Re: [PATCH WIP 3/8] rust: alloc: implement AllocatorWithFlags trait

[Gary Guo <gary@garyguo.net>]

On Wed, 1 May 2024 14:50:27 +0200
Danilo Krummrich <dakr@redhat.com> wrote:

> >   
> > > +
> > > +    fn default_allocate(&self, layout: Layout) -> Result<NonNull<[u8]>, AllocError> {
> > > +        unsafe { self.realloc_flags(ptr::null_mut(), 0, layout, GFP_KERNEL) }
> > > +    }  
> > 
> > Why do we want to have these functions? I think that it would make sense
> > to forbid all other ways of allocating memory. So only allow allocation
> > where the flags are explicitly passed.  
> 
> I agree that we should forbid allocating memory with implicit default page
> flags.
> 
> I added them, since I think we'll always need some implementation of the
> Allocator trait. And this just was the obvious generic implementation.

Ignoring Benno's point about enforcing explicit allocation, these
functions still shouldn't exist. Given `Allocator` is a super trait,
all implementors should just implement their default allocation
behaviour in their `Allocator` implementation rather than calling into
the `default_allocate` function.

- Gary