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Date: Tue, 21 Oct 2025 19:43:58 +0200
Message-Id: <DDO6QBSWU8MN.3UA0DT8WDUPZT@kernel.org>
Subject: Re: [PATCH] rust: driver: let probe() return impl PinInit<Self,
 Error>
Cc: <viresh.kumar@linaro.org>, <acourbot@nvidia.com>, <ira.weiny@intel.com>,
 <leon@kernel.org>, <daniel.almeida@collabora.com>, <bhelgaas@google.com>,
 <kwilczynski@kernel.org>, <abdiel.janulgue@gmail.com>,
 <robin.murphy@arm.com>, <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>, <aliceryhl@google.com>,
 <tmgross@umich.edu>, <rust-for-linux@vger.kernel.org>,
 <linux-pci@vger.kernel.org>, <linux-pm@vger.kernel.org>,
 <nouveau@lists.freedesktop.org>, <dri-devel@lists.freedesktop.org>,
 <linux-kernel@vger.kernel.org>
To: <gregkh@linuxfoundation.org>, <rafael@kernel.org>
From: "Danilo Krummrich" <dakr@kernel.org>
References: <20251016125544.15559-1-dakr@kernel.org>
In-Reply-To: <20251016125544.15559-1-dakr@kernel.org>

On Thu Oct 16, 2025 at 2:55 PM CEST, Danilo Krummrich wrote:
> The driver model defines the lifetime of the private data stored in (and
> owned by) a bus device to be valid from when the driver is bound to a
> device (i.e. from successful probe()) until the driver is unbound from
> the device.
>
> This is already taken care of by the Rust implementation of the driver
> model. However, we still ask drivers to return a Result<Pin<KBox<Self>>>
> from probe().
>
> Unlike in C, where we do not have the concept of initializers, but
> rather deal with uninitialized memory, drivers can just return an
> impl PinInit<Self, Error> instead.
>
> This contributed to more clarity to the fact that a driver returns it's
> device private data in probe() and the Rust driver model owns the data,
> manages the lifetime and - considering the lifetime - provides (safe)
> accessors for the driver.
>
> Hence, let probe() functions return an impl PinInit<Self, Error> instead
> of Result<Pin<KBox<Self>>>.
>
> Signed-off-by: Danilo Krummrich <dakr@kernel.org>

Applied to driver-core-testing, thanks!