Re: [PATCH v6 01/26] rust: alloc: add `Allocator` trait

[Benno Lossin]

On 29.08.24 23:56, Danilo Krummrich wrote:
> On Thu, Aug 29, 2024 at 06:19:09PM +0000, Benno Lossin wrote:
>> On 16.08.24 02:10, Danilo Krummrich wrote:
>>> Add a kernel specific `Allocator` trait, that in contrast to the one in
>>> Rust's core library doesn't require unstable features and supports GFP
>>> flags.
>>>
>>> Subsequent patches add the following trait implementors: `Kmalloc`,
>>> `Vmalloc` and `KVmalloc`.
>>>
>>> Reviewed-by: Alice Ryhl <aliceryhl@xxxxxxxxxx>
>>> Signed-off-by: Danilo Krummrich <dakr@xxxxxxxxxx>
>>
>> We discussed this in our weekly meeting (I think ~one week ago?). If you
>> give me a draft version of the comment that you plan to add regarding
>> the `old_layout` parameter, I can see if I am happy with it. If I am, I
>> would give you my RB.
> 
> May I propose you let me know what you would like to see covered, rather than
> me trying to guess it. :-)

I was hoping that we put that in our meeting notes, but I failed to find
them... I would put this in a normal comment, so it doesn't show up in the
documentation. Preface it like implementation decision/detail:
- Why do `Allocator::{realloc,free}` not have an `old_layout` parameter
  like in the stdlib? (the reasons you had for that decision, like we
  don't need it etc.)
- Then something along the lines of "Note that no technical reason is
  listed above, so if you need/want to implement an allocator taking
  advantage of that, you can change it"

I don't think we need a lot here. Additionally it would be very useful
to also put this in an issue to not lose track of it.

---
Cheers,
Benno