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Date: Mon, 21 Jul 2025 17:58:30 +0200
Message-Id: <DBHUVGOM4AN2.6JKUWB03D5DJ@kernel.org>
From: "Danilo Krummrich" <dakr@kernel.org>
Subject: Re: [PATCH v5] rust: drm: Drop the use of Opaque for ioctl
 arguments
Cc: <ojeda@kernel.org>, <alex.gaynor@gmail.com>, <aliceryhl@google.com>,
 <daniel.almeida@collabora.com>, <boqun.feng@gmail.com>, <gary@garyguo.net>,
 <bjorn3_gh@protonmail.com>, <lossin@kernel.org>, <a.hindborg@kernel.org>,
 <tmgross@umich.edu>, <alyssa@rosenzweig.io>, <lyude@redhat.com>,
 <rust-for-linux@vger.kernel.org>, <dri-devel@lists.freedesktop.org>
To: "Beata Michalska" <beata.michalska@arm.com>
References: <20250626162313.2755584-1-beata.michalska@arm.com>
In-Reply-To: <20250626162313.2755584-1-beata.michalska@arm.com>

On Thu Jun 26, 2025 at 6:23 PM CEST, Beata Michalska wrote:
> With the Opaque<T>, the expectations are that Rust should not
> make any assumptions on the layout or invariants of the wrapped
> C types. That runs rather counter to ioctl arguments, which must
> adhere to certain data-layout constraints. By using Opaque<T>,
> ioctl handlers are forced to use unsafe code where none is actually
> needed. This adds needless complexity and maintenance overhead,
> brining no safety benefits.
> Drop the use of Opaque for ioctl arguments as that is not the best
> fit here.
>
> Signed-off-by: Beata Michalska <beata.michalska@arm.com>
> Acked-by: Danilo Krummrich <dakr@kernel.org>
> Reviewed-by: Boqun Feng <boqun.feng@gmail.com>

Applied to drm-misc-next, thanks!