linux-kernel - Re: [PATCH] rust: opp: use to

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Message-ID: <20250821092137.wttiixhiidt27hnq@vireshk-i7>
Date: Thu, 21 Aug 2025 14:51:37 +0530
From: Viresh Kumar <viresh.kumar@...aro.org>
To: Onur Özkan <work@...rozkan.dev>
Cc: rust-for-linux@...r.kernel.org, vireshk@...nel.org, nm@...com,
	sboyd@...nel.org, ojeda@...nel.org, alex.gaynor@...il.com,
	boqun.feng@...il.com, gary@...yguo.net, bjorn3_gh@...tonmail.com,
	lossin@...nel.org, a.hindborg@...nel.org, aliceryhl@...gle.com,
	tmgross@...ch.edu, dakr@...nel.org, linux-pm@...r.kernel.org,
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH] rust: opp: use to_result for error handling

On 21-08-25, 12:16, Onur Özkan wrote:
> Simplifies error handling by replacing the manual check
> of the return value with the `to_result` helper.
> 
> Signed-off-by: Onur Özkan <work@...rozkan.dev>
> ---
>  rust/kernel/opp.rs | 16 +++++-----------
>  1 file changed, 5 insertions(+), 11 deletions(-)
> 
> diff --git a/rust/kernel/opp.rs b/rust/kernel/opp.rs
> index 08126035d2c6..9d79c2816af5 100644
> --- a/rust/kernel/opp.rs
> +++ b/rust/kernel/opp.rs
> @@ -12,7 +12,7 @@
>      clk::Hertz,
>      cpumask::{Cpumask, CpumaskVar},
>      device::Device,
> -    error::{code::*, from_err_ptr, from_result, to_result, Error, Result, VTABLE_DEFAULT_ERROR},
> +    error::{code::*, from_err_ptr, from_result, to_result, Result, VTABLE_DEFAULT_ERROR},
>      ffi::c_ulong,
>      prelude::*,
>      str::CString,
> @@ -500,11 +500,8 @@ pub fn set(self, dev: &Device) -> Result<ConfigToken> {
>          // requirements. The OPP core guarantees not to access fields of [`Config`] after this call
>          // and so we don't need to save a copy of them for future use.
>          let ret = unsafe { bindings::dev_pm_opp_set_config(dev.as_raw(), &mut config) };
> -        if ret < 0 {
> -            Err(Error::from_errno(ret))
> -        } else {
> -            Ok(ConfigToken(ret))
> -        }
> +
> +        to_result(ret).map(|()| ConfigToken(ret))
>      }
> 
>      /// Config's clk callback.
> @@ -713,11 +710,8 @@ pub fn opp_count(&self) -> Result<u32> {
>          // SAFETY: The requirements are satisfied by the existence of [`Device`] and its safety
>          // requirements.
>          let ret = unsafe { bindings::dev_pm_opp_get_opp_count(self.dev.as_raw()) };
> -        if ret < 0 {
> -            Err(Error::from_errno(ret))
> -        } else {
> -            Ok(ret as u32)
> -        }
> +
> +        to_result(ret).map(|()| ret as u32)
>      }

I would get rid of `ret` as well in both the cases, like it is done by
other users of `to_result()`.

-- 
viresh