rust: make pin-init its own crate

Rename relative paths inside of the crate to still refer to the same
items, also rename paths inside of the kernel crate and adjust the build
system to build the crate.

[ Remove the `expect` (and thus the `lint_reasons` feature) since
  the tree now uses `quote!` from `rust/macros/export.rs`. Remove the
  `TokenStream` import removal, since it is now used as well.

  In addition, temporarily (i.e. just for this commit) use an `--extern
  force:alloc` to prevent an unknown `new_uninit` error in the `rustdoc`
  target. For context, please see a similar case in:

      https://lore.kernel.org/lkml/20240422090644.525520-1-ojeda@kernel.org/

  And adjusted the message above. - Miguel ]

Signed-off-by: Benno Lossin <benno.lossin@proton.me>
Reviewed-by: Fiona Behrens <me@kloenk.dev>
Tested-by: Andreas Hindborg <a.hindborg@kernel.org>
Link: https://lore.kernel.org/r/20250308110339.2997091-16-benno.lossin@proton.me
Signed-off-by: Miguel Ojeda <ojeda@kernel.org>

rust/Makefile

@@ -116,13 +116,13 @@ rustdoc-ffi: $(src)/ffi.rs rustdoc-core FORCE
 rustdoc-pin_init_internal: private rustdoc_host = yes
 rustdoc-pin_init_internal: private rustc_target_flags = --cfg kernel \
     --extern proc_macro --crate-type proc-macro
-rustdoc-pin_init_internal: $(src)/pin-init/internal/src/_lib.rs FORCE
+rustdoc-pin_init_internal: $(src)/pin-init/internal/src/lib.rs FORCE
 	+$(call if_changed,rustdoc)
 
 rustdoc-pin_init: private rustdoc_host = yes
 rustdoc-pin_init: private rustc_target_flags = --extern pin_init_internal \
-    --extern macros --extern alloc --cfg kernel --cfg feature=\"alloc\"
-rustdoc-pin_init: $(src)/pin-init/src/_lib.rs rustdoc-pin_init_internal \
+    --extern macros --extern force:alloc --cfg kernel --cfg feature=\"alloc\"
+rustdoc-pin_init: $(src)/pin-init/src/lib.rs rustdoc-pin_init_internal \
     rustdoc-macros FORCE
 	+$(call if_changed,rustdoc)
 
@@ -158,12 +158,12 @@ rusttestlib-macros: $(src)/macros/lib.rs FORCE
 rusttestlib-pin_init_internal: private rustc_target_flags = --cfg kernel \
     --extern proc_macro
 rusttestlib-pin_init_internal: private rustc_test_library_proc = yes
-rusttestlib-pin_init_internal: $(src)/pin-init/internal/src/_lib.rs FORCE
+rusttestlib-pin_init_internal: $(src)/pin-init/internal/src/lib.rs FORCE
 	+$(call if_changed,rustc_test_library)
 
 rusttestlib-pin_init: private rustc_target_flags = --extern pin_init_internal \
     --extern macros --cfg kernel
-rusttestlib-pin_init: $(src)/pin-init/src/_lib.rs rusttestlib-macros \
+rusttestlib-pin_init: $(src)/pin-init/src/lib.rs rusttestlib-macros \
     rusttestlib-pin_init_internal $(obj)/$(libpin_init_internal_name) FORCE
 	+$(call if_changed,rustc_test_library)
 
@@ -401,7 +401,7 @@ $(obj)/$(libmacros_name): $(src)/macros/lib.rs FORCE
 	+$(call if_changed_dep,rustc_procmacro)
 
 $(obj)/$(libpin_init_internal_name): private rustc_target_flags = --cfg kernel
-$(obj)/$(libpin_init_internal_name): $(src)/pin-init/internal/src/_lib.rs FORCE
+$(obj)/$(libpin_init_internal_name): $(src)/pin-init/internal/src/lib.rs FORCE
 	+$(call if_changed_dep,rustc_procmacro)
 
 quiet_cmd_rustc_library = $(if $(skip_clippy),RUSTC,$(RUSTC_OR_CLIPPY_QUIET)) L $@
@@ -486,7 +486,7 @@ $(obj)/compiler_builtins.o: $(src)/compiler_builtins.rs $(obj)/core.o FORCE
 $(obj)/pin_init.o: private skip_gendwarfksyms = 1
 $(obj)/pin_init.o: private rustc_target_flags = --extern pin_init_internal \
     --extern macros --cfg kernel
-$(obj)/pin_init.o: $(src)/pin-init/src/_lib.rs $(obj)/compiler_builtins.o \
+$(obj)/pin_init.o: $(src)/pin-init/src/lib.rs $(obj)/compiler_builtins.o \
     $(obj)/$(libpin_init_internal_name) $(obj)/$(libmacros_name) FORCE
 	+$(call if_changed_rule,rustc_library)
 

rust/kernel/alloc/kbox.rs

@@ -15,9 +15,9 @@ use core::pin::Pin;
 use core::ptr::NonNull;
 use core::result::Result;
 
