linux-kernel - Re: [PATCH v2 3/6] rust: arc: split unsafe block, add missing comment

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <CAH5fLgiMHE5GXQv8pSR_KYWsa44zr1o_FNrg1mj8QuTvNQmXhQ@mail.gmail.com>
Date: Fri, 8 Nov 2024 12:38:01 +0100
From: Alice Ryhl <aliceryhl@...gle.com>
To: Tamir Duberstein <tamird@...il.com>
Cc: Miguel Ojeda <ojeda@...nel.org>, Alex Gaynor <alex.gaynor@...il.com>, 
	Boqun Feng <boqun.feng@...il.com>, Gary Guo <gary@...yguo.net>, 
	Björn Roy Baron <bjorn3_gh@...tonmail.com>, 
	Benno Lossin <benno.lossin@...ton.me>, Andreas Hindborg <a.hindborg@...nel.org>, 
	Trevor Gross <tmgross@...ch.edu>, Danilo Krummrich <dakr@...nel.org>, rust-for-linux@...r.kernel.org, 
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH v2 3/6] rust: arc: split unsafe block, add missing comment

On Mon, Nov 4, 2024 at 10:20 PM Tamir Duberstein <tamird@...il.com> wrote:
>
> The new SAFETY comment style is taken from existing comments in `deref`
> and `drop.
>
> Signed-off-by: Tamir Duberstein <tamird@...il.com>

Reviewed-by: Alice Ryhl <aliceryhl@...gle.com>

> diff --git a/rust/kernel/sync/arc.rs b/rust/kernel/sync/arc.rs
> index af383bcd003e1122ebe1b62a49fe40279458e379..9adea755a5ad1a7b03f7fc30a7abc76c1f966c6c 100644
> --- a/rust/kernel/sync/arc.rs
> +++ b/rust/kernel/sync/arc.rs
> @@ -377,10 +377,14 @@ fn as_ref(&self) -> &T {
>
>  impl<T: ?Sized> Clone for Arc<T> {
>      fn clone(&self) -> Self {
> +        // SAFETY: By the type invariant, there is necessarily a reference to the object, so it is
> +        // safe to dereference it.
> +        let refcount = unsafe { self.ptr.as_ref() }.refcount.get();

I would normally prefer to avoid creating a reference to the entire
ArcInner, but in this particular case it is okay due to the specifics
of how Arc works.

Alice