Messages in this thread Patch in this message | | | Date | Wed, 2 Aug 2023 18:52:58 +0100 | From | Gary Guo <> | Subject | Re: [PATCH v3 05/13] rust: init: wrap type checking struct initializers in a closure |
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On Sat, 29 Jul 2023 09:09:46 +0000 Benno Lossin <benno.lossin@proton.me> wrote:
> In the implementation of the init macros there is a `if false` statement > that type checks the initializer to ensure every field is initialized. > Since the next patch has a stack variable to store the struct, the > function might allocate too much memory on debug builds. Putting the > struct into a closure that is never executed ensures that even in debug > builds no stack overflow error is caused. In release builds this was not > a problem since the code was optimized away due to the `if false`. > > Reviewed-by: Martin Rodriguez Reboredo <yakoyoku@gmail.com> > Reviewed-by: Alice Ryhl <aliceryhl@google.com> > Signed-off-by: Benno Lossin <benno.lossin@proton.me>
Reviewed-by: Gary Guo <gary@garyguo.net>
> --- > v2 -> v3: > - added Reviewed-by's from Martin and Alice. > > v1 -> v2: > - do not call the created closure. > > rust/kernel/init/macros.rs | 8 ++++---- > 1 file changed, 4 insertions(+), 4 deletions(-) > > diff --git a/rust/kernel/init/macros.rs b/rust/kernel/init/macros.rs > index 454f31b8c614..2bad086cda0a 100644 > --- a/rust/kernel/init/macros.rs > +++ b/rust/kernel/init/macros.rs > @@ -1040,14 +1040,14 @@ macro_rules! __init_internal { > // once, this struct initializer will still be type-checked and complain with a > // very natural error message if a field is forgotten/mentioned more than once. > #[allow(unreachable_code, clippy::diverging_sub_expression)] > - if false { > + let _ = || { > $crate::__init_internal!(make_initializer: > @slot(slot), > @type_name($t), > @munch_fields($($fields)*,), > @acc(), > ); > - } > + }; > } > Ok(__InitOk) > } > @@ -1168,8 +1168,8 @@ macro_rules! __init_internal { > @acc($($acc:tt)*), > ) => { > // Endpoint, nothing more to munch, create the initializer. > - // Since we are in the `if false` branch, this will never get executed. We abuse `slot` to > - // get the correct type inference here: > + // Since we are in the closure that is never called, this will never get executed. > + // We abuse `slot` to get the correct type inference here: > unsafe { > ::core::ptr::write($slot, $t { > $($acc)*
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