overhaul posix semaphores to fix destructability race

[musl] / src / thread / sem_timedwait.c

diff --git a/src/thread/sem_timedwait.c b/src/thread/sem_timedwait.c
index db05b41..1d4b3e2 100644 (file)
--- a/src/thread/sem_timedwait.c
+++ b/src/thread/sem_timedwait.c
@@ -8,31 +8,21 @@ static void cleanup(void *p)
 
 int sem_timedwait(sem_t *sem, const struct timespec *at)
 {
-       int r;
-
-       if (a_fetch_add(sem->__val, -1) > 0) return 0;
-       a_inc(sem->__val);
-
-       if (at && at->tv_nsec >= 1000000000UL) {
-               errno = EINVAL;
-               return -1;
-       }
-
-       a_inc(sem->__val+1);
-       pthread_cleanup_push(cleanup, sem->__val+1)
-
-       for (;;) {
-               r = 0;
-               if (!sem_trywait(sem)) break;
-               r = __timedwait_cp(sem->__val, 0, CLOCK_REALTIME, at, 0);
+       while (sem_trywait(sem)) {
+               int r;
+               if (at && at->tv_nsec >= 1000000000UL) {
+                       errno = EINVAL;
+                       return -1;
+               }
+               a_inc(sem->__val+1);
+               a_cas(sem->__val, 0, -1);
+               pthread_cleanup_push(cleanup, sem->__val+1);
+               r = __timedwait_cp(sem->__val, -1, CLOCK_REALTIME, at, 0);
+               pthread_cleanup_pop(1);
                if (r) {
                        errno = r;
-                       r = -1;
-                       break;
+                       return -1;
                }
        }
-
-       pthread_cleanup_pop(1);
-
-       return r;
+       return 0;
 }