linux-kernel - Re: [PATCH] rust: opp: simplify callers of `to_c_str

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Message-ID: <ms55ue7qqbvoyfhptzu2a5cuthusihtobremhuqfm7lyu7b62o@qasunalgkptl>
Date: Wed, 22 Oct 2025 11:10:33 +0530
From: Viresh Kumar <viresh.kumar@...aro.org>
To: Tamir Duberstein <tamird@...nel.org>
Cc: Viresh Kumar <vireshk@...nel.org>, Nishanth Menon <nm@...com>, 
	Stephen Boyd <sboyd@...nel.org>, Miguel Ojeda <ojeda@...nel.org>, 
	Alex Gaynor <alex.gaynor@...il.com>, Boqun Feng <boqun.feng@...il.com>, Gary Guo <gary@...yguo.net>, 
	Björn Roy Baron <bjorn3_gh@...tonmail.com>, Benno Lossin <lossin@...nel.org>, 
	Andreas Hindborg <a.hindborg@...nel.org>, Alice Ryhl <aliceryhl@...gle.com>, 
	Trevor Gross <tmgross@...ch.edu>, Danilo Krummrich <dakr@...nel.org>, linux-pm@...r.kernel.org, 
	rust-for-linux@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] rust: opp: simplify callers of `to_c_str_array`

Hi Tamir,

On 20-10-25, 09:07, Tamir Duberstein wrote:
> Use `Option` combinators to make this a bit less noisy.
> 
> Signed-off-by: Tamir Duberstein <tamird@...nel.org>
> ---
>  rust/kernel/opp.rs | 25 ++++++++-----------------
>  1 file changed, 8 insertions(+), 17 deletions(-)
> 
> diff --git a/rust/kernel/opp.rs b/rust/kernel/opp.rs
> index 9d6c58178a6f..b84786f45522 100644
> --- a/rust/kernel/opp.rs
> +++ b/rust/kernel/opp.rs
> @@ -443,23 +443,14 @@ pub fn set_supported_hw(mut self, hw: KVec<u32>) -> Result<Self> {
>      ///
>      /// The returned [`ConfigToken`] will remove the configuration when dropped.
>      pub fn set(self, dev: &Device) -> Result<ConfigToken> {
> -        let (_clk_list, clk_names) = match &self.clk_names {
> -            Some(x) => {
> -                let list = to_c_str_array(x)?;
> -                let ptr = list.as_ptr();
> -                (Some(list), ptr)
> -            }
> -            None => (None, ptr::null()),
> -        };
> -
> -        let (_regulator_list, regulator_names) = match &self.regulator_names {
> -            Some(x) => {
> -                let list = to_c_str_array(x)?;
> -                let ptr = list.as_ptr();
> -                (Some(list), ptr)
> -            }
> -            None => (None, ptr::null()),
> -        };
> +        let clk_names = self.clk_names.as_deref().map(to_c_str_array).transpose()?;
> +        let clk_names = clk_names.map_or(ptr::null(), |c| c.as_ptr());
> +        let regulator_names = self
> +            .regulator_names
> +            .as_deref()
> +            .map(to_c_str_array)
> +            .transpose()?;
> +        let regulator_names = regulator_names.map_or(ptr::null(), |c| c.as_ptr());

I had to keep _clk_list and _regulator_list earlier to make sure the list isn't
freed while its pointer is still used (sent to dev_pm_opp_set_config()). Won't
this change cause an issue here ?

-- 
viresh