source: rtems/cpukit/score/src/coremutexsurrender.c @ fd84982

4.104.114.9
Last change on this file since fd84982 was fd84982, checked in by Joel Sherrill <joel.sherrill@…>, on Dec 21, 2007 at 3:50:09 PM

2007-12-21 Xi Yang <hiyangxi@…>

  • configure.ac, score/include/rtems/score/coremutex.h, score/include/rtems/score/thread.h, score/inline/rtems/score/coremutex.inl, score/src/coremutexsurrender.c, score/src/threadinitialize.c: Add support for proper stacking of priority inheritance on mutexes as well as enforce proper order of release.
  • Property mode set to 100644
File size: 5.7 KB
Line 
1/*
2 *  Mutex Handler
3 *
4 *  DESCRIPTION:
5 *
6 *  This package is the implementation of the Mutex Handler.
7 *  This handler provides synchronization and mutual exclusion capabilities.
8 *
9 *  COPYRIGHT (c) 1989-2006.
10 *  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.com/license/LICENSE.
15 *
16 *  $Id$
17 */
18
19#if HAVE_CONFIG_H
20#include "config.h"
21#endif
22
23#include <rtems/system.h>
24#include <rtems/score/isr.h>
25#include <rtems/score/coremutex.h>
26#include <rtems/score/states.h>
27#include <rtems/score/thread.h>
28#include <rtems/score/threadq.h>
29
30/*
31 *  _CORE_mutex_Surrender
32 *
33 *  DESCRIPTION:
34 *
35 *  This routine frees a unit to the mutex.  If a task was blocked waiting for
36 *  a unit from this mutex, then that task will be readied and the unit
37 *  given to that task.  Otherwise, the unit will be returned to the mutex.
38 *
39 *  Input parameters:
40 *    the_mutex            - the mutex to be flushed
41 *    id                   - id of parent mutex
42 *    api_mutex_mp_support - api dependent MP support actions
43 *
44 *  Output parameters:
45 *    CORE_MUTEX_STATUS_SUCCESSFUL - if successful
46 *    core error code              - if unsuccessful
47 */
48
49CORE_mutex_Status _CORE_mutex_Surrender(
50  CORE_mutex_Control                *the_mutex,
51  Objects_Id                         id,
52  CORE_mutex_API_mp_support_callout  api_mutex_mp_support
53)
54{
55  Thread_Control *the_thread;
56  Thread_Control *holder;
57#ifdef __STRICT_ORDER_MUTEX__
58  Chain_Node *first_node;
59#endif
60  holder    = the_mutex->holder;
61
62  /*
63   *  The following code allows a thread (or ISR) other than the thread
64   *  which acquired the mutex to release that mutex.  This is only
65   *  allowed when the mutex in quetion is FIFO or simple Priority
66   *  discipline.  But Priority Ceiling or Priority Inheritance mutexes
67   *  must be released by the thread which acquired them.
68   */
69
70  if ( the_mutex->Attributes.only_owner_release ) {
71    if ( !_Thread_Is_executing( holder ) )
72      return CORE_MUTEX_STATUS_NOT_OWNER_OF_RESOURCE;
73  }
74
75  /* XXX already unlocked -- not right status */
76
77  if ( !the_mutex->nest_count )
78    return CORE_MUTEX_STATUS_SUCCESSFUL;
79
80  the_mutex->nest_count--;
81
82  if ( the_mutex->nest_count != 0 ) {
83    switch ( the_mutex->Attributes.lock_nesting_behavior ) {
84      case CORE_MUTEX_NESTING_ACQUIRES:
85        return CORE_MUTEX_STATUS_SUCCESSFUL;
86      case CORE_MUTEX_NESTING_IS_ERROR:
87        /* should never occur */
88        return CORE_MUTEX_STATUS_NESTING_NOT_ALLOWED;
89      case CORE_MUTEX_NESTING_BLOCKS:
90        /* Currently no API exercises this behavior. */
91        break;
92    }
93  }
94
95  /*
96   *  Formally release the mutex before possibly transferring it to a
