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. Signed-off-by: Alvin Sun <[email protected]> --- rust/kernel/module.rs | 8 ++++++++ rust/macros/module.rs | 18 +++++++++++++++++- 2 files changed, 25 insertions(+), 1 deletion(-) diff --git a/rust/kernel/module.rs b/rust/kernel/module.rs index be242a82e86d2..5aca42f7a33fc 100644 --- a/rust/kernel/module.rs +++ b/rust/kernel/module.rs @@ -42,6 +42,14 @@ fn init(module: &'static ThisModule) -> impl pin_init::PinInit<Self, crate::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 } /// Equivalent to `THIS_MODULE` in the C API. diff --git a/rust/macros/module.rs b/rust/macros/module.rs index 06c18e2075083..aa9a618d5d19e 100644 --- a/rust/macros/module.rs +++ b/rust/macros/module.rs @@ -519,6 +519,22 @@ pub(crate) fn module(info: ModuleInfo) -> Result<TokenStream> { 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 +632,7 @@ 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::module::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 -- 2.43.0
