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/**
* @file
*
* @brief Changes the Priority of a Thread
*
* @ingroup ScoreThread
*/
/*
* COPYRIGHT (c) 1989-2014.
* 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.
*/
#if HAVE_CONFIG_H
#include "config.h"
#endif
#include <rtems/score/threadimpl.h>
#include <rtems/score/schedulerimpl.h>
void _Thread_Change_priority(
Thread_Control *the_thread,
Priority_Control new_priority,
void *arg,
Thread_Change_priority_filter filter,
bool prepend_it
)
{
ISR_lock_Context lock_context;
ISR_lock_Control *lock;
lock = _Thread_Lock_acquire( the_thread, &lock_context );
/*
* For simplicity set the priority restore hint unconditionally since this is
* an average case optimization. Otherwise complicated atomic operations
* would be necessary. Synchronize with a potential read of the resource
* count in the filter function. See also _CORE_mutex_Surrender(),
* _Thread_Set_priority_filter() and _Thread_Restore_priority_filter().
*/
the_thread->priority_restore_hint = true;
_Atomic_Fence( ATOMIC_ORDER_ACQ_REL );
/*
* Do not bother recomputing all the priority related information if
* we are not REALLY changing priority.
*/
if ( ( *filter )( the_thread, &new_priority, arg ) ) {
uint32_t my_generation;
my_generation = the_thread->priority_generation + 1;
the_thread->current_priority = new_priority;
the_thread->priority_generation = my_generation;
( *the_thread->Wait.operations->priority_change )(
the_thread,
new_priority,
the_thread->Wait.queue
);
_Thread_Lock_release( lock, &lock_context );
_Scheduler_Acquire( the_thread, &lock_context );
if ( the_thread->priority_generation == my_generation ) {
if ( _States_Is_ready( the_thread->current_state ) ) {
_Scheduler_Change_priority(
the_thread,
new_priority,
prepend_it
);
} else {
_Scheduler_Update_priority( the_thread, new_priority );
}
}
_Scheduler_Release( the_thread, &lock_context );
} else {
_Thread_Lock_release( lock, &lock_context );
}
}
static bool _Thread_Raise_priority_filter(
Thread_Control *the_thread,
Priority_Control *new_priority,
void *arg
)
{
return _Thread_Priority_less_than(
the_thread->current_priority,
*new_priority
);
}
void _Thread_Raise_priority(
Thread_Control *the_thread,
Priority_Control new_priority
)
{
_Thread_Change_priority(
the_thread,
new_priority,
NULL,
_Thread_Raise_priority_filter,
false
);
}
static bool _Thread_Restore_priority_filter(
Thread_Control *the_thread,
Priority_Control *new_priority,
void *arg
)
{
*new_priority = the_thread->real_priority;
the_thread->priority_restore_hint = false;
return *new_priority != the_thread->current_priority;
}
void _Thread_Restore_priority( Thread_Control *the_thread )
{
_Thread_Change_priority(
the_thread,
0,
NULL,
_Thread_Restore_priority_filter,
true
);
}
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