Re: [PATCH] uaccess: decouple INLINE_COPY_FROM_USER and CONFIG_RUST

[Alice Ryhl]

On Fri, Oct 24, 2025 at 3:45 PM Yury Norov <yury.norov@xxxxxxxxx> wrote:
>
> On Fri, Oct 24, 2025 at 09:12:56AM +0000, Alice Ryhl wrote:
> > On Thu, Oct 23, 2025 at 01:16:06PM -0400, Yury Norov (NVIDIA) wrote:
> > > Commit 1f9a8286bc0c ("uaccess: always export _copy_[from|to]_user with
> > > CONFIG_RUST") exports _copy_{from,to}_user() unconditionally, if RUST
> > > is enabled. This pollutes exported symbols namespace, and spreads RUST
> > > ifdefery in core files.
> > >
> > > It's better to declare a corresponding helper under the rust/helpers,
> > > similarly to how non-underscored copy_{from,to}_user() is handled.
> > >
> > > Signed-off-by: Yury Norov (NVIDIA) <yury.norov@xxxxxxxxx>
> >
> > Overall LGTM:
> > Reviewed-by: Alice Ryhl <aliceryhl@xxxxxxxxxx>
> > Tested-by: Alice Ryhl <aliceryhl@xxxxxxxxxx>
> >
> >
> > In include/linux/uaccess.h there is the comment:
> >
> >       Rust code always uses the extern definition.
> >
> > I think we should reword this comment as part of this change. You can
> > say that Rust accesses _inline_copy_from_user() through a helper, or
> > similar.
> >
> > After all, when using LTO or other mechanism to inline helpers, it is no
> > longer the case that Rust always uses the a function call.
>
> It is actually worth to just drop the rust part of the comment - with
> this patch there's nothing special in managing the _copy_from_user().

Yeah, makes sense.

Alice