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Date: Tue, 27 Jan 2026 21:09:45 +0100
Message-Id: <DFZN7C8P37RK.3IF24Z1YUVVOX@kernel.org>
To: "Zhi Wang" <zhiw@nvidia.com>
From: "Danilo Krummrich" <dakr@kernel.org>
Subject: Re: [PATCH v2 1/2] rust: introduce abstractions for fwctl
Cc: "Jason Gunthorpe" <jgg@nvidia.com>, <rust-for-linux@vger.kernel.org>,
 <linux-pci@vger.kernel.org>, <linux-kernel@vger.kernel.org>,
 <aliceryhl@google.com>, <bhelgaas@google.com>, <kwilczynski@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>, <markus.probst@posteo.de>,
 <helgaas@kernel.org>, <cjia@nvidia.com>, <smitra@nvidia.com>,
 <ankita@nvidia.com>, <aniketa@nvidia.com>, <kwankhede@nvidia.com>,
 <targupta@nvidia.com>, <acourbot@nvidia.com>, <joelagnelf@nvidia.com>,
 <jhubbard@nvidia.com>, <zhiwang@kernel.org>, <daniel.almeida@collabora.com>
References: <20260122204232.15988-1-zhiw@nvidia.com>
 <20260122204232.15988-2-zhiw@nvidia.com>
 <20260126181912.GA2131321@nvidia.com>
 <20260127215744.332380fe.zhiw@nvidia.com>
In-Reply-To: <20260127215744.332380fe.zhiw@nvidia.com>

On Tue Jan 27, 2026 at 8:57 PM CET, Zhi Wang wrote:
> On Mon, 26 Jan 2026 14:19:12 -0400
> Jason Gunthorpe <jgg@nvidia.com> wrote:
>> fwctl_unregister is not safe from any context, it must be called
>> while the Device is still bound.
>>=20
>
> The registration is wrapped in Devres<> in the sample driver, which
> guarantees that drop is called while the Device is still bound.
>
> I agree that the current abstraction itself does not strictly enforce thi=
s
> (e.g., if the object is moved out of Devres). I will investigate an
> approach to enforce this requirement in the next re-spin.

The code is fine, the Registration object can't be moved out of devres safe=
ly.
You just need to update the safety comment accordingly. :)