Re: [PATCH v8 1/8] rust: types: add `NotThreadSafe`

[Alice Ryhl]

On Thu, Jul 25, 2024 at 5:30 PM Peter Zijlstra <peterz@xxxxxxxxxxxxx> wrote:
>
> On Thu, Jul 25, 2024 at 05:09:14PM +0200, Alice Ryhl wrote:
>
> > > As per always for not being able to read rust; how does this extend to
> > > get_task_struct()? Once you've taken a reference on current, you should
> > > be free to pass it along to whomever.
> >
> > Once you take a reference on current, it becomes thread-safe. This is
> > because taking a reference creates a value of type ARef<Task> rather
> > than TaskRef, and ARef<Task> is considered thread-safe.
>
> Ignoring comments, there isn't a single mention of ARef there. Where
> does it come from?

That's because the conversion to ARef<Task> is a two-step process. The
TaskRef type just provides a conversion from &TaskRef to &Task via the
`impl Deref` block. There is a conversion from &Task to ARef<Task>
elsewhere, and this conversion is where the call to get_task_struct()
happens.

Alice