linux-kernel - Re: [PATCH v2 07/11] PCI/VGA: vga_client_register() return -ENODEV on failure, not -1

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Message-ID: <b1a964e-a94b-2316-eeaf-fec2b2fa833b@linux.intel.com>
Date:   Wed, 9 Aug 2023 16:52:09 +0300 (EEST)
From:   Ilpo Järvinen <ilpo.jarvinen@...ux.intel.com>
To:     Sui Jingfeng <sui.jingfeng@...ux.dev>
cc:     Bjorn Helgaas <bhelgaas@...gle.com>,
        Dave Airlie <airlied@...hat.com>,
        Daniel Vetter <daniel@...ll.ch>, linux-pci@...r.kernel.org,
        dri-devel@...ts.freedesktop.org, linux-kernel@...r.kernel.org,
        Sui Jingfeng <suijingfeng@...ngson.cn>
Subject: Re: [PATCH v2 07/11] PCI/VGA: vga_client_register() return -ENODEV
 on failure, not -1

On Wed, 9 Aug 2023, Sui Jingfeng wrote:

> From: Sui Jingfeng <suijingfeng@...ngson.cn>
> 

Changelog body is missing.

> Fixes: 934f992c763a ("drm/i915: Recognise non-VGA display devices")
> Signed-off-by: Sui Jingfeng <suijingfeng@...ngson.cn>
> ---
>  drivers/pci/vgaarb.c | 15 ++++++---------
>  1 file changed, 6 insertions(+), 9 deletions(-)
> 
> diff --git a/drivers/pci/vgaarb.c b/drivers/pci/vgaarb.c
> index 811510253553..a6b8c0def35d 100644
> --- a/drivers/pci/vgaarb.c
> +++ b/drivers/pci/vgaarb.c
> @@ -964,7 +964,7 @@ EXPORT_SYMBOL(vga_set_legacy_decoding);
>   *
>   * To unregister just call vga_client_unregister().
>   *
> - * Returns: 0 on success, -1 on failure
> + * Returns: 0 on success, -ENODEV on failure

So this is the true substance of this change??

It doesn't warrant Fixes tag which requires a real problem to fix. An 
incorrect comment is not enough.

I think the shortlog is a bit misleading as is because it doesn't in any 
way indicate the problem is only in a comment.

>   */
>  int vga_client_register(struct pci_dev *pdev,
>  		unsigned int (*set_decode)(struct pci_dev *pdev, bool decode))
> @@ -975,16 +975,13 @@ int vga_client_register(struct pci_dev *pdev,
>  
>  	spin_lock_irqsave(&vga_lock, flags);
>  	vgadev = vgadev_find(pdev);
> -	if (!vgadev)
> -		goto bail;
> -
> -	vgadev->set_decode = set_decode;
> -	ret = 0;
> -
> -bail:
> +	if (vgadev) {
> +		vgadev->set_decode = set_decode;
> +		ret = 0;
> +	}
>  	spin_unlock_irqrestore(&vga_lock, flags);
> -	return ret;
>  
> +	return ret;

No logic changes in this at all? I don't think it belongs to the same 
patch. I'm not sure if the new logic is improvement anyway. I'd prefer to 
initialize ret = 0 instead:

	int ret = 0;
	...
	if (!vgadev) {
		err = -ENODEV;
		goto unlock;
	}
	...
unlock:
	...

-- 
 i.