Message-ID: <7f461661-2dcf-056d-f78a-93c409388f29@linux.intel.com>
Date:   Mon, 30 Jan 2023 16:34:58 +0800
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Subject: Re: [RFC PATCH v2 07/22] ASoC: Add SOC USB APIs for adding an USB
 backend
To:     Greg KH <gregkh@linuxfoundation.org>
Cc:     Wesley Cheng <quic_wcheng@quicinc.com>,
        srinivas.kandagatla@linaro.org, mathias.nyman@intel.com,
        perex@perex.cz, lgirdwood@gmail.com, andersson@kernel.org,
        krzysztof.kozlowski+dt@linaro.org, Thinh.Nguyen@synopsys.com,
        broonie@kernel.org, bgoswami@quicinc.com, tiwai@suse.com,
        robh+dt@kernel.org, agross@kernel.org,
        linux-kernel@vger.kernel.org, linux-arm-msm@vger.kernel.org,
        alsa-devel@alsa-project.org, devicetree@vger.kernel.org,
        linux-usb@vger.kernel.org, quic_jackp@quicinc.com,
        quic_plai@quicinc.com
References: <20230126031424.14582-1-quic_wcheng@quicinc.com>
 <20230126031424.14582-8-quic_wcheng@quicinc.com> <Y9UiiMbJFjkzyEol@kroah.com>
 <7c1d80b6-5db3-9955-0a67-908455bd77fa@linux.intel.com>
 <Y9YbumlV9qh+k68h@kroah.com>
Content-Language: en-US
From:   Zhou Furong <furong.zhou@linux.intel.com>
In-Reply-To: <Y9YbumlV9qh+k68h@kroah.com>
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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.