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Corrected implementation of timed wait on condition variables. First

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the timeout is given as a wall-time not an interval as was previously
implemented.  Second, the interpretation of ETIMEDOUT behavior was
incorrect as all possible error cases needed to be checked before
this error was returned.  This caused problems when the wall-time
specified was in the past.
This commit is contained in:
Joel Sherrill
1996-09-17 21:29:51 +00:00
parent ded66f8f41
commit 9093c3c29b
2 changed files with 104 additions and 58 deletions
Download Patch File Download Diff File Expand all files Collapse all files
c/src/exec/posix/src/cond.c
+52 -29
View File
@@ -363,12 +363,14 @@ int pthread_cond_broadcast(
int _POSIX_Condition_variables_Wait_support(
pthread_cond_t *cond,
pthread_mutex_t *mutex,
Watchdog_Interval timeout
Watchdog_Interval timeout,
boolean already_timedout
)
{
register POSIX_Condition_variables_Control *the_cond;
Objects_Locations location;
int status;
int mutex_status;
if ( !_POSIX_Mutex_Get( mutex, &location ) ) {
return EINVAL;
@@ -391,38 +393,44 @@ int _POSIX_Condition_variables_Wait_support(
return EINVAL;
}
the_cond->Mutex = *mutex;
status = pthread_mutex_unlock( mutex );
/* XXX ignore this for now
if ( status ) {
(void) pthread_mutex_unlock( mutex );
/* XXX ignore this for now since behavior is undefined
if ( mutex_status ) {
_Thread_Enable_dispatch();
return EINVAL;
}
*/
if ( !already_timedout ) {
the_cond->Mutex = *mutex;
_Thread_queue_Enter_critical_section( &the_cond->Wait_queue );
_Thread_Executing->Wait.return_code = 0;
_Thread_Executing->Wait.queue = &the_cond->Wait_queue;
_Thread_Executing->Wait.id = *cond;
_Thread_queue_Enter_critical_section( &the_cond->Wait_queue );
_Thread_Executing->Wait.return_code = 0;
_Thread_Executing->Wait.queue = &the_cond->Wait_queue;
_Thread_Executing->Wait.id = *cond;
_Thread_queue_Enqueue( &the_cond->Wait_queue, timeout );
_Thread_queue_Enqueue( &the_cond->Wait_queue, timeout );
_Thread_Enable_dispatch();
_Thread_Enable_dispatch();
/*
* Switch ourself out because we blocked as a result of the
* _Thread_queue_Enqueue.
*/
/*
* Switch ourself out because we blocked as a result of the
* _Thread_queue_Enqueue.
*/
if ( _Thread_Executing->Wait.return_code )
return _Thread_Executing->Wait.return_code;
status = _Thread_Executing->Wait.return_code;
if ( status && status != ETIMEDOUT )
return status;
status = pthread_mutex_lock( mutex );
if ( status )
}
else
status = ETIMEDOUT;
mutex_status = pthread_mutex_lock( mutex );
if ( mutex_status )
return EINVAL;
return _Thread_Executing->Wait.return_code;
return status;
}
return POSIX_BOTTOM_REACHED();
}
@@ -440,7 +448,8 @@ int pthread_cond_wait(
return _POSIX_Condition_variables_Wait_support(
cond,
mutex,
THREAD_QUEUE_WAIT_FOREVER
THREAD_QUEUE_WAIT_FOREVER,
FALSE
);
}
@@ -455,20 +464,34 @@ int pthread_cond_timedwait(
const struct timespec *abstime
)
{
Watchdog_Interval timeout;
struct timespec current_time;
struct timespec difference;
boolean already_timedout = FALSE;
if ( !abstime )
return EINVAL;
/* XXX need to fully address an error occuring in the total timespec */
/*
* The abstime is a walltime. We turn it into an interval.
