Re: [PATCH -next v7 1/2] rust: clist: Add support to interface with C linked lists

[Daniel Almeida]

>> 
>> 
>> Yeah, but my point being: is there a reason why the underlying list has to
>> remain read-only? Is this a safety requirement or an invariant that is established
>> by the code above?
> I'm not fully sure if it's an invariant or a safety requirement, but anyone
> creating a C list head on the rust side must guarantee that it is not modified.
> Since rust has no visibility on the C side, I believe it is a Rust invariant
> here that the existence of CListHead assumes that the list cannot be modified
> once Rust has access over it.  That is up to the creator (user) of the CListHead
> to guarantee. In the DRM buddy case, once the list is allocated and accessible
> from Rust, C code will not modify it while the Rust object exists.
> 
> Does that make sense, or is there a better way to document this?
> 
> --
> Joel Fernandes


In which case, I recommend moving this to a safety requirement when
creating the list.

I assume the purpose of not modifying the list on the C side is to avoid
corrupting the list in Rust somehow?

— Daniel