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From: spidermana <xuyiwen14@gmail.com>
To: mehmet.mkoseoglu@gmail.com
Cc: a.hindborg@kernel.org, acourbot@nvidia.com, aliceryhl@google.com,
	bjorn3_gh@protonmail.com, boqun@kernel.org, dakr@kernel.org,
	daniel.almeida@collabora.com, gary@garyguo.net,
	linux-kernel@vger.kernel.org, linux-pm@vger.kernel.org,
	lossin@kernel.org, ojeda@kernel.org, rafael@kernel.org,
	rust-for-linux@vger.kernel.org, tamird@kernel.org,
	tmgross@umich.edu, viresh.kumar@linaro.org, work@onurozkan.dev
Subject: Re: [PATCH v3] rust: cpufreq: reject NULL from cpufreq_cpu_get()
Date: Mon, 28 Sep 2026 18:22:14 +0200	[thread overview]
Message-ID: <20260928162214.487564-1-xuyiwen14@gmail.com> (raw)
In-Reply-To: <20260829161013.102967-1-mehmet.mkoseoglu@gmail.com>

On Sat, 29 Aug 2026 19:10:13 +0300, Mehmet Koseoglu wrote:
> cpufreq_cpu_get() returns either a referenced policy or NULL.
> PolicyCpu::from_cpu() passed its return value to from_err_ptr(), which
> rejects ERR_PTR values but accepts NULL.
[...]
>          Ok(Self(
>              // SAFETY: The `ptr` is guaranteed to be valid and remains valid for the lifetime of
>              // the returned reference.
> -            unsafe { Policy::from_raw_mut(ptr) },
> +            unsafe { Policy::from_raw_mut(ptr.as_ptr()) },

Just a quick nit here, maybe rephrase this SAFETY comment, e.g.:

            // SAFETY: `ptr` is non-NULL and `cpufreq_cpu_get()` took a reference on it, so it is
            // valid for writing and remains valid for the lifetime of the returned reference.

Either way, looks good to me.
FWIW, I hit this too and have a reproducer [1].
[1] https://github.com/Rust-for-Linux/linux/issues/1258

Reviewed-by: Elowen Xu <malanalyzing@gmail.com>

  parent reply	other threads:[~2026-09-28 16:22 UTC|newest]

Thread overview: 4+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2026-08-29 16:10 Mehmet Koseoglu
2026-08-29 19:52 ` Onur Özkan
2026-09-28 16:22 ` spidermana [this message]
2026-09-28 17:17   ` Miguel Ojeda

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