linux-kernel - Re: [PATCH v3] rust: Add support for feeding entropy to randomness pool

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Message-ID: <CAGSQo03F5S3SH5Z1=E+a=kLud-KvLYf_KhFHKqSUm5-n63L6dg@mail.gmail.com>
Date: Tue, 30 Dec 2025 09:47:14 -0800
From: Matthew Maurer <mmaurer@...gle.com>
To: Brendan Shephard <bshephar@...-home.net>
Cc: Miguel Ojeda <ojeda@...nel.org>, 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>, 
	Alice Ryhl <aliceryhl@...gle.com>, Trevor Gross <tmgross@...ch.edu>, 
	Danilo Krummrich <dakr@...nel.org>, linux-kernel@...r.kernel.org, 
	rust-for-linux@...r.kernel.org
Subject: Re: [PATCH v3] rust: Add support for feeding entropy to randomness pool

On Sun, Dec 28, 2025 at 1:13 AM Brendan Shephard <bshephar@...-home.net> wrote:
>
> On Fri, Dec 26, 2025 at 07:15:10PM +0000, Matthew Maurer wrote:
> > +/// Adds the given buffer to the entropy pool, but does not credit any entropy.
> > +///
> > +/// This is intended for use mixing in data that is likely to differ between devices or boots, but
> Yeah, I agree with Alexandre here. I think this would probably be better
> written as: "This function mixes in data that is likely to differ between
> devices or boots". Or, "add_device_randomness mixes in data that is
> likely to differ between devices or boots." If you would prefer to avoid
> saying "this function".

I believe the grammar to be correct here - if it helps, the "use" in
this case is the "yoos" variant of use, not the "yooz" variant.

That said, if it's confusing, it's confusing. I'll reword it as suggested.

> > +/// may otherwise be predictable. Examples include MAC addresses or RTC values. This slightly
> > +/// improves randomness in entropy-constrained environments (especially common for embedded
> > +/// devices).
> > +pub fn add_device_randomness(buf: &[u8]) {
> > +    // SAFETY: We just need the pointer to be valid for the length, which a slice provides.
> > +    unsafe { bindings::add_device_randomness(buf.as_ptr().cast::<c_void>(), buf.len()) };
> > +}
> >
> > ---
> > base-commit: 008d3547aae5bc86fac3eda317489169c3fda112
> > change-id: 20251029-add-entropy-f57e12ebe110
> >
> > Best regards,
> > --
> > Matthew Maurer <mmaurer@...gle.com>
> >
> >