source: rtems/cpukit/score/src/threadchangepriority.c @ a55e305

4.11
Last change on this file since a55e305 was a55e305, checked in by Joel Sherrill <joel.sherrill@…>, on Jul 29, 2010 at 5:52:10 PM

2010-07-29 Gedare Bloom <giddyup44@…>

PR 1635/cpukit

  • sapi/src/exinit.c, score/Makefile.am, score/preinstall.am, score/include/rtems/score/bitfield.h, score/include/rtems/score/priority.h, score/include/rtems/score/thread.h, score/inline/rtems/score/priority.inl, score/inline/rtems/score/thread.inl, score/src/threadchangepriority.c, score/src/threadclearstate.c, score/src/threadready.c, score/src/threadresume.c, score/src/threadsetpriority.c, score/src/threadsetstate.c, score/src/threadsettransient.c, score/src/threadsuspend.c: Refactoring of priority handling, to isolate the bitmap implementation of priorities in the supercore so that priority management is a little more modular. This change is in anticipation of scheduler implementations that can select how they manage tracking priority levels / finding the highest priority ready task. Note that most of the changes here are simple renaming, to clarify the use of the bitmap-based priority management.
  • score/include/rtems/score/prioritybitmap.h, score/inline/rtems/score/prioritybitmap.inl: New files.
  • Property mode set to 100644
File size: 4.0 KB
Line 
1/*
2 *  Thread Handler
3 *
4 *
5 *  COPYRIGHT (c) 1989-2006.
6 *  On-Line Applications Research Corporation (OAR).
7 *
8 *  The license and distribution terms for this file may be
9 *  found in found in the file LICENSE in this distribution or at
10 *  http://www.rtems.com/license/LICENSE.
11 *
12 *  $Id$
13 */
14
15#if HAVE_CONFIG_H
16#include "config.h"
17#endif
18
19#include <rtems/system.h>
20#include <rtems/score/apiext.h>
21#include <rtems/score/context.h>
22#include <rtems/score/interr.h>
23#include <rtems/score/isr.h>
24#include <rtems/score/object.h>
25#include <rtems/score/priority.h>
26#include <rtems/score/states.h>
27#include <rtems/score/sysstate.h>
28#include <rtems/score/thread.h>
29#include <rtems/score/threadq.h>
30#include <rtems/score/userext.h>
31#include <rtems/score/wkspace.h>
32
33/*PAGE
34 *
35 *  _Thread_Change_priority
36 *
37 *  This kernel routine changes the priority of the thread.  The
38 *  thread chain is adjusted if necessary.
39 *
40 *  Input parameters:
41 *    the_thread   - pointer to thread control block
42 *    new_priority - ultimate priority
43 *    prepend_it   - true if the thread should be prepended to the chain
44 *
45 *  Output parameters:  NONE
46 *
47 *  INTERRUPT LATENCY:
48 *    ready chain
49 *    select heir
50 */
51
52void _Thread_Change_priority(
53  Thread_Control   *the_thread,
54  Priority_Control  new_priority,
55  bool              prepend_it
56)
57{
58  ISR_Level      level;
59  States_Control state, original_state;
60
61  /*
62   *  If this is a case where prepending the task to its priority is
63   *  potentially desired, then we need to consider whether to do it.
64   *  This usually occurs when a task lowers its priority implcitly as
65   *  the result of losing inherited priority.  Normal explicit priority
66   *  change calls (e.g. rtems_task_set_priority) should always do an
67   *  append not a prepend.
68   */
69/*
70  if ( prepend_it &&
71       _Thread_Is_executing( the_thread ) &&
72       new_priority >= the_thread->current_priority )
73    prepend_it = true;
74*/
75
76  /*
77   * Save original state
78   */
79  original_state = the_thread->current_state;
80
81  /*
82   * Set a transient state for the thread so it is pulled off the Ready chains.
83   * This will prevent it from being scheduled no matter what happens in an
84   * ISR.
85   */
86  _Thread_Set_transient( the_thread );
87
88  /*
89   *  Do not bother recomputing all the priority related information if
90   *  we are not REALLY changing priority.
91   */
92 if ( the_thread->current_priority != new_priority )
93    _Thread_Set_priority( the_thread, new_priority );
94
95  _ISR_Disable( level );
96
97  /*
98   *  If the thread has more than STATES_TRANSIENT set, then it is blocked,
99   *  If it is blocked on a thread queue, then we need to requeue it.
100   */
101  state = the_thread->current_state;
102  if ( state != STATES_TRANSIENT ) {
103    /* Only clear the transient state if it wasn't set already */
104    if ( ! _States_Is_transient( original_state ) )
105      the_thread->current_state = _States_Clear( STATES_TRANSIENT, state );
106    _ISR_Enable( level );
107    if ( _States_Is_waiting_on_thread_queue( state ) ) {
108      _Thread_queue_Requeue( the_thread->Wait.queue, the_thread );
109    }
110    return;
111  }
112
113  /* Only clear the transient state if it wasn't set already */
114  if ( ! _States_Is_transient( original_state ) ) {
115    /*
116     *  Interrupts are STILL disabled.
117     *  We now know the thread will be in the READY state when we remove
118     *  the TRANSIENT state.  So we have to place it on the appropriate
119     *  Ready Queue with interrupts off.
120     */
121    the_thread->current_state = _States_Clear( STATES_TRANSIENT, state );
122
123    _Priority_bit_map_Add( &the_thread->Priority_map );
124    if ( prepend_it )
125      _Chain_Prepend_unprotected( the_thread->ready, &the_thread->Object.Node );
126    else
127      _Chain_Append_unprotected( the_thread->ready, &the_thread->Object.Node );
128  }
129
130  _ISR_Flash( level );
131
132  /*
133   *  We altered the set of thread priorities.  So let's figure out
134   *  who is the heir and if we need to switch to them.
135   */
136  _Thread_Calculate_heir();
137
138  if ( !_Thread_Is_executing_also_the_heir() &&
139       _Thread_Executing->is_preemptible )
140    _Context_Switch_necessary = true;
141  _ISR_Enable( level );
142}
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