Пример #1
0
int
_sched_yield(void)
{
	struct pthread	*curthread = _get_curthread();

	if (curthread->attr.flags & PTHREAD_SCOPE_SYSTEM)
		return (__sys_sched_yield());

	/* Reset the accumulated time slice value for the current thread: */
	curthread->slice_usec = -1;

	/* Schedule the next thread: */
	_thr_sched_switch(curthread);
	/* Always return no error. */
	return(0);
}
Пример #2
0
/* Draft 4 yield */
void
_pthread_yield(void)
{
	struct pthread	*curthread = _get_curthread();

	if (curthread->attr.flags & PTHREAD_SCOPE_SYSTEM) {
		__sys_sched_yield();
		return;
	}

	/* Reset the accumulated time slice value for the current thread: */
	curthread->slice_usec = -1;

	/* Schedule the next thread: */
	_thr_sched_switch(curthread);
}
Пример #3
0
int
_pthread_join(pthread_t pthread, void **thread_return)
{
	struct pthread *curthread = _get_curthread();
	void *tmp;
	kse_critical_t crit;
	int ret = 0;
 
	_thr_cancel_enter(curthread);

	/* Check if the caller has specified an invalid thread: */
	if (pthread == NULL || pthread->magic != THR_MAGIC) {
		/* Invalid thread: */
		_thr_cancel_leave(curthread, 1);
		return (EINVAL);
	}

	/* Check if the caller has specified itself: */
	if (pthread == curthread) {
		/* Avoid a deadlock condition: */
		_thr_cancel_leave(curthread, 1);
		return (EDEADLK);
	}

	/*
	 * Find the thread in the list of active threads or in the
	 * list of dead threads:
	 */
	if ((ret = _thr_ref_add(curthread, pthread, /*include dead*/1)) != 0) {
		/* Return an error: */
		_thr_cancel_leave(curthread, 1);
		return (ESRCH);
	}

	THR_SCHED_LOCK(curthread, pthread);
	/* Check if this thread has been detached: */
	if ((pthread->attr.flags & PTHREAD_DETACHED) != 0) {
		THR_SCHED_UNLOCK(curthread, pthread);
		/* Remove the reference and return an error: */
		_thr_ref_delete(curthread, pthread);
		ret = EINVAL;
	} else {
		/* Lock the target thread while checking its state. */
		if (pthread->state == PS_DEAD) {
			/* Return the thread's return value: */
			tmp = pthread->ret;

			/* Detach the thread. */
			pthread->attr.flags |= PTHREAD_DETACHED;

			/* Unlock the thread. */
			THR_SCHED_UNLOCK(curthread, pthread);

			/*
			 * Remove the thread from the list of active
			 * threads and add it to the GC list.
			 */
			crit = _kse_critical_enter();
			KSE_LOCK_ACQUIRE(curthread->kse, &_thread_list_lock);
			THR_LIST_REMOVE(pthread);
			THR_GCLIST_ADD(pthread);
			KSE_LOCK_RELEASE(curthread->kse, &_thread_list_lock);
			_kse_critical_leave(crit);

			/* Remove the reference. */
			_thr_ref_delete(curthread, pthread);
			if (thread_return != NULL)
				*thread_return = tmp;
		}
		else if (pthread->joiner != NULL) {
			/* Unlock the thread and remove the reference. */
			THR_SCHED_UNLOCK(curthread, pthread);
			_thr_ref_delete(curthread, pthread);

			/* Multiple joiners are not supported. */
			ret = ENOTSUP;
		}
		else {
			/* Set the running thread to be the joiner: */
			pthread->joiner = curthread;

			/* Keep track of which thread we're joining to: */
			curthread->join_status.thread = pthread;

			/* Unlock the thread and remove the reference. */
			THR_SCHED_UNLOCK(curthread, pthread);
			_thr_ref_delete(curthread, pthread);

			THR_SCHED_LOCK(curthread, curthread);
			while (curthread->join_status.thread == pthread) {
				THR_SET_STATE(curthread, PS_JOIN);
				THR_SCHED_UNLOCK(curthread, curthread);
				/* Schedule the next thread: */
				_thr_sched_switch(curthread);
				THR_SCHED_LOCK(curthread, curthread);
			}
			THR_SCHED_UNLOCK(curthread, curthread);

			if ((curthread->cancelflags & THR_CANCELLING) &&
			   !(curthread->cancelflags & PTHREAD_CANCEL_DISABLE)) {
				if (_thr_ref_add(curthread, pthread, 1) == 0) {
					THR_SCHED_LOCK(curthread, pthread);
					pthread->joiner = NULL;
					THR_SCHED_UNLOCK(curthread, pthread);
					_thr_ref_delete(curthread, pthread);
				}
				_pthread_exit(PTHREAD_CANCELED);
			}

			/*
			 * The thread return value and error are set by the
			 * thread we're joining to when it exits or detaches:
			 */
			ret = curthread->join_status.error;
			if ((ret == 0) && (thread_return != NULL))
				*thread_return = curthread->join_status.ret;
		}
	}
	_thr_cancel_leave(curthread, 1);

	/* Return the completion status: */
	return (ret);
}
Пример #4
0
int
_pthread_cond_timedwait(pthread_cond_t * cond, pthread_mutex_t * mutex,
		       const struct timespec * abstime)
{
	struct pthread	*curthread = _get_curthread();
	int	rval = 0;
	int	done = 0;
	int	mutex_locked = 1;
	int	seqno;

