Re: [PATCH 3/3] rust: dma: add as_slice/write functions for CoherentAllocation

[Alexandre Courbot]

On Thu Apr 10, 2025 at 6:02 PM JST, Abdiel Janulgue wrote:
> Hi Alex,
>
> On 08/04/2025 06:08, Alexandre Courbot wrote:
>>> +        }
>>> +        // SAFETY:
>>> +        // - The pointer is valid due to type invariant on `CoherentAllocation`
>>> +        // and we've just checked that the range and index is within bounds.
>>> +        // - `offset` can't overflow since it is smaller than `self.count` and we've checked
>>> +        // that `self.count` won't overflow early in the constructor.
>>> +        unsafe {
>>> +            core::ptr::copy_nonoverlapping(src.as_ptr(), self.cpu_addr.add(offset), src.len())
>>> +        };
>> 
>> How about leveraging as_slice_mut() so this unsafe block can be removed?
>
> as_slice_mut is still unsafe, no? So we couldn't remove unsafe block still?

Ah, that's right. In that case it would at least factorize the bound
check and make the method a bit shorter, unless I missed something else.