Merge tag 'pin-init-v6.18' of https://github.com/Rust-for-Linux/linux into drm-rust-next

Danilo Krummrich · Danilo Krummrich · commit 3760401981f1 · 2025-09-12T20:07:15.000+02:00
pin-init changes for v6.18 Changed: - `#[pin_data]` now generates a `*Projection` struct similar to the `pin-project` crate. - Add initializer code blocks to `[try_][pin_]init!` macros: make initializer macros accept any number of `_: {/* arbitrary code */},` & make them run the code at that point. - Make the `[try_][pin_]init!` macros expose initialized fields via a `let` binding as `&mut T` or `Pin<&mut T>` for later fields. Upstream dev news: - Released v0.0.10 before the changes included in this tag. - Inform users of the impending rename from `pinned-init` to `pin-init` (in the kernel the rename already happened). - More CI improvements. Signed-off-by: Danilo Krummrich <dakr@kernel.org> From: Benno Lossin <lossin@kernel.org> Link: https://lore.kernel.org/r/20250912174148.373530-1-lossin@kernel.org
diff --git a/rust/kernel/devres.rs b/rust/kernel/devres.rs
@@ -134,11 +134,9 @@ impl<T: Send> Devres<T> {
         T: 'a,
         Error: From<E>,
     {
-        let callback = Self::devres_callback;
-
         try_pin_init!(&this in Self {
             dev: dev.into(),
-            callback,
+            callback: Self::devres_callback,
             // INVARIANT: `inner` is properly initialized.
             inner <- {
                 // SAFETY: `this` is a valid pointer to uninitialized memory.
@@ -151,7 +149,7 @@ impl<T: Send> Devres<T> {
                 //    properly initialized, because we require `dev` (i.e. the *bound* device) to
                 //    live at least as long as the returned `impl PinInit<Self, Error>`.
                 to_result(unsafe {
-                    bindings::devm_add_action(dev.as_raw(), Some(callback), inner.cast())
+                    bindings::devm_add_action(dev.as_raw(), Some(*callback), inner.cast())
                 })?;
 
                 Opaque::pin_init(try_pin_init!(Inner {
diff --git a/rust/kernel/workqueue.rs b/rust/kernel/workqueue.rs
@@ -356,18 +356,11 @@ struct ClosureWork<T> {
     func: Option<T>,
 }
 
-impl<T> ClosureWork<T> {
-    fn project(self: Pin<&mut Self>) -> &mut Option<T> {
-        // SAFETY: The `func` field is not structurally pinned.
-        unsafe { &mut self.get_unchecked_mut().func }
-    }
-}
-
 impl<T: FnOnce()> WorkItem for ClosureWork<T> {
     type Pointer = Pin<KBox<Self>>;
 
     fn run(mut this: Pin<KBox<Self>>) {
-        if let Some(func) = this.as_mut().project().take() {
+        if let Some(func) = this.as_mut().project().func.take() {
             (func)()
         }
     }
diff --git a/rust/pin-init/README.md b/rust/pin-init/README.md
@@ -6,6 +6,18 @@
 ![GitHub Workflow Status](https://img.shields.io/github/actions/workflow/status/Rust-for-Linux/pin-init/test.yml)
 # `pin-init`
 
+> [!NOTE]
+> 
+> This crate was originally named [`pinned-init`], but the migration to
+> `pin-init` is not yet complete. The `legcay` branch contains the current
+> version of the `pinned-init` crate & the `main` branch already incorporates
+> the rename to `pin-init`.
+>
+> There are still some changes needed on the kernel side before the migration
+> can be completed.
+
+[`pinned-init`]: https://crates.io/crates/pinned-init
+
 <!-- cargo-rdme start -->
 
 Library to safely and fallibly initialize pinned `struct`s using in-place constructors.
diff --git a/rust/pin-init/examples/error.rs b/rust/pin-init/examples/error.rs
@@ -24,4 +24,6 @@ impl From<AllocError> for Error {
 }
 
