linux-kernel - Re: [PATCH] HID: hiddev: return -ENOMEM when kmalloc failed

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Message-ID: <YIauhinYt+USHmaB@hovoldconsulting.com>
Date:   Mon, 26 Apr 2021 14:13:58 +0200
From:   Johan Hovold <johan@...nel.org>
To:     Yang Li <yang.lee@...ux.alibaba.com>
Cc:     jikos@...nel.org, benjamin.tissoires@...hat.com,
        linux-usb@...r.kernel.org, linux-input@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH] HID: hiddev: return -ENOMEM when kmalloc failed

On Mon, Apr 26, 2021 at 05:35:26PM +0800, Yang Li wrote:
> The driver is using -1 instead of the -ENOMEM defined macro to
> specify that a buffer allocation failed. Using the correct error
> code is more intuitive.
> 
> Smatch tool warning:
> drivers/hid/usbhid/hiddev.c:894 hiddev_connect() warn: returning -1
> instead of -ENOMEM is sloppy
> 
> No functional change, just more standardized.
>
> Reported-by: Abaci Robot <abaci@...ux.alibaba.com>
> Signed-off-by: Yang Li <yang.lee@...ux.alibaba.com>
> ---
>  drivers/hid/usbhid/hiddev.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/drivers/hid/usbhid/hiddev.c b/drivers/hid/usbhid/hiddev.c
> index 45e0b1c..88020f3 100644
> --- a/drivers/hid/usbhid/hiddev.c
> +++ b/drivers/hid/usbhid/hiddev.c
> @@ -891,7 +891,7 @@ int hiddev_connect(struct hid_device *hid, unsigned int force)
>  	}
>  
>  	if (!(hiddev = kzalloc(sizeof(struct hiddev), GFP_KERNEL)))
> -		return -1;
> +		return -ENOMEM;

Please try to understand the code that you're changing based on feedback
from some tool.

All other error paths here return -1 and the return value of this
function is only compared to zero.

How is changing only one of these paths an improvement in any way?

>  
>  	init_waitqueue_head(&hiddev->wait);
>  	INIT_LIST_HEAD(&hiddev->list);

Johan