X-Git-Url: http://nsz.repo.hu/git/?a=blobdiff_plain;f=src%2Fthread%2Fpthread_once.c;h=8e8d40ae8331dad752553bac7f1ccaac8e909efa;hb=b1dfb734a45d4f74c7a24c5f07d37f7e74451802;hp=41872f16cb47462845c62d70417e2143448fdfa5;hpb=7e6be42a77989c01155bdc7333ea58206e1563d4;p=musl

diff --git a/src/thread/pthread_once.c b/src/thread/pthread_once.c
index 41872f16..8e8d40ae 100644
--- a/src/thread/pthread_once.c
+++ b/src/thread/pthread_once.c
@@ -2,36 +2,49 @@
 
 static void undo(void *control)
 {
-	a_store(control, 0);
-	__wake(control, 1, 0);
+	/* Wake all waiters, since the waiter status is lost when
+	 * resetting control to the initial state. */
+	if (a_swap(control, 0) == 3)
+		__wake(control, -1, 1);
 }
 
-int pthread_once(pthread_once_t *control, void (*init)(void))
+hidden int __pthread_once_full(pthread_once_t *control, void (*init)(void))
 {
-	static int waiters;
-
-	/* Return immediately if init finished before */
-	if (*control == 2) return 0;
-
-	/* Try to enter initializing state. Three possibilities:
+	/* Try to enter initializing state. Four possibilities:
 	 *  0 - we're the first or the other cancelled; run init
 	 *  1 - another thread is running init; wait
-	 *  2 - another thread finished running init; just return */
+	 *  2 - another thread finished running init; just return
+	 *  3 - another thread is running init, waiters present; wait */
 
-	for (;;) switch (a_swap(control, 1)) {
+	for (;;) switch (a_cas(control, 0, 1)) {
 	case 0:
 		pthread_cleanup_push(undo, control);
 		init();
 		pthread_cleanup_pop(0);
 
-		a_store(control, 2);
-		if (waiters) __wake(control, -1, 0);
+		if (a_swap(control, 2) == 3)
+			__wake(control, -1, 1);
 		return 0;
 	case 1:
-		__wait(control, &waiters, 1, 0);
+		/* If this fails, so will __wait. */
+		a_cas(control, 1, 3);
+	case 3:
+		__wait(control, 0, 3, 1);
 		continue;
 	case 2:
-		a_store(control, 2);
 		return 0;
 	}
 }
+
+int __pthread_once(pthread_once_t *control, void (*init)(void))
+{
+	/* Return immediately if init finished before, but ensure that
+	 * effects of the init routine are visible to the caller. */
+	if (*(volatile int *)control == 2) {
+		a_barrier();
+		return 0;
+	}
+	return __pthread_once_full(control, init);
+}
+
+weak_alias(__pthread_once, pthread_once);