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-rw-r--r--src/thread/sem_trywait.c5
1 files changed, 2 insertions, 3 deletions
diff --git a/src/thread/sem_trywait.c b/src/thread/sem_trywait.c
index c5370c70..beb7aa5d 100644
--- a/src/thread/sem_trywait.c
+++ b/src/thread/sem_trywait.c
@@ -3,9 +3,8 @@
 
 int sem_trywait(sem_t *sem)
 {
-	int val = a_fetch_add(sem->__val, -1);
-	if (val > 0) return 0;
-	if (!a_fetch_add(sem->__val, 1))
+	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);
 	errno = EAGAIN;
 	return -1;