linux-kernel - Re: [PATCH v2 22/28] mfd: core: Ensure disabled devices are skiped without aborting

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Message-ID: <20230727092209.GA8175@google.com>
Date:   Thu, 27 Jul 2023 10:22:09 +0100
From:   Lee Jones <lee@...nel.org>
To:     Herve Codina <herve.codina@...tlin.com>
Cc:     "David S. Miller" <davem@...emloft.net>,
        Eric Dumazet <edumazet@...gle.com>,
        Jakub Kicinski <kuba@...nel.org>,
        Paolo Abeni <pabeni@...hat.com>, Andrew Lunn <andrew@...n.ch>,
        Rob Herring <robh+dt@...nel.org>,
        Krzysztof Kozlowski <krzysztof.kozlowski+dt@...aro.org>,
        Conor Dooley <conor+dt@...nel.org>,
        Linus Walleij <linus.walleij@...aro.org>,
        Qiang Zhao <qiang.zhao@....com>, Li Yang <leoyang.li@....com>,
        Liam Girdwood <lgirdwood@...il.com>,
        Mark Brown <broonie@...nel.org>,
        Jaroslav Kysela <perex@...ex.cz>,
        Takashi Iwai <tiwai@...e.com>,
        Shengjiu Wang <shengjiu.wang@...il.com>,
        Xiubo Li <Xiubo.Lee@...il.com>,
        Fabio Estevam <festevam@...il.com>,
        Nicolin Chen <nicoleotsuka@...il.com>,
        Christophe Leroy <christophe.leroy@...roup.eu>,
        Randy Dunlap <rdunlap@...radead.org>, netdev@...r.kernel.org,
        linuxppc-dev@...ts.ozlabs.org, devicetree@...r.kernel.org,
        linux-kernel@...r.kernel.org, linux-gpio@...r.kernel.org,
        linux-arm-kernel@...ts.infradead.org, alsa-devel@...a-project.org,
        Thomas Petazzoni <thomas.petazzoni@...tlin.com>
Subject: Re: [PATCH v2 22/28] mfd: core: Ensure disabled devices are skiped
 without aborting

On Wed, 26 Jul 2023, Herve Codina wrote:

> The loop searching for a matching device based on its compatible
> string is aborted when a matching disabled device is found.
> This abort avoid to add devices as soon as one disabled device
> is found.
> 
> Continue searching for an other device instead of aborting on the
> first disabled one fixes the issue.
> 
> Fixes: 22380b65dc70 ("mfd: mfd-core: Ensure disabled devices are ignored without error")
> Signed-off-by: Herve Codina <herve.codina@...tlin.com>
> ---
>  drivers/mfd/mfd-core.c | 18 +++++++++++++-----
>  1 file changed, 13 insertions(+), 5 deletions(-)
> 
> diff --git a/drivers/mfd/mfd-core.c b/drivers/mfd/mfd-core.c
> index 0ed7c0d7784e..bcc26e64639a 100644
> --- a/drivers/mfd/mfd-core.c
> +++ b/drivers/mfd/mfd-core.c
> @@ -146,6 +146,7 @@ static int mfd_add_device(struct device *parent, int id,
>  	struct platform_device *pdev;
>  	struct device_node *np = NULL;
>  	struct mfd_of_node_entry *of_entry, *tmp;
> +	bool disabled;
>  	int ret = -ENOMEM;
>  	int platform_id;
>  	int r;
> @@ -181,13 +182,13 @@ static int mfd_add_device(struct device *parent, int id,
>  		goto fail_res;
>  
>  	if (IS_ENABLED(CONFIG_OF) && parent->of_node && cell->of_compatible) {
> +		disabled = false;

This does not appear to reside in a loop.

Why not set it to false on declaration?

>  		for_each_child_of_node(parent->of_node, np) {
>  			if (of_device_is_compatible(np, cell->of_compatible)) {
> -				/* Ignore 'disabled' devices error free */
> +				/* Skip 'disabled' devices */
>  				if (!of_device_is_available(np)) {
> -					of_node_put(np);

Doesn't this result in a resource leak?

> -					ret = 0;
> -					goto fail_alias;
> +					disabled = true;
> +					continue;
>  				}
>  
>  				ret = mfd_match_of_node_to_dev(pdev, np, cell);
> @@ -197,10 +198,17 @@ static int mfd_add_device(struct device *parent, int id,
>  				if (ret)
>  					goto fail_alias;
>  
> -				break;
> +				goto match;
>  			}
>  		}
>  
> +		if (disabled) {
> +			/* Ignore 'disabled' devices error free */
> +			ret = 0;
> +			goto fail_alias;
> +		}
> +
> +match:
>  		if (!pdev->dev.of_node)
>  			pr_warn("%s: Failed to locate of_node [id: %d]\n",
>  				cell->name, platform_id);
> -- 
> 2.41.0
> 

-- 
Lee Jones [李琼斯]