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rust: task: add Send marker to Task

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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>
Reviewed-by: Gary Guo <gary@garyguo.net>
Reviewed-by: Martin Rodriguez Reboredo <yakoyoku@gmail.com>
Reviewed-by: Benno Lossin <benno.lossin@proton.me>
Link: https://lore.kernel.org/r/20230531145939.3714886-5-aliceryhl@google.com
Signed-off-by: Miguel Ojeda <ojeda@kernel.org>
This commit is contained in:
Alice Ryhl 2023-05-31 14:59:39 +00:00 committed by Miguel Ojeda
parent be7724cdbb
commit d09a61024f
1 changed files with 8 additions and 2 deletions
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10
rust/kernel/task.rs
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@ -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 {}