void _Thread_Change_priority(
Thread_Control *the_thread,
Priority_Control new_priority,
bool prepend_it
)
{
ISR_Level level;
States_Control state, original_state;
/*
* Save original state
*/
original_state = the_thread->current_state;
/*
* Set a transient state for the thread so it is pulled off the Ready chains.
* This will prevent it from being scheduled no matter what happens in an
* ISR.
*/
_Thread_Set_transient( the_thread );
/*
* Do not bother recomputing all the priority related information if
* we are not REALLY changing priority.
*/
if ( the_thread->current_priority != new_priority )
_Thread_Set_priority( the_thread, new_priority );
_ISR_Disable( level );
/*
* If the thread has more than STATES_TRANSIENT set, then it is blocked,
* If it is blocked on a thread queue, then we need to requeue it.
*/
state = the_thread->current_state;
if ( state != STATES_TRANSIENT ) {
/* Only clear the transient state if it wasn't set already */
if ( ! _States_Is_transient( original_state ) )
the_thread->current_state = _States_Clear( STATES_TRANSIENT, state );
_ISR_Enable( level );
if ( _States_Is_waiting_on_thread_queue( state ) ) {
_Thread_queue_Requeue( the_thread->Wait.queue, the_thread );
}
return;
}
/* Only clear the transient state if it wasn't set already */
if ( ! _States_Is_transient( original_state ) ) {
/*
* Interrupts are STILL disabled.
* We now know the thread will be in the READY state when we remove
* the TRANSIENT state. So we have to place it on the appropriate
* Ready Queue with interrupts off.
*/
the_thread->current_state = _States_Clear( STATES_TRANSIENT, state );
if ( prepend_it )
_Scheduler_Enqueue_first( the_thread );
else
_Scheduler_Enqueue( the_thread );
}
_ISR_Flash( level );
/*
* We altered the set of thread priorities. So let's figure out
* who is the heir and if we need to switch to them.
*/
_Scheduler_Schedule();
if ( !_Thread_Is_executing_also_the_heir() &&
_Thread_Executing->is_preemptible )
_Thread_Dispatch_necessary = true;
_ISR_Enable( level );
}
rtems_status_code rtems_task_mode(
rtems_mode mode_set,
rtems_mode mask,
rtems_mode *previous_mode_set
)
{
Thread_Control *executing;
RTEMS_API_Control *api;
ASR_Information *asr;
bool preempt_enabled;
bool needs_asr_dispatching;
rtems_mode old_mode;
if ( !previous_mode_set )
return RTEMS_INVALID_ADDRESS;
executing = _Thread_Get_executing();
api = executing->API_Extensions[ THREAD_API_RTEMS ];
asr = &api->Signal;
old_mode = (executing->is_preemptible) ? RTEMS_PREEMPT : RTEMS_NO_PREEMPT;
if ( executing->budget_algorithm == THREAD_CPU_BUDGET_ALGORITHM_NONE )
old_mode |= RTEMS_NO_TIMESLICE;
else
old_mode |= RTEMS_TIMESLICE;
old_mode |= (asr->is_enabled) ? RTEMS_ASR : RTEMS_NO_ASR;
old_mode |= _ISR_Get_level();
*previous_mode_set = old_mode;
/*
* These are generic thread scheduling characteristics.
*/
preempt_enabled = false;
if ( mask & RTEMS_PREEMPT_MASK ) {
#if defined( RTEMS_SMP )
if ( rtems_configuration_is_smp_enabled() &&
!_Modes_Is_preempt( mode_set ) ) {
return RTEMS_NOT_IMPLEMENTED;
}
#endif
bool is_preempt_enabled = _Modes_Is_preempt( mode_set );
preempt_enabled = !executing->is_preemptible && is_preempt_enabled;
executing->is_preemptible = is_preempt_enabled;
}
if ( mask & RTEMS_TIMESLICE_MASK ) {
if ( _Modes_Is_timeslice(mode_set) ) {
executing->budget_algorithm = THREAD_CPU_BUDGET_ALGORITHM_RESET_TIMESLICE;
executing->cpu_time_budget =
rtems_configuration_get_ticks_per_timeslice();
} else
executing->budget_algorithm = THREAD_CPU_BUDGET_ALGORITHM_NONE;
}
/*
* Set the new interrupt level
*/
if ( mask & RTEMS_INTERRUPT_MASK )
_Modes_Set_interrupt_level( mode_set );
/*
* This is specific to the RTEMS API
*/
needs_asr_dispatching = false;
if ( mask & RTEMS_ASR_MASK ) {
bool is_asr_enabled = !_Modes_Is_asr_disabled( mode_set );
if ( is_asr_enabled != asr->is_enabled ) {
asr->is_enabled = is_asr_enabled;
_ASR_Swap_signals( asr );
if ( _ASR_Are_signals_pending( asr ) ) {
needs_asr_dispatching = true;
_Thread_Add_post_switch_action(
executing,
&api->Signal_action,
_Signal_Action_handler
);
}
}
}
if ( preempt_enabled || needs_asr_dispatching ) {
Per_CPU_Control *cpu_self;
ISR_lock_Context lock_context;
cpu_self = _Thread_Dispatch_disable();
_Scheduler_Acquire( executing, &lock_context );
_Scheduler_Schedule( executing );
_Scheduler_Release( executing, &lock_context );
_Thread_Dispatch_enable( cpu_self );
}
return RTEMS_SUCCESSFUL;
}