-use crate::init::{InPlaceWrite, Init, PinInit, ZeroableOption};
-use crate::init_ext::InPlaceInit;
+use crate::init::InPlaceInit;
 use crate::types::ForeignOwnable;
+use pin_init::{InPlaceWrite, Init, PinInit, ZeroableOption};
 
 /// The kernel's [`Box`] type -- a heap allocation for a single value of type `T`.
 ///

rust/kernel/block/mq/tag_set.rs

@@ -10,12 +10,11 @@ use crate::{
     bindings,
     block::mq::{operations::OperationsVTable, request::RequestDataWrapper, Operations},
     error,
-    prelude::PinInit,
-    try_pin_init,
+    prelude::try_pin_init,
     types::Opaque,
 };
 use core::{convert::TryInto, marker::PhantomData};
-use macros::{pin_data, pinned_drop};
+use pin_init::{pin_data, pinned_drop, PinInit};
 
 /// A wrapper for the C `struct blk_mq_tag_set`.
 ///

rust/kernel/driver.rs

@@ -6,9 +6,9 @@
 //! register using the [`Registration`] class.
 
 use crate::error::{Error, Result};
-use crate::{device, init::PinInit, of, str::CStr, try_pin_init, types::Opaque, ThisModule};
+use crate::{device, of, str::CStr, try_pin_init, types::Opaque, ThisModule};
 use core::pin::Pin;
-use macros::{pin_data, pinned_drop};
+use pin_init::{pin_data, pinned_drop, PinInit};
 
 /// The [`RegistrationOps`] trait serves as generic interface for subsystems (e.g., PCI, Platform,
 /// Amba, etc.) to provide the corresponding subsystem specific implementation to register /
@@ -114,7 +114,7 @@ macro_rules! module_driver {
         impl $crate::InPlaceModule for DriverModule {
             fn init(
                 module: &'static $crate::ThisModule
-            ) -> impl $crate::init::PinInit<Self, $crate::error::Error> {
+            ) -> impl ::pin_init::PinInit<Self, $crate::error::Error> {
                 $crate::try_pin_init!(Self {
                     _driver <- $crate::driver::Registration::new(
                         <Self as $crate::ModuleMetadata>::NAME,

rust/kernel/init.rs

@@ -23,7 +23,7 @@
 //!
 //! [`Opaque<T>`]: crate::types::Opaque
 //! [`Opaque::ffi_init`]: crate::types::Opaque::ffi_init
-//! [`pin_init!`]: crate::pin_init
+//! [`pin_init!`]: pin_init::pin_init
 //!
 //! # Examples
 //!
@@ -137,8 +137,8 @@
 use crate::{
     alloc::{AllocError, Flags},
     error::{self, Error},
-    init::{init_from_closure, pin_init_from_closure, Init, PinInit},
 };
+use pin_init::{init_from_closure, pin_init_from_closure, Init, PinInit};
 
