Re: [PATCH v2 1/4] rust: sync: reword the `Arc` safety comment for `Send`

[Gary Guo]

On Tue, 23 May 2023 14:44:15 +0000
Alice Ryhl <aliceryhl@xxxxxxxxxx> 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@xxxxxxxxx>
> Signed-off-by: Alice Ryhl <aliceryhl@xxxxxxxxxx>
> Reviewed-by: Andreas Hindborg <a.hindborg@xxxxxxxxxxx>
> Reviewed-by: Boqun Feng <boqun.feng@xxxxxxxxx>

Reviewed-by: Gary Guo <gary@xxxxxxxxxxx>

> ---
>  rust/kernel/sync/arc.rs | 4 ++--
>  1 file changed, 2 insertions(+), 2 deletions(-)
> 
> diff --git a/rust/kernel/sync/arc.rs b/rust/kernel/sync/arc.rs
> index e6d206242465..87a4c9ed712b 100644
> --- a/rust/kernel/sync/arc.rs
> +++ b/rust/kernel/sync/arc.rs
> @@ -146,8 +146,8 @@ impl<T: ?Sized + Unsize<U>, U: ?Sized> core::ops::DispatchFromDyn<Arc<U>> for Ar
>  
>  // 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