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Subject: Re: [PATCH 3/3] bus: mhi: replace snprintf in show functions with
 sysfs_emit
To:     Manivannan Sadhasivam <manivannan.sadhasivam@linaro.org>,
        Greg KH <gregkh@linuxfoundation.org>
Cc:     Joe Perches <joe@perches.com>, bbhatt@codeaurora.org,
        loic.poulain@linaro.org, wangqing@vivo.com, mhi@lists.linux.dev,
        linux-arm-msm@vger.kernel.org, linux-kernel@vger.kernel.org,
        Manivannan Sadhasivam <mani@kernel.org>
References: <20211016065734.28802-1-manivannan.sadhasivam@linaro.org>
 <20211016065734.28802-4-manivannan.sadhasivam@linaro.org>
 <YWqBTj4slHq7HexS@kroah.com>
 <6ddc01b24b1c72f7e92174a037043b5cfffa3431.camel@perches.com>
 <YWrqmiT1pC+SbecM@kroah.com> <20211016161531.GA4048@thinkpad>
From:   Hemant Kumar <hemantk@codeaurora.org>
Message-ID: <c276a912-a382-46af-1573-570c3429be94@codeaurora.org>
Date:   Mon, 18 Oct 2021 21:30:41 -0700
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On 10/16/2021 9:15 AM, Manivannan Sadhasivam wrote:
> On Sat, Oct 16, 2021 at 05:07:06PM +0200, Greg KH wrote:
>> On Sat, Oct 16, 2021 at 03:24:17AM -0700, Joe Perches wrote:
>>> On Sat, 2021-10-16 at 09:37 +0200, Greg KH wrote:
>>>> On Sat, Oct 16, 2021 at 12:27:34PM +0530, Manivannan Sadhasivam wrote:
>>>>> From: Qing Wang <wangqing@vivo.com>
>>>>> coccicheck complains about the use of snprintf() in sysfs show functions.
>>> []
>>>>> diff --git a/drivers/bus/mhi/core/init.c b/drivers/bus/mhi/core/init.c
>>> []
>>>>> @@ -94,7 +94,7 @@ static ssize_t serial_number_show(struct device *dev,
>>>>>   	struct mhi_device *mhi_dev = to_mhi_device(dev);
>>>>>   	struct mhi_controller *mhi_cntrl = mhi_dev->mhi_cntrl;
>>>>>   
>>>>> -	return snprintf(buf, PAGE_SIZE, "Serial Number: %u\n",
>>>>> +	return sysfs_emit(buf, "Serial Number: %u\n",
>>>>>   			mhi_cntrl->serial_number);
>>>>
>>>> The text "Serial Number: " should not be in here, right?  It's obvious
>>>> this is a serial number, that's what the documentation and file name
>>>> says.  Userspace should not have to parse sysfs files.
>>>
>>> sysfs is ABI right?  Parsing or not, it's what's already there.
>>
>> If no tools rely on this, and we can change it, we should at least try.
>>
>> We can not change ABI if something breaks.  If nothing relies on it,
>> then it is fine to do so.
>>
> 
> Hemant, Bhaumik, do you guys know if there are any possible users (scripts/apps)
> of this ABI? I'm not 100% inclined to change it but if we are _sure_ that there
> are no users yet, then I'm ok with it.

Mani, i dont know if any script being used by any user to parse "Serial 
Number".

Thanks,
Hemant
> 
> Thanks,
> Mani
> 
>> thanks,
>>
>> greg k-h

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