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From: Alice Ryhl <aliceryhl@google.com>
To: Benno Lossin <benno.lossin@proton.me>
Cc: "Miguel Ojeda" <ojeda@kernel.org>,
	"Alex Gaynor" <alex.gaynor@gmail.com>,
	"Boqun Feng" <boqun.feng@gmail.com>,
	"Gary Guo" <gary@garyguo.net>,
	"Björn Roy Baron" <bjorn3_gh@protonmail.com>,
	"Andreas Hindborg" <a.hindborg@samsung.com>,
	rust-for-linux@vger.kernel.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH 1/2] rust: sync: require `Send` and `Sync` for `Backend::State`
Date: Tue, 3 Sep 2024 11:30:14 +0200	[thread overview]
Message-ID: <CAH5fLgihM6OeuVrAhSXAqb9RDKBa8p7+EOsFuuqkGu-OzoapZw@mail.gmail.com> (raw)
In-Reply-To: <20240903091700.172734-1-benno.lossin@proton.me>

On Tue, Sep 3, 2024 at 11:17 AM Benno Lossin <benno.lossin@proton.me> wrote:
>
> `Lock<T, B>` implements `Send` and `Sync` when `T` is `Send` or `Sync`
> respectively. Since this does not depend on `B`, creating a `Lock` that
> is `Send` and `Sync`, but with a `!Sync` or `!Send` state is possible.
> This is a soundness issue, thus add the bounds to the respective impls.
>
> Signed-off-by: Benno Lossin <benno.lossin@proton.me>

Currently, B::State is set directly to `bindings::spinlock_t` or
`bindings::mutex` and these types are pretty unlikely to be Send/Sync
on all kernel configurations. If you're going to make this change, you
will need to change these types.

Considering that B::State is already stored in Opaque meaning that we
don't run its destructor either, it's not really treated as a normal
field right now. Perhaps it would be better to change the safety
requirements of the `Backend` trait to impose restrictions on the
thread safety of B::State?

Alice

  parent reply	other threads:[~2024-09-03  9:30 UTC|newest]

Thread overview: 8+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2024-09-03  9:17 [PATCH 1/2] rust: sync: require `Send` and `Sync` for `Backend::State` Benno Lossin
2024-09-03  9:17 ` [PATCH 2/2] rust: sync: require `Sync` for `Backend::GuardState` Benno Lossin
2024-09-03  9:32   ` Alice Ryhl
2024-09-03 10:06     ` Benno Lossin
2024-09-03 11:34       ` Alice Ryhl
2024-09-03  9:30 ` Alice Ryhl [this message]
2024-09-03  9:57   ` [PATCH 1/2] rust: sync: require `Send` and `Sync` for `Backend::State` Benno Lossin
2024-09-03 11:31     ` Alice Ryhl

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