source: rtems/cpukit/score/src/coremutexsurrender.c @ 6c7caa1a

4.11
Last change on this file since 6c7caa1a was 6c7caa1a, checked in by Sebastian Huber <sebastian.huber@…>, on May 28, 2014 at 11:37:54 AM

score: Add and use _Thread_Owns_resources()

  • Property mode set to 100644
File size: 6.3 KB
Line 
1/**
2 * @file
3 *
4 * @brief Surrender the Mutex
5 * @ingroup ScoreMutex
6 */
7
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.org/license/LICENSE.
15 */
16
17#if HAVE_CONFIG_H
18#include "config.h"
19#endif
20
21#include <rtems/system.h>
22#include <rtems/score/isr.h>
23#include <rtems/score/coremuteximpl.h>
24#include <rtems/score/thread.h>
25
26#ifdef __RTEMS_STRICT_ORDER_MUTEX__
27  static inline void _CORE_mutex_Push_priority(
28    CORE_mutex_Control *mutex,
29    Thread_Control *thread
30  )
31  {
32    _Chain_Prepend_unprotected(
33      &thread->lock_mutex,
34      &mutex->queue.lock_queue
35    );
36    mutex->queue.priority_before = thread->current_priority;
37  }
38
39  static inline CORE_mutex_Status _CORE_mutex_Pop_priority(
40    CORE_mutex_Control *mutex,
41    Thread_Control *holder
42  )
43  {
44    /*
45     *  Check whether the holder release the mutex in LIFO order if not return
46     *  error code.
47     */
48    if ( _Chain_First( &holder->lock_mutex ) != &mutex->queue.lock_queue ) {
49      mutex->nest_count++;
50
51      return CORE_MUTEX_RELEASE_NOT_ORDER;
52    }
53
54    /*
55     *  This pops the first node from the list.
56     */
57    _Chain_Get_first_unprotected( &holder->lock_mutex );
58
59    if ( mutex->queue.priority_before != holder->current_priority )
60      _Thread_Change_priority( holder, mutex->queue.priority_before, true );
61
62    return CORE_MUTEX_STATUS_SUCCESSFUL;
63  }
64#else
65  #define _CORE_mutex_Push_priority( mutex, thread ) ((void) 0)
66
67  #define _CORE_mutex_Pop_priority( mutex, thread ) \
68    CORE_MUTEX_STATUS_SUCCESSFUL
69#endif
70
71/*
72 *  _CORE_mutex_Surrender
73 *
74 *  DESCRIPTION:
75 *
76 *  This routine frees a unit to the mutex.  If a task was blocked waiting for
77 *  a unit from this mutex, then that task will be readied and the unit
78 *  given to that task.  Otherwise, the unit will be returned to the mutex.
79 *
80 *  Input parameters:
81 *    the_mutex            - the mutex to be flushed
82 *    id                   - id of parent mutex
83 *    api_mutex_mp_support - api dependent MP support actions
84 *
85 *  Output parameters:
86 *    CORE_MUTEX_STATUS_SUCCESSFUL - if successful
87 *    core error code              - if unsuccessful
88 */
89
90CORE_mutex_Status _CORE_mutex_Surrender(
91  CORE_mutex_Control                *the_mutex,
92#if defined(RTEMS_MULTIPROCESSING)
93  Objects_Id                         id,
94  CORE_mutex_API_mp_support_callout  api_mutex_mp_support
95#else
96  Objects_Id                         id __attribute__((unused)),
97  CORE_mutex_API_mp_support_callout  api_mutex_mp_support __attribute__((unused))
98#endif
99)
100{
101  Thread_Control *the_thread;
102  Thread_Control *holder;
103
104  holder = the_mutex->holder;
105
106  /*
107   *  The following code allows a thread (or ISR) other than the thread
108   *  which acquired the mutex to release that mutex.  This is only
109   *  allowed when the mutex in quetion is FIFO or simple Priority
110   *  discipline.  But Priority Ceiling or Priority Inheritance mutexes
111   *  must be released by the thread which acquired them.
112   */
113
114  if ( the_mutex->Attributes.only_owner_release ) {
115    if ( !_Thread_Is_executing( holder ) )
116      return CORE_MUTEX_STATUS_NOT_OWNER_OF_RESOURCE;
