source: rtems/cpukit/score/src/threadchangepriority.c @ f6142c19

/**
 * @file
 *
 * @brief Changes the Priority of a Thread
 *
 * @ingroup ScoreThread
 */

/*
 *  COPYRIGHT (c) 1989-2014.
 *  On-Line Applications Research Corporation (OAR).
 *
 *  Copyright (c) 2013, 2016 embedded brains GmbH
 *
 *  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/assert.h>
#include <rtems/score/schedulerimpl.h>

static void _Thread_Set_scheduler_node_priority(
  Priority_Aggregation *priority_aggregation,
  bool                  prepend_it
)
{
  _Scheduler_Node_set_priority(
    SCHEDULER_NODE_OF_WAIT_PRIORITY_NODE( priority_aggregation ),
    _Priority_Get_priority( priority_aggregation ),
    prepend_it
  );
}

#if defined(RTEMS_SMP)
static void _Thread_Priority_action_add(
  Priority_Aggregation *priority_aggregation,
  Priority_Actions     *priority_actions,
  void                 *arg
)
{
  Scheduler_Node *scheduler_node;
  Thread_Control *the_thread;

  scheduler_node = SCHEDULER_NODE_OF_WAIT_PRIORITY( priority_aggregation );
  the_thread = arg;

  _Chain_Append_unprotected(
    &the_thread->Scheduler.Wait_nodes,
    &scheduler_node->Thread.Wait_node
  );
  _Thread_Set_scheduler_node_priority( priority_aggregation, false );
  _Priority_Set_action_type( priority_aggregation, PRIORITY_ACTION_ADD );
  _Priority_Actions_add( priority_actions, priority_aggregation );
}

static void _Thread_Priority_action_remove(
  Priority_Aggregation *priority_aggregation,
  Priority_Actions     *priority_actions,
  void                 *arg
)
{
  Scheduler_Node *scheduler_node;

  scheduler_node = SCHEDULER_NODE_OF_WAIT_PRIORITY( priority_aggregation );

  _Chain_Extract_unprotected( &scheduler_node->Thread.Wait_node );
  _Thread_Set_scheduler_node_priority( priority_aggregation, true );
  _Priority_Set_action_type( priority_aggregation, PRIORITY_ACTION_REMOVE );
  _Priority_Actions_add( priority_actions, priority_aggregation );
}
#endif

static void _Thread_Priority_action_change(
  Priority_Aggregation *priority_aggregation,
  bool                  prepend_it,
  Priority_Actions     *priority_actions,
  void                 *arg
)
{
  _Thread_Set_scheduler_node_priority( priority_aggregation, prepend_it );
#if defined(RTEMS_SMP) || defined(RTEMS_DEBUG)
  _Priority_Set_action_type( priority_aggregation, PRIORITY_ACTION_CHANGE );
#endif
  _Priority_Actions_add( priority_actions, priority_aggregation );
}

static void _Thread_Priority_do_perform_actions(
  Thread_Control                *the_thread,
  Thread_queue_Queue            *queue,
  const Thread_queue_Operations *operations,
  bool                           prepend_it,
  Thread_queue_Context          *queue_context
)
{
  Priority_Aggregation *priority_aggregation;

  _Assert( !_Priority_Actions_is_empty( &queue_context->Priority.Actions ) );
  priority_aggregation = _Priority_Actions_move( &queue_context->Priority.Actions );

  do {
    Priority_Aggregation *next_aggregation;
    Priority_Node        *priority_action_node;
    Priority_Action_type  priority_action_type;

    next_aggregation = _Priority_Get_next_action( priority_aggregation );

    priority_action_node = priority_aggregation->Action.node;
    priority_action_type = priority_aggregation->Action.type;

    switch ( priority_action_type ) {
      case PRIORITY_ACTION_ADD:
#if defined(RTEMS_SMP)
        _Priority_Insert(
          priority_aggregation,
          priority_action_node,
          &queue_context->Priority.Actions,
          _Thread_Priority_action_add,
          _Thread_Priority_action_change,
          the_thread
        );
#else
        _Priority_Non_empty_insert(
          priority_aggregation,
          priority_action_node,
          &queue_context->Priority.Actions,
          _Thread_Priority_action_change,
          NULL
        );
#endif
        break;
      case PRIORITY_ACTION_REMOVE:
#if defined(RTEMS_SMP)
        _Priority_Extract(
          priority_aggregation,
          priority_action_node,
          &queue_context->Priority.Actions,
          _Thread_Priority_action_remove,
          _Thread_Priority_action_change,
          NULL
        );
#else
        _Priority_Extract_non_empty(
          priority_aggregation,
          priority_action_node,
          &queue_context->Priority.Actions,
          _Thread_Priority_action_change,
          NULL
        );
#endif
        break;
      default:
        _Assert( priority_action_type == PRIORITY_ACTION_CHANGE );
        _Priority_Changed(
          priority_aggregation,
          priority_action_node,
          prepend_it,
          &queue_context->Priority.Actions,
          _Thread_Priority_action_change,
          NULL
        );
        break;
    }

    priority_aggregation = next_aggregation;
  } while ( _Priority_Actions_is_valid( priority_aggregation ) );

  if ( !_Priority_Actions_is_empty( &queue_context->Priority.Actions ) ) {
    _Thread_queue_Context_add_priority_update( queue_context, the_thread );

