+ StgMainThread *m;
+
+ m = stgMallocBytes(sizeof(StgMainThread), "waitThread");
+ m->tso = tso;
+ m->ret = ret;
+ m->stat = NoStatus;
+#if defined(RTS_SUPPORTS_THREADS)
+ initCondition(&m->wakeup);
+#endif
+
+ /* Put the thread on the main-threads list prior to scheduling the TSO.
+ Failure to do so introduces a race condition in the MT case (as
+ identified by Wolfgang Thaller), whereby the new task/OS thread
+ created by scheduleThread_() would complete prior to the thread
+ that spawned it managed to put 'itself' on the main-threads list.
+ The upshot of it all being that the worker thread wouldn't get to
+ signal the completion of the its work item for the main thread to
+ see (==> it got stuck waiting.) -- sof 6/02.
+ */
+ ACQUIRE_LOCK(&sched_mutex);
+ IF_DEBUG(scheduler, sched_belch("== scheduler: waiting for thread (%d)\n", tso->id));
+
+ m->link = main_threads;
+ main_threads = m;
+
+ /* Inefficient (scheduleThread_() acquires it again right away),
+ * but obviously correct.
+ */
+ RELEASE_LOCK(&sched_mutex);
+
+ scheduleThread_(tso, rtsTrue);
+#if defined(THREADED_RTS)
+ return waitThread_(m, rtsTrue);
+#else
+ return waitThread_(m);
+#endif