Re: [PATCH v3] rust: locks: Add `get_mut` method to `Lock`

From: Alice Ryhl <aliceryhl@google.com>
To: Boqun Feng <boqun.feng@gmail.com>
Cc: mathys35.gasnier@gmail.com, "Miguel Ojeda" <ojeda@kernel.org>,
	"Alex Gaynor" <alex.gaynor@gmail.com>,
	"Wedson Almeida Filho" <wedsonaf@gmail.com>,
	"Gary Guo" <gary@garyguo.net>,
	"Björn Roy Baron" <bjorn3_gh@protonmail.com>,
	"Benno Lossin" <benno.lossin@proton.me>,
	"Andreas Hindborg" <a.hindborg@samsung.com>,
	rust-for-linux@vger.kernel.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH v3] rust: locks: Add `get_mut` method to `Lock`
Date: Fri, 23 Feb 2024 11:49:15 +0100	[thread overview]
Message-ID: <CAH5fLgj8g1d47u0eFD83topKg2d7FEG+cHS5+Be6+TLt06NmHg@mail.gmail.com> (raw)
In-Reply-To: <ZdgIVxrwBfTEjuEe@boqun-archlinux>

On Fri, Feb 23, 2024 at 3:52 AM Boqun Feng <boqun.feng@gmail.com> wrote:
> BTW, while we are at it, I think we should document the
> "structural/non-structural pinning" design decisions somewhere, for
> example in the struct definition:
>
>         #[pin_data]
>         pub struct Lock<T: ?Sized, B: Backend> {
>             ...
>             /// The data protected by the lock.
>             /// This field is non-structural pinned.
>             pub(crate) data: UnsafeCell<T>,
>         }
>
> Thoughts? Or do we think "non-structural pinned" should be the default
> case so no need to document it? I want to have a clear document for each
> field to avoid the accidental "everyone forgets what's the decision
> here" ;-)

I would normally assume that "field is not marked #[pin]" implies that
it's not structurally pinned. But it could still be worth to call out
here.

I prefer the wording "not structurally pinnned" over "non-structural pinned".

Alice