Commit d09a6102 authored by Alice Ryhl's avatar Alice Ryhl Committed by Miguel Ojeda
Browse files

rust: task: add `Send` marker to `Task` 



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: default avatarAlice Ryhl <aliceryhl@google.com>
Reviewed-by: default avatarAndreas Hindborg <a.hindborg@samsung.com>
Reviewed-by: default avatarGary Guo <gary@garyguo.net>
Reviewed-by: default avatarMartin Rodriguez Reboredo <yakoyoku@gmail.com>
Reviewed-by: default avatarBenno Lossin <benno.lossin@proton.me>
Link: https://lore.kernel.org/r/20230531145939.3714886-5-aliceryhl@google.com


Signed-off-by: default avatarMiguel Ojeda <ojeda@kernel.org>
parent be7724cd

rust/kernel/task.rs

+8 −2
Original line number Diff line number Diff line
@@ -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 {}