X-Git-Url: http://nsz.repo.hu/git/?a=blobdiff_plain;f=src%2Fthread%2Fsem_trywait.c;h=04edf46b524de72a575b1db7687f56d93fc1e291;hb=e864ddc36819814b3b9ed17620459d66add512d3;hp=beb7aa5d3d359b793e11bf106ee21dda92feef73;hpb=a113434cd68ce30642c4995b1caadcd084be6f09;p=musl

diff --git a/src/thread/sem_trywait.c b/src/thread/sem_trywait.c
index beb7aa5d..04edf46b 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;
+	while ((val=sem->__val[0]) > 0) {
+		int new = val-1-(val==1 && sem->__val[1]);
+		if (a_cas(sem->__val, val, new)==val) return 0;
+	}
 	errno = EAGAIN;
 	return -1;
 }