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Message-ID: <72aca706-c2ff-b363-717c-323ea24d3908@gmail.com>
Date:   Fri, 14 Jul 2023 11:28:37 -0300
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Subject: Re: [PATCH RFC 04/11] rust: siphash: Add a simple siphash abstraction
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To:     Asahi Lina <lina@asahilina.net>, Miguel Ojeda <ojeda@kernel.org>,
        Alex Gaynor <alex.gaynor@gmail.com>,
        Wedson Almeida Filho <wedsonaf@gmail.com>,
        Boqun Feng <boqun.feng@gmail.com>, Gary Guo <gary@garyguo.net>,
        =?UTF-8?Q?Bj=c3=b6rn_Roy_Baron?= <bjorn3_gh@protonmail.com>,
        Benno Lossin <benno.lossin@proton.me>,
        Masahiro Yamada <masahiroy@kernel.org>,
        Nathan Chancellor <nathan@kernel.org>,
        Nick Desaulniers <ndesaulniers@google.com>,
        Nicolas Schier <nicolas@fjasle.eu>, Tom Rix <trix@redhat.com>,
        Daniel Vetter <daniel@ffwll.ch>
Cc:     Hector Martin <marcan@marcan.st>, Sven Peter <sven@svenpeter.dev>,
        Alyssa Rosenzweig <alyssa@rosenzweig.io>,
        asahi@lists.linux.dev, rust-for-linux@vger.kernel.org,
        linux-kernel@vger.kernel.org, linux-kbuild@vger.kernel.org,
        llvm@lists.linux.dev
References: <20230714-classless_lockdep-v1-0-229b9671ce31@asahilina.net>
 <20230714-classless_lockdep-v1-4-229b9671ce31@asahilina.net>
From:   Martin Rodriguez Reboredo <yakoyoku@gmail.com>
In-Reply-To: <20230714-classless_lockdep-v1-4-229b9671ce31@asahilina.net>
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On 7/14/23 06:13, Asahi Lina wrote:
> This simple wrapper allows Rust code to use the Hasher interface with
> the kernel siphash implementation. No fancy features supported for now,
> just basic bag-of-bytes hashing. No guarantee that hash outputs will
> remain stable in the future either.
> 
> Signed-off-by: Asahi Lina <lina@asahilina.net>
> ---
> [...]
> --- /dev/null
> +++ b/rust/kernel/siphash.rs
> @@ -0,0 +1,39 @@
> +// SPDX-License-Identifier: GPL-2.0
> +
> +//! A core::hash::Hasher wrapper for the kernel siphash implementation.
> +//!
> +//! This module allows Rust code to use the kernel's siphash implementation
> +//! to hash Rust objects.
> +
> +use core::hash::Hasher;
> +
> +/// A Hasher implementation that uses the kernel siphash implementation.
> +#[derive(Default)]
> +pub struct SipHasher {
> +    // SipHash state is 4xu64, but the Linux implementation
> +    // doesn't expose incremental hashing so let's just chain
> +    // individual SipHash calls for now, which return a u64
> +    // hash.

Isn't this detail relevant to mention in the doc comment? At least to
explain the difference between them.

> +    state: u64,
> +}
> [...]