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/**
* @brief Constants and Structures Related with Thread Dispatch
*/
/*
* 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_THREADDISPATCH_H
#define _RTEMS_SCORE_THREADDISPATCH_H
#include <rtems/score/percpu.h>
#include <rtems/score/smplock.h>
#include <rtems/score/profiling.h>
#ifdef __cplusplus
extern "C" {
#endif /* __cplusplus */
#if defined(RTEMS_HEAVY_STACK_DEBUG) || \
defined(RTEMS_HEAVY_MALLOC_DEBUG)
#define __THREAD_DO_NOT_INLINE_DISABLE_DISPATCH__
#endif
#if defined(RTEMS_SMP) || \
(CPU_INLINE_ENABLE_DISPATCH == FALSE) || \
(__RTEMS_DO_NOT_INLINE_THREAD_ENABLE_DISPATCH__ == 1)
#define __THREAD_DO_NOT_INLINE_ENABLE_DISPATCH__
#endif
/**
* @addtogroup ScoreThread
*
* @{
*/
/**
* @brief Indicates if the executing thread is inside a thread dispatch
* critical section.
*
* @retval true Thread dispatching is enabled.
* @retval false The executing thread is inside a thread dispatch critical
* section and dispatching is not allowed.
*/
RTEMS_INLINE_ROUTINE bool _Thread_Dispatch_is_enabled(void)
{
bool enabled;
#if defined(RTEMS_SMP)
ISR_Level level;
_ISR_Disable_without_giant( level );
#endif
enabled = _Thread_Dispatch_disable_level == 0;
#if defined(RTEMS_SMP)
_ISR_Enable_without_giant( level );
#endif
return enabled;
}
/**
* @brief Gets thread dispatch disable level.
*
* @return The value of the thread dispatch level.
*/
RTEMS_INLINE_ROUTINE uint32_t _Thread_Dispatch_get_disable_level(void)
{
return _Thread_Dispatch_disable_level;
}
/**
* @brief Thread dispatch initialization.
*
* This routine initializes the thread dispatching subsystem.
*/
RTEMS_INLINE_ROUTINE void _Thread_Dispatch_initialization( void )
{
_Thread_Dispatch_disable_level = 1;
}
#if defined(RTEMS_SMP)
/**
* @brief Acquires the giant lock.
*
* The giant lock is a recursive SMP lock protecting nearly all operating
* system services.
*
* This lock is implicitly acquired in
* _Thread_Dispatch_increment_disable_level().
*
* Thread dispatching must be disabled before the Giant lock can be acquired
* and must no be enabled while owning the Giant lock. The thread dispatch
* disable level is not altered by this function.
*
* @param[in] cpu_self The current processor.
*/
void _Giant_Acquire( Per_CPU_Control *cpu_self );
/**
* @brief Releases the giant lock.
*
* This lock is implicitly released in
* _Thread_Dispatch_decrement_disable_level().
*
* The thread dispatch disable level is not altered by this function.
*
* @param[in] cpu_self The current processor.
*/
void _Giant_Release( Per_CPU_Control *cpu_self );
/**
* @brief Releases the giant lock completely if held by the executing processor.
*
* The thread dispatch disable level is not altered by this function.
*
* The only use case for this operation is in _SMP_Request_shutdown().
*
* @param[in] cpu_self The current processor.
*/
void _Giant_Drop( Per_CPU_Control *cpu_self );
/**
* @brief Increments the thread dispatch level.
*
* This rountine increments the thread dispatch level
*/
uint32_t _Thread_Dispatch_increment_disable_level(void);
/**
* @brief Decrements the thread dispatch level.
*
* This routine decrements the thread dispatch level.
*/
uint32_t _Thread_Dispatch_decrement_disable_level(void);
#else /* RTEMS_SMP */
/**
* @brief Increase thread dispatch disable level.
*
* This rountine increments the thread dispatch level
*/
RTEMS_INLINE_ROUTINE uint32_t _Thread_Dispatch_increment_disable_level(void)
{
uint32_t disable_level = _Thread_Dispatch_disable_level;
#if defined( RTEMS_PROFILING )
ISR_Level level;
_ISR_Disable( level );
_Profiling_Thread_dispatch_disable( _Per_CPU_Get(), disable_level );
#endif
++disable_level;
_Thread_Dispatch_disable_level = disable_level;
#if defined( RTEMS_PROFILING )
_ISR_Enable( level );
#endif
return disable_level;
}
/**
* @brief Decrease thread dispatch disable level.
*
* This routine decrements the thread dispatch level.
*/
RTEMS_INLINE_ROUTINE uint32_t _Thread_Dispatch_decrement_disable_level(void)
{
uint32_t disable_level = _Thread_Dispatch_disable_level;
#if defined( RTEMS_PROFILING )
ISR_Level level;
_ISR_Disable( level );
#endif
--disable_level;
_Thread_Dispatch_disable_level = disable_level;
#if defined( RTEMS_PROFILING )
_Profiling_Thread_dispatch_enable( _Per_CPU_Get(), disable_level );
_ISR_Enable( level );
#endif
return disable_level;
}
RTEMS_INLINE_ROUTINE void _Giant_Acquire( Per_CPU_Control *cpu_self )
{
(void) cpu_self;
}
RTEMS_INLINE_ROUTINE void _Giant_Release( Per_CPU_Control *cpu_self )
{
(void) cpu_self;
}
#endif /* RTEMS_SMP */
/**
* @brief Performs a thread dispatch if necessary.
