linux-kernel - Re: [PATCH 02/10] pmdomain: rockchip: Simplify locking with guard()

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Message-ID: <20240827105927.00007ac7@Huawei.com>
Date: Tue, 27 Aug 2024 10:59:27 +0100
From: Jonathan Cameron <Jonathan.Cameron@...wei.com>
To: Krzysztof Kozlowski <krzysztof.kozlowski@...aro.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 02/10] pmdomain: rockchip: Simplify locking with guard()

On Fri, 23 Aug 2024 14:51:06 +0200
Krzysztof Kozlowski <krzysztof.kozlowski@...aro.org> wrote:

> Simplify error handling (smaller error handling) over locks with
> guard().
> 
> Signed-off-by: Krzysztof Kozlowski <krzysztof.kozlowski@...aro.org>
Musing inline.

LGTM
Reviewed-by: Jonathan Cameron <Jonathan.Cameron@...wei.com>


> ---
>  drivers/pmdomain/rockchip/pm-domains.c | 5 +----
>  1 file changed, 1 insertion(+), 4 deletions(-)
> 
> diff --git a/drivers/pmdomain/rockchip/pm-domains.c b/drivers/pmdomain/rockchip/pm-domains.c
> index 5679ad336a11..538dde58d924 100644
> --- a/drivers/pmdomain/rockchip/pm-domains.c
> +++ b/drivers/pmdomain/rockchip/pm-domains.c
> @@ -910,7 +910,7 @@ static int rockchip_pm_domain_probe(struct platform_device *pdev)
>  	 * Prevent any rockchip_pmu_block() from racing with the remainder of
>  	 * setup (clocks, register initialization).
>  	 */
> -	mutex_lock(&dmc_pmu_mutex);
> +	guard(mutex)(&dmc_pmu_mutex);
>  
>  	for_each_available_child_of_node_scoped(np, node) {
>  		error = rockchip_pm_add_one_domain(pmu, node);
> @@ -943,13 +943,10 @@ static int rockchip_pm_domain_probe(struct platform_device *pdev)
>  	if (!WARN_ON_ONCE(dmc_pmu))
>  		dmc_pmu = pmu;
>  
> -	mutex_unlock(&dmc_pmu_mutex);
> -
>  	return 0;
>  
>  err_out:
>  	rockchip_pm_domain_cleanup(pmu);

I wonder.  Could you use a devm_add_action_or_reset for this and allow early
returns throughout?

Would need to take the lock again perhaps and I haven't checked if there
is any issue in dropping and retaking the mutex however.
The block logic is non obvious so I couldn't quickly figure this out.
 
> -	mutex_unlock(&dmc_pmu_mutex);
>  	return error;
>  }
>  
>