 /// Smart pointer that can initialize memory in-place.
 pub trait InPlaceInit<T>: Sized {
@@ -205,7 +205,8 @@ pub trait InPlaceInit<T>: Sized {
 /// # Examples
 ///
 /// ```rust
-/// use kernel::{init::zeroed, error::Error};
+/// use kernel::error::Error;
+/// use pin_init::zeroed;
 /// struct BigBuf {
 ///     big: KBox<[u8; 1024 * 1024 * 1024]>,
 ///     small: [u8; 1024 * 1024],
@@ -222,7 +223,7 @@ pub trait InPlaceInit<T>: Sized {
 /// ```
 ///
 /// [`Infallible`]: core::convert::Infallible
-/// [`init!`]: crate::init!
+/// [`init!`]: pin_init::init
 /// [`try_pin_init!`]: crate::try_pin_init!
 /// [`Error`]: crate::error::Error
 #[macro_export]
@@ -230,14 +231,14 @@ macro_rules! try_init {
     ($(&$this:ident in)? $t:ident $(::<$($generics:ty),* $(,)?>)? {
         $($fields:tt)*
     }) => {
-        $crate::_try_init!($(&$this in)? $t $(::<$($generics),* $(,)?>)? {
+        ::pin_init::try_init!($(&$this in)? $t $(::<$($generics),* $(,)?>)? {
             $($fields)*
         }? $crate::error::Error)
     };
     ($(&$this:ident in)? $t:ident $(::<$($generics:ty),* $(,)?>)? {
         $($fields:tt)*
     }? $err:ty) => {
-        $crate::_try_init!($(&$this in)? $t $(::<$($generics),* $(,)?>)? {
+        ::pin_init::try_init!($(&$this in)? $t $(::<$($generics),* $(,)?>)? {
             $($fields)*
         }? $err)
     };
@@ -262,7 +263,8 @@ macro_rules! try_init {
 ///
 /// ```rust
 /// # #![feature(new_uninit)]
-/// use kernel::{init::zeroed, error::Error};
+/// use kernel::error::Error;
+/// use pin_init::zeroed;
 /// #[pin_data]
 /// struct BigBuf {
 ///     big: KBox<[u8; 1024 * 1024 * 1024]>,
@@ -282,21 +284,21 @@ macro_rules! try_init {
 /// ```
 ///
 /// [`Infallible`]: core::convert::Infallible
-/// [`pin_init!`]: crate::pin_init
+/// [`pin_init!`]: pin_init::pin_init
 /// [`Error`]: crate::error::Error
 #[macro_export]
 macro_rules! try_pin_init {
     ($(&$this:ident in)? $t:ident $(::<$($generics:ty),* $(,)?>)? {
         $($fields:tt)*
     }) => {
-        $crate::_try_pin_init!($(&$this in)? $t $(::<$($generics),* $(,)?>)? {
+        ::pin_init::try_pin_init!($(&$this in)? $t $(::<$($generics),* $(,)?>)? {
             $($fields)*
         }? $crate::error::Error)
     };
     ($(&$this:ident in)? $t:ident $(::<$($generics:ty),* $(,)?>)? {
         $($fields:tt)*
     }? $err:ty) => {
-        $crate::_try_pin_init!($(&$this in)? $t $(::<$($generics),* $(,)?>)? {
+        ::pin_init::try_pin_init!($(&$this in)? $t $(::<$($generics),* $(,)?>)? {
             $($fields)*
         }? $err)
     };

rust/kernel/lib.rs

@@ -50,11 +50,7 @@ pub mod faux;
 #[cfg(CONFIG_RUST_FW_LOADER_ABSTRACTIONS)]
 pub mod firmware;
 pub mod fs;
-#[path = "../pin-init/src/lib.rs"]
 pub mod init;
-// momentarily use the name `init_ext` and set the path manually
-#[path = "init.rs"]
-pub mod init_ext;
 pub mod io;
 pub mod ioctl;
 pub mod jump_label;
@@ -116,11 +112,11 @@ pub trait InPlaceModule: Sync + Send {
     /// Creates an initialiser for the module.
     ///
     /// It is called when the module is loaded.
-    fn init(module: &'static ThisModule) -> impl init::PinInit<Self, error::Error>;
+    fn init(module: &'static ThisModule) -> impl pin_init::PinInit<Self, error::Error>;
 }
 
 impl<T: Module> InPlaceModule for T {
-    fn init(module: &'static ThisModule) -> impl init::PinInit<Self, error::Error> {
+    fn init(module: &'static ThisModule) -> impl pin_init::PinInit<Self, error::Error> {
         let initer = move |slot: *mut Self| {
             let m = <Self as Module>::init(module)?;
 
@@ -130,7 +126,7 @@ impl<T: Module> InPlaceModule for T {
         };
 
         // SAFETY: On success, `initer` always fully initialises an instance of `Self`.
-        unsafe { init::pin_init_from_closure(initer) }
+        unsafe { pin_init::pin_init_from_closure(initer) }
     }
 }
 

rust/kernel/list.rs

@@ -4,12 +4,12 @@
 
 //! A linked list implementation.
 
