linux-kernel - Re: [RFC PATCH v2 07/22] ASoC: Add SOC USB APIs for adding an USB backend

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Date:   Mon, 30 Jan 2023 16:34:58 +0800
From:   Zhou Furong <furong.zhou@...ux.intel.com>
To:     Greg KH <gregkh@...uxfoundation.org>
Cc:     Wesley Cheng <quic_wcheng@...cinc.com>,
        srinivas.kandagatla@...aro.org, mathias.nyman@...el.com,
        perex@...ex.cz, lgirdwood@...il.com, andersson@...nel.org,
        krzysztof.kozlowski+dt@...aro.org, Thinh.Nguyen@...opsys.com,
        broonie@...nel.org, bgoswami@...cinc.com, tiwai@...e.com,
        robh+dt@...nel.org, agross@...nel.org,
        linux-kernel@...r.kernel.org, linux-arm-msm@...r.kernel.org,
        alsa-devel@...a-project.org, devicetree@...r.kernel.org,
        linux-usb@...r.kernel.org, quic_jackp@...cinc.com,
        quic_plai@...cinc.com
Subject: Re: [RFC PATCH v2 07/22] ASoC: Add SOC USB APIs for adding an USB
 backend



On 2023/1/29 15:09, Greg KH wrote:
> On Sun, Jan 29, 2023 at 02:54:43PM +0800, Zhou Furong wrote:
>>
>>
>>>> +void *snd_soc_usb_get_priv_data(struct device *usbdev)
>>>> +{
>>>> +	struct snd_soc_usb *ctx;
>>>> +
>>>> +	if (!usbdev)
>>>> +		return NULL;
>>>
>>> How could usbdev ever be NULL?
>> The method is exported to public, valid check should be reasonable
>> as someone may call it by mistake
> 
> We do not protect the kernel from itself like this, no need to check
> things that should never happen.  If the caller gets it wrong, their
> code will break :)
> 
> thanks,
> 
> greg k-h

Thank you Greg!

This has been confused me for long time when I found Linux kernel don't 
check input even for public method.