X-Git-Url: http://nsz.repo.hu/git/?p=musl;a=blobdiff_plain;f=src%2Fthread%2Fsem_trywait.c;h=55d90075e274a5e0a82359ffc96e6b45a279e286;hp=beb7aa5d3d359b793e11bf106ee21dda92feef73;hb=e7655ed37bc9c2d79d921af4f287ee5cf2788661;hpb=a113434cd68ce30642c4995b1caadcd084be6f09

diff --git a/src/thread/sem_trywait.c b/src/thread/sem_trywait.c
index beb7aa5d..55d90075 100644
--- a/src/thread/sem_trywait.c
+++ b/src/thread/sem_trywait.c
@@ -3,9 +3,11 @@
 
 int sem_trywait(sem_t *sem)
 {
-	if (a_fetch_add(sem->__val, -1) > 0) return 0;
-	if (!a_fetch_add(sem->__val, 1) && sem->__val[1])
-		__wake(sem->__val, 1, 0);
+	int val = sem->__val[0];
+	if (val>0) {
+		int new = val-1-(val==1 && sem->__val[1]);
+		if (a_cas(sem->__val, val, new)==val) return 0;
+	}
 	errno = EAGAIN;
 	return -1;
 }