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Date: Thu, 12 Jun 2025 18:20:10 +0200
From: Danilo Krummrich <dakr@kernel.org>
To: Benno Lossin <lossin@kernel.org>
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, benno.lossin@proton.me,
	a.hindborg@kernel.org, aliceryhl@google.com, tmgross@umich.edu,
	rust-for-linux@vger.kernel.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH 1/4] rust: revocable: support fallible PinInit types
Message-ID: <aEr-OnKiL5MKzur2@cassiopeiae>
References: <20250612145145.12143-1-dakr@kernel.org>
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 <DAKO8MMSCUE4.1WVR6SBADGP8W@kernel.org>
 <aEr5FNDaueo5SG5R@cassiopeiae>
 <DAKOUVS4YP4L.3I6FD9JKN02EU@kernel.org>
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In-Reply-To: <DAKOUVS4YP4L.3I6FD9JKN02EU@kernel.org>

On Thu, Jun 12, 2025 at 06:17:40PM +0200, Benno Lossin wrote:
> On Thu Jun 12, 2025 at 5:58 PM CEST, Danilo Krummrich wrote:
> > On Thu, Jun 12, 2025 at 05:48:36PM +0200, Benno Lossin wrote:
> >> On Thu Jun 12, 2025 at 4:51 PM CEST, Danilo Krummrich wrote:
> >> > diff --git a/rust/kernel/revocable.rs b/rust/kernel/revocable.rs
> >> > index fa1fd70efa27..41b8fe374af6 100644
> >> > --- a/rust/kernel/revocable.rs
> >> > +++ b/rust/kernel/revocable.rs
> >> > @@ -82,8 +82,11 @@ unsafe impl<T: Sync + Send> Sync for Revocable<T> {}
> >> >  
> >> >  impl<T> Revocable<T> {
> >> >      /// Creates a new revocable instance of the given data.
> >> > -    pub fn new(data: impl PinInit<T>) -> impl PinInit<Self> {
> >> > -        pin_init!(Self {
> >> > +    pub fn new<E>(data: impl PinInit<T, E>) -> impl PinInit<Self, Error>
> >> > +    where
> >> > +        Error: From<E>,
> >> 
> >> I don't think we need this bound as you don't use it in the function
> >> body.
> >
> > I think it's needed by try_pin_init!() below, no?
> >
> > Without it I get the compilation error in [1].
> >
> >> > +    {
> >> > +        try_pin_init!(Self {
> >> >              is_available: AtomicBool::new(true),
> >> >              data <- Opaque::pin_init(data),
> >> >          })
> 
> Does it work with this?
> 
>     try_pin_init!(Self {
>         is_available: AtomicBool::new(true),
>         data <- Opaque::pin_init(data),
>     }? E)

Yes, it does -- thanks!