[PATCH v8 04/10] rust: macros: auto-insert OwnerModule in #[vtable]

[Alvin Sun]

Auto-add `type OwnerModule: ::kernel::ModuleMetadata;` as a required
associated type on the trait side if not already defined, and
auto-insert `type OwnerModule = crate::LocalModule;` on the impl side
if not explicitly provided, eliminating the need to manually declare
and implement `OwnerModule` in every vtable trait and impl.

Assisted-by: opencode:glm-5.2
Reviewed-by: Andreas Hindborg <a.hin...@kernel.org>
Suggested-by: Gary Guo <ga...@garyguo.net>
Link: https://lore.kernel.org/all/DIMMWHUOLPSH....@garyguo.net
Reviewed-by: Gary Guo <ga...@garyguo.net>
Acked-by: Danilo Krummrich <da...@kernel.org>
Signed-off-by: Alvin Sun <alvi...@linux.dev>
---
rust/macros/lib.rs | 6 ++++++
rust/macros/vtable.rs | 41 ++++++++++++++++++++++++++++++++++++-----
2 files changed, 42 insertions(+), 5 deletions(-)

diff --git a/rust/macros/lib.rs b/rust/macros/lib.rs
index 2cfd59e0f9e7c..bc7ded353c5ca 100644
--- a/rust/macros/lib.rs
+++ b/rust/macros/lib.rs
@@ -176,6 +176,12 @@ pub fn module(input: TokenStream) -> TokenStream {
///
/// This macro should not be used when all functions are required.
///
+/// Additionally, this macro automatically handles the `OwnerModule`
+/// associated type: on the trait side, `type OwnerModule: ModuleMetadata;`
+/// is added as a required associated type if not already defined; on the
+/// impl side, `type OwnerModule = LocalModule;` is automatically inserted
+/// if not explicitly defined.
+///
/// # Examples
///
/// ```
diff --git a/rust/macros/vtable.rs b/rust/macros/vtable.rs
index c6510b0c4ea1d..be9a5ed8abe5e 100644
--- a/rust/macros/vtable.rs
+++ b/rust/macros/vtable.rs
@@ -30,6 +30,22 @@ fn handle_trait(mut item: ItemTrait) -> Result<ItemTrait> {
const USE_VTABLE_ATTR: ();
});

+ // Add `type OwnerModule: ModuleMetadata` as a required associated type if
+ // the trait does not already define it.
+ if !item
+ .items
+ .iter()
+ .any(|i| matches!(i, TraitItem::Type(t) if t.ident == "OwnerModule"))
+ {
+ gen_items.push(parse_quote! {
+ /// The module implementing this vtable trait.
+ ///
+ /// Automatically set to `crate::LocalModule` by the `#[vtable]`
+ /// impl macro.
+ type OwnerModule: ::kernel::ModuleMetadata;
+ });
+ }
+
for item in &item.items {
if let TraitItem::Fn(fn_item) = item {
let name = &fn_item.sig.ident;
@@ -57,12 +73,18 @@ fn handle_trait(mut item: ItemTrait) -> Result<ItemTrait> {

fn handle_impl(mut item: ItemImpl) -> Result<ItemImpl> {
let mut gen_items = Vec::new();
- let mut defined_consts = HashSet::new();
+ let mut defined_items = HashSet::new();

- // Iterate over all user-defined constants to gather any possible explicit overrides.
+ // Iterate over all user-defined items to gather any possible explicit overrides.
for item in &item.items {
- if let ImplItem::Const(const_item) = item {
- defined_consts.insert(const_item.ident.clone());
+ match item {
+ ImplItem::Const(const_item) => {
+ defined_items.insert(const_item.ident.clone());
+ }
+ ImplItem::Type(type_item) => {
+ defined_items.insert(type_item.ident.clone());
+ }
+ _ => {}
}
}

@@ -70,6 +92,15 @@ fn handle_impl(mut item: ItemImpl) -> Result<ItemImpl> {
const USE_VTABLE_ATTR: () = ();
});

+ // Auto-insert `type OwnerModule = crate::LocalModule` if not explicitly defined.
+ // `crate::LocalModule` resolves to the real module type (via `module!`) or a
+ // dummy fallback in non-module contexts (e.g., doctests).
+ if !defined_items.contains(&parse_quote!(OwnerModule)) {
+ gen_items.push(parse_quote! {
+ type OwnerModule = crate::LocalModule;
+ });
+ }
+
for item in &item.items {
if let ImplItem::Fn(fn_item) = item {
let name = &fn_item.sig.ident;
@@ -78,7 +109,7 @@ fn handle_impl(mut item: ItemImpl) -> Result<ItemImpl> {
name.span(),
);
// Skip if it's declared already -- this allows user override.
- if defined_consts.contains(&gen_const_name) {
+ if defined_items.contains(&gen_const_name) {
continue;
}
let cfg_attrs = crate::helpers::gather_cfg_attrs(&fn_item.attrs);

--
2.43.0

[Alvin Sun]

Auto-add `type OwnerModule: ::kernel::ModuleMetadata;` as a required
associated type on the trait side if not already defined, and
auto-insert `type OwnerModule = crate::LocalModule;` on the impl side
if not explicitly provided, eliminating the need to manually declare
and implement `OwnerModule` in every vtable trait and impl.

Assisted-by: opencode:glm-5.2
Reviewed-by: Andreas Hindborg <a.hin...@kernel.org>
Suggested-by: Gary Guo <ga...@garyguo.net>
Link: https://lore.kernel.org/all/DIMMWHUOLPSH....@garyguo.net
Reviewed-by: Gary Guo <ga...@garyguo.net>
Acked-by: Danilo Krummrich <da...@kernel.org>

Reviewed-by: Alice Ryhl <alic...@google.com>