linux-kernel - Re: [PATCH] extcon: palmas: Fail gracefully if invalid configuration

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Date:   Wed, 07 Dec 2016 21:46:25 +0900
From:   Chanwoo Choi <cw00.choi@...sung.com>
To:     Roger Quadros <rogerq@...com>, myungjoo.ham@...sung.com
Cc:     linux-kernel@...r.kernel.org
Subject: Re: [PATCH] extcon: palmas: Fail gracefully if invalid configuration

Hi Roger,

Looks good to me.
But I have some comment.

How about changing the subject as following?

- old : Fail gracefully if invalid configuration
- new : Check the parent instance to prevent the NULL pointer error

On 2016년 12월 07일 21:12, Roger Quadros wrote:
> extcon-palmas must be child of palmas and expects parent's
> drvdata to be valid. Check for non NULL parent drvdata and
> fail if it is NULL. Not doing so will result in a NULL
> pointer dereference later in the probe() parent drvdata
> is NULL (e.g. misplaced extcon-palmas node in device tree).
> 
> Signed-off-by: Roger Quadros <rogerq@...com>
> ---
>  drivers/extcon/extcon-palmas.c | 5 +++++
>  1 file changed, 5 insertions(+)
> 
> diff --git a/drivers/extcon/extcon-palmas.c b/drivers/extcon/extcon-palmas.c
> index 634ba70..ec987ab 100644
> --- a/drivers/extcon/extcon-palmas.c
> +++ b/drivers/extcon/extcon-palmas.c
> @@ -190,6 +190,11 @@ static int palmas_usb_probe(struct platform_device *pdev)
>  	struct palmas_usb *palmas_usb;
>  	int status;
>  
> +	if (!palmas) {
> +		dev_err(&pdev->dev, "device has invalid parent\n");

How about changing the error message as following?
because the extcon-palmas used the 'failed to ..' style for error message.
- "failed to get valid parent"

> +		return -EINVAL;
> +	}
> +
>  	palmas_usb = devm_kzalloc(&pdev->dev, sizeof(*palmas_usb), GFP_KERNEL);
>  	if (!palmas_usb)
>  		return -ENOMEM;
> 


Best Regards,
Chanwoo Choi