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rust: pin-init: move the default error behavior of try_[pin_]init

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Move the ability to just write `try_pin_init!(Foo { a <- a_init })`
(note the missing `? Error` at the end) into the kernel crate.
Remove this notation from the pin-init crate, since the default when no
error is specified is the kernel-internal `Error` type. Instead add two
macros in the kernel crate that serve this default and are used instead
of the ones from `pin-init`.

This is done, because the `Error` type that is used as the default is
from the kernel crate and it thus prevents making the pin-init crate
standalone.

In order to not cause a build error due to a name overlap, the macros in
the pin-init crate are renamed, but this change is reverted in a future
commit when it is a standalone crate.

Signed-off-by: Benno Lossin <benno.lossin@proton.me>
Reviewed-by: Fiona Behrens <me@kloenk.dev>
Reviewed-by: Andreas Hindborg <a.hindborg@kernel.org>
Tested-by: Andreas Hindborg <a.hindborg@kernel.org>
Link: https://lore.kernel.org/r/20250308110339.2997091-8-benno.lossin@proton.me
Signed-off-by: Miguel Ojeda <ojeda@kernel.org>
This commit is contained in:
Benno Lossin 2025-03-08 11:04:30 +00:00 committed by Miguel Ojeda
parent c2ddbdbb8a
commit 578eb8b6db
2 changed files with 126 additions and 42 deletions
repo.diff.show_diff_stats Download patch file Download diff file Expand all files Collapse all files

113
rust/kernel/init.rs
View file

@ -133,3 +133,116 @@
//! }
//! }
//! ```
/// Construct an in-place fallible initializer for `struct`s.
///
/// This macro defaults the error to [`Error`]. If you need [`Infallible`], then use
/// [`init!`].
///
/// The syntax is identical to [`try_pin_init!`]. If you want to specify a custom error,
/// append `? $type` after the `struct` initializer.
/// The safety caveats from [`try_pin_init!`] also apply:
/// - `unsafe` code must guarantee either full initialization or return an error and allow
/// deallocation of the memory.
/// - the fields are initialized in the order given in the initializer.
/// - no references to fields are allowed to be created inside of the initializer.
///
/// # Examples
///
/// ```rust
/// use kernel::{init::zeroed, error::Error};
/// struct BigBuf {
/// big: KBox<[u8; 1024 * 1024 * 1024]>,
/// small: [u8; 1024 * 1024],
/// }
///
/// impl BigBuf {
/// fn new() -> impl Init<Self, Error> {
/// try_init!(Self {
/// big: KBox::init(zeroed(), GFP_KERNEL)?,
/// small: [0; 1024 * 1024],
/// }? Error)
/// }
/// }
/// ```
///
/// [`Infallible`]: core::convert::Infallible
/// [`init!`]: crate::init!
/// [`try_pin_init!`]: crate::try_pin_init!
/// [`Error`]: crate::error::Error
#[macro_export]
macro_rules! try_init {
($(&$this:ident in)? $t:ident $(::<$($generics:ty),* $(,)?>)? {
$($fields:tt)*
}) => {
$crate::_try_init!($(&$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),* $(,)?>)? {
$($fields)*
}? $err)
};
}
/// Construct an in-place, fallible pinned initializer for `struct`s.
///
/// If the initialization can complete without error (or [`Infallible`]), then use [`pin_init!`].
///
/// You can use the `?` operator or use `return Err(err)` inside the initializer to stop
/// initialization and return the error.
///
/// IMPORTANT: if you have `unsafe` code inside of the initializer you have to ensure that when
/// initialization fails, the memory can be safely deallocated without any further modifications.
///
/// This macro defaults the error to [`Error`].
///
/// The syntax is identical to [`pin_init!`] with the following exception: you can append `? $type`
/// after the `struct` initializer to specify the error type you want to use.
///
/// # Examples
///
/// ```rust
/// # #![feature(new_uninit)]
/// use kernel::{init::zeroed, error::Error};
/// #[pin_data]
/// struct BigBuf {
/// big: KBox<[u8; 1024 * 1024 * 1024]>,
/// small: [u8; 1024 * 1024],
/// ptr: *mut u8,
/// }
///
/// impl BigBuf {
/// fn new() -> impl PinInit<Self, Error> {
/// try_pin_init!(Self {
/// big: KBox::init(zeroed(), GFP_KERNEL)?,
/// small: [0; 1024 * 1024],
/// ptr: core::ptr::null_mut(),
/// }? Error)
/// }
/// }
/// ```
///
/// [`Infallible`]: core::convert::Infallible
/// [`pin_init!`]: crate::pin_init
/// [`Error`]: crate::error::Error
#[macro_export]
macro_rules! try_pin_init {
($(&$this:ident in)? $t:ident $(::<$($generics:ty),* $(,)?>)? {
$($fields:tt)*
}) => {
$crate::_try_pin_init!($(&$this in)? $t $(::<$($generics),* $(,)?>)? {
$($fields)*
}? $crate::error::Error)
};
($(&$this:ident in)? $t:ident $(::<$($generics:ty),* $(,)?>)? {
$($fields:tt)*
}? $err:ty) => {
$crate::_try_pin_init!($(&$this in)? $t $(::<$($generics),* $(,)?>)? {
$($fields)*
}? $err)
};
}

