linux-kernel - Re: [PATCH 2/5] devres: export devres_node_init() and devres_node

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Message-ID: <CAH5fLgjS+QEGdGnxUBCeMFCapeErRJ6n1rDenbF1ahc5xsJv+Q@mail.gmail.com>
Date: Fri, 6 Feb 2026 12:34:01 +0100
From: Alice Ryhl <aliceryhl@...gle.com>
To: Danilo Krummrich <dakr@...nel.org>
Cc: Greg KH <gregkh@...uxfoundation.org>, rafael@...nel.org, ojeda@...nel.org, 
	boqun.feng@...il.com, gary@...yguo.net, bjorn3_gh@...tonmail.com, 
	lossin@...nel.org, a.hindborg@...nel.org, tmgross@...ch.edu, 
	driver-core@...ts.linux.dev, rust-for-linux@...r.kernel.org, 
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH 2/5] devres: export devres_node_init() and devres_node_add()

On Fri, Feb 6, 2026 at 12:32 PM Danilo Krummrich <dakr@...nel.org> wrote:
>
> On Fri Feb 6, 2026 at 12:04 PM CET, Greg KH wrote:
> > On Fri, Feb 06, 2026 at 11:43:48AM +0100, Danilo Krummrich wrote:
> >> On Thu Feb 5, 2026 at 11:31 PM CET, Danilo Krummrich wrote:
> >> > +EXPORT_SYMBOL_GPL(devres_node_init);
> >>
> >> I actually intended to use a Rust helper instead of exporting those symbols
> >> directly, but forgot to do it eventually.
> >>
> >
> > I don't understand, does that mean we do not need to export these?
> > Shouldn't the rust bindings just export these symbols are rust exports,
> > and the C exports are not needed?
> >
> > We "only" want these symbols to go to the rust binding, not to any
> > module at all, which is what this patch series does, and is probably not
> > a good idea.
>
> Correct, I just forgot to replace the exports with a Rust helper.
>
> The Rust compiler might inline some of the core code into modules (e.g. due to
> generics), thus requiring an export.
>
> But, instead of adding
>
>         EXPORT_SYMBOL_GPL(devres_node_init)
>
> in drivers/base/devres.c, I actually intended to create a Rust helper in
> rust/helpers/devres.c:
>
>         __rust_helper void rust_helper_devres_node_init(struct devres_node *node,
>                                                         dr_node_release_t release,
>                                                         dr_node_free_t free_node)
>         {
>                 devres_nod_init(node, release, free_node);
>         }
>
> This will automatically create:
>
>         EXPORT_SYMBOL_RUST_GPL(rust_helper_devres_node_init)
>
> behind the scenes.

That doesn't work if this option is enabled:
https://lore.kernel.org/all/20260203-inline-helpers-v2-0-beb8547a03c9@google.com/

then the helper is linked into the module, so it still has a direct
call to devres_nod_init.

Alice