source: rtems/cpukit/score/src/schedulerpriorityunblock.c @ dafa5d88

5
Last change on this file since dafa5d88 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: 1.6 KB
Line 
1/**
2 *  @file
3 *
4 *  @brief Scheduler Priority Unblock
5 *  @ingroup ScoreScheduler
6 */
7
8/*
9 *  Scheduler Handler
10 *
11 *  Copyright (C) 2010 Gedare Bloom.
12 *  Copyright (C) 2011 On-Line Applications Research Corporation (OAR).
13 *
14 *  The license and distribution terms for this file may be
15 *  found in the file LICENSE in this distribution or at
16 *  http://www.rtems.org/license/LICENSE.
17 */
18
19#if HAVE_CONFIG_H
20#include "config.h"
21#endif
22
23#include <rtems/score/schedulerpriorityimpl.h>
24
25Scheduler_Void_or_thread _Scheduler_priority_Unblock (
26  const Scheduler_Control *scheduler,
27  Thread_Control          *the_thread
28)
29{
30  Scheduler_priority_Context *context =
31    _Scheduler_priority_Get_context( scheduler );
32  Scheduler_priority_Node *node = _Scheduler_priority_Thread_get_node( the_thread );
33
34  _Scheduler_priority_Ready_queue_enqueue(
35    &the_thread->Object.Node,
36    &node->Ready_queue,
37    &context->Bit_map
38  );
39
40  /* TODO: flash critical section? */
41
42  /*
43   *  If the thread that was unblocked is more important than the heir,
44   *  then we have a new heir.  This may or may not result in a
45   *  context switch.
46   *
47   *  Normal case:
48   *    If the current thread is preemptible, then we need to do
49   *    a context switch.
50   *  Pseudo-ISR case:
51   *    Even if the thread isn't preemptible, if the new heir is
52   *    a pseudo-ISR system task, we need to do a context switch.
53   */
54  if ( the_thread->current_priority < _Thread_Heir->current_priority ) {
55    _Scheduler_Update_heir(
56      the_thread,
57      the_thread->current_priority == PRIORITY_PSEUDO_ISR
58    );
59  }
60
61  SCHEDULER_RETURN_VOID_OR_NULL;
62}
Note: See TracBrowser for help on using the repository browser.