linux-kernel - Re: [PATCH v4] soc: qcom: apr: Add check for idr_alloc and of_property_read_string

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Message-ID: <20221007025021.vcy5x2rvvclxqgrz@builder.lan>
Date:   Thu, 6 Oct 2022 21:50:21 -0500
From:   Bjorn Andersson <andersson@...nel.org>
To:     Jiasheng Jiang <jiasheng@...as.ac.cn>
Cc:     quic_jjohnson@...cinc.com, agross@...nel.org,
        bjorn.andersson@...aro.org, konrad.dybcio@...ainline.org,
        linux-arm-msm@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v4] soc: qcom: apr: Add check for idr_alloc and
 of_property_read_string_index

On Wed, Sep 14, 2022 at 09:22:52AM +0800, Jiasheng Jiang wrote:
> As idr_alloc() and of_property_read_string_index() can return negative
> numbers, it should be better to check the return value and deal with
> the exception.
> Therefore, it should be better to use goto statement to deal with the
> exception.
> 

Thank you for your patch Jiasheng, just a few small requests below.

> Fixes: 6adba21eb434 ("soc: qcom: Add APR bus driver")
> Signed-off-by: Jiasheng Jiang <jiasheng@...as.ac.cn>
> ---
> Changelog:
> 
> v3 -> v4:
> 
> 1. Change the title and remove the kfree.
> 
> v2 -> v3:
> 
> 1. Change the title and use goto statement to deal with the exception.
> 
> v1 -> v2:
> 
> 1. Add dev_err and put_device in order to maintain the code consistency.
> ---
>  drivers/soc/qcom/apr.c | 21 +++++++++++++++++----
>  1 file changed, 17 insertions(+), 4 deletions(-)
> 
> diff --git a/drivers/soc/qcom/apr.c b/drivers/soc/qcom/apr.c
> index b4046f393575..8101b92e352c 100644
> --- a/drivers/soc/qcom/apr.c
> +++ b/drivers/soc/qcom/apr.c
> @@ -454,20 +454,33 @@ static int apr_add_device(struct device *dev, struct device_node *np,
>  	adev->dev.driver = NULL;
>  
>  	spin_lock(&apr->svcs_lock);
> -	idr_alloc(&apr->svcs_idr, svc, svc_id, svc_id + 1, GFP_ATOMIC);
> +	ret = idr_alloc(&apr->svcs_idr, svc, svc_id, svc_id + 1, GFP_ATOMIC);
>  	spin_unlock(&apr->svcs_lock);
> +	if (ret < 0) {
> +		dev_err(dev, "idr_alloc failed: %d\n", ret);
> +		goto error;
> +	}
>  
> -	of_property_read_string_index(np, "qcom,protection-domain",
> -				      1, &adev->service_path);
> +	ret = of_property_read_string_index(np, "qcom,protection-domain",
> +					    1, &adev->service_path);
> +	if (ret < 0) {
> +		dev_err(dev, "of_property_read_string_index failed: %d\n", ret);

I think "Failed to read second value of qcom,protection-domain" would be
more useful. Probably no need to include "ret".

> +		goto error;
> +	}
>  
>  	dev_info(dev, "Adding APR/GPR dev: %s\n", dev_name(&adev->dev));
>  
>  	ret = device_register(&adev->dev);
>  	if (ret) {
>  		dev_err(dev, "device_register failed: %d\n", ret);
> -		put_device(&adev->dev);
> +		goto error;
>  	}
>  
> +	goto end;

I unfortunately do not fancy the goto dance here. Please add
put_device() in each of the error cases above.

> +
> +error:
> +	put_device(&adev->dev);
> +end:

I would prefer this label to be named "out".

Thanks,
Bjorn

>  	return ret;
>  }
>  
> -- 
> 2.25.1
>