void _Semaphore_Wait( struct _Semaphore_Control *_sem )
{
Semaphore_Control *sem ;
Thread_queue_Context queue_context;
Thread_Control *executing;
unsigned int count;
sem = _Semaphore_Get( _sem );
_Thread_queue_Context_initialize( &queue_context );
executing = _Semaphore_Queue_acquire( sem, &queue_context );
count = sem->count;
if ( count > 0 ) {
sem->count = count - 1;
_Semaphore_Queue_release( sem, &queue_context );
} else {
_Thread_queue_Context_set_expected_level( &queue_context, 1 );
_Thread_queue_Context_set_no_timeout( &queue_context );
_Thread_queue_Enqueue_critical(
&sem->Queue.Queue,
SEMAPHORE_TQ_OPERATIONS,
executing,
STATES_WAITING_FOR_SYS_LOCK_SEMAPHORE,
&queue_context
);
}
}
Status_Control _CORE_barrier_Seize(
CORE_barrier_Control *the_barrier,
Thread_Control *executing,
bool wait,
Watchdog_Interval timeout,
Thread_queue_Context *queue_context
)
{
uint32_t number_of_waiting_threads;
_CORE_barrier_Acquire_critical( the_barrier, queue_context );
number_of_waiting_threads = the_barrier->number_of_waiting_threads;
++number_of_waiting_threads;
if (
_CORE_barrier_Is_automatic( &the_barrier->Attributes )
&& number_of_waiting_threads == the_barrier->Attributes.maximum_count
) {
_CORE_barrier_Surrender( the_barrier, queue_context );
return STATUS_BARRIER_AUTOMATICALLY_RELEASED;
} else {
the_barrier->number_of_waiting_threads = number_of_waiting_threads;
_Thread_queue_Context_set_expected_level( queue_context, 1 );
_Thread_queue_Enqueue_critical(
&the_barrier->Wait_queue.Queue,
CORE_BARRIER_TQ_OPERATIONS,
executing,
STATES_WAITING_FOR_BARRIER,
timeout,
queue_context
);
return _Thread_Wait_get_status( executing );
}
}
static int _POSIX_Threads_Join( pthread_t thread, void **value_ptr )
{
Thread_Control *the_thread;
Thread_queue_Context queue_context;
Per_CPU_Control *cpu_self;
Thread_Control *executing;
void *value;
_Thread_queue_Context_initialize( &queue_context );
_Thread_queue_Context_set_expected_level( &queue_context, 1 );
the_thread = _Thread_Get( thread, &queue_context.Lock_context );
if ( the_thread == NULL ) {
return ESRCH;
}
cpu_self = _Per_CPU_Get();
executing = _Per_CPU_Get_executing( cpu_self );
if ( executing == the_thread ) {
_ISR_lock_ISR_enable( &queue_context.Lock_context );
return EDEADLK;
}
_Thread_State_acquire_critical( the_thread, &queue_context.Lock_context );
if ( !_Thread_Is_joinable( the_thread ) ) {
_Thread_State_release( the_thread, &queue_context.Lock_context );
return EINVAL;
}
if ( _States_Is_waiting_for_join_at_exit( the_thread->current_state ) ) {
value = the_thread->Life.exit_value;
_Thread_Clear_state_locked( the_thread, STATES_WAITING_FOR_JOIN_AT_EXIT );
_Thread_Dispatch_disable_with_CPU( cpu_self, &queue_context.Lock_context );
_Thread_State_release( the_thread, &queue_context.Lock_context );
_Thread_Dispatch_enable( cpu_self );
} else {
_Thread_Join(
the_thread,
STATES_INTERRUPTIBLE_BY_SIGNAL | STATES_WAITING_FOR_JOIN,
executing,
&queue_context
);
if ( _POSIX_Get_error_after_wait( executing ) != 0 ) {
_Assert( _POSIX_Get_error_after_wait( executing ) == EINTR );
return EINTR;
}
value = executing->Wait.return_argument;
}
if ( value_ptr != NULL ) {
*value_ptr = value;
}
return 0;
}
Status_Control _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 );
return STATUS_SUCCESSFUL;
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 );
return STATUS_UNAVAILABLE;
}
/*
* We need to wait to enter this critical section
*/
executing->Wait.option = CORE_RWLOCK_THREAD_WAITING_FOR_WRITE;
_Thread_queue_Context_set_expected_level( queue_context, 1 );
_Thread_queue_Enqueue_critical(
&the_rwlock->Wait_queue.Queue,
CORE_RWLOCK_TQ_OPERATIONS,
executing,
STATES_WAITING_FOR_RWLOCK,
timeout,
queue_context
);
return _Thread_Wait_get_status( executing );
}
void _Thread_Close( Thread_Control *the_thread, Thread_Control *executing )
{
Thread_queue_Context queue_context;
_Thread_queue_Context_initialize( &queue_context );
_Thread_queue_Context_set_expected_level( &queue_context, 2 );
_Thread_queue_Context_set_no_timeout( &queue_context );
_Thread_State_acquire( the_thread, &queue_context.Lock_context.Lock_context );
_Thread_Join(
the_thread,
STATES_WAITING_FOR_JOIN,
executing,
&queue_context
);
_Thread_Cancel( the_thread, executing, NULL );
}
static void _Mutex_Acquire_slow(
Mutex_Control *mutex,
Thread_Control *owner,
Thread_Control *executing,
Thread_queue_Context *queue_context
)
{
_Thread_queue_Context_set_expected_level( queue_context, 1 );
_Thread_queue_Context_set_deadlock_callout(
queue_context,
_Thread_queue_Deadlock_fatal
);
_Thread_queue_Enqueue_critical(
&mutex->Queue.Queue,
MUTEX_TQ_OPERATIONS,
executing,
STATES_WAITING_FOR_SYS_LOCK_MUTEX,
queue_context
);
}
int _POSIX_Condition_variables_Wait_support(
pthread_cond_t *cond,
pthread_mutex_t *mutex,
const struct timespec *abstime
)
{
POSIX_Condition_variables_Control *the_cond;
Thread_queue_Context queue_context;
int error;
int mutex_error;
Per_CPU_Control *cpu_self;
Thread_Control *executing;
Watchdog_Interval timeout;
bool already_timedout;
TOD_Absolute_timeout_conversion_results status;
if ( mutex == NULL ) {
return EINVAL;
}
the_cond = _POSIX_Condition_variables_Get( cond, &queue_context );
if ( the_cond == NULL ) {
return EINVAL;
}
already_timedout = false;
if ( abstime != NULL ) {
/*
* POSIX requires that blocking calls with timeouts that take
* an absolute timeout must ignore issues with the absolute
* time provided if the operation would otherwise succeed.
* So we check the abstime provided, and hold on to whether it
* is valid or not. If it isn't correct and in the future,
* then we do a polling operation and convert the UNSATISFIED
* status into the appropriate error.
*/
_Assert( the_cond->clock );
status = _TOD_Absolute_timeout_to_ticks(abstime, the_cond->clock, &timeout);
if ( status == TOD_ABSOLUTE_TIMEOUT_INVALID )
return EINVAL;
if ( status == TOD_ABSOLUTE_TIMEOUT_IS_IN_PAST ||
status == TOD_ABSOLUTE_TIMEOUT_IS_NOW ) {
already_timedout = true;
} else {
_Thread_queue_Context_set_relative_timeout( &queue_context, timeout );
}
} else {
_Thread_queue_Context_set_no_timeout( &queue_context );
}
_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,
&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;
}
