Function sys_futex 

pub fn sys_futex(
    locked: &mut Locked<Unlocked>,
    current_task: &mut CurrentTask,
    addr: UserAddress,
    op: u32,
    value: u32,
    timeout_or_value2: SyscallArg,
    addr2: UserAddress,
    value3: u32,
) -> Result<usize, Errno>