*
* This routine is responsible for transferring control of the processor from
* the executing thread to the heir thread. Once the heir is running an
* attempt is made to run the pending post-switch thread actions.
*
* As part of this process, it is responsible for the following actions
* - update timing information of the executing thread,
* - save the context of the executing thread,
* - invokation of the thread switch user extensions,
* - restore the context of the heir thread, and
* - run of pending post-switch thread actions of the resulting executing
* thread.
*
* On entry the thread dispatch level must be equal to zero.
*/
void _Thread_Dispatch( void );
/**
* @brief Performs a thread dispatch on the current processor.
*
* On entry the thread dispatch disable level must be equal to one and
* interrupts must be disabled.
*
* This function assumes that a thread dispatch is necessary.
*
* @param[in] cpu_self The current processor.
* @param[in] level The previous interrupt level.
*
* @see _Thread_Dispatch().
*/
void _Thread_Do_dispatch( Per_CPU_Control *cpu_self, ISR_Level level );
/**
* @brief Disables thread dispatching inside a critical section (interrupts
* disabled).
*
* This function does not acquire the Giant lock.
*
* @param[in] cpu_self The current processor.
*/
RTEMS_INLINE_ROUTINE void _Thread_Dispatch_disable_critical(
Per_CPU_Control *cpu_self
)
{
uint32_t disable_level = cpu_self->thread_dispatch_disable_level;
_Profiling_Thread_dispatch_disable( cpu_self, disable_level );
cpu_self->thread_dispatch_disable_level = disable_level + 1;
}
/**
* @brief Disables thread dispatching.
*
* This function does not acquire the Giant lock.
*
* @return The current processor.
*/
RTEMS_INLINE_ROUTINE Per_CPU_Control *_Thread_Dispatch_disable( void )
{
Per_CPU_Control *cpu_self;
#if defined( RTEMS_SMP ) || defined( RTEMS_PROFILING )
ISR_Level level;
_ISR_Disable_without_giant( level );
#endif
cpu_self = _Per_CPU_Get();
_Thread_Dispatch_disable_critical( cpu_self );
#if defined( RTEMS_SMP ) || defined( RTEMS_PROFILING )
_ISR_Enable_without_giant( level );
#endif
return cpu_self;
}
/**
* @brief Enables thread dispatching.
*
* May perfrom a thread dispatch if necessary as a side-effect.
*
* This function does not release the Giant lock.
*
* @param[in] cpu_self The current processor.
*/
RTEMS_INLINE_ROUTINE void _Thread_Dispatch_enable( Per_CPU_Control *cpu_self )
{
uint32_t disable_level = cpu_self->thread_dispatch_disable_level;
if ( disable_level == 1 ) {
ISR_Level level;
_ISR_Disable_without_giant( level );
if ( cpu_self->dispatch_necessary ) {
_Thread_Do_dispatch( cpu_self, level );
} else {
cpu_self->thread_dispatch_disable_level = 0;
_Profiling_Thread_dispatch_enable( cpu_self, 0 );
}
_ISR_Enable_without_giant( level );
} else {
cpu_self->thread_dispatch_disable_level = disable_level - 1;
}
}
/**
* @brief Disables thread dispatching and acquires the Giant lock.
*/
#if defined ( __THREAD_DO_NOT_INLINE_DISABLE_DISPATCH__ )
void _Thread_Disable_dispatch( void );
#else
RTEMS_INLINE_ROUTINE void _Thread_Disable_dispatch( void )
{
_Thread_Dispatch_increment_disable_level();
RTEMS_COMPILER_MEMORY_BARRIER();
}
#endif
RTEMS_INLINE_ROUTINE void _Thread_Enable_dispatch_body( void )
{
Per_CPU_Control *cpu_self = _Per_CPU_Get();
_Giant_Release( cpu_self );
_Thread_Dispatch_enable( cpu_self );
}
/**
* @brief Enables thread dispatching and releases the Giant lock.
*
* May perfrom a thread dispatch if necessary as a side-effect.
*/
#if defined ( __THREAD_DO_NOT_INLINE_ENABLE_DISPATCH__ )
void _Thread_Enable_dispatch( void );
#else
/* inlining of enable dispatching must be true */
RTEMS_INLINE_ROUTINE void _Thread_Enable_dispatch( void )
{
RTEMS_COMPILER_MEMORY_BARRIER();
_Thread_Enable_dispatch_body();
}
#endif
/**
* @brief Enables thread dispatching and releases the Giant lock.
*
* @warning A thread dispatch is not performed as a side-effect. Use this
* function with
*/
RTEMS_INLINE_ROUTINE void _Thread_Unnest_dispatch( void )
{
RTEMS_COMPILER_MEMORY_BARRIER();
_Thread_Dispatch_decrement_disable_level();
}
/** @} */
#ifdef __cplusplus
}
#endif /* __cplusplus */
#endif /* _RTEMS_SCORE_THREADDISPATCH_H */
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