diff options
| -rw-r--r-- | rust/kernel/sync/arc.rs | 8 |
1 files changed, 5 insertions, 3 deletions
diff --git a/rust/kernel/sync/arc.rs b/rust/kernel/sync/arc.rs index a8c2177950cd..a89843cacaad 100644 --- a/rust/kernel/sync/arc.rs +++ b/rust/kernel/sync/arc.rs @@ -150,9 +150,11 @@ impl<T: ?Sized + Unsize<U>, U: ?Sized> core::ops::DispatchFromDyn<Arc<U>> for Ar // mutable reference 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 -// same reason as above. `T` needs to be `Send` as well because a thread can clone an `&Arc<T>` -// into an `Arc<T>`, which may lead to `T` being accessed by the same reasoning as above. +// 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 a `&Arc<T>` may clone it and get an +// `Arc<T>` on that thread, so the thread may ultimately access `T` using a mutable reference when +// the reference count reaches zero and `T` is dropped. unsafe impl<T: ?Sized + Sync + Send> Sync for Arc<T> {} impl<T> Arc<T> { |