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Message-ID: <d30f085a-a031-4208-a15a-e85c7a56347f@kernel.org>
Date: Fri, 22 Aug 2025 13:54:32 +0200
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Subject: Re: [PATCH v2 3/5] rust: scatterlist: Add type-state abstraction for
 sg_table
To: Alice Ryhl <aliceryhl@google.com>
Cc: akpm@linux-foundation.org, ojeda@kernel.org, alex.gaynor@gmail.com,
 boqun.feng@gmail.com, gary@garyguo.net, bjorn3_gh@protonmail.com,
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 abdiel.janulgue@gmail.com, acourbot@nvidia.com, jgg@ziepe.ca,
 lyude@redhat.com, robin.murphy@arm.com, daniel.almeida@collabora.com,
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References: <20250820165431.170195-1-dakr@kernel.org>
 <20250820165431.170195-4-dakr@kernel.org> <aKhYCf6wgSztcdXU@google.com>
 <DC8XLP6C3E5I.10QJQVI4LORSF@kernel.org> <aKhZ9jdiNS2SAZv2@google.com>
From: Danilo Krummrich <dakr@kernel.org>
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On 8/22/25 1:52 PM, Alice Ryhl wrote:
> On Fri, Aug 22, 2025 at 01:48:47PM +0200, Danilo Krummrich wrote:
>> On Fri Aug 22, 2025 at 1:44 PM CEST, Alice Ryhl wrote:
>>>> +impl<P> Owned<P>
>>>> +where
>>>> +    for<'a> P: page::AsPageIter<Iter<'a> = VmallocPageIter<'a>> + 'static,
>>>> +{
>>>> +    fn new(
>>>> +        dev: &Device<Bound>,
>>>> +        mut pages: P,
>>>> +        dir: dma::DataDirection,
>>>> +        flags: alloc::Flags,
>>>> +    ) -> Result<impl PinInit<Self, Error> + '_> {
>>>> +        let page_iter = pages.page_iter();
>>>> +        let size = page_iter.size();
>>>
>>> Variable naming here is confusing. There's another variable called size
>>> in an inner scope, and then afterwards in RawSGTable you use *this* size
>>> variable again.
>>
>> I can change the size in the assignment block of max_segment to max_size, or do
>> you have other suggestions?
> 
> How about just this?
> 
> let max_segment = {
>      // SAFETY: `dev.as_raw()` is a valid pointer to a `struct device`.
>      let max_segment = unsafe { bindings::dma_max_mapping_size(dev.as_raw()) };
>      if max_segment == 0 {
>          u32::MAX
>      } else {
>          u32::try_from(max_segment).unwrap_or(u32::MAX)
>      }
> };

Looks good, thanks!