switch p.pidStatus() {
	case statusDone:
		return ErrProcessDone
	case statusReleased:
		return errors.New("os: process already released")
	}

	return convertESRCH(syscall.Kill(p.Pid, s))
}

func convertESRCH(err error) error {
	if err == syscall.ESRCH {
		return ErrProcessDone
	}
	return err
}

func (p *Process) release() error {

	return uintptr(*sysAttr.PidFD), true
}

func pidfdFind(pid int) (uintptr, error) {
	if !pidfdWorks() {
		return 0, syscall.ENOSYS
	}

	h, err := unix.PidFDOpen(pid, 0)
	if err != nil {
		return 0, convertESRCH(err)
	}
	return h, nil
}

// _P_PIDFD is used as idtype argument to waitid syscall.
const _P_PIDFD = 3

func (p *Process) pidfdWait() (*ProcessState, error) {