 #[allow(dead_code)]
-fn main() {}
+fn main() {
+    let _ = Error;
+}
diff --git a/rust/pin-init/src/lib.rs b/rust/pin-init/src/lib.rs
@@ -740,6 +740,8 @@ macro_rules! stack_try_pin_init {
 /// As already mentioned in the examples above, inside of `pin_init!` a `struct` initializer with
 /// the following modifications is expected:
 /// - Fields that you want to initialize in-place have to use `<-` instead of `:`.
+/// - You can use `_: { /* run any user-code here */ },` anywhere where you can place fields in
+///   order to run arbitrary code.
 /// - In front of the initializer you can write `&this in` to have access to a [`NonNull<Self>`]
 ///   pointer named `this` inside of the initializer.
 /// - Using struct update syntax one can place `..Zeroable::init_zeroed()` at the very end of the
@@ -994,7 +996,7 @@ macro_rules! try_init {
 /// }
 ///
 /// impl<T> Foo<T> {
-///     fn project(self: Pin<&mut Self>) -> Pin<&mut T> {
+///     fn project_this(self: Pin<&mut Self>) -> Pin<&mut T> {
 ///         assert_pinned!(Foo<T>, elem, T, inline);
 ///
 ///         // SAFETY: The field is structurally pinned.
diff --git a/rust/pin-init/src/macros.rs b/rust/pin-init/src/macros.rs
@@ -831,6 +831,17 @@ macro_rules! __pin_data {
             $($fields)*
         }
 
