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

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Message-ID: <20250822081343.4041a3d5@nimda.home>
Date: Fri, 22 Aug 2025 08:13:43 +0300
From: Onur Özkan <work@...rozkan.dev>
To: Viresh Kumar <viresh.kumar@...aro.org>
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 Thu, 21 Aug 2025 14:51:37 +0530
Viresh Kumar <viresh.kumar@...aro.org> wrote:

> 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()`.
> 

`ret` is returned at the end unlike other `to_result` usages in other
functions.

-Onur