117  }
118
119  /* XXX already unlocked -- not right status */
120
121  if ( !the_mutex->nest_count )
122    return CORE_MUTEX_STATUS_SUCCESSFUL;
123
124  the_mutex->nest_count--;
125
126  if ( the_mutex->nest_count != 0 ) {
127    /*
128     *  All error checking is on the locking side, so if the lock was
129     *  allowed to acquired multiple times, then we should just deal with
130     *  that.  The RTEMS_DEBUG is just a validation.
131     */
132    #if defined(RTEMS_DEBUG)
133      switch ( the_mutex->Attributes.lock_nesting_behavior ) {
134        case CORE_MUTEX_NESTING_ACQUIRES:
135          return CORE_MUTEX_STATUS_SUCCESSFUL;
136        #if defined(RTEMS_POSIX_API)
137          case CORE_MUTEX_NESTING_IS_ERROR:
138            /* should never occur */
139            return CORE_MUTEX_STATUS_NESTING_NOT_ALLOWED;
140        #endif
141        case CORE_MUTEX_NESTING_BLOCKS:
142          /* Currently no API exercises this behavior. */
143          break;
144      }
145    #else
146      /* must be CORE_MUTEX_NESTING_ACQUIRES or we wouldn't be here */
147      return CORE_MUTEX_STATUS_SUCCESSFUL;
148    #endif
149  }
150
151  /*
152   *  Formally release the mutex before possibly transferring it to a
153   *  blocked thread.
154   */
155  if ( _CORE_mutex_Is_inherit_priority( &the_mutex->Attributes ) ||
156       _CORE_mutex_Is_priority_ceiling( &the_mutex->Attributes ) ) {
157    CORE_mutex_Status pop_status =
158      _CORE_mutex_Pop_priority( the_mutex, holder );
159
160    if ( pop_status != CORE_MUTEX_STATUS_SUCCESSFUL )
161      return pop_status;
162
163    holder->resource_count--;
164
165    /*
166     *  Whether or not someone is waiting for the mutex, an
167     *  inherited priority must be lowered if this is the last
168     *  mutex (i.e. resource) this task has.
169     */
170    if ( !_Thread_Owns_resources( holder ) &&
171         holder->real_priority != holder->current_priority ) {
172      _Thread_Change_priority( holder, holder->real_priority, true );
173    }
174  }
175  the_mutex->holder = NULL;
176
177  /*
178   *  Now we check if another thread was waiting for this mutex.  If so,
179   *  transfer the mutex to that thread.
180   */
181  if ( ( the_thread = _Thread_queue_Dequeue( &the_mutex->Wait_queue ) ) ) {
182
183#if defined(RTEMS_MULTIPROCESSING)
184    if ( !_Objects_Is_local_id( the_thread->Object.id ) ) {
185
186      the_mutex->holder     = NULL;
187      the_mutex->nest_count = 1;
188
189      ( *api_mutex_mp_support)( the_thread, id );
190
191    } else
192#endif
193    {
194
195      the_mutex->holder     = the_thread;
196      the_mutex->nest_count = 1;
197
198      switch ( the_mutex->Attributes.discipline ) {
199        case CORE_MUTEX_DISCIPLINES_FIFO:
200        case CORE_MUTEX_DISCIPLINES_PRIORITY:
201          break;
202        case CORE_MUTEX_DISCIPLINES_PRIORITY_INHERIT:
203          _CORE_mutex_Push_priority( the_mutex, the_thread );
204          the_thread->resource_count++;
205          break;
206        case CORE_MUTEX_DISCIPLINES_PRIORITY_CEILING:
207          _CORE_mutex_Push_priority( the_mutex, the_thread );
208          the_thread->resource_count++;
209          if (the_mutex->Attributes.priority_ceiling <
210              the_thread->current_priority){
211              _Thread_Change_priority(
212                the_thread,
213                the_mutex->Attributes.priority_ceiling,
214                false
215              );
216          }
217          break;
218      }
219    }
220  }
221
222  return CORE_MUTEX_STATUS_SUCCESSFUL;
223}
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