minor locking optimizations

[musl] / src / thread / sem_trywait.c

diff --git a/src/thread/sem_trywait.c b/src/thread/sem_trywait.c
index d0e928e..dd8f57e 100644 (file)
--- 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;
-       a_inc(sem->__val);
+       int val = sem->__val[0];
+       if (val>0 && a_cas(sem->__val, val, val-1)==val) return 0;
        errno = EAGAIN;
        return -1;
 }