Messages in this thread Patch in this message | | | Date | Tue, 23 May 2023 14:44:18 +0000 | Subject | [PATCH v2 4/4] rust: task: add `Send` marker to `Task` | From | Alice Ryhl <> |
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When a type also implements `Sync`, the meaning of `Send` is just "this type may be accessed mutably from threads other than the one it is created on". That's ok for this type.
Signed-off-by: Alice Ryhl <aliceryhl@google.com> Reviewed-by: Andreas Hindborg <a.hindborg@samsung.com> --- rust/kernel/task.rs | 10 ++++++++-- 1 file changed, 8 insertions(+), 2 deletions(-)
diff --git a/rust/kernel/task.rs b/rust/kernel/task.rs index 526d29a0ae27..7eda15e5f1b3 100644 --- a/rust/kernel/task.rs +++ b/rust/kernel/task.rs @@ -64,8 +64,14 @@ macro_rules! current { #[repr(transparent)] pub struct Task(pub(crate) Opaque<bindings::task_struct>); -// SAFETY: It's OK to access `Task` through references from other threads because we're either -// accessing properties that don't change (e.g., `pid`, `group_leader`) or that are properly +// SAFETY: By design, the only way to access a `Task` is via the `current` function or via an +// `ARef<Task>` obtained through the `AlwaysRefCounted` impl. This means that the only situation in +// which a `Task` can be accessed mutably is when the refcount drops to zero and the destructor +// runs. It is safe for that to happen on any thread, so it is ok for this type to be `Send`. +unsafe impl Send for Task {} + +// SAFETY: It's OK to access `Task` through shared references from other threads because we're +// either accessing properties that don't change (e.g., `pid`, `group_leader`) or that are properly // synchronised by C code (e.g., `signal_pending`). unsafe impl Sync for Task {} -- 2.40.1.698.g37aff9b760-goog
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