Messages in this thread | | | Date | Tue, 23 May 2023 13:41:35 -0300 | Subject | Re: [PATCH v2 4/4] rust: task: add `Send` marker to `Task` | From | Martin Rodriguez Reboredo <> |
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On 5/23/23 11:44, Alice Ryhl wrote: > 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> > --- > [...] > > -// 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 {} >
Reviewed-by: Martin Rodriguez Reboredo <yakoyoku@gmail.com>
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