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 <[email protected]>
> ---
> 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?
Best,
Gary
>
> /// Equivalent to `THIS_MODULE` in the C API.
> diff --git a/rust/macros/module.rs b/rust/macros/module.rs
> index 06c18e2075083..b9fdee2f2af47 100644
> --- a/rust/macros/module.rs
> +++ b/rust/macros/module.rs
> @@ -497,28 +497,28 @@ pub(crate) fn module(info: ModuleInfo) ->
> Result<TokenStream> {
> /// Used by the printing macros, e.g. [`info!`].
> const __LOG_PREFIX: &[u8] = #name_cstr.to_bytes_with_nul();
>
> - // SAFETY: `__this_module` is constructed by the kernel at load time
> and will not be
> - // freed until the module is unloaded.
> - #[cfg(MODULE)]
> - static THIS_MODULE: ::kernel::ThisModule = unsafe {
> - extern "C" {
> - static __this_module:
> ::kernel::types::Opaque<::kernel::bindings::module>;
> - };
> -
> - ::kernel::ThisModule::from_ptr(__this_module.get())
> - };
> -
> - #[cfg(not(MODULE))]
> - static THIS_MODULE: ::kernel::ThisModule = unsafe {
> - ::kernel::ThisModule::from_ptr(::core::ptr::null_mut())
> - };
> -
> /// The `LocalModule` type is the type of the module created by
> `module!`,
> /// `module_pci_driver!`, `module_platform_driver!`, etc.
> type LocalModule = #type_;
>
> impl ::kernel::ModuleMetadata for #type_ {
> const NAME: &'static ::kernel::str::CStr = #name_cstr;
> +
> + #[cfg(MODULE)]
> + const THIS_MODULE: ::kernel::ThisModule = {
> + extern "C" {
> + static __this_module:
> ::kernel::types::Opaque<::kernel::bindings::module>;
> + }
> +
> + // SAFETY: `__this_module` is constructed by the kernel at
> load time
> + // and lives until the module is unloaded.
> + unsafe { ::kernel::ThisModule::from_ptr(__this_module.get())
> }
> + };
> +
> + #[cfg(not(MODULE))]
> + const THIS_MODULE: ::kernel::ThisModule = unsafe {
> + ::kernel::ThisModule::from_ptr(::core::ptr::null_mut())
> + };
> }
>
> // Double nested modules, since then nobody can access the public
> items inside.
> @@ -616,7 +616,7 @@ pub extern "C" fn #ident_exit() {
> /// This function must only be called once.
> unsafe fn __init() -> ::kernel::ffi::c_int {
> let initer = <super::super::LocalModule as
> ::kernel::InPlaceModule>::init(
> - &super::super::THIS_MODULE
> + ::kernel::this_module::<super::super::LocalModule>()
> );
> // SAFETY: No data race, since `__MOD` can only be
> accessed by this module
> // and there only `__init` and `__exit` access it. These
> functions are only
