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Date: Fri, 19 Jun 2026 00:24:12 +0200
Message-Id: <DJCIZMUFKMTK.BO46M40UO3XY@kernel.org>
Cc: <lossin@kernel.org>, <gary@garyguo.net>, <ojeda@kernel.org>,
 <bjorn3_gh@protonmail.com>, <a.hindborg@kernel.org>,
 <aliceryhl@google.com>, <tmgross@umich.edu>,
 <daniel.almeida@collabora.com>, <tamird@kernel.org>, <acourbot@nvidia.com>,
 <work@onurozkan.dev>, <lyude@redhat.com>, <deborah.brouwer@collabora.com>,
 <rust-for-linux@vger.kernel.org>, <driver-core@lists.linux.dev>,
 <stable@vger.kernel.org>, "Sashiko" <sashiko-bot@kernel.org>
To: "Boqun Feng" <boqun@kernel.org>
From: "Danilo Krummrich" <dakr@kernel.org>
Subject: Re: [PATCH 2/2] rust: revocable: fix race between concurrent
 revokers
References: <20260618193951.601239-1-dakr@kernel.org>
 <20260618193951.601239-3-dakr@kernel.org> <ajRknQIsXaHtDzzJ@MacBook-0RXW5>
In-Reply-To: <ajRknQIsXaHtDzzJ@MacBook-0RXW5>

On Thu Jun 18, 2026 at 11:35 PM CEST, Boqun Feng wrote:
> This issue happens particularly when we want to save the extra refcount
> (and indirect reference), and I think this is the issue that `Foo`
> should handle instead of `Revocable`. So maybe we should move the fix
> into `Devres` layer? Thoughts?
>
> (I'm still hoping there could be some lightweight usage of Revocable
> other than Devres, hence the ask.)

I agree that a "lightweight" usage of Revocable is reasonable, and we can s=
till
have that; nothing prevents that (see below).

We could also turn it around and have revoke_wait() and make no wait the
default, but I think it is a bit of a footgun.

Another alternative would be a new type over Revocable, which may be a bit
cleaner. (Although in that case I can also just move it into Devres for now=
, as
it is the sole user of Revocable anyway.)

>> If needed, a revoke_no_wait() variant that does not wait for concurrent
>> revocations to complete can be added in the future.