-use crate::init::PinInit;
 use crate::sync::ArcBorrow;
 use crate::types::Opaque;
 use core::iter::{DoubleEndedIterator, FusedIterator};
 use core::marker::PhantomData;
 use core::ptr;
+use pin_init::PinInit;
 
 mod impl_list_item_mod;
 pub use self::impl_list_item_mod::{

rust/kernel/prelude.rs

@@ -17,7 +17,9 @@ pub use core::pin::Pin;
 pub use crate::alloc::{flags::*, Box, KBox, KVBox, KVVec, KVec, VBox, VVec, Vec};
 
 #[doc(no_inline)]
-pub use macros::{export, module, pin_data, pinned_drop, vtable, Zeroable};
+pub use macros::{export, module, vtable};
+
+pub use pin_init::{init, pin_data, pin_init, pinned_drop, InPlaceWrite, Init, PinInit, Zeroable};
 
 pub use super::{build_assert, build_error};
 
@@ -28,7 +30,7 @@ pub use super::fmt;
 pub use super::{dev_alert, dev_crit, dev_dbg, dev_emerg, dev_err, dev_info, dev_notice, dev_warn};
 pub use super::{pr_alert, pr_crit, pr_debug, pr_emerg, pr_err, pr_info, pr_notice, pr_warn};
 
-pub use super::{init, pin_init, try_init, try_pin_init};
+pub use super::{try_init, try_pin_init};
 
 pub use super::static_assert;
 
@@ -36,7 +38,6 @@ pub use super::error::{code::*, Error, Result};
 
 pub use super::{str::CStr, ThisModule};
 
-pub use super::init::{InPlaceWrite, Init, PinInit};
-pub use super::init_ext::InPlaceInit;
+pub use super::init::InPlaceInit;
 
 pub use super::current;

rust/kernel/sync/arc.rs

@@ -19,8 +19,7 @@
 use crate::{
     alloc::{AllocError, Flags, KBox},
     bindings,
-    init::{self, InPlaceWrite, Init, PinInit},
-    init_ext::InPlaceInit,
+    init::InPlaceInit,
     try_init,
     types::{ForeignOwnable, Opaque},
 };
@@ -33,7 +32,7 @@ use core::{
     pin::Pin,
     ptr::NonNull,
 };
-use macros::pin_data;
+use pin_init::{self, pin_data, InPlaceWrite, Init, PinInit};
 
 mod std_vendor;
 
@@ -738,7 +737,7 @@ impl<T> UniqueArc<T> {
             try_init!(ArcInner {
                 // SAFETY: There are no safety requirements for this FFI call.
                 refcount: Opaque::new(unsafe { bindings::REFCOUNT_INIT(1) }),
-                data <- init::uninit::<T, AllocError>(),
+                data <- pin_init::uninit::<T, AllocError>(),
             }? AllocError),
             flags,
         )?;

rust/kernel/sync/condvar.rs

@@ -8,8 +8,6 @@
 use super::{lock::Backend, lock::Guard, LockClassKey};
 use crate::{
     ffi::{c_int, c_long},
-    init::PinInit,
-    pin_init,
     str::CStr,
     task::{MAX_SCHEDULE_TIMEOUT, TASK_INTERRUPTIBLE, TASK_NORMAL, TASK_UNINTERRUPTIBLE},
     time::Jiffies,
@@ -17,7 +15,7 @@ use crate::{
 };
 use core::marker::PhantomPinned;
 use core::ptr;
-use macros::pin_data;
+use pin_init::{pin_data, pin_init, PinInit};
 
 /// Creates a [`CondVar`] initialiser with the given name and a newly-created lock class.
 #[macro_export]

rust/kernel/sync/lock.rs

@@ -7,13 +7,11 @@
 
 use super::LockClassKey;
 use crate::{
-    init::PinInit,
-    pin_init,
     str::CStr,
     types::{NotThreadSafe, Opaque, ScopeGuard},
 };
 use core::{cell::UnsafeCell, marker::PhantomPinned};
-use macros::pin_data;
+use pin_init::{pin_data, pin_init, PinInit};
 
 pub mod mutex;
 pub mod spinlock;

rust/kernel/sync/lock/mutex.rs

@@ -26,7 +26,7 @@ pub use new_mutex;
 /// Since it may block, [`Mutex`] needs to be used with care in atomic contexts.
 ///
 /// Instances of [`Mutex`] need a lock class and to be pinned. The recommended way to create such
-/// instances is with the [`pin_init`](crate::pin_init) and [`new_mutex`] macros.
+/// instances is with the [`pin_init`](pin_init::pin_init) and [`new_mutex`] macros.
 ///
 /// # Examples
 ///

rust/kernel/sync/lock/spinlock.rs

@@ -24,7 +24,7 @@ pub use new_spinlock;
 /// unlocked, at which point another CPU will be allowed to make progress.
 ///
 /// Instances of [`SpinLock`] need a lock class and to be pinned. The recommended way to create such
-/// instances is with the [`pin_init`](crate::pin_init) and [`new_spinlock`] macros.
+/// instances is with the [`pin_init`](pin_init::pin_init) and [`new_spinlock`] macros.
 ///
 /// # Examples
 ///

rust/kernel/types.rs

@@ -2,7 +2,6 @@
 
 //! Kernel types.
 
