Re: [PATCH 1/2] rust: Add cpumask helpers

[Viresh Kumar]

Hi Yury,

On 21-02-25, 15:56, Yury Norov wrote:
> Question: zalloc_cpumask_war() is a convenient wrapper around
> alloc_cpumask_var_node(). Maybe rust can use the latter directly as it's
> a true outlined function? There's more flexibility, if you need it, but
> also a higher risk that the API will change: ~40 users vs 180 for zalloc
> thing. Up to you guys. I can send v2 if needed.

I looked at the APIs again and here is what I feel:

- I am not sure if the Rust code will have any users of the *_node()
  APIs in the near future. i.e. There is no need for the Rust code to
  implement Cpumask::new_node() version for now.

- I have missed implementing the uninitialized version earlier,
  alloc_cpumask_var(), which I think should be implemented right away.
  Bindings for alloc_cpumask_var() are required to be added for this
  though.

- One advantage of using zalloc_cpumask_var() instead of
  alloc_cpumask_var() is that we don't need to open code it in the
  Rust code, specifically for the !CONFIG_CPUMASK_OFFSTACK case where
  we need to call cpumask_clear() separately.

- The Rust side can have following abstractions for now:

  pub fn new() -> Result<Self>;
  pub fn new_zeroed() -> Result<Self>;

-- 
viresh