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From: Andreas Hindborg <a.hindborg@kernel.org>
To: "Danilo Krummrich" <dakr@kernel.org>
Cc: <abdiel.janulgue@gmail.com>,  <daniel.almeida@collabora.com>,
  <robin.murphy@arm.com>,  <ojeda@kernel.org>,  <alex.gaynor@gmail.com>,
  <boqun.feng@gmail.com>,  <gary@garyguo.net>,  <bjorn3_gh@protonmail.com>,
  <lossin@kernel.org>,  <aliceryhl@google.com>,  <tmgross@umich.edu>,
  <acourbot@nvidia.com>,  <rust-for-linux@vger.kernel.org>,
  <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH] rust: dma: require mutable reference for as_slice_mut()
 and write()
In-Reply-To: <20250628165120.90149-1-dakr@kernel.org> (Danilo Krummrich's
	message of "Sat, 28 Jun 2025 18:49:54 +0200")
References: <VIEdXN6CCu8vh_24Ew2HvHggO8rA-9Vg6BHi7y6kj3Wh2W-s1If1YITFfHta4MCYR3GQbYhffNc81E0AjI1AUg==@protonmail.internalid>
	<20250628165120.90149-1-dakr@kernel.org>
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Date: Mon, 30 Jun 2025 12:33:16 +0200
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"Danilo Krummrich" <dakr@kernel.org> writes:

> Given the safety requirements of as_slice_mut() and write() taking an
> immutable reference is technically not incorrect.
>
> However, let's leverage the compiler's capabilities and require a
> mutable reference to ensure exclusive access.
>
> This also fixes a clippy warning introduced with 1.88:
>
>   warning: mutable borrow from immutable input(s)
>      --> rust/kernel/dma.rs:297:78
>       |
>   297 |     pub unsafe fn as_slice_mut(&self, offset: usize, count: usize) -> Result<&mut [T]> {
>       |                                                                              ^^^^^^^^
>
> Fixes: d37a39f607c4 ("rust: dma: add as_slice/write functions for CoherentAllocation")
> Signed-off-by: Danilo Krummrich <dakr@kernel.org>


Reviewed-by: Andreas Hindborg <a.hindborg@kernel.org>


Best regards,
Andreas Hindborg