Function io_uring_enter 

pub unsafe fn io_uring_enter(
    fd_or_idx: u32,
    to_submit: u32,
    min_complete: u32,
    flags: u32,
    arg: *const u8,
    arg_size: usize,
) -> Result<i32>

Tell the kernel about new pending submission entries, and/or wait for new completion entries.

Safety

If arg is not ptr::null(), then arg_size must contain the size of the value it is pointing to, and the value must be valid.