linux-kernel - Re: [PATCH V12 00/15] Rust abstractions for clk, cpumask, cpufreq, OPP

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Message-ID: <aEH6GzCTgXZSneHt@tardis.local>
Date: Thu, 5 Jun 2025 13:12:11 -0700
From: Boqun Feng <boqun.feng@...il.com>
To: Andreas Hindborg <a.hindborg@...nel.org>
Cc: Viresh Kumar <viresh.kumar@...aro.org>,
	"Rafael J. Wysocki" <rafael@...nel.org>,
	Miguel Ojeda <miguel.ojeda.sandonis@...il.com>,
	Danilo Krummrich <dakr@...hat.com>,	Alex Gaynor <alex.gaynor@...il.com>,
	Alice Ryhl <aliceryhl@...gle.com>,	Benno Lossin <benno.lossin@...ton.me>,
	Björn Roy Baron <bjorn3_gh@...tonmail.com>,
	Danilo Krummrich <dakr@...nel.org>, Gary Guo <gary@...yguo.net>,
	Michael Turquette <mturquette@...libre.com>,
	Miguel Ojeda <ojeda@...nel.org>, Nishanth Menon <nm@...com>,
	Peter Zijlstra <peterz@...radead.org>,	Stephen Boyd <sboyd@...nel.org>,
	Thomas Gleixner <tglx@...utronix.de>,	Trevor Gross <tmgross@...ch.edu>,
 Viresh Kumar <vireshk@...nel.org>,	Yury Norov <yury.norov@...il.com>,
 linux-pm@...r.kernel.org,	Vincent Guittot <vincent.guittot@...aro.org>,
	rust-for-linux@...r.kernel.org,
	Manos Pitsidianakis <manos.pitsidianakis@...aro.org>,
	Alex Bennée <alex.bennee@...aro.org>,
	Joakim Bech <joakim.bech@...aro.org>, Rob Herring <robh@...nel.org>,
	Burak Emir <bqe@...gle.com>,	Rasmus Villemoes <linux@...musvillemoes.dk>,
	Russell King <linux@...linux.org.uk>, linux-clk@...r.kernel.org,
	Andrew Ballance <andrewjballance@...il.com>,
	Anisse Astier <anisse@...ier.eu>,
	Daniel Almeida <daniel.almeida@...labora.com>,
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH V12 00/15] Rust abstractions for clk, cpumask, cpufreq,
 OPP

On Thu, Jun 05, 2025 at 09:41:47PM +0200, Andreas Hindborg wrote:
> Hi Viresh,
> 
> "Viresh Kumar" <viresh.kumar@...aro.org> writes:
> 
> > Hello,
> >
> > I have queued this up for v6.16-rc1, will merge it via the PM tree soon.
> > Thanks.
> >
> > This series introduces initial Rust abstractions for a few subsystems: clk,
> > cpumask, cpufreq and Operating Performance Points (OPP).
> >
> > The abstractions cover most of the interfaces exposed by cpufreq and OPP
> > subsystems. It also includes minimal abstractions for the clk and cpumask
> > frameworks, which are required by the cpufreq / OPP abstractions.
> >
> > Additionally, a sample `rcpufreq-dt` driver is included. This is a
> > duplicate of the existing `cpufreq-dt` driver, which is a
> > platform-agnostic, device-tree based cpufreq driver commonly used on ARM
> > platforms.
> >
> > The implementation has been tested using QEMU, ensuring that frequency
> > transitions, various configurations, and driver binding/unbinding work as
> > expected. However, performance measurements have not been conducted yet.
> >
> > For those interested in testing these patches, they can be found at:
> >
> > git://git.kernel.org/pub/scm/linux/kernel/git/vireshk/pm.git rust/cpufreq-dt
> >
> > Based on 6.15-rc1 + rust/devres dependencies + PM/cpufreq dependencies.
> 
> I was testing an unrelated patch and found this kunit failure in
> mainline today:
> 
> [19:45:34] # rust_doctest_kernel_cpumask_rs_0.location: rust/kernel/cpumask.rs:180
> [19:45:34] # rust_doctest_kernel_cpumask_rs_0: ASSERTION FAILED at rust/kernel/cpumask.rs:190
> 

I assume you run it in a VM? How many vcpus are you using? I've checked
the code, cpumask_{set,test}() can set or set bits out of nr_cpu_ids
without triggering warning if CONFIG_DEBUG_PER_CPU_MAPS=n, but
cpumask_weight() only examine nr_cpu_ids bits. So if you run with
nr_cpu_ids < 4, the test case may fail.

Regards,
Boqun

> This is for arm64 defconfig. The test seems to passes on x86_64.
> 
> 
> Best regards,
> Andreas Hindborg
> 
>