linux-kernel - Re: [PATCH] media: davinci/vpfe_capture.c: Avoid BUG

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Date:   Fri, 06 Dec 2019 06:20:00 -0300
From:   Ezequiel Garcia <ezequiel@...labora.com>
To:     Aditya Pakki <pakki001@....edu>
Cc:     kjlu@....edu, "Lad, Prabhakar" <prabhakar.csengg@...il.com>,
        Mauro Carvalho Chehab <mchehab@...nel.org>,
        linux-media@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] media: davinci/vpfe_capture.c: Avoid BUG_ON for
 register failure

Hello Aditya,

Thanks for the patch.

On Thu, 2019-12-05 at 19:00 -0600, Aditya Pakki wrote:
> In vpfe_register_ccdc_device(), failure to allocate dev->hw_ops
> invokes calls to BUG_ON(). This patch returns the error to callers
> instead of crashing.
> 

I'm curious, are you actually getting this type of crash?

> Signed-off-by: Aditya Pakki <pakki001@....edu>
> ---
>  drivers/media/platform/davinci/vpfe_capture.c | 21 ++++++-------------
>  1 file changed, 6 insertions(+), 15 deletions(-)
> 
> diff --git a/drivers/media/platform/davinci/vpfe_capture.c b/drivers/media/platform/davinci/vpfe_capture.c
> index 916ed743d716..6d394a006977 100644
> --- a/drivers/media/platform/davinci/vpfe_capture.c
> +++ b/drivers/media/platform/davinci/vpfe_capture.c
> @@ -168,21 +168,11 @@ int vpfe_register_ccdc_device(const struct ccdc_hw_device *dev)
>  	int ret = 0;
>  	printk(KERN_NOTICE "vpfe_register_ccdc_device: %s\n", dev->name);
>  
> -	BUG_ON(!dev->hw_ops.open);
> -	BUG_ON(!dev->hw_ops.enable);
> -	BUG_ON(!dev->hw_ops.set_hw_if_params);
> -	BUG_ON(!dev->hw_ops.configure);
> -	BUG_ON(!dev->hw_ops.set_buftype);
> -	BUG_ON(!dev->hw_ops.get_buftype);
> -	BUG_ON(!dev->hw_ops.enum_pix);
> -	BUG_ON(!dev->hw_ops.set_frame_format);
> -	BUG_ON(!dev->hw_ops.get_frame_format);
> -	BUG_ON(!dev->hw_ops.get_pixel_format);
> -	BUG_ON(!dev->hw_ops.set_pixel_format);
> -	BUG_ON(!dev->hw_ops.set_image_window);
> -	BUG_ON(!dev->hw_ops.get_image_window);
> -	BUG_ON(!dev->hw_ops.get_line_length);
> -	BUG_ON(!dev->hw_ops.getfid);
> +	if (!dev->hw_ops) {
> +		printk(KERN_ERR "could not allocate hw_ops\n");

I'd drop this error message, as hw_ops is not really allocated here.

> +		ret = -EINVAL;
> +		goto rvalue;

Instead of a goto to a return, just return -EINVAL here.

> +	}
>  
>  	mutex_lock(&ccdc_lock);
>  	if (!ccdc_cfg) {
> @@ -211,6 +201,7 @@ int vpfe_register_ccdc_device(const struct ccdc_hw_device *dev)
>  	ccdc_dev = dev;
>  unlock:
>  	mutex_unlock(&ccdc_lock);
> +rvalue:
>  	return ret;
>  }
>  EXPORT_SYMBOL(vpfe_register_ccdc_device);

With those changes, the patch looks good.

Reviewed-by: Ezequiel Garcia <ezequiel@...labora.com>

Thanks,
Ezequiel