Re: [PATCH v2 1/6] rust_binder: avoid allocating under node_refs for freeze listeners

[Matthew Maurer]

On Tue, Jun 9, 2026 at 2:46 AM Alice Ryhl <aliceryhl@xxxxxxxxxx> wrote:
>
> The node_refs mutex needs to be changed to a spinlock, so in preparation
> for that, update freeze.rs to avoid allocating under the node_refs lock.
> This is done by adding a retry loop so that if add_freeze_listener()
> requires reallocating the KVVec<_> of freeze listeners, the caller will
> allocate a larger vector and retry.
>
> Analogously, the remove_freeze_listener() function is updated to return
> the empty KVVec<_> when it is no longer needed, to avoid calling
> kvfree() under the node_refs lock.
>
> Signed-off-by: Alice Ryhl <aliceryhl@xxxxxxxxxx>

Nit: Consider moving the clone to the success path at the end, since
the cloned node is not used until then? It's probably cheap enough
that it doesn't matter though.

>
> +            node = node_ref.node.clone();

This is wrapping a single line, and is only called once. Why add a
separate function for it?

> +    pub(crate) fn resize_for_add_freeze_listener(
> +        vec_alloc: &mut KVVec<Arc<Process>>,
> +        target_size: usize,
> +    ) -> Result {
> +        *vec_alloc = KVVec::with_capacity(target_size.next_power_of_two(), GFP_KERNEL)?;
> +        Ok(())
>      }

Otherwise looks fine.

Reviewed-By: Matthew Maurer <mmaurer@xxxxxxxxxx>