#include <semaphore.h> | |
#include "futex_impl.h" | |
#include "threads_impl.h" | |
int sem_post(sem_t* sem) { | |
int val, waiters; | |
do { | |
val = atomic_load(&sem->_s_value); | |
waiters = atomic_load(&sem->_s_waiters); | |
if (val == SEM_VALUE_MAX) { | |
errno = EOVERFLOW; | |
return -1; | |
} | |
} while (a_cas_shim(&sem->_s_value, val, val + 1 + (val < 0)) != val); | |
if (val < 0 || waiters) | |
_zx_futex_wake(&sem->_s_value, 1); | |
return 0; | |
} |