97   *  blocked thread.
98   */
99  if ( _CORE_mutex_Is_inherit_priority( &the_mutex->Attributes ) ||
100       _CORE_mutex_Is_priority_ceiling( &the_mutex->Attributes ) ){
101#ifdef __STRICT_ORDER_MUTEX__
102    /*Check whether the holder release the mutex in LIFO order
103      if not return error code*/
104    if(holder->lock_mutex.first != &the_mutex->queue.lock_queue){
105      the_mutex->nest_count++;
106      return CORE_MUTEX_RELEASE_NOT_ORDER;
107    }
108    first_node = _Chain_Get_first_unprotected(&holder->lock_mutex);
109#endif
110    holder->resource_count--;
111  }
112  the_mutex->holder    = NULL;
113  the_mutex->holder_id = 0;
114
115  /*
116   *  Whether or not someone is waiting for the mutex, an
117   *  inherited priority must be lowered if this is the last
118   *  mutex (i.e. resource) this task has.
119   */
120  if ( _CORE_mutex_Is_inherit_priority( &the_mutex->Attributes ) ||
121       _CORE_mutex_Is_priority_ceiling( &the_mutex->Attributes ) ) {
122#ifdef __STRICT_ORDER_MUTEX__
123    if(the_mutex->queue.priority_before != holder->current_priority)
124      _Thread_Change_priority(holder,the_mutex->queue.priority_before,TRUE);
125#endif
126    if ( holder->resource_count == 0 &&
127         holder->real_priority != holder->current_priority ) {
128      _Thread_Change_priority( holder, holder->real_priority, TRUE );
129    }
130  }
131
132  /*
133   *  Now we check if another thread was waiting for this mutex.  If so,
134   *  transfer the mutex to that thread.
135   */
136  if ( ( the_thread = _Thread_queue_Dequeue( &the_mutex->Wait_queue ) ) ) {
137
138#if defined(RTEMS_MULTIPROCESSING)
139    if ( !_Objects_Is_local_id( the_thread->Object.id ) ) {
140
141      the_mutex->holder     = NULL;
142      the_mutex->holder_id  = the_thread->Object.id;
143      the_mutex->nest_count = 1;
144
145      ( *api_mutex_mp_support)( the_thread, id );
146
147    } else
148#endif
149    {
150
151      the_mutex->holder     = the_thread;
152      the_mutex->holder_id  = the_thread->Object.id;
153      the_mutex->nest_count = 1;
154
155      switch ( the_mutex->Attributes.discipline ) {
156        case CORE_MUTEX_DISCIPLINES_FIFO:
157        case CORE_MUTEX_DISCIPLINES_PRIORITY:
158          break;
159        case CORE_MUTEX_DISCIPLINES_PRIORITY_INHERIT:
160#ifdef __STRICT_ORDER_MUTEX__
161          _Chain_Prepend_unprotected(&the_thread->lock_mutex,&the_mutex->queue.lock_queue);
162          the_mutex->queue.priority_before = the_thread->current_priority;
163#endif
164          the_thread->resource_count++;
165          break;
166        case CORE_MUTEX_DISCIPLINES_PRIORITY_CEILING:
167#ifdef __STRICT_ORDER_MUTEX__
168          _Chain_Prepend_unprotected(&the_thread->lock_mutex,&the_mutex->queue.lock_queue);
169          the_mutex->queue.priority_before = the_thread->current_priority;
170#endif
171          the_thread->resource_count++;
172          if (the_mutex->Attributes.priority_ceiling <
173              the_thread->current_priority){
174              _Thread_Change_priority(
175                the_thread,
176                the_mutex->Attributes.priority_ceiling,
177                FALSE
178              );
179          }
180          break;
181      }
182    }
183  } else
184    the_mutex->lock = CORE_MUTEX_UNLOCKED;
185
186  return CORE_MUTEX_STATUS_SUCCESSFUL;
187}
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