+        $crate::__pin_data!(make_pin_projections:
+            @vis($vis),
+            @name($name),
+            @impl_generics($($impl_generics)*),
+            @ty_generics($($ty_generics)*),
+            @decl_generics($($decl_generics)*),
+            @where($($whr)*),
+            @pinned($($pinned)*),
+            @not_pinned($($not_pinned)*),
+        );
+
         // We put the rest into this const item, because it then will not be accessible to anything
         // outside.
         const _: () = {
@@ -980,6 +991,56 @@ macro_rules! __pin_data {
             stringify!($($rest)*),
         );
     };
+    (make_pin_projections:
+        @vis($vis:vis),
+        @name($name:ident),
+        @impl_generics($($impl_generics:tt)*),
+        @ty_generics($($ty_generics:tt)*),
+        @decl_generics($($decl_generics:tt)*),
+        @where($($whr:tt)*),
+        @pinned($($(#[$($p_attr:tt)*])* $pvis:vis $p_field:ident : $p_type:ty),* $(,)?),
+        @not_pinned($($(#[$($attr:tt)*])* $fvis:vis $field:ident : $type:ty),* $(,)?),
+    ) => {
+        $crate::macros::paste! {
+            #[doc(hidden)]
+            $vis struct [< $name Projection >] <'__pin, $($decl_generics)*> {
+                $($(#[$($p_attr)*])* $pvis $p_field : ::core::pin::Pin<&'__pin mut $p_type>,)*
+                $($(#[$($attr)*])* $fvis $field : &'__pin mut $type,)*
+                ___pin_phantom_data: ::core::marker::PhantomData<&'__pin mut ()>,
+            }
+
+            impl<$($impl_generics)*> $name<$($ty_generics)*>
+            where $($whr)*
+            {
+                /// Pin-projects all fields of `Self`.
+                ///
+                /// These fields are structurally pinned:
+                $(#[doc = ::core::concat!(" - `", ::core::stringify!($p_field), "`")])*
+                ///
+                /// These fields are **not** structurally pinned:
+                $(#[doc = ::core::concat!(" - `", ::core::stringify!($field), "`")])*
+                #[inline]
+                $vis fn project<'__pin>(
+                    self: ::core::pin::Pin<&'__pin mut Self>,
+                ) -> [< $name Projection >] <'__pin, $($ty_generics)*> {
+                    // SAFETY: we only give access to `&mut` for fields not structurally pinned.
+                    let this = unsafe { ::core::pin::Pin::get_unchecked_mut(self) };
+                    [< $name Projection >] {
+                        $(
+                            // SAFETY: `$p_field` is structurally pinned.
+                            $(#[$($p_attr)*])*
+                            $p_field : unsafe { ::core::pin::Pin::new_unchecked(&mut this.$p_field) },
+                        )*
+                        $(
+                            $(#[$($attr)*])*
+                            $field : &mut this.$field,
+                        )*
+                        ___pin_phantom_data: ::core::marker::PhantomData,
+                    }
+                }
+            }
+        }
+    };
     (make_pin_data:
         @pin_data($pin_data:ident),
         @impl_generics($($impl_generics:tt)*),
@@ -988,38 +1049,56 @@ macro_rules! __pin_data {
         @pinned($($(#[$($p_attr:tt)*])* $pvis:vis $p_field:ident : $p_type:ty),* $(,)?),
         @not_pinned($($(#[$($attr:tt)*])* $fvis:vis $field:ident : $type:ty),* $(,)?),
     ) => {
-        // For every field, we create a projection function according to its projection type. If a
-        // field is structurally pinned, then it must be initialized via `PinInit`, if it is not
-        // structurally pinned, then it can be initialized via `Init`.
-        //
-        // The functions are `unsafe` to prevent accidentally calling them.
-        #[allow(dead_code)]
-        #[expect(clippy::missing_safety_doc)]
-        impl<$($impl_generics)*> $pin_data<$($ty_generics)*>
-        where $($whr)*
-        {
-            $(
-                $(#[$($p_attr)*])*
-                $pvis unsafe fn $p_field<E>(
-                    self,
-                    slot: *mut $p_type,
-                    init: impl $crate::PinInit<$p_type, E>,
-                ) -> ::core::result::Result<(), E> {
-                    // SAFETY: TODO.
-                    unsafe { $crate::PinInit::__pinned_init(init, slot) }
-                }
-            )*
-            $(
-                $(#[$($attr)*])*
-                $fvis unsafe fn $field<E>(
-                    self,
-                    slot: *mut $type,
-                    init: impl $crate::Init<$type, E>,
-                ) -> ::core::result::Result<(), E> {
-                    // SAFETY: TODO.
-                    unsafe { $crate::Init::__init(init, slot) }
-                }
-            )*
+        $crate::macros::paste! {
+            // For every field, we create a projection function according to its projection type. If a
+            // field is structurally pinned, then it must be initialized via `PinInit`, if it is not
+            // structurally pinned, then it can be initialized via `Init`.
+            //
+            // The functions are `unsafe` to prevent accidentally calling them.
+            #[allow(dead_code)]
+            #[expect(clippy::missing_safety_doc)]
+            impl<$($impl_generics)*> $pin_data<$($ty_generics)*>
+            where $($whr)*
+            {
+                $(
+                    $(#[$($p_attr)*])*
+                    $pvis unsafe fn $p_field<E>(
+                        self,
+                        slot: *mut $p_type,
+                        init: impl $crate::PinInit<$p_type, E>,
+                    ) -> ::core::result::Result<(), E> {
+                        // SAFETY: TODO.
+                        unsafe { $crate::PinInit::__pinned_init(init, slot) }
+                    }
+
+                    $(#[$($p_attr)*])*
+                    $pvis unsafe fn [<__project_ $p_field>]<'__slot>(
+                        self,
+                        slot: &'__slot mut $p_type,
+                    ) -> ::core::pin::Pin<&'__slot mut $p_type> {
