Re: [PATCH 2/6] rust: binder: transmute transaction data

[Tamir Duberstein]

On Tue, May 26, 2026 at 8:33 AM Alice Ryhl <aliceryhl@xxxxxxxxxx> wrote:
>
> On Fri, May 22, 2026 at 07:12:47PM +0200, Tamir Duberstein wrote:
> > `BinderTransactionData` is a transparent wrapper around
> > `binder_transaction_data`. Use a transmute to view the transaction data in
> > `BinderTransactionDataSecctx` through that wrapper, matching the safety
> > argument at the conversion site and avoiding the raw pointer round trip.
> >
> > Signed-off-by: Tamir Duberstein <tamird@xxxxxxxxxx>
>
> I think it is an anti-pattern to transmute references. Please keep the
> raw pointer cast.

Can you please elaborate? We already have this for kernel::io::Mmio:

```
  rust/kernel/io.rs-    pub fn relaxed(&self) -> &RelaxedMmio<SIZE> {
  rust/kernel/io.rs-        // SAFETY: `RelaxedMmio` is
`#[repr(transparent)]` over `Mmio`, so `Mmio<SIZE>` and
  rust/kernel/io.rs-        // `RelaxedMmio<SIZE>` have identical layout.
  rust/kernel/io.rs:        unsafe { core::mem::transmute(self) }
  rust/kernel/io.rs-    }
```