linux-kernel - Re: [PATCH v4 1/2] rust: kernel: create `overflow

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Message-ID: <20250720161733.364025-1-contact@antoniohickey.com>
Date: Sun, 20 Jul 2025 16:17:40 +0000
From: Antonio Hickey <contact@...oniohickey.com>
To: tamird@...il.com
Cc: a.hindborg@...nel.org, alex.gaynor@...il.com, aliceryhl@...gle.com, bjorn3_gh@...tonmail.com, boqun.feng@...il.com, contact@...oniohickey.com, dakr@...nel.org, danielstonecote@...il.com, gary@...yguo.net, linux-kernel@...r.kernel.org, lossin@...nel.org, ojeda@...nel.org, rust-for-linux@...r.kernel.org, tmgross@...ch.edu
Subject: Re: [PATCH v4 1/2] rust: kernel: create `overflow_assert!` macro

Tamir Duberstein wrote:
> On Sat, Jun 28, 2025 at 10:43 PM Antonio Hickey
> <contact@...oniohickey.com> wrote:
> > +//! Overflow assertion.
> > +
> > +/// Verifies at runtime that an expression is within an expected bound.
> 
> This is a strange comment, imo. The only thing special about this
> macro relative to a plain `assert` is that it disabled when
> CONFIG_RUST_OVERFLOW_CHECKS=n.

Special yes, but it also documents the intent of the `assert`.
I did include a comment about the conditional behaviour with 
CONFIG_RUST_OVERFLOW_CHECKS being enabled/disabled. 

I'm open to rewording this doc comment to be better though. 
I should also add information about the optional panic message 
like the `static_assert` does as well, what about something like:

```
/// Overflow assertion.
///
/// Runtime assertion that an expression is within an expected bounds.
///
/// This macro is only enabled when `CONFIG_RUST_OVERFLOW_CHECKS` is true.
///
/// An optional panic message can be supplied after the expression.
/// Currently only a string literal without formatting is supported
/// due to constness limitations of the [`assert!`] macro.
```

Thanks

> 
> > +///
> > +/// This macro is only active when `CONFIG_RUST_OVERFLOW_CHECKS` is enabled.