55
rust/pin-init/src/lib.rs
View file

@ -481,7 +481,7 @@ macro_rules! stack_try_pin_init {
/// Construct an in-place, pinned initializer for `struct`s.
///
/// This macro defaults the error to [`Infallible`]. If you need [`Error`], then use
/// This macro defaults the error to [`Infallible`]. If you need a different error, then use
/// [`try_pin_init!`].
///
/// The syntax is almost identical to that of a normal `struct` initializer:
@ -676,7 +676,7 @@ macro_rules! pin_init {
($(&$this:ident in)? $t:ident $(::<$($generics:ty),* $(,)?>)? {
$($fields:tt)*
}) => {
$crate::try_pin_init!($(&$this in)? $t $(::<$($generics),*>)? {
$crate::_try_pin_init!($(&$this in)? $t $(::<$($generics),*>)? {
$($fields)*
}? ::core::convert::Infallible)
};
@ -692,9 +692,7 @@ macro_rules! pin_init {
/// IMPORTANT: if you have `unsafe` code inside of the initializer you have to ensure that when
/// initialization fails, the memory can be safely deallocated without any further modifications.
///
/// This macro defaults the error to [`Error`].
///
/// The syntax is identical to [`pin_init!`] with the following exception: you can append `? $type`
/// The syntax is identical to [`pin_init!`] with the following exception: you must append `? $type`
/// after the `struct` initializer to specify the error type you want to use.
///
/// # Examples
@ -724,21 +722,7 @@ macro_rules! pin_init {
// For a detailed example of how this macro works, see the module documentation of the hidden
// module `__internal` inside of `init/__internal.rs`.
#[macro_export]
macro_rules! try_pin_init {
($(&$this:ident in)? $t:ident $(::<$($generics:ty),* $(,)?>)? {
$($fields:tt)*
}) => {
$crate::__init_internal!(
@this($($this)?),
@typ($t $(::<$($generics),*>)? ),
@fields($($fields)*),
@error($crate::error::Error),
@data(PinData, use_data),
@has_data(HasPinData, __pin_data),
@construct_closure(pin_init_from_closure),
@munch_fields($($fields)*),
)
};
macro_rules! _try_pin_init {
($(&$this:ident in)? $t:ident $(::<$($generics:ty),* $(,)?>)? {
$($fields:tt)*
}? $err:ty) => {
@ -752,12 +736,12 @@ macro_rules! try_pin_init {
@construct_closure(pin_init_from_closure),
@munch_fields($($fields)*),
)
};
}
}
/// Construct an in-place initializer for `struct`s.
///
/// This macro defaults the error to [`Infallible`]. If you need [`Error`], then use
/// This macro defaults the error to [`Infallible`]. If you need a different error, then use
/// [`try_init!`].
///
/// The syntax is identical to [`pin_init!`] and its safety caveats also apply:
@ -777,7 +761,7 @@ macro_rules! init {
($(&$this:ident in)? $t:ident $(::<$($generics:ty),* $(,)?>)? {
$($fields:tt)*
}) => {
$crate::try_init!($(&$this in)? $t $(::<$($generics),*>)? {
$crate::_try_init!($(&$this in)? $t $(::<$($generics),*>)? {
$($fields)*
}? ::core::convert::Infallible)
}
@ -785,11 +769,11 @@ macro_rules! init {
/// Construct an in-place fallible initializer for `struct`s.
///
/// This macro defaults the error to [`Error`]. If you need [`Infallible`], then use
/// If the initialization can complete without error (or [`Infallible`]), then use
/// [`init!`].
///
/// The syntax is identical to [`try_pin_init!`]. If you want to specify a custom error,
/// append `? $type` after the `struct` initializer.
/// The syntax is identical to [`try_pin_init!`]. You need to specify a custom error
/// via `? $type` after the `struct` initializer.
/// The safety caveats from [`try_pin_init!`] also apply:
/// - `unsafe` code must guarantee either full initialization or return an error and allow
/// deallocation of the memory.
@ -816,24 +800,11 @@ macro_rules! init {
/// }
/// }
/// ```
/// [`try_pin_init!`]: crate::try_pin_init
// For a detailed example of how this macro works, see the module documentation of the hidden
// module `__internal` inside of `init/__internal.rs`.
#[macro_export]
macro_rules! try_init {
($(&$this:ident in)? $t:ident $(::<$($generics:ty),* $(,)?>)? {
$($fields:tt)*
}) => {
$crate::__init_internal!(
@this($($this)?),
@typ($t $(::<$($generics),*>)?),
@fields($($fields)*),
@error($crate::error::Error),
@data(InitData, /*no use_data*/),
@has_data(HasInitData, __init_data),
@construct_closure(init_from_closure),
@munch_fields($($fields)*),
)
};
macro_rules! _try_init {
($(&$this:ident in)? $t:ident $(::<$($generics:ty),* $(,)?>)? {
$($fields:tt)*
}? $err:ty) => {
@ -847,7 +818,7 @@ macro_rules! try_init {
@construct_closure(init_from_closure),
@munch_fields($($fields)*),
)
};
}
}
/// Asserts that a field on a struct using `#[pin_data]` is marked with `#[pin]` ie. that it is