linux-kernel - Re: [PATCH V4 1/2] rust: Add initial cpumask abstractions

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Message-ID: <20250411070941.6xbz4lrwkejr3aqf@vireshk-i7>
Date: Fri, 11 Apr 2025 12:39:41 +0530
From: Viresh Kumar <viresh.kumar@...aro.org>
To: Burak Emir <bqe@...gle.com>
Cc: Yury Norov <yury.norov@...il.com>,
	Rasmus Villemoes <linux@...musvillemoes.dk>,
	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 <benno.lossin@...ton.me>,
	Andreas Hindborg <a.hindborg@...nel.org>,
	Alice Ryhl <aliceryhl@...gle.com>, Trevor Gross <tmgross@...ch.edu>,
	linux-kernel@...r.kernel.org, Danilo Krummrich <dakr@...hat.com>,
	rust-for-linux@...r.kernel.org,
	Vincent Guittot <vincent.guittot@...aro.org>
Subject: Re: [PATCH V4 1/2] rust: Add initial cpumask abstractions

On 02-04-25, 18:00, Burak Emir wrote:
> On Wed, Apr 2, 2025 at 5:47 PM Yury Norov <yury.norov@...il.com> wrote:
> > On Wed, Apr 02, 2025 at 11:08:42AM +0530, Viresh Kumar wrote:
> > > +    pub fn set(&mut self, cpu: u32) {
> > > +        // SAFETY: By the type invariant, `self.as_raw` is a valid argument to `cpumask_set_cpus`.
> > > +        unsafe { bindings::cpumask_set_cpu(cpu, self.as_raw()) };
> > > +    }
> >
> > Alright, this is an atomic operation. For bitmaps in rust, Burak and
> > Alice decided to switch naming, so 'set()' in C becomes 'set_atomic()'
> > in rust, and correspondingly, '__set()' becomes 'set()'.
> >
> > I think it's maybe OK to switch naming for a different language. But
> > guys, can you please be consistent once you made a decision?
> >
> > Burak, Alice, please comment.
> 
> I really like the explicit naming convention that includes "atomic" if
> an operation is atomic.
> It seems also consistent with std library.
> 
> > Regardless, without looking at the end code I can't judge if you need
> > atomic or non-atomic ops. Can you link the project that actually uses
> > this API? Better if you just prepend that series with this 2 patches
> > and move them together.
> 
> The type &mut self gives it away: the Rust type system enforces
> exclusive access here due to aliasing rules.
> So a non-atomic operation is sufficient here.

I should leave it as is then, right ? Don't rename to set_atomic() ?

-- 
viresh