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author | Joel Sherrill <joel.sherrill@OARcorp.com> | 1999-11-02 21:48:15 +0000 |
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committer | Joel Sherrill <joel.sherrill@OARcorp.com> | 1999-11-02 21:48:15 +0000 |
commit | 7cc8d6c3b1a207684892d207055ceff9f37d5731 (patch) | |
tree | 3da2f9ee0425a6b49a32df5c8298789de0672add /c/src/exec/score/src/coremutexsurrender.c | |
parent | Split core message queue and watchdog handler objects into separate files. (diff) | |
download | rtems-7cc8d6c3b1a207684892d207055ceff9f37d5731.tar.bz2 |
Split core mutex and semaphore handlers into separate files.
Diffstat (limited to '')
-rw-r--r-- | c/src/exec/score/src/coremutexsurrender.c | 139 |
1 files changed, 139 insertions, 0 deletions
diff --git a/c/src/exec/score/src/coremutexsurrender.c b/c/src/exec/score/src/coremutexsurrender.c new file mode 100644 index 0000000000..b7f38eb2b0 --- /dev/null +++ b/c/src/exec/score/src/coremutexsurrender.c @@ -0,0 +1,139 @@ +/* + * Mutex Handler + * + * DESCRIPTION: + * + * This package is the implementation of the Mutex Handler. + * This handler provides synchronization and mutual exclusion capabilities. + * + * COPYRIGHT (c) 1989-1998. + * On-Line Applications Research Corporation (OAR). + * Copyright assigned to U.S. Government, 1994. + * + * The license and distribution terms for this file may be + * found in the file LICENSE in this distribution or at + * http://www.OARcorp.com/rtems/license.html. + * + * $Id$ + */ + +#include <rtems/system.h> +#include <rtems/score/isr.h> +#include <rtems/score/coremutex.h> +#include <rtems/score/states.h> +#include <rtems/score/thread.h> +#include <rtems/score/threadq.h> + +/* + * _CORE_mutex_Surrender + * + * DESCRIPTION: + * + * This routine frees a unit to the mutex. If a task was blocked waiting for + * a unit from this mutex, then that task will be readied and the unit + * given to that task. Otherwise, the unit will be returned to the mutex. + * + * Input parameters: + * the_mutex - the mutex to be flushed + * id - id of parent mutex + * api_mutex_mp_support - api dependent MP support actions + * + * Output parameters: + * CORE_MUTEX_STATUS_SUCCESSFUL - if successful + * core error code - if unsuccessful + */ + +CORE_mutex_Status _CORE_mutex_Surrender( + CORE_mutex_Control *the_mutex, + Objects_Id id, + CORE_mutex_API_mp_support_callout api_mutex_mp_support +) +{ + Thread_Control *the_thread; + Thread_Control *executing; + + executing = _Thread_Executing; + + /* + * The following code allows a thread (or ISR) other than the thread + * which acquired the mutex to release that mutex. This is only + * allowed when the mutex in quetion is FIFO or simple Priority + * discipline. But Priority Ceiling or Priority Inheritance mutexes + * must be released by the thread which acquired them. + */ + + if ( !_Objects_Are_ids_equal( + _Thread_Executing->Object.id, the_mutex->holder_id ) ) { + + switch ( the_mutex->Attributes.discipline ) { + case CORE_MUTEX_DISCIPLINES_FIFO: + case CORE_MUTEX_DISCIPLINES_PRIORITY: + break; + case CORE_MUTEX_DISCIPLINES_PRIORITY_CEILING: + case CORE_MUTEX_DISCIPLINES_PRIORITY_INHERIT: + return( CORE_MUTEX_STATUS_NOT_OWNER_OF_RESOURCE ); + break; + } + } + + the_mutex->nest_count--; + + if ( the_mutex->nest_count != 0 ) + return( CORE_MUTEX_STATUS_SUCCESSFUL ); + + _Thread_Executing->resource_count--; + the_mutex->holder = NULL; + the_mutex->holder_id = 0; + + /* + * Whether or not someone is waiting for the mutex, an + * inherited priority must be lowered if this is the last + * mutex (i.e. resource) this task has. + */ + + switch ( the_mutex->Attributes.discipline ) { + case CORE_MUTEX_DISCIPLINES_FIFO: + case CORE_MUTEX_DISCIPLINES_PRIORITY: + break; + case CORE_MUTEX_DISCIPLINES_PRIORITY_CEILING: + case CORE_MUTEX_DISCIPLINES_PRIORITY_INHERIT: + if ( executing->resource_count == 0 && + executing->real_priority != executing->current_priority ) { + _Thread_Change_priority( executing, executing->real_priority, TRUE ); + } + break; + } + + + if ( ( the_thread = _Thread_queue_Dequeue( &the_mutex->Wait_queue ) ) ) { + +#if defined(RTEMS_MULTIPROCESSING) + if ( !_Objects_Is_local_id( the_thread->Object.id ) ) { + + the_mutex->holder = NULL; + the_mutex->holder_id = the_thread->Object.id; + the_mutex->nest_count = 1; + + ( *api_mutex_mp_support)( the_thread, id ); + + } else +#endif + { + + the_mutex->holder = the_thread; + the_mutex->holder_id = the_thread->Object.id; + the_thread->resource_count++; + the_mutex->nest_count = 1; + + /* + * No special action for priority inheritance or priority ceiling + * because the_thread is guaranteed to be the highest priority + * thread waiting for the mutex. + */ + } + } else + the_mutex->lock = CORE_MUTEX_UNLOCKED; + + return( CORE_MUTEX_STATUS_SUCCESSFUL ); +} + |