+                        ::core::pin::Pin::new_unchecked(slot)
+                    }
+                )*
+                $(
+                    $(#[$($attr)*])*
+                    $fvis unsafe fn $field<E>(
+                        self,
+                        slot: *mut $type,
+                        init: impl $crate::Init<$type, E>,
+                    ) -> ::core::result::Result<(), E> {
+                        // SAFETY: TODO.
+                        unsafe { $crate::Init::__init(init, slot) }
+                    }
+
+                    $(#[$($attr)*])*
+                    $fvis unsafe fn [<__project_ $field>]<'__slot>(
+                        self,
+                        slot: &'__slot mut $type,
+                    ) -> &'__slot mut $type {
+                        slot
+                    }
+                )*
+            }
         }
     };
 }
@@ -1202,6 +1281,21 @@ macro_rules! __init_internal {
         // have been initialized. Therefore we can now dismiss the guards by forgetting them.
         $(::core::mem::forget($guards);)*
     };
+    (init_slot($($use_data:ident)?):
+        @data($data:ident),
+        @slot($slot:ident),
+        @guards($($guards:ident,)*),
+        // arbitrary code block
+        @munch_fields(_: { $($code:tt)* }, $($rest:tt)*),
+    ) => {
+        { $($code)* }
+        $crate::__init_internal!(init_slot($($use_data)?):
+            @data($data),
+            @slot($slot),
+            @guards($($guards,)*),
+            @munch_fields($($rest)*),
+        );
+    };
     (init_slot($use_data:ident): // `use_data` is present, so we use the `data` to init fields.
         @data($data:ident),
         @slot($slot:ident),
@@ -1216,6 +1310,13 @@ macro_rules! __init_internal {
         // return when an error/panic occurs.
         // We also use the `data` to require the correct trait (`Init` or `PinInit`) for `$field`.
         unsafe { $data.$field(::core::ptr::addr_of_mut!((*$slot).$field), init)? };
+        // SAFETY:
+        // - the project function does the correct field projection,
+        // - the field has been initialized,
+        // - the reference is only valid until the end of the initializer.
+        #[allow(unused_variables)]
+        let $field = $crate::macros::paste!(unsafe { $data.[< __project_ $field >](&mut (*$slot).$field) });
+
         // Create the drop guard:
         //
         // We rely on macro hygiene to make it impossible for users to access this local variable.
@@ -1247,6 +1348,14 @@ macro_rules! __init_internal {
         // SAFETY: `slot` is valid, because we are inside of an initializer closure, we
         // return when an error/panic occurs.
         unsafe { $crate::Init::__init(init, ::core::ptr::addr_of_mut!((*$slot).$field))? };
+
+        // SAFETY:
+        // - the field is not structurally pinned, since the line above must compile,
+        // - the field has been initialized,
+        // - the reference is only valid until the end of the initializer.
+        #[allow(unused_variables)]
+        let $field = unsafe { &mut (*$slot).$field };
+
         // Create the drop guard:
         //
         // We rely on macro hygiene to make it impossible for users to access this local variable.
@@ -1265,7 +1374,48 @@ macro_rules! __init_internal {
             );
         }
     };
-    (init_slot($($use_data:ident)?):
+    (init_slot(): // No `use_data`, so all fields are not structurally pinned
+        @data($data:ident),
+        @slot($slot:ident),
+        @guards($($guards:ident,)*),
+        // Init by-value.
+        @munch_fields($field:ident $(: $val:expr)?, $($rest:tt)*),
+    ) => {
+        {
+            $(let $field = $val;)?
+            // Initialize the field.
+            //
+            // SAFETY: The memory at `slot` is uninitialized.
+            unsafe { ::core::ptr::write(::core::ptr::addr_of_mut!((*$slot).$field), $field) };
+        }
+
+        #[allow(unused_variables)]
+        // SAFETY:
+        // - the field is not structurally pinned, since no `use_data` was required to create this
+        //   initializer,
+        // - the field has been initialized,
+        // - the reference is only valid until the end of the initializer.
+        let $field = unsafe { &mut (*$slot).$field };
+
+        // Create the drop guard:
+        //
+        // We rely on macro hygiene to make it impossible for users to access this local variable.
+        // We use `paste!` to create new hygiene for `$field`.
+        $crate::macros::paste! {
+            // SAFETY: We forget the guard later when initialization has succeeded.
+            let [< __ $field _guard >] = unsafe {
+                $crate::__internal::DropGuard::new(::core::ptr::addr_of_mut!((*$slot).$field))
+            };
+
+            $crate::__init_internal!(init_slot():
+                @data($data),
+                @slot($slot),
+                @guards([< __ $field _guard >], $($guards,)*),
+                @munch_fields($($rest)*),
+            );
+        }
+    };
+    (init_slot($use_data:ident):
         @data($data:ident),
         @slot($slot:ident),
         @guards($($guards:ident,)*),
@@ -1279,6 +1429,13 @@ macro_rules! __init_internal {
             // SAFETY: The memory at `slot` is uninitialized.
             unsafe { ::core::ptr::write(::core::ptr::addr_of_mut!((*$slot).$field), $field) };
         }
+        // SAFETY:
+        // - the project function does the correct field projection,
+        // - the field has been initialized,
+        // - the reference is only valid until the end of the initializer.
+        #[allow(unused_variables)]
+        let $field = $crate::macros::paste!(unsafe { $data.[< __project_ $field >](&mut (*$slot).$field) });
+
         // Create the drop guard:
         //
         // We rely on macro hygiene to make it impossible for users to access this local variable.
@@ -1289,14 +1446,28 @@ macro_rules! __init_internal {
                 $crate::__internal::DropGuard::new(::core::ptr::addr_of_mut!((*$slot).$field))
             };
 