*/
if ( abstime->tv_sec < 0 || abstime->tv_nsec < 0 )
return EINVAL;
(void) clock_gettime( CLOCK_REALTIME, &current_time );
/* XXX probably some error checking should go here */
_POSIX_Timespec_subtract( &current_time, abstime, &difference );
if ( ( difference.tv_sec < 0 ) || ( ( difference.tv_sec == 0 ) &&
( difference.tv_nsec < 0 ) ) )
already_timedout = TRUE;
timeout = _POSIX_Timespec_to_interval( &difference );
if ( abstime->tv_nsec >= TOD_NANOSECONDS_PER_SECOND )
return EINVAL;
return _POSIX_Condition_variables_Wait_support(
cond,
mutex,
_POSIX_Timespec_to_interval( abstime )
timeout,
already_timedout
);
}
cpukit/posix/src/cond.c
+52 -29
View File
@@ -363,12 +363,14 @@ int pthread_cond_broadcast(
int _POSIX_Condition_variables_Wait_support(
pthread_cond_t *cond,
pthread_mutex_t *mutex,
Watchdog_Interval timeout
Watchdog_Interval timeout,
boolean already_timedout
)
{
register POSIX_Condition_variables_Control *the_cond;
Objects_Locations location;
int status;
int mutex_status;
if ( !_POSIX_Mutex_Get( mutex, &location ) ) {
return EINVAL;
@@ -391,38 +393,44 @@ int _POSIX_Condition_variables_Wait_support(
return EINVAL;
}
the_cond->Mutex = *mutex;
status = pthread_mutex_unlock( mutex );
/* XXX ignore this for now
if ( status ) {
(void) pthread_mutex_unlock( mutex );
/* XXX ignore this for now since behavior is undefined
if ( mutex_status ) {
_Thread_Enable_dispatch();
return EINVAL;
}
*/
if ( !already_timedout ) {
the_cond->Mutex = *mutex;
_Thread_queue_Enter_critical_section( &the_cond->Wait_queue );
_Thread_Executing->Wait.return_code = 0;
_Thread_Executing->Wait.queue = &the_cond->Wait_queue;
_Thread_Executing->Wait.id = *cond;
_Thread_queue_Enter_critical_section( &the_cond->Wait_queue );
_Thread_Executing->Wait.return_code = 0;
_Thread_Executing->Wait.queue = &the_cond->Wait_queue;
_Thread_Executing->Wait.id = *cond;
_Thread_queue_Enqueue( &the_cond->Wait_queue, timeout );
_Thread_queue_Enqueue( &the_cond->Wait_queue, timeout );
_Thread_Enable_dispatch();
_Thread_Enable_dispatch();
/*
* Switch ourself out because we blocked as a result of the
* _Thread_queue_Enqueue.
*/
/*
* Switch ourself out because we blocked as a result of the
* _Thread_queue_Enqueue.
*/
if ( _Thread_Executing->Wait.return_code )
return _Thread_Executing->Wait.return_code;
status = _Thread_Executing->Wait.return_code;
if ( status && status != ETIMEDOUT )
return status;
status = pthread_mutex_lock( mutex );
if ( status )
}
else
status = ETIMEDOUT;
mutex_status = pthread_mutex_lock( mutex );
if ( mutex_status )
return EINVAL;
return _Thread_Executing->Wait.return_code;
return status;
}
return POSIX_BOTTOM_REACHED();
}
@@ -440,7 +448,8 @@ int pthread_cond_wait(
return _POSIX_Condition_variables_Wait_support(
cond,
mutex,
THREAD_QUEUE_WAIT_FOREVER
THREAD_QUEUE_WAIT_FOREVER,
FALSE
);
}
@@ -455,20 +464,34 @@ int pthread_cond_timedwait(
const struct timespec *abstime
)
{
Watchdog_Interval timeout;
struct timespec current_time;
struct timespec difference;
boolean already_timedout = FALSE;
if ( !abstime )
return EINVAL;
/* XXX need to fully address an error occuring in the total timespec */
/*
* The abstime is a walltime. We turn it into an interval.
*/
if ( abstime->tv_sec < 0 || abstime->tv_nsec < 0 )
return EINVAL;
(void) clock_gettime( CLOCK_REALTIME, &current_time );
/* XXX probably some error checking should go here */
_POSIX_Timespec_subtract( &current_time, abstime, &difference );
if ( ( difference.tv_sec < 0 ) || ( ( difference.tv_sec == 0 ) &&
( difference.tv_nsec < 0 ) ) )
already_timedout = TRUE;
timeout = _POSIX_Timespec_to_interval( &difference );
if ( abstime->tv_nsec >= TOD_NANOSECONDS_PER_SECOND )
return EINVAL;
return _POSIX_Condition_variables_Wait_support(
cond,
mutex,
_POSIX_Timespec_to_interval( abstime )
timeout,
already_timedout
);
}