rem: else if (ret == 0) {  ret = -1;
add: else {  return(1);
context: int kvu_fd_wait(int fd, int timeout){  int nfds = 1;  struct pollfd ufds;  ufds.fd = fd;  ufds.events = POLLIN | POLLPRI | POLLOUT;  ufds.revents = 0;  int ret = poll(&ufds, nfds, timeout);  if (ret > 0) {    if (ufds.revents & POLLERR ||	ufds.revents & POLLHUP ||	ufds.revents & POLLNVAL) {      ret = -1;    }    else if (ret == 0) {      /* timeout */      ret = -1;    }  }  return(ret);}