-            $crate::__init_internal!(init_slot($($use_data)?):
+            $crate::__init_internal!(init_slot($use_data):
                 @data($data),
                 @slot($slot),
                 @guards([< __ $field _guard >], $($guards,)*),
                 @munch_fields($($rest)*),
             );
         }
     };
+    (make_initializer:
+        @slot($slot:ident),
+        @type_name($t:path),
+        @munch_fields(_: { $($code:tt)* }, $($rest:tt)*),
+        @acc($($acc:tt)*),
+    ) => {
+        // code blocks are ignored for the initializer check
+        $crate::__init_internal!(make_initializer:
+            @slot($slot),
+            @type_name($t),
+            @munch_fields($($rest)*),
+            @acc($($acc)*),
+        );
+    };
     (make_initializer:
         @slot($slot:ident),
         @type_name($t:path),
diff --git a/samples/rust/rust_driver_pci.rs b/samples/rust/rust_driver_pci.rs

Original file line number	Diff line number	Diff line change
`@@ -356,18 +356,11 @@ struct ClosureWork<T> {`
`356`	`356`	`func: Option<T>,`
`357`	`357`	`}`
`358`	`358`
`359`		`-impl<T> ClosureWork<T> {`
`360`		`- fn project(self: Pin<&mut Self>) -> &mut Option<T> {`
`361`		- // SAFETY: The `func` field is not structurally pinned.
`362`		`- unsafe { &mut self.get_unchecked_mut().func }`
`363`		`- }`
`364`		`-}`
`365`		`-`
`366`	`359`	`impl<T: FnOnce()> WorkItem for ClosureWork<T> {`
`367`	`360`	`type Pointer = Pin<KBox<Self>>;`
`368`	`361`
`369`	`362`	`fn run(mut this: Pin<KBox<Self>>) {`
`370`		`- if let Some(func) = this.as_mut().project().take() {`
	`363`	`+ if let Some(func) = this.as_mut().project().func.take() {`
`371`	`364`	`(func)()`
`372`	`365`	`}`
`373`	`366`	`}`
Original file line number	Diff line number	Diff line change
`@@ -24,4 +24,6 @@ impl From<AllocError> for Error {`
`24`	`24`	`}`
`25`	`25`
`26`	`26`	`#[allow(dead_code)]`
`27`		`-fn main() {}`
	`27`	`+fn main() {`
	`28`	`+ let _ = Error;`
	`29`	`+}`