-use crate::init::{self, PinInit, Zeroable};
 use core::{
     cell::UnsafeCell,
     marker::{PhantomData, PhantomPinned},
@@ -10,6 +9,7 @@ use core::{
     ops::{Deref, DerefMut},
     ptr::NonNull,
 };
+use pin_init::{PinInit, Zeroable};
 
 /// Used to transfer ownership to and from foreign (non-Rust) languages.
 ///
@@ -336,7 +336,7 @@ impl<T> Opaque<T> {
             //   - `ptr` is a valid pointer to uninitialized memory,
             //   - `slot` is not accessed on error; the call is infallible,
             //   - `slot` is pinned in memory.
-            let _ = unsafe { init::PinInit::<T>::__pinned_init(slot, ptr) };
+            let _ = unsafe { PinInit::<T>::__pinned_init(slot, ptr) };
         })
     }
 
@@ -352,7 +352,7 @@ impl<T> Opaque<T> {
         // SAFETY: We contain a `MaybeUninit`, so it is OK for the `init_func` to not fully
         // initialize the `T`.
         unsafe {
-            init::pin_init_from_closure::<_, ::core::convert::Infallible>(move |slot| {
+            pin_init::pin_init_from_closure::<_, ::core::convert::Infallible>(move |slot| {
                 init_func(Self::raw_get(slot));
                 Ok(())
             })
@@ -372,7 +372,9 @@ impl<T> Opaque<T> {
     ) -> impl PinInit<Self, E> {
         // SAFETY: We contain a `MaybeUninit`, so it is OK for the `init_func` to not fully
         // initialize the `T`.
-        unsafe { init::pin_init_from_closure::<_, E>(move |slot| init_func(Self::raw_get(slot))) }
+        unsafe {
+            pin_init::pin_init_from_closure::<_, E>(move |slot| init_func(Self::raw_get(slot)))
+        }
     }
 
     /// Returns a raw pointer to the opaque data.

rust/macros/helpers.rs

@@ -86,5 +86,3 @@ pub(crate) fn function_name(input: TokenStream) -> Option<Ident> {
     }
     None
 }
-
-include!("../pin-init/internal/src/helpers.rs");

rust/macros/lib.rs

@@ -13,13 +13,7 @@ mod export;
 mod helpers;
 mod module;
 mod paste;
-#[path = "../pin-init/internal/src/pin_data.rs"]
-mod pin_data;
-#[path = "../pin-init/internal/src/pinned_drop.rs"]
-mod pinned_drop;
 mod vtable;
-#[path = "../pin-init/internal/src/zeroable.rs"]
-mod zeroable;
 
 use proc_macro::TokenStream;
 
@@ -398,5 +392,3 @@ pub fn paste(input: TokenStream) -> TokenStream {
     paste::expand(&mut tokens);
     tokens.into_iter().collect()
 }
-
-include!("../pin-init/internal/src/lib.rs");

rust/macros/module.rs

@@ -244,7 +244,7 @@ pub(crate) fn module(ts: TokenStream) -> TokenStream {
             mod __module_init {{
                 mod __module_init {{
                     use super::super::{type_};
-                    use kernel::init::PinInit;
+                    use pin_init::PinInit;
 
                     /// The \"Rust loadable module\" mark.
                     //

rust/macros/quote.rs

@@ -2,6 +2,7 @@
 
 use proc_macro::{TokenStream, TokenTree};
 
+#[allow(dead_code)]
 pub(crate) trait ToTokens {
     fn to_tokens(&self, tokens: &mut TokenStream);
 }

rust/pin-init/internal/src/_lib.rs

@@ -1,3 +0,0 @@
-// SPDX-License-Identifier: Apache-2.0 OR MIT
-
-//! Will be removed in a future commit, only exists to prevent compilation errors.

rust/pin-init/internal/src/helpers.rs

@@ -1,5 +1,7 @@
 // SPDX-License-Identifier: Apache-2.0 OR MIT
 
+use proc_macro::{TokenStream, TokenTree};
+
 /// Parsed generics.
 ///
 /// See the field documentation for an explanation what each of the fields represents.