Re: [PATCH] rust: task: adjust safety comments in Task methods

[Alice Ryhl]

On 10/15/24 8:45 PM, Boqun Feng wrote:
> On Tue, Oct 15, 2024 at 08:37:36PM +0200, Alice Ryhl wrote:
> > On 10/15/24 8:24 PM, Boqun Feng wrote:
> > > On Tue, Oct 15, 2024 at 02:02:12PM +0000, Alice Ryhl wrote:
> > > > The `Task` struct has several safety comments that aren't so great. For
> > > > example, the reason that it's okay to read the `pid` is that the field
> > > > is immutable, so there is no data race, which is not what the safety
> > > > comment says.
> > > >
> > > > Thus, improve the safety comments. Also add an `as_ptr` helper. This
> > > > makes it easier to read the various accessors on Task, as `self.0` may
> > > > be confusing syntax for new Rust users.
> > > >
> > > > Signed-off-by: Alice Ryhl <aliceryhl@xxxxxxxxxx>
> > > > ---
> > > > This is based on top of vfs.rust.file as the file series adds some new
> > > > task methods. Christian, can you take this through that tree?
> > > > ---
> > > >    rust/kernel/task.rs | 43 ++++++++++++++++++++++++-------------------
> > > >    1 file changed, 24 insertions(+), 19 deletions(-)
> > > >
> > > > diff --git a/rust/kernel/task.rs b/rust/kernel/task.rs
> > > > index 1a36a9f19368..080599075875 100644
> > > > --- a/rust/kernel/task.rs
> > > > +++ b/rust/kernel/task.rs
> > > > @@ -145,11 +145,17 @@ fn deref(&self) -> &Self::Target {
> > > >            }
> > > >        }
> > > > +    /// Returns a raw pointer to the task.
> > > > +    #[inline]
> > > > +    pub fn as_ptr(&self) -> *mut bindings::task_struct {
> > >
> > > FWIW, I think the name convention is `as_raw()` for a wrapper type of
> > > `Opaque<T>` to return `*mut T`, e.g. `kernel::device::Device`.
> > >
> > > Otherwise this looks good to me.
> > Both names are in use. See e.g. Page and File that use as_ptr.
>
> `Page` is a different case because it currently is a pointer.
>
> > In fact, I was asked to change the name on File *to* as_ptr.
>
> I'm not able to find the discussion on that ask. Appreciate it if you
> can share a link.

Hmm, it's possible that I misremember. I can't find it either. But it is 
called as_ptr on File.

> Anyway, this is not important for now, and might not be in the future.
> So:
>
> Reviewed-by: Boqun Feng <boqun.feng@xxxxxxxxx>

Thanks!

Alice