    ( *operations->priority_actions )(
      queue,
      &queue_context->Priority.Actions
    );
  }
}

void _Thread_Priority_perform_actions(
  Thread_Control       *start_of_path,
  Thread_queue_Context *queue_context
)
{
  Thread_Control *the_thread;
  size_t          update_count;

  _Assert( start_of_path != NULL );

  /*
   * This function is tricky on SMP configurations.  Please note that we do not
   * use the thread queue path available via the thread queue context.  Instead
   * we directly use the thread wait information to traverse the thread queue
   * path.  Thus, we do not necessarily acquire all thread queue locks on our
   * own.  In case of a deadlock, we use locks acquired by other processors
   * along the path.
   */

  the_thread = start_of_path;
  update_count = _Thread_queue_Context_save_priority_updates( queue_context );

  while ( true ) {
    Thread_queue_Queue *queue;

    queue = the_thread->Wait.queue;

    _Thread_Priority_do_perform_actions(
      the_thread,
      queue,
      the_thread->Wait.operations,
      false,
      queue_context
    );

    if ( _Priority_Actions_is_empty( &queue_context->Priority.Actions ) ) {
      return;
    }

    _Assert( queue != NULL );
    the_thread = queue->owner;
    _Assert( the_thread != NULL );

    /*
     * In case the priority action list is non-empty, then the current thread
     * is enqueued on a thread queue.  There is no need to notify the scheduler
     * about a priority change, since it will pick up the new priority once it
     * is unblocked.  Restore the previous set of threads bound to update the
     * priority.
     */
    _Thread_queue_Context_restore_priority_updates(
      queue_context,
      update_count
    );
  }
}

static void _Thread_Priority_apply(
  Thread_Control       *the_thread,
  Priority_Node        *priority_action_node,
  Thread_queue_Context *queue_context,
  bool                  prepend_it,
  Priority_Action_type  priority_action_type
)
{
  Scheduler_Node     *own_node;
  Thread_queue_Queue *queue;

  own_node = _Thread_Scheduler_get_own_node( the_thread );
  _Priority_Actions_initialize_one(
    &queue_context->Priority.Actions,
    &own_node->Wait.Priority,
    priority_action_node,
    priority_action_type
  );
  queue = the_thread->Wait.queue;
  _Thread_Priority_do_perform_actions(
    the_thread,
    queue,
    the_thread->Wait.operations,
    prepend_it,
    queue_context
  );

  if ( !_Priority_Actions_is_empty( &queue_context->Priority.Actions ) ) {
#if defined(RTEMS_SMP)
    _Thread_queue_Path_acquire_critical( queue, the_thread, queue_context );
#endif
    _Thread_Priority_perform_actions( queue->owner, queue_context );
#if defined(RTEMS_SMP)
    _Thread_queue_Path_release_critical( queue_context );
#endif
  }
}

void _Thread_Priority_add(
  Thread_Control       *the_thread,
  Priority_Node        *priority_node,
  Thread_queue_Context *queue_context
)
{
  _Thread_Priority_apply(
    the_thread,
    priority_node,
    queue_context,
    false,
    PRIORITY_ACTION_ADD
  );
}

void _Thread_Priority_remove(
  Thread_Control       *the_thread,
  Priority_Node        *priority_node,
  Thread_queue_Context *queue_context
)
{
  _Thread_Priority_apply(
    the_thread,
    priority_node,
    queue_context,
    true,
    PRIORITY_ACTION_REMOVE
  );
}

void _Thread_Priority_changed(
  Thread_Control       *the_thread,
  Priority_Node        *priority_node,
  bool                  prepend_it,
  Thread_queue_Context *queue_context
)
{
  _Thread_Priority_apply(
    the_thread,
    priority_node,
    queue_context,
    prepend_it,
    PRIORITY_ACTION_CHANGE
  );
}

void _Thread_Priority_replace(
  Thread_Control *the_thread,
  Priority_Node  *victim_node,
  Priority_Node  *replacement_node
)
{
  Scheduler_Node *own_node;

  own_node = _Thread_Scheduler_get_own_node( the_thread );
  _Priority_Replace( &own_node->Wait.Priority, victim_node, replacement_node );
}

void _Thread_Priority_update( Thread_queue_Context *queue_context )
{
  size_t i;
  size_t n;

  n = queue_context->Priority.update_count;

  /*
   * Update the priority of all threads of the set.  Do not care to clear the
   * set, since the thread queue context will soon get destroyed anyway.
   */
  for ( i = 0; i < n ; ++i ) {
    Thread_Control   *the_thread;
    ISR_lock_Context  lock_context;

    the_thread = queue_context->Priority.update[ i ];
    _Thread_State_acquire( the_thread, &lock_context );
    _Scheduler_Update_priority( the_thread );
    _Thread_State_release( the_thread, &lock_context );
  }
}