Re: [PATCH v2 5/7] rust: file: add `Kuid` wrapper

[Alice Ryhl]

On Wed, Dec 6, 2023 at 1:34 PM Peter Zijlstra <peterz@xxxxxxxxxxxxx> wrote:
>
> On Wed, Dec 06, 2023 at 11:59:50AM +0000, Alice Ryhl wrote:
>
> > diff --git a/rust/helpers.c b/rust/helpers.c
> > index fd633d9db79a..58e3a9dff349 100644
> > --- a/rust/helpers.c
> > +++ b/rust/helpers.c
> > @@ -142,6 +142,51 @@ void rust_helper_put_task_struct(struct task_struct *t)
> >  }
> >  EXPORT_SYMBOL_GPL(rust_helper_put_task_struct);
> >
> > +kuid_t rust_helper_task_uid(struct task_struct *task)
> > +{
> > +     return task_uid(task);
> > +}
> > +EXPORT_SYMBOL_GPL(rust_helper_task_uid);
> > +
> > +kuid_t rust_helper_task_euid(struct task_struct *task)
> > +{
> > +     return task_euid(task);
> > +}
> > +EXPORT_SYMBOL_GPL(rust_helper_task_euid);
>
> So I still object to these on the ground that they're obvious and
> trivial speculation gadgets.
>
> We should not have (exported) functions that are basically a single
> dereference of a pointer argument.
>
> And I do not appreciate my feedback on the previous round being ignored.

I'm sorry about that. I barely know what speculation gadgets are, so I
didn't really know what to respond. But I should have responded by
saying that.

I can reimplement these specific functions as inline Rust functions,
but I don't think I can give you a general solution to the
rust_helper_* problem in this patch series.

Alice