linux-kernel - Re: [PATCH 09/10] pmdomain: renesas: rcar-gen4-sysc: Use scoped device node handling to simplify error paths

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Message-ID: <58f5d332-2f2a-4607-9662-e71fd23b1316@linaro.org>
Date: Tue, 27 Aug 2024 11:39:30 +0200
From: Krzysztof Kozlowski <krzysztof.kozlowski@...aro.org>
To: Geert Uytterhoeven <geert@...ux-m68k.org>
Cc: Ulf Hansson <ulf.hansson@...aro.org>, Heiko Stuebner <heiko@...ech.de>,
 Shawn Guo <shawnguo@...nel.org>, Sascha Hauer <s.hauer@...gutronix.de>,
 Pengutronix Kernel Team <kernel@...gutronix.de>,
 Fabio Estevam <festevam@...il.com>, Bjorn Andersson <andersson@...nel.org>,
 Konrad Dybcio <konradybcio@...nel.org>,
 Geert Uytterhoeven <geert+renesas@...der.be>,
 Magnus Damm <magnus.damm@...il.com>, linux-pm@...r.kernel.org,
 linux-arm-kernel@...ts.infradead.org, linux-rockchip@...ts.infradead.org,
 linux-kernel@...r.kernel.org, imx@...ts.linux.dev,
 linux-arm-msm@...r.kernel.org, linux-renesas-soc@...r.kernel.org
Subject: Re: [PATCH 09/10] pmdomain: renesas: rcar-gen4-sysc: Use scoped
 device node handling to simplify error paths

On 27/08/2024 11:33, Krzysztof Kozlowski wrote:
> On 27/08/2024 09:48, Geert Uytterhoeven wrote:
>> Hi Krzysztof,
>>
>> On Fri, Aug 23, 2024 at 2:51 PM Krzysztof Kozlowski
>> <krzysztof.kozlowski@...aro.org> wrote:
>>> Obtain the device node reference with scoped/cleanup.h to reduce error
>>> handling and make the code a bit simpler.
>>>
>>> Signed-off-by: Krzysztof Kozlowski <krzysztof.kozlowski@...aro.org>
>>
>> Thanks for your patch!
>>
>>> --- a/drivers/pmdomain/renesas/rcar-gen4-sysc.c
>>> +++ b/drivers/pmdomain/renesas/rcar-gen4-sysc.c
>>> @@ -303,12 +304,12 @@ static int __init rcar_gen4_sysc_pd_init(void)
>>>         const struct rcar_gen4_sysc_info *info;
>>>         const struct of_device_id *match;
>>>         struct rcar_gen4_pm_domains *domains;
>>> -       struct device_node *np;
>>>         void __iomem *base;
>>>         unsigned int i;
>>>         int error;
>>>
>>> -       np = of_find_matching_node_and_match(NULL, rcar_gen4_sysc_matches, &match);
>>> +       struct device_node *np __free(device_node) =
>>> +               of_find_matching_node_and_match(NULL, rcar_gen4_sysc_matches, &match);
>>
>> This breaks the declarations/blank-line/code structure, so please move
>> this up.
> 
> What do you mean "declaration structure"? That's the way how variables
> with constructors are expected to be declared - within the code.

Continuing thoughts, so you prefer:

	struct rcar_gen4_pm_domains *domains;
	void __iomem *base;
	struct device_node *np __free(device_node) =
		of_find_matching_node_and_match(NULL, rcar_gen4_sysc_matches, &match);

(assuming I will put it at the end of declarations).

Are you sure this is more readable? It's really long line so it
obfuscates a bit the declarations. The point of the scoped assignment is that
you declare it at point of need/first use.

> 
>>
>> If you insist on keeping assignment to and validation of np together,
>> the line should be split in declaration and assignment.
> 
> No, that would be inconsistent with cleanup/constructor coding style.
> Maybe this is something new, so let me bring previous discussions:
> 
> https://lore.kernel.org/all/CAHk-=wicfvWPuRVDG5R1mZSxD8Xg=-0nLOiHay2T_UJ0yDX42g@mail.gmail.com/
> 
> https://lore.kernel.org/all/CAHk-=wgRHiV5VSxtfXA4S6aLUmcQYEuB67u3BJPJPtuESs1JyA@mail.gmail.com/
> 
> https://lore.kernel.org/all/CAHk-=whvOGL3aNhtps0YksGtzvaob_bvZpbaTcVEqGwNMxB6xg@mail.gmail.com/
> 
> and finally it will reach documentation (although it focuses on
> unwinding process to be specific - "When the unwind order ..."):
> https://lore.kernel.org/all/171175585714.2192972.12661675876300167762.stgit@dwillia2-xfh.jf.intel.com/
> 
>>
>>>         if (!np)
>>>                 return -ENODEV;
>>>
>>
>>> @@ -369,14 +365,12 @@ static int __init rcar_gen4_sysc_pd_init(void)
>>>                 if (error) {
>>>                         pr_warn("Failed to add PM subdomain %s to parent %u\n",
>>>                                 area->name, area->parent);
>>> -                       goto out_put;
>>> +                       return error;
>>>                 }
>>>         }
>>>
>>>         error = of_genpd_add_provider_onecell(np, &domains->onecell_data);
>>>
>>> -out_put:
>>> -       of_node_put(np);
>>>         return error;
>>
>> return of_genpd_add_provider_onecell(...);
> 
> Ack.
> 
> Best regards,
> Krzysztof
> 

Best regards,
Krzysztof