE_mutex_Is_priority_ceiling( &the_mutex->Attributes ) ){
executing->resource_count++;
}
if ( !_CORE_mutex_Is_priority_ceiling( &the_mutex->Attributes ) ) {
_CORE_mutex_Release( the_mutex, queue_context );
} else {
/*
* must be CORE_MUTEX_DISCIPLINES_PRIORITY_CEILING
*
* we possibly bump the priority of the current holder -- which
* happens to be _Thread_Executing.
*/
Priority_Control ceiling;
Priority_Control current;
ceiling = the_mutex->Attributes.priority_ceiling;
current = executing->current_priority;
if ( current == ceiling ) {
_CORE_mutex_Release( the_mutex, queue_context );
} else if ( current > ceiling ) {
Per_CPU_Control *cpu_self;
cpu_self = _Thread_Dispatch_disable_critical(
&queue_context->Lock_context
);
_CORE_mutex_Release( the_mutex, queue_context );
_Thread_Raise_priority( executing, ceiling );
_Thread_Dispatch_enable( cpu_self );
} else /* if ( current < ceiling ) */ {
the_mutex->holder = NULL;
the_mutex->nest_count = 0; /* undo locking above */
executing->resource_count--; /* undo locking above */
_CORE_mutex_Release( the_mutex, queue_context );
return STATUS_MUTEX_CEILING_VIOLATED;
}
}
return STATUS_SUCCESSFUL;
}
/*
* At this point, we know the mutex was not available. If this thread
* is the thread that has locked the mutex, let's see if we are allowed
* to nest access.
*/
if ( _Thread_Is_executing( the_mutex->holder ) ) {
switch ( the_mutex->Attributes.lock_nesting_behavior ) {
case CORE_MUTEX_NESTING_ACQUIRES:
the_mutex->nest_count++;
_CORE_mutex_Release( the_mutex, queue_context );
return STATUS_SUCCESSFUL;
#if defined(RTEMS_POSIX_API)
case CORE_MUTEX_NESTING_IS_ERROR:
_CORE_mutex_Release( the_mutex, queue_context );
return STATUS_NESTING_NOT_ALLOWED;
#endif
case CORE_MUTEX_NESTING_BLOCKS:
break;
}
}
/*
* The mutex is not available and the caller must deal with the possibility
* of blocking.
*/
return STATUS_UNAVAILABLE;
}
/**
* @brief Attempt to obtain the mutex.
*
* 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[in] the_mutex is the mutex to attempt to lock
* @param[in] wait is true if the thread is willing to wait
* @param[in] timeout is the maximum number of ticks to block
* @param[in] queue_context is a temporary variable used to contain the ISR
* disable level cookie
*
* @note If the mutex is called from an interrupt service routine,
* with context switching disabled, or before multitasking,
* then a fatal error is generated.
*
* The logic on this routine is as follows:
*
* * If incorrect system state
* return an error
* * If mutex is available without any contention or blocking
* obtain it with interrupts disabled and returned
* * If the caller is willing to wait
* then they are blocked.
*/
RTEMS_INLINE_ROUTINE Status_Control _CORE_mutex_Seize(
CORE_mutex_Control *the_mutex,
Thread_Control *executing,
bool wait,
Watchdog_Interval timeout,
Thread_queue_Context *queue_context
)
{
Status_Control status;
if ( _CORE_mutex_Check_dispatch_for_seize( wait ) ) {
_Terminate(
INTERNAL_ERROR_CORE,
false,
INTERNAL_ERROR_MUTEX_OBTAIN_FROM_BAD_STATE
);
}
_CORE_mutex_Acquire_critical( the_mutex, queue_context );
status = _CORE_mutex_Seize_interrupt_trylock(
the_mutex,
executing,
queue_context
);
if ( status != STATUS_UNAVAILABLE ) {
return status;
}
if ( !wait ) {
_CORE_mutex_Release( the_mutex, queue_context );
return status;
}
return _CORE_mutex_Seize_interrupt_blocking(
the_mutex,
executing,
timeout,
&queue_context->Lock_context
);
}
Status_Control _CORE_mutex_Surrender(
CORE_mutex_Control *the_mutex,
Thread_queue_Context *queue_context
);
RTEMS_INLINE_ROUTINE void _CORE_mutex_Flush(
CORE_mutex_Control *the_mutex,
Thread_queue_Flush_filter filter,
Thread_queue_Context *queue_context
)
{
_Thread_queue_Flush_critical(
&the_mutex->Wait_queue.Queue,
the_mutex->operations,
filter,
queue_context
);
}
RTEMS_INLINE_ROUTINE bool _CORE_mutex_Is_owner(
const CORE_mutex_Control *the_mutex,
const Thread_Control *the_thread
)
{
return the_mutex->holder == the_thread;
}
/**
* @brief Does core mutex use FIFO blocking.
*
* This routine returns true if the mutex's wait discipline is FIFO and false
* otherwise.
*
* @param[in] the_attribute is the attribute set of the mutex.
*
* @retval true The mutex is using FIFO blocking order.
* @retval false The mutex is not using FIFO blocking order.
*/
RTEMS_INLINE_ROUTINE bool _CORE_mutex_Is_fifo(
const CORE_mutex_Attributes *the_attribute
)
{
return the_attribute->discipline == CORE_MUTEX_DISCIPLINES_FIFO;
}
/** @} */
#ifdef __cplusplus
}
#endif
#endif
/* end of include file */
