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-rw-r--r--src/thread/sem_trywait.c6
1 files changed, 3 insertions, 3 deletions
diff --git a/src/thread/sem_trywait.c b/src/thread/sem_trywait.c
index 04edf46b..beb435da 100644
--- a/src/thread/sem_trywait.c
+++ b/src/thread/sem_trywait.c
@@ -1,12 +1,12 @@
 #include <semaphore.h>
+#include <limits.h>
 #include "pthread_impl.h"
 
 int sem_trywait(sem_t *sem)
 {
 	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;
+	while ((val=sem->__val[0]) & SEM_VALUE_MAX) {
+		if (a_cas(sem->__val, val, val-1)==val) return 0;
 	}
 	errno = EAGAIN;
 	return -1;