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authorBenno Lossin <benno.lossin@proton.me>2023-08-14 08:46:55 +0000
committerMiguel Ojeda <ojeda@kernel.org>2023-08-21 14:31:48 +0200
commitb9b88be046a92a43d70badb340cac9ffd9695dcb (patch)
tree923a5b1f6733aa127751afb56f8e763e471b3656 /rust
parent97de919d574e6a22f0d43a169b96274f1862e770 (diff)
downloadlwn-b9b88be046a92a43d70badb340cac9ffd9695dcb.tar.gz
lwn-b9b88be046a92a43d70badb340cac9ffd9695dcb.zip
rust: init: wrap type checking struct initializers in a closure
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> Reviewed-by: Gary Guo <gary@garyguo.net> Signed-off-by: Benno Lossin <benno.lossin@proton.me> Link: https://lore.kernel.org/r/20230814084602.25699-6-benno.lossin@proton.me Signed-off-by: Miguel Ojeda <ojeda@kernel.org>
Diffstat (limited to 'rust')
-rw-r--r--rust/kernel/init/macros.rs8
1 files changed, 4 insertions, 4 deletions
diff --git a/rust/kernel/init/macros.rs b/rust/kernel/init/macros.rs
index 5063b45970f3..a1ccc978feab 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)*