Re: [PATCH v3 1/5] mm: userfaultfd: rename functions for clarity + consistency

Peter Xu
2023-03-07T01:04:03Z

On Mon, Mar 06, 2023 at 02:50:20PM -0800, Axel Rasmussen wrote:
> The basic problem is, over time we've added new userfaultfd ioctls, and
> we've refactored the code so functions which used to handle only one
> case are now re-used to deal with several cases. While this happened, we
> didn't bother to rename the functions.
>
> Similarly, as we added new functions, we cargo-culted pieces of the
> now-inconsistent naming scheme, so those functions too ended up with
> names that don't make a lot of sense.
>
> A key point here is, "copy" in most userfaultfd code refers specifically
> to UFFDIO_COPY, where we allocate a new page and copy its contents from
> userspace. There are many functions with "copy" in the name that don't
> actually do this (at least in some cases).
>
> So, rename things into a consistent scheme. The high level idea is that
> the call stack for userfaultfd ioctls becomes:
>
> userfaultfd_ioctl
> -> userfaultfd_(particular ioctl)
> -> mfill_atomic_(particular kind of fill operation)
> -> mfill_atomic /* loops over pages in range */
> -> mfill_atomic_pte /* deals with single pages */
> -> mfill_atomic_pte_(particular kind of fill operation)
> -> mfill_atomic_install_pte
>
> There are of course some special cases (shmem, hugetlb), but this is the
> general structure which all function names now adhere to.
>
> Signed-off-by: Axel Rasmussen <axelrasmussen@google.com>

Acked-by: Peter Xu <peterx@redhat.com>

--
Peter Xu