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Date: Mon, 20 Oct 2025 11:49:17 +0200
Message-Id: <DDN20C4Z22X3.2ML01WB1HRDRI@kernel.org>
From: "Danilo Krummrich" <dakr@kernel.org>
Subject: Re: [PATCH 3/7] rust: debugfs: support for binary large objects
Cc: <gregkh@linuxfoundation.org>, <rafael@kernel.org>, <ojeda@kernel.org>,
 <alex.gaynor@gmail.com>, <boqun.feng@gmail.com>, <gary@garyguo.net>,
 <bjorn3_gh@protonmail.com>, <lossin@kernel.org>, <a.hindborg@kernel.org>,
 <tmgross@umich.edu>, <mmaurer@google.com>,
 <rust-for-linux@vger.kernel.org>, <linux-kernel@vger.kernel.org>
To: "Alice Ryhl" <aliceryhl@google.com>
References: <20251003222729.322059-1-dakr@kernel.org>
 <20251003222729.322059-4-dakr@kernel.org> <aPI9tNoh0I3KGDjl@google.com>
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In-Reply-To: <CAH5fLgjw4cZ3Y3Z60v8Wtp1EsR3AjyopJBE-UzZH5H3qkFrWmQ@mail.gmail.com>

On Mon Oct 20, 2025 at 11:42 AM CEST, Alice Ryhl wrote:
> On Mon, Oct 20, 2025 at 11:40=E2=80=AFAM Danilo Krummrich <dakr@kernel.or=
g> wrote:
>>
>> On Mon Oct 20, 2025 at 10:12 AM CEST, Alice Ryhl wrote:
>> > On Sun, Oct 19, 2025 at 02:01:03PM +0200, Danilo Krummrich wrote:
>> >> On Sun Oct 19, 2025 at 11:44 AM CEST, Alice Ryhl wrote:
>> >> > On Fri, Oct 17, 2025 at 04:53:09PM +0200, Danilo Krummrich wrote:
>> >> >> On Fri Oct 17, 2025 at 4:37 PM CEST, Danilo Krummrich wrote:
>> >> >> > The reason I went with a trait is because that's consistent with=
in the file.
>> >> >> >
>> >> >> > Otherwise, I don't mind one or the other. If we always want to u=
se a struct, I'm
>> >> >> > fine with that. :)
>> >> >>
>> >> >> Actually, there's another reason I forgot about since I sent the s=
eries. :)
>> >> >>
>> >> >> We need it because we derive it from blanket implementations:
>> >> >>
>> >> >>   impl<T: BinaryWriter + Sync> BinaryReadFile<T> for T
>> >> >>   impl<T: BinaryReader + Sync> BinaryWriteFile<T> for T
>> >> >>   impl<T: BinaryWriter + BinaryReader + Sync> BinaryReadWriteFile<=
T> for T
>> >> >
>> >> > You can still use a struct:
>> >> >
>> >> > struct BinaryWriterVtable<T: BinaryWriter + Sync>;
>> >> >
>> >> > impl<T: BinaryWriter + Sync> BinaryWriterVtable<T> {
>> >> >     const VTABLE: bindings::foo =3D ...;
>> >> > }
>> >>
>> >> Yeah, but do we get something for adding yet another type in this cas=
e?
>> >>
>> >> Another point to consider is if we want a more generic fops abstracti=
on type.
>> >>
>> >> In any case, I'd like to add this as good first issue for the whole f=
ile to be
>> >> changed accordingly.
>> >
>> > Yes, keep it as-is for consistency with the rest of the file, even if
>> > the file is inconsistent with the rest of `kernel`. Please go ahead an=
d
>> > file a good-first-issue for this.
>>
>> Before doing so, can you please answer the question above? While I'm all=
 for
>> consistency, in this specific case it seems we'd need another indirectio=
n for
>> that. And I'm not convinced that's an improvement.
>
> The choice is between adding a new type or a new trait. There's no
> intrinsic advantage to choosing either one, but the rest of `kernel`
> chose "new type" over "new trait", so it makes sense to be consistent.

My hesitation came from the assumption that we'd need another type (additio=
nal
to the existing trait). But we can indeed replace it, so that's fine.