linux-kernel - Re: [PATCH] drm: remove duplicate check on parent and avoid BUG

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Date:   Tue, 17 Dec 2019 14:13:38 +0100
From:   Daniel Vetter <daniel@...ll.ch>
To:     Aditya Pakki <pakki001@....edu>
Cc:     kjlu@....edu,
        Maarten Lankhorst <maarten.lankhorst@...ux.intel.com>,
        Maxime Ripard <mripard@...nel.org>,
        Sean Paul <sean@...rly.run>, David Airlie <airlied@...ux.ie>,
        Daniel Vetter <daniel@...ll.ch>,
        dri-devel@...ts.freedesktop.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] drm: remove duplicate check on parent and avoid BUG_ON

On Sun, Dec 15, 2019 at 01:43:44PM -0600, Aditya Pakki wrote:
> In drm_dev_init, parent is checked for NULL via assert after
> checked in devm_drm_dev_init(). The patch removes the duplicate
> check and replaces the assertion with WARN_ON. Further, it returns
> -EINVAL consistent with the usage in devm_drm_dev_init.
> 
> Signed-off-by: Aditya Pakki <pakki001@....edu>

Makes sense, patch applied to drm-misc-next.

Thanks, Daniel

> ---
>  drivers/gpu/drm/drm_drv.c | 5 +++--
>  1 file changed, 3 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/gpu/drm/drm_drv.c b/drivers/gpu/drm/drm_drv.c
> index 1b9b40a1c7c9..7c18a980cd4b 100644
> --- a/drivers/gpu/drm/drm_drv.c
> +++ b/drivers/gpu/drm/drm_drv.c
> @@ -622,7 +622,8 @@ int drm_dev_init(struct drm_device *dev,
>  		return -ENODEV;
>  	}
>  
> -	BUG_ON(!parent);
> +	if (WARN_ON(!parent))
> +		return -EINVAL;
>  
>  	kref_init(&dev->ref);
>  	dev->dev = get_device(parent);
> @@ -725,7 +726,7 @@ int devm_drm_dev_init(struct device *parent,
>  {
>  	int ret;
>  
> -	if (WARN_ON(!parent || !driver->release))
> +	if (WARN_ON(!driver->release))
>  		return -EINVAL;
>  
>  	ret = drm_dev_init(dev, driver, parent);
> -- 
> 2.20.1
> 

-- 
Daniel Vetter
Software Engineer, Intel Corporation
http://blog.ffwll.ch