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/**
* @file
*
* @brief POSIX Condition Variables Wait Support
* @ingroup POSIX_COND_VARS
*/
/*
* COPYRIGHT (c) 1989-2014.
* 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/posix/condimpl.h>
#include <rtems/posix/posixapi.h>
#include <rtems/score/assert.h>
#include <rtems/score/statesimpl.h>
#include <rtems/score/status.h>
#include <rtems/score/threaddispatch.h>
THREAD_QUEUE_OBJECT_ASSERT( POSIX_Condition_variables_Control, Wait_queue );
int _POSIX_Condition_variables_Wait_support(
pthread_cond_t *cond,
pthread_mutex_t *mutex,
Watchdog_Interval timeout,
bool already_timedout
)
{
POSIX_Condition_variables_Control *the_cond;
Thread_queue_Context queue_context;
int error;
int mutex_error;
Per_CPU_Control *cpu_self;
Thread_Control *executing;
if ( mutex == NULL ) {
return EINVAL;
}
the_cond = _POSIX_Condition_variables_Get( cond, &queue_context );
if ( the_cond == NULL ) {
return EINVAL;
}
_POSIX_Condition_variables_Acquire_critical( the_cond, &queue_context );
if (
the_cond->mutex != POSIX_CONDITION_VARIABLES_NO_MUTEX
&& the_cond->mutex != *mutex
) {
_POSIX_Condition_variables_Release( the_cond, &queue_context );
return EINVAL;
}
the_cond->mutex = *mutex;
cpu_self = _Thread_Dispatch_disable_critical( &queue_context.Lock_context );
executing = _Per_CPU_Get_executing( cpu_self );
if ( !already_timedout ) {
_Thread_queue_Context_set_expected_level( &queue_context, 2 );
_Thread_queue_Enqueue_critical(
&the_cond->Wait_queue.Queue,
POSIX_CONDITION_VARIABLES_TQ_OPERATIONS,
executing,
STATES_WAITING_FOR_CONDITION_VARIABLE,
timeout,
&queue_context
);
} else {
_POSIX_Condition_variables_Release( the_cond, &queue_context );
executing->Wait.return_code = STATUS_TIMEOUT;
}
mutex_error = pthread_mutex_unlock( mutex );
if ( mutex_error != 0 ) {
/*
* Historically, we ignored the unlock status since the behavior
* is undefined by POSIX. But GNU/Linux returns EPERM in this
* case, so we follow their lead.
*/
_Assert( mutex_error == EINVAL || mutex_error == EPERM );
_Thread_queue_Extract( executing );
_Thread_Dispatch_enable( cpu_self );
return EPERM;
}
/*
* Switch ourself out because we blocked as a result of the
* _Thread_queue_Enqueue_critical().
*/
_Thread_Dispatch_enable( cpu_self );
error = _POSIX_Get_error_after_wait( executing );
/*
* If the thread is interrupted, while in the thread queue, by
* a POSIX signal, then pthread_cond_wait returns spuriously,
* according to the POSIX standard. It means that pthread_cond_wait
* returns a success status, except for the fact that it was not
* woken up a pthread_cond_signal() or a pthread_cond_broadcast().
*/
if ( error == EINTR ) {
error = 0;
}
/*
* When we get here the dispatch disable level is 0.
*/
mutex_error = pthread_mutex_lock( mutex );
if ( mutex_error != 0 ) {
_Assert( mutex_error == EINVAL );
return EINVAL;
}
return error;
}
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