rust: module: add `THIS_MODULE` const to `ModuleMetadata` trait

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`.

Add a `this_module()` helper to retrieve the `THIS_MODULE` pointer of a
given module type, and update `__init` to use it instead of the
`THIS_MODULE` static generated by the `module!` macro.

The `static THIS_MODULE` generated by the `module!` macro is retained
for backwards compatibility with existing users and removed in a later
patch once all references have been migrated.

Assisted-by: opencode:glm-5.2
Reviewed-by: Andreas Hindborg <a.hindborg@kernel.org>
Reviewed-by: Gary Guo <gary@garyguo.net>
Acked-by: Danilo Krummrich <dakr@kernel.org>
Reviewed-by: Alice Ryhl <aliceryhl@google.com>
Acked-by: Petr Pavlu <petr.pavlu@suse.com>
Signed-off-by: Alvin Sun <alvin.sun@linux.dev>
Link: https://patch.msgid.link/20260811-fix-fops-owner-v10-2-7e71776f9dbe@linux.dev
Signed-off-by: Miguel Ojeda <ojeda@kernel.org>

1 files changed, 9 insertions, 0 deletions

diff --git a/rust/kernel/module.rs b/rust/kernel/module.rs
index be242a82e86d..d71370598447 100644
--- a/rust/kernel/module.rs
+++ b/rust/kernel/module.rs
@@ -42,6 +42,15 @@ impl<T: Module> InPlaceModule for T {
 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.
+#[inline]
+pub const fn this_module<M: ModuleMetadata>() -> &'static ThisModule {
+    &M::THIS_MODULE
 }
 
 /// Equivalent to `THIS_MODULE` in the C API.