source: rtems/cpukit/score/src/schedulerpriorityyield.c @ 469dc47

5
Last change on this file since 469dc47 was b8a5abf, checked in by Sebastian Huber <sebastian.huber@…>, on 02/26/15 at 09:33:36

score: Update _Thread_Heir only if necessary

Previously, the _Thread_Heir was updated unconditionally in case a new
heir was determined. The _Thread_Dispatch_necessary was only updated in
case the executing thread was preemptible or an internal thread was
unblocked. Change this to update the _Thread_Heir and
_Thread_Dispatch_necessary only in case the currently selected heir
thread is preemptible or a dispatch is forced. Move the schedule
decision into the change priority operation and use the schedule
operation only in rtems_task_mode() in case preemption is enabled or an
ASR dispatch is necessary. This is a behaviour change. Previously, the
RTEMS_NO_PREEMPT also prevented signal delivery in certain cases (not
always). Now, signal delivery is no longer influenced by
RTEMS_NO_PREEMPT. Since the currently selected heir thread is used to
determine if a new heir is chosen, non-preemptible heir threads
currently not executing now prevent a new heir. This may have an
application impact, see change test tm04. Document this change in sp04.

Update #2273.
  • Property mode set to 100644
File size: 1.0 KB
Line 
1/**
2 *  @file
3 *
4 *  @brief Scheduler Priority Yield
5 *  @ingroup ScoreScheduler
6 */
7
8/*
9 *  Copyright (C) 2010 Gedare Bloom.
10 *  Copyright (C) 2011 On-Line Applications Research Corporation (OAR).
11 *
12 *  The license and distribution terms for this file may be
13 *  found in the file LICENSE in this distribution or at
14 *  http://www.rtems.org/license/LICENSE.
15 */
16
17#if HAVE_CONFIG_H
18#include "config.h"
19#endif
20
21#include <rtems/score/schedulerpriorityimpl.h>
22#include <rtems/score/threadimpl.h>
23
24Scheduler_Void_or_thread _Scheduler_priority_Yield(
25  const Scheduler_Control *scheduler,
26  Thread_Control          *the_thread
27)
28{
29  Scheduler_priority_Node *node = _Scheduler_priority_Thread_get_node( the_thread );
30  Chain_Control *ready_chain = node->Ready_queue.ready_chain;
31
32  if ( !_Chain_Has_only_one_node( ready_chain ) ) {
33    _Chain_Extract_unprotected( &the_thread->Object.Node );
34    _Chain_Append_unprotected( ready_chain, &the_thread->Object.Node );
35  }
36
37  _Scheduler_priority_Schedule_body( scheduler, the_thread, true );
38
39  SCHEDULER_RETURN_VOID_OR_NULL;
40}
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