Re: [PATCH v2 3/5] mm: userfaultfd: combine 'mode' and 'wp_copy' arguments

[Axel Rasmussen <axelrasmussen@google.com>]

On Thu, Feb 23, 2023 at 10:51 AM Nadav Amit <namit@vmware.com> wrote:
>
>
>
> > On Feb 22, 2023, at 4:57 PM, Axel Rasmussen <axelrasmussen@google.com> wrote:
> >
> > Many userfaultfd ioctl functions take both a 'mode' and a 'wp_copy'
> > argument. In future commits we plan to plumb the flags through to more
> > places, so we'd be proliferating the very long argument list even
> > further.
> >
> > Let's take the time to simplify the argument list. Combine the two
> > arguments into one - and generalize, so when we add more flags in the
> > future, it doesn't imply more function arguments.
> >
> > Since the modes (copy, zeropage, continue) are mutually exclusive, store
> > them as an integer value (0, 1, 2) in the low bits. Place combine-able
> > flag bits in the high bits.
> >
> > Signed-off-by: Axel Rasmussen <axelrasmussen@google.com>
>
> Hi Axel,
>
> I sent a patch a long time ago called “userfaultfd: introduce uffd_flags”.
> For some reason it does not appear on lore, but you were a recipient.
>
> It was pretty similar, but one thing that I preferred in my version is
> that it defined a different type to avoid confusion. Since “flags” is
> a very generic name, perhaps you’d like to adapt this approach.

Oh! I must have missed it, or just forgot. I'll take a look and see
about making some improvements. I'll also be sure to credit you in the
commit message.

>