[PATCH v2 1/7] rust: module: add `THIS_MODULE` const to `ModuleMetadata` trait

[Alvin Sun]

Add a `THIS_MODULE` const to the `ModuleMetadata` trait so that
modules can provide their `ThisModule` pointer usable in const
contexts such as static file_operations.

Move the `THIS_MODULE` static from the `module!` macro into the
`ModuleMetadata` impl, and update `__init` to use
`LocalModule::THIS_MODULE` instead.

Signed-off-by: Alvin Sun <alvi...@linux.dev>
---
rust/kernel/lib.rs | 3 +++
rust/macros/module.rs | 34 +++++++++++++++++-----------------
2 files changed, 20 insertions(+), 17 deletions(-)

diff --git a/rust/kernel/lib.rs b/rust/kernel/lib.rs
index b72b2fbe046d6..f0cf0705d9697 100644
--- a/rust/kernel/lib.rs
+++ b/rust/kernel/lib.rs
@@ -184,6 +184,9 @@ 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;
}

/// Equivalent to `THIS_MODULE` in the C API.
diff --git a/rust/macros/module.rs b/rust/macros/module.rs
index 06c18e2075083..b6d7b3299fbf9 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
+ &<super::super::LocalModule as ::kernel::ModuleMetadata>::THIS_MODULE
);
// 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

[Andreas Hindborg]

Is it possible we could make this more ergonomic? Perhaps by adding a
helper:

fn this_module<M: ::kernel::ModuleMetadata>() -> &'static ::kernel::ThisModule {
&M::THIS_MODULE
}

Then the invocation is a little better:

let initer = <super::super::LocalModule as ::kernel::InPlaceModule>::init(

this_module::<super::super::LocalModule>()
);


Best regards,
Andreas Hindborg

[Gary Guo]

On Thu May 21, 2026 at 8:52 AM BST, Alvin Sun wrote:
> Add a `THIS_MODULE` const to the `ModuleMetadata` trait so that
> modules can provide their `ThisModule` pointer usable in const
> contexts such as static file_operations.
>
> Move the `THIS_MODULE` static from the `module!` macro into the
> `ModuleMetadata` impl, and update `__init` to use
> `LocalModule::THIS_MODULE` instead.

Perhaps you could mention that this is made possible by const_refs_to_static
which is stable since the MSRV bump.

Best,
Gary

[Alvin Sun]

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 <alvi...@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

}

/// Equivalent to `THIS_MODULE` in the C API.
diff --git a/rust/macros/module.rs b/rust/macros/module.rs

index 06c18e2075083..b9fdee2f2af47 100644

+ ::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

--
2.43.0

[Andreas Hindborg]

Alvin Sun <alvi...@linux.dev> writes:

> 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 <alvi...@linux.dev>

Reviewed-by: Andreas Hindborg <a.hin...@kernel.org>


Best regards,
Andreas Hindborg

[Gary Guo]

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.

Doesn't this break existing users of THIS_MODULE?

Binder, rnull and configfs macros are using it.

Best,
Gary

[Gary Guo]

On Mon Jun 22, 2026 at 3:44 AM BST, Alvin Sun wrote:

Also, FWIW I think this should not put this in the crate root. Perhaps create a
modules.rs?

Best,
Gary

[Alvin Sun]

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`.

Best regards,
Alvin Sun

[Gary Guo]

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

[Alvin Sun]

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 <alvi...@linux.dev>
---

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

[Andreas Hindborg]

Alvin Sun <alvi...@linux.dev> writes:

> 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 <alvi...@linux.dev>

[Gary Guo]

#[inline]

> +pub const fn this_module<M: ModuleMetadata>() -> &'static ThisModule {
> + &M::THIS_MODULE
> }

With the change,

Reviewed-by: Gary Guo <ga...@garyguo.net>

[Alvin Sun]

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.hin...@kernel.org>
Reviewed-by: Gary Guo <ga...@garyguo.net>

Signed-off-by: Alvin Sun <alvi...@linux.dev>
---

rust/kernel/module.rs | 9 +++++++++
rust/macros/module.rs | 18 +++++++++++++++++-
2 files changed, 26 insertions(+), 1 deletion(-)

diff --git a/rust/kernel/module.rs b/rust/kernel/module.rs
index be242a82e86d2..d713705984477 100644
--- a/rust/kernel/module.rs
+++ b/rust/kernel/module.rs
@@ -42,6 +42,15 @@ 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.

+#[inline]

+pub const fn this_module<M: ModuleMetadata>() -> &'static ThisModule {
+ &M::THIS_MODULE
}

--
2.43.0

[Alvin Sun]

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.hin...@kernel.org>
Reviewed-by: Gary Guo <ga...@garyguo.net>

Acked-by: Danilo Krummrich <da...@kernel.org>

[Alvin Sun]