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Message-ID: <02633e09-cabc-43f0-a09b-b95c0f1271ab@kernel.org>
Date: Thu, 26 Mar 2026 16:02:54 +0100
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Subject: Re: [PATCH 1/7] rust: dma: add from-slice constructors for Coherent
 and CoherentBox
To: Alexandre Courbot <acourbot@nvidia.com>
Cc: Gary Guo <gary@garyguo.net>, Abdiel Janulgue <abdiel.janulgue@gmail.com>,
 Daniel Almeida <daniel.almeida@collabora.com>,
 Robin Murphy <robin.murphy@arm.com>, Andreas Hindborg
 <a.hindborg@kernel.org>, Miguel Ojeda <ojeda@kernel.org>,
 Boqun Feng <boqun@kernel.org>, =?UTF-8?Q?Bj=C3=B6rn_Roy_Baron?=
 <bjorn3_gh@protonmail.com>, Benno Lossin <lossin@kernel.org>,
 Alice Ryhl <aliceryhl@google.com>, Trevor Gross <tmgross@umich.edu>,
 David Airlie <airlied@gmail.com>, Simona Vetter <simona@ffwll.ch>,
 John Hubbard <jhubbard@nvidia.com>, Alistair Popple <apopple@nvidia.com>,
 Joel Fernandes <joelagnelf@nvidia.com>, Timur Tabi <ttabi@nvidia.com>,
 Zhi Wang <zhiw@nvidia.com>, Eliot Courtney <ecourtney@nvidia.com>,
 driver-core@lists.linux.dev, rust-for-linux@vger.kernel.org,
 linux-kernel@vger.kernel.org
References: <20260321-b4-nova-dma-removal-v1-0-5cf18a75ff64@nvidia.com>
 <20260321-b4-nova-dma-removal-v1-1-5cf18a75ff64@nvidia.com>
 <DHABINRM1861.3HQ3J4IZ150F4@garyguo.net>
 <DHCSXDEMMPZ9.FPPFUV6AMU4P@nvidia.com>
From: Danilo Krummrich <dakr@kernel.org>
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In-Reply-To: <DHCSXDEMMPZ9.FPPFUV6AMU4P@nvidia.com>
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On 3/26/26 3:59 PM, Alexandre Courbot wrote:
> Then it looks like this:
> 
>     let mut slice = Self(Coherent::<T>::alloc_slice_with_attrs(
>         dev,
>         data.len(),
>         gfp_flags,
>         dma_attrs,
>     )?);
> 
>     // PANIC: `slice` was created with length `data.len()`.
>     slice.copy_from_slice(data);
> 
>     Ok(slice)
> 
> FWIW I find using `map` more elegant, but I've made the change for v2
> nonetheless.
I also prefer map() in this case.