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/**
* @file
*
* @brief RWLock Obtain for Writing
* @ingroup ScoreRWLock
*/
/*
* COPYRIGHT (c) 1989-2006.
* On-Line Applications Research Corporation (OAR).
*
* The license and distribution terms for this file may be
* found in the file LICENSE in this distribution or at
* http://www.rtems.org/license/LICENSE.
*/
#if HAVE_CONFIG_H
#include "config.h"
#endif
#include <rtems/score/corerwlockimpl.h>
#include <rtems/score/threadqimpl.h>
#include <rtems/score/statesimpl.h>
#include <rtems/score/watchdog.h>
void _CORE_RWLock_Seize_for_writing(
CORE_RWLock_Control *the_rwlock,
Thread_Control *executing,
bool wait,
Watchdog_Interval timeout,
Thread_queue_Context *queue_context
)
{
/*
* If unlocked, then OK to read.
* Otherwise, we have to block.
* If locked for reading and no waiters, then OK to read.
* If any thread is waiting, then we wait.
*/
_CORE_RWLock_Acquire_critical( the_rwlock, queue_context );
switch ( the_rwlock->current_state ) {
case CORE_RWLOCK_UNLOCKED:
the_rwlock->current_state = CORE_RWLOCK_LOCKED_FOR_WRITING;
_CORE_RWLock_Release( the_rwlock, queue_context );
executing->Wait.return_code = CORE_RWLOCK_SUCCESSFUL;
return;
case CORE_RWLOCK_LOCKED_FOR_READING:
case CORE_RWLOCK_LOCKED_FOR_WRITING:
break;
}
/*
* If the thread is not willing to wait, then return immediately.
*/
if ( !wait ) {
_CORE_RWLock_Release( the_rwlock, queue_context );
executing->Wait.return_code = CORE_RWLOCK_UNAVAILABLE;
return;
}
/*
* We need to wait to enter this critical section
*/
executing->Wait.option = CORE_RWLOCK_THREAD_WAITING_FOR_WRITE;
executing->Wait.return_code = CORE_RWLOCK_SUCCESSFUL;
_Thread_queue_Enqueue_critical(
&the_rwlock->Wait_queue.Queue,
CORE_RWLOCK_TQ_OPERATIONS,
executing,
STATES_WAITING_FOR_RWLOCK,
timeout,
CORE_RWLOCK_TIMEOUT,
&queue_context->Lock_context
);
}
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