tasksetpriority.c

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/*
 *  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.
 */

#ifdef HAVE_CONFIG_H
#include "config.h"
#endif

#include <rtems/rtems/tasksimpl.h>
#include <rtems/score/schedulerimpl.h>
#include <rtems/score/threadimpl.h>

static rtems_status_code _RTEMS_tasks_Set_priority(
  Thread_Control          *the_thread,
  const Scheduler_Control *scheduler,
  Priority_Control         new_priority,
  Thread_queue_Context    *queue_context
)
{
  Priority_Control core_new_priority;
  bool             valid;
  Per_CPU_Control *cpu_self;

  core_new_priority = _RTEMS_Priority_To_core(
    scheduler,
    new_priority,
    &valid
  );

  if ( !valid ) {
    _Thread_Wait_release( the_thread, queue_context );
    return RTEMS_INVALID_PRIORITY;
  }

  _Thread_Priority_change(
    the_thread,
    &the_thread->Real_priority,
    core_new_priority,
    false,
    queue_context
  );
  cpu_self = _Thread_queue_Dispatch_disable( queue_context );
  _Thread_Wait_release( the_thread, queue_context );
  _Thread_Priority_update( queue_context );
  _Thread_Dispatch_enable( cpu_self );
  return RTEMS_SUCCESSFUL;
}

rtems_status_code rtems_task_set_priority(
  rtems_id             id,
  rtems_task_priority  new_priority,
  rtems_task_priority *old_priority_p
)
{
  Thread_Control          *the_thread;
  Thread_queue_Context     queue_context;
  const Scheduler_Control *scheduler;
  Priority_Control         old_priority;
  rtems_status_code        status;

  if ( old_priority_p == NULL ) {
    return RTEMS_INVALID_ADDRESS;
  }

  _Thread_queue_Context_initialize( &queue_context );
  _Thread_queue_Context_clear_priority_updates( &queue_context );
  the_thread = _Thread_Get( id, &queue_context.Lock_context.Lock_context );

  if ( the_thread == NULL ) {
#if defined(RTEMS_MULTIPROCESSING)
    return _RTEMS_tasks_MP_Set_priority( id, new_priority, old_priority_p );
#else
    return RTEMS_INVALID_ID;
#endif
  }

  _Thread_Wait_acquire_critical( the_thread, &queue_context );

  scheduler = _Thread_Scheduler_get_home( the_thread );
  old_priority = _Thread_Get_priority( the_thread );

  if ( new_priority != RTEMS_CURRENT_PRIORITY ) {
    status = _RTEMS_tasks_Set_priority(
      the_thread,
      scheduler,
      new_priority,
      &queue_context
    );
  } else {
    _Thread_Wait_release( the_thread, &queue_context );
    status = RTEMS_SUCCESSFUL;
  }

  *old_priority_p = _RTEMS_Priority_From_core( scheduler, old_priority );
  return status;
}