Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 2620:137:e000::1:20 as permitted sender) client-ip=2620:137:e000::1:20;
Date:   Tue, 23 May 2023 14:44:15 +0000
In-Reply-To: <20230523144418.1250547-1-aliceryhl@google.com>
Mime-Version: 1.0
References: <20230523144418.1250547-1-aliceryhl@google.com>
Message-ID: <20230523144418.1250547-2-aliceryhl@google.com>
Subject: [PATCH v2 1/4] rust: sync: reword the `Arc` safety comment for `Send`
From:   Alice Ryhl <aliceryhl@google.com>
To:     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=20Roy=20Baron?=" <bjorn3_gh@protonmail.com>,
        Benno Lossin <benno.lossin@proton.me>,
        Alice Ryhl <aliceryhl@google.com>,
        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>
Content-Type: text/plain; charset="UTF-8"
Precedence: bulk

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>
---
 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
-- 
2.40.1.698.g37aff9b760-goog