	THR_ASSERT(curthread->locklevel == 0,
	    "cv_timedwait: locklevel is not zero!");

	if (abstime == NULL || abstime->tv_sec < 0 || abstime->tv_nsec < 0 ||
	    abstime->tv_nsec >= 1000000000)
		return (EINVAL);
	/*
	 * If the condition variable is statically initialized, perform dynamic
	 * initialization.
	 */
	if (*cond == NULL && (rval = _pthread_cond_init(cond, NULL)) != 0)
		return (rval);

	if (!_kse_isthreaded())
		_kse_setthreaded(1);

	/*
	 * Enter a loop waiting for a condition signal or broadcast
	 * to wake up this thread.  A loop is needed in case the waiting
	 * thread is interrupted by a signal to execute a signal handler.
	 * It is not (currently) possible to remain in the waiting queue
	 * while running a handler.  Instead, the thread is interrupted
	 * and backed out of the waiting queue prior to executing the
	 * signal handler.
	 */

	/* Lock the condition variable structure: */
	THR_LOCK_ACQUIRE(curthread, &(*cond)->c_lock);
	seqno = (*cond)->c_seqno;
	do {
		/*
		 * If the condvar was statically allocated, properly
		 * initialize the tail queue.
		 */
		if (((*cond)->c_flags & COND_FLAGS_INITED) == 0) {
			TAILQ_INIT(&(*cond)->c_queue);
			(*cond)->c_flags |= COND_FLAGS_INITED;
		}

		/* Process according to condition variable type: */
		switch ((*cond)->c_type) {
		/* Fast condition variable: */
		case COND_TYPE_FAST:
			if ((mutex == NULL) || (((*cond)->c_mutex != NULL) &&
			    ((*cond)->c_mutex != *mutex))) {
				/* Return invalid argument error: */
				rval = EINVAL;
			} else {
				/* Reset the timeout and interrupted flags: */
				curthread->timeout = 0;
				curthread->interrupted = 0;

				/*
				 * Queue the running thread for the condition
				 * variable:
				 */
				cond_queue_enq(*cond, curthread);

				/* Unlock the mutex: */
				if (mutex_locked &&
				   ((rval = _mutex_cv_unlock(mutex)) != 0)) {
					/*
					 * Cannot unlock the mutex; remove the
					 * running thread from the condition
					 * variable queue: 
					 */
					cond_queue_remove(*cond, curthread);
				} else {
					/* Remember the mutex: */
					(*cond)->c_mutex = *mutex;

					/*
					 * Don't unlock the mutex the next
					 * time through the loop (if the
					 * thread has to be requeued after
					 * handling a signal).
					 */
					mutex_locked = 0;

					/*
					 * This thread is active and is in a
					 * critical region (holding the cv
					 * lock); we should be able to safely
					 * set the state.
					 */
					THR_SCHED_LOCK(curthread, curthread);
					/* Set the wakeup time: */
					curthread->wakeup_time.tv_sec =
					    abstime->tv_sec;
					curthread->wakeup_time.tv_nsec =
					    abstime->tv_nsec;
					THR_SET_STATE(curthread, PS_COND_WAIT);

					/* Remember the CV: */
					curthread->data.cond = *cond;
					curthread->sigbackout = cond_wait_backout;
					THR_SCHED_UNLOCK(curthread, curthread);

					/* Unlock the CV structure: */
					THR_LOCK_RELEASE(curthread,
					    &(*cond)->c_lock);

					/* Schedule the next thread: */
					_thr_sched_switch(curthread);

					/*
					 * XXX - This really isn't a good check
					 * since there can be more than one
					 * thread waiting on the CV.  Signals
					 * sent to threads waiting on mutexes
					 * or CVs should really be deferred
					 * until the threads are no longer
					 * waiting, but POSIX says that signals
					 * should be sent "as soon as possible".
					 */
					done = (seqno != (*cond)->c_seqno);
					if (done && !THR_IN_CONDQ(curthread)) {
						/*
						 * The thread is dequeued, so
						 * it is safe to clear these.
						 */
						curthread->data.cond = NULL;
						curthread->sigbackout = NULL;
						check_continuation(curthread,
						    NULL, mutex);
						return (_mutex_cv_lock(mutex));
					}

					/* Relock the CV structure: */
					THR_LOCK_ACQUIRE(curthread,
					    &(*cond)->c_lock);

					/*
					 * Clear these after taking the lock to
					 * prevent a race condition where a
					 * signal can arrive before dequeueing
					 * the thread.
					 */
					curthread->data.cond = NULL;
					curthread->sigbackout = NULL;

					done = (seqno != (*cond)->c_seqno);

					if (THR_IN_CONDQ(curthread)) {
						cond_queue_remove(*cond,
						    curthread);

						/* Check for no more waiters: */
						if (TAILQ_EMPTY(&(*cond)->c_queue))
							(*cond)->c_mutex = NULL;
					}

					if (curthread->timeout != 0) {
						/* The wait timedout. */
						rval = ETIMEDOUT;
					}
				}
			}
			break;

		/* Trap invalid condition variable types: */
		default:
			/* Return an invalid argument error: */
			rval = EINVAL;
			break;
		}

		check_continuation(curthread, *cond,
		    mutex_locked ? NULL : mutex);
	} while ((done == 0) && (rval == 0));

	/* Unlock the condition variable structure: */
	THR_LOCK_RELEASE(curthread, &(*cond)->c_lock);

	if (mutex_locked == 0)
		_mutex_cv_lock(mutex);

	/* Return the completion status: */
	return (rval);
}