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Message-ID: <640a6624-73d9-5650-4570-d822e7515900@gmail.com>
Date:   Tue, 23 May 2023 13:27:46 -0300
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Subject: Re: [PATCH v2 1/4] rust: sync: reword the `Arc` safety comment for
 `Send`
To:     Alice Ryhl <aliceryhl@google.com>, Miguel Ojeda <ojeda@kernel.org>,
        Wedson Almeida Filho <wedsonaf@gmail.com>,
        Alex Gaynor <alex.gaynor@gmail.com>
Cc:     Boqun Feng <boqun.feng@gmail.com>, Gary Guo <gary@garyguo.net>,
        =?UTF-8?Q?Bj=c3=b6rn_Roy_Baron?= <bjorn3_gh@protonmail.com>,
        Benno Lossin <benno.lossin@proton.me>,
        Ingo Molnar <mingo@redhat.com>,
        Peter Zijlstra <peterz@infradead.org>,
        Will Deacon <will@kernel.org>,
        Mark Rutland <mark.rutland@arm.com>,
        rust-for-linux@vger.kernel.org, linux-kernel@vger.kernel.org,
        patches@lists.linux.dev, Andreas Hindborg <a.hindborg@samsung.com>
References: <20230523144418.1250547-1-aliceryhl@google.com>
 <20230523144418.1250547-2-aliceryhl@google.com>
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From:   Martin Rodriguez Reboredo <yakoyoku@gmail.com>
In-Reply-To: <20230523144418.1250547-2-aliceryhl@google.com>
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On 5/23/23 11:44, Alice Ryhl wrote:
> The safety comment on `impl Send for Arc` talks about "directly"
> accessing the value, when it really means "accessing the value with a
> mutable reference". This commit clarifies that.
> 
> Suggested-by: Boqun Feng <boqun.feng@gmail.com>
> Signed-off-by: Alice Ryhl <aliceryhl@google.com>
> Reviewed-by: Andreas Hindborg <a.hindborg@samsung.com>
> Reviewed-by: Boqun Feng <boqun.feng@gmail.com>
> ---
> [...]
>   
>   // SAFETY: It is safe to send `Arc<T>` to another thread when the underlying `T` is `Sync` because
>   // it effectively means sharing `&T` (which is safe because `T` is `Sync`); additionally, it needs
> -// `T` to be `Send` because any thread that has an `Arc<T>` may ultimately access `T` directly, for
> -// example, when the reference count reaches zero and `T` is dropped.
> +// `T` to be `Send` because any thread that has an `Arc<T>` may ultimately access `T` using a
> +// mutable reference, for example, when the reference count reaches zero and `T` is dropped.
>   unsafe impl<T: ?Sized + Sync + Send> Send for Arc<T> {}
>   
>   // SAFETY: It is safe to send `&Arc<T>` to another thread when the underlying `T` is `Sync` for the

Reviewed-by: Martin Rodriguez Reboredo <yakoyoku@gmail.com>