linux-kernel - Re: [PATCH v3] rust: regulator: add a bare minimum regulator abstraction

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-Id: <D9VS6WE94O04.GXFI0K5BH4XN@kernel.org>
Date: Wed, 14 May 2025 11:37:46 +0200
From: "Benno Lossin" <lossin@...nel.org>
To: "Mark Brown" <broonie@...nel.org>
Cc: "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"
 <benno.lossin@...ton.me>, "Andreas Hindborg" <a.hindborg@...nel.org>,
 "Alice Ryhl" <aliceryhl@...gle.com>, "Trevor Gross" <tmgross@...ch.edu>,
 "Danilo Krummrich" <dakr@...nel.org>, "Boris Brezillon"
 <boris.brezillon@...labora.com>, "Sebastian Reichel"
 <sebastian.reichel@...labora.com>, "Liam Girdwood" <lgirdwood@...il.com>,
 <linux-kernel@...r.kernel.org>, <rust-for-linux@...r.kernel.org>
Subject: Re: [PATCH v3] rust: regulator: add a bare minimum regulator
 abstraction

On Wed May 14, 2025 at 9:46 AM CEST, Mark Brown wrote:
> On Tue, May 13, 2025 at 10:01:05PM +0200, Benno Lossin wrote:
>> On Tue May 13, 2025 at 5:44 PM CEST, Daniel Almeida wrote:
>
>> > +/// A [`Regulator`] that is known to be enabled.
>> > +///
>> > +/// # Invariants
>> > +///
>> > +/// - [`EnabledRegulator`] is a valid regulator that has been enabled.
>
>> This isn't fully clear what it's supposed to mean to me. Maybe mention
>> the `regulator_enable` function?
>
> I suspect this is adequately clear to someone with the domain specific
> knowledge required to be using the API.

I still think it's useful to name the exact function that is meant by
"enabled".

>> > +impl EnabledRegulator {
>> > +    fn as_ptr(&self) -> *mut bindings::regulator {
>> > +        self.inner.inner.as_ptr()
>> > +    }
>
>> > +    /// Disables the regulator.
>> > +    pub fn disable(self) -> Result<Regulator> {
>> > +        // Keep the count on `regulator_get()`.
>> > +        let regulator = ManuallyDrop::new(self);
>
>> Why don't we drop the refcount if the `regulator_disable` call fails?
>
> If you fail to disable the regulator then the underlying C code won't
> drop it's reference count.

So if it fails, the regulator should stay alive indefinitely? Would be
useful to explain that in the comment above the `ManuallyDrop`.

---
Cheers,
Benno