linux-kernel - Re: [PATCH] powermac: Call of_node_put(bk_node) only once in pmac_has_backlight

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Message-ID: <d9bdc1b6-ea7e-47aa-80aa-02ae649abf72@csgroup.eu>
Date: Wed, 2 Oct 2024 22:43:46 +0200
From: Christophe Leroy <christophe.leroy@...roup.eu>
To: Markus Elfring <Markus.Elfring@....de>, linuxppc-dev@...ts.ozlabs.org,
 Jani Nikula <jani.nikula@...el.com>,
 Madhavan Srinivasan <maddy@...ux.ibm.com>,
 Michael Ellerman <mpe@...erman.id.au>, Naveen N Rao <naveen@...nel.org>,
 Nicholas Piggin <npiggin@...il.com>, Paul Mackerras <paulus@...ba.org>,
 Stephen Rothwell <sfr@...b.auug.org.au>,
 Thomas Zimmermann <tzimmermann@...e.de>
Cc: LKML <linux-kernel@...r.kernel.org>, kernel-janitors@...r.kernel.org,
 Krzysztof Kozlowski <krzysztof.kozlowski@...aro.org>
Subject: Re: [PATCH] powermac: Call of_node_put(bk_node) only once in
 pmac_has_backlight_type()



Le 02/10/2024 à 22:02, Markus Elfring a écrit :
> From: Markus Elfring <elfring@...rs.sourceforge.net>
> Date: Wed, 2 Oct 2024 21:50:27 +0200
> 
> An of_node_put(bk_node) call was immediately used after a pointer check
> for an of_get_property() call in this function implementation.
> Thus call such a function only once instead directly before the check.

It seems pointless to perform a put immediately after a get. Shouldn't 
of_find_property() be used instead ? And then of_property_read_string() 
would probably be better.

Maybe you can even use of_property_match_string().

> 
> This issue was transformed by using the Coccinelle software.
> 
> Signed-off-by: Markus Elfring <elfring@...rs.sourceforge.net>
> ---
>   arch/powerpc/platforms/powermac/backlight.c | 6 ++----
>   1 file changed, 2 insertions(+), 4 deletions(-)
> 
> diff --git a/arch/powerpc/platforms/powermac/backlight.c b/arch/powerpc/platforms/powermac/backlight.c
> index 12bc01353bd3..d3666595a62e 100644
> --- a/arch/powerpc/platforms/powermac/backlight.c
> +++ b/arch/powerpc/platforms/powermac/backlight.c
> @@ -61,11 +61,9 @@ int pmac_has_backlight_type(const char *type)
>   	if (bk_node) {
>   		const char *prop = of_get_property(bk_node,
>   				"backlight-control", NULL);
> -		if (prop && strncmp(prop, type, strlen(type)) == 0) {
> -			of_node_put(bk_node);
> -			return 1;
> -		}
>   		of_node_put(bk_node);
> +		if (prop && strncmp(prop, type, strlen(type)) == 0)
> +			return 1;
>   	}
> 
>   	return 0;
> --
> 2.46.1
>