Re: [PATCH v3 1/6] rust: module: add `THIS_MODULE` const to `ModuleMetadata` trait

["Gary Guo" <gary@garyguo.net>]

On Mon Jun 22, 2026 at 1:52 PM BST, Alvin Sun wrote:
>
> On 6/22/26 18:50, Gary Guo wrote:
>> On Mon Jun 22, 2026 at 3:44 AM BST, Alvin Sun wrote:
>>> Since `const_refs_to_static` has been stable as of the MSRV bump, a
>>> `ThisModule` pointer can now be used in const contexts.
>>>
>>> Add a `THIS_MODULE` const to the `ModuleMetadata` trait so that modules
>>> can provide their `ThisModule` pointer in const contexts such as static
>>> `file_operations`.
>>>
>>> Move the `THIS_MODULE` static from the `module!` macro into the
>>> `ModuleMetadata` impl, add a `this_module()` helper, and update `__init`
>>> to use it.
>>>
>>> Signed-off-by: Alvin Sun <alvin.sun@linux.dev>
>>> ---
>>>   rust/kernel/lib.rs    |  8 ++++++++
>>>   rust/macros/module.rs | 34 +++++++++++++++++-----------------
>>>   2 files changed, 25 insertions(+), 17 deletions(-)
>>>
>>> diff --git a/rust/kernel/lib.rs b/rust/kernel/lib.rs
>>> index b72b2fbe046d6..50f5a7b5f028e 100644
>>> --- a/rust/kernel/lib.rs
>>> +++ b/rust/kernel/lib.rs
>>> @@ -184,6 +184,14 @@ fn init(module: &'static ThisModule) -> impl pin_init::PinInit<Self, error::Erro
>>>   pub trait ModuleMetadata {
>>>       /// The name of the module as specified in the `module!` macro.
>>>       const NAME: &'static crate::str::CStr;
>>> +
>>> +    /// The module's `THIS_MODULE` pointer.
>>> +    const THIS_MODULE: ThisModule;
>>> +}
>>> +
>>> +/// Returns a reference to the `THIS_MODULE` of the given module type.
>>> +pub const fn this_module<M: ModuleMetadata>() -> &'static ThisModule {
>>> +    &M::THIS_MODULE
>>>   }
>> Also, FWIW I think this should not put this in the crate root. Perhaps create a
>> modules.rs?
>
> Makes sense. I'll create a new `module.rs` and move the module-related items
> (`ModuleMetadata`, `ThisModule`, `this_module()`) there, then re-export from
> `lib.rs`.

Please do not re-export `this_module`. For the other two, I think it's fine to
re-export to avoid tree-wide changes, but please do update users on code that
would route via the Rust tree.

Best,
Gary