linux-kernel - Re: [PATCH v2 3/7] rust: cpufreq: always inline functions using build

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Message-ID: <aSlsQmiSCC2ZdfLr@google.com>
Date: Fri, 28 Nov 2025 09:32:50 +0000
From: Alice Ryhl <aliceryhl@...gle.com>
To: Viresh Kumar <viresh.kumar@...aro.org>
Cc: Alexandre Courbot <acourbot@...dia.com>, Danilo Krummrich <dakr@...nel.org>, 
	Daniel Almeida <daniel.almeida@...labora.com>, Miguel Ojeda <ojeda@...nel.org>, 
	Alex Gaynor <alex.gaynor@...il.com>, Boqun Feng <boqun.feng@...il.com>, 
	Gary Guo <gary@...yguo.net>, 
	"Björn Roy Baron" <bjorn3_gh@...tonmail.com>, Benno Lossin <lossin@...nel.org>, 
	Andreas Hindborg <a.hindborg@...nel.org>, Trevor Gross <tmgross@...ch.edu>, 
	"Rafael J. Wysocki" <rafael@...nel.org>, Will Deacon <will@...nel.org>, 
	Peter Zijlstra <peterz@...radead.org>, Mark Rutland <mark.rutland@....com>, 
	rust-for-linux@...r.kernel.org, linux-kernel@...r.kernel.org, 
	linux-pm@...r.kernel.org
Subject: Re: [PATCH v2 3/7] rust: cpufreq: always inline functions using
 build_assert with arguments

On Fri, Nov 28, 2025 at 11:42:55AM +0530, Viresh Kumar wrote:
> On 28-11-25, 11:11, Alexandre Courbot wrote:
> > `build_assert` relies on the compiler to optimize out its error path.
> > Functions using it with its arguments must thus always be inlined,
> > otherwise the error path of `build_assert` might not be optimized out,
> > triggering a build error.
> > 
> > Signed-off-by: Alexandre Courbot <acourbot@...dia.com>
> > ---
> >  rust/kernel/cpufreq.rs | 2 ++
> >  1 file changed, 2 insertions(+)
> > 
> > diff --git a/rust/kernel/cpufreq.rs b/rust/kernel/cpufreq.rs
> > index 1a555fcb120a..df5d9f6f43f3 100644
> > --- a/rust/kernel/cpufreq.rs
> > +++ b/rust/kernel/cpufreq.rs
> > @@ -1015,6 +1015,8 @@ impl<T: Driver> Registration<T> {
> >          ..pin_init::zeroed()
> >      };
> >  
> > +    // Always inline to optimize out error path of `build_assert`.
> > +    #[inline(always)]
> >      const fn copy_name(name: &'static CStr) -> [c_char; CPUFREQ_NAME_LEN] {
> >          let src = name.to_bytes_with_nul();
> >          let mut dst = [0; CPUFREQ_NAME_LEN];
> 
> Acked-by: Viresh Kumar <viresh.kumar@...aro.org>
> 
> Lemme know if you want me to pick this instead.

There's no reason these can't be picked up independently, so it would be
fine if you pick up this one.

Alice