change sem_trywait algorithm so it never has to call __wake

This commit is contained in:
Rich Felker 2011-04-14 15:10:50 -04:00
parent ec2e50d0d7
commit e983aea0ae
1 changed files with 2 additions and 3 deletions

View File

@ -3,9 +3,8 @@
int sem_trywait(sem_t *sem)
{
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);
int val = sem->__val[0];
if (val>0 && a_cas(sem->__val, val, val-1)==val) return 0;
errno = EAGAIN;
return -1;
}