linux-kernel - Re: [PATCH v3 1/2] vsprintf: Add %p[mM]U for uppercase MAC address

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Date:   Thu, 4 May 2023 15:25:40 +0200
From:   Konrad Gräfe <k.graefe@...eware.de>
To:     Petr Mladek <pmladek@...e.com>,
        Rasmus Villemoes <linux@...musvillemoes.dk>
Cc:     Quentin Schulz <quentin.schulz@...obroma-systems.com>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Steven Rostedt <rostedt@...dmis.org>,
        Sergey Senozhatsky <senozhatsky@...omium.org>,
        Andy Shevchenko <andriy.shevchenko@...ux.intel.com>,
        linux-usb@...r.kernel.org, linux-kernel@...r.kernel.org,
        Kyungmin Park <kyungmin.park@...sung.com>,
        Andrzej Pietrasiewicz <andrzej.p@...labora.com>,
        Felipe Balbi <balbi@...com>, stable@...r.kernel.org
Subject: Re: [PATCH v3 1/2] vsprintf: Add %p[mM]U for uppercase MAC address

On 02.05.23 14:23, Petr Mladek wrote:
> On Fri 2023-04-28 08:56:59, Rasmus Villemoes wrote:
>> On 27/04/2023 13.51, Konrad Gräfe wrote:
>>> The CDC-ECM specification requires an USB gadget to send the host MAC
>>> address as uppercase hex string. This change adds the appropriate
>>> modifier.
>>
>> Thinking more about it, I'm not sure this is appropriate, not for a
>> single user like this. vsprintf() should not and cannot satisfy all
>> possible string formatting requirements for the whole kernel. The %pX
>> extensions are convenient for use with printk() and friends where one
>> needs what in other languages would be "string interpolation" (because
>> then the caller doesn't need to deal with temporary stack buffers and
>> pass them as %s arguments), but for single items like this, snprintf()
>> is not necessarily the right tool for the job.
>>
>> In this case, the caller can just as well call string_upper() on the
>> result
> 
> I tend to agree with Rasmus. string_upper() is a super-easy solution.
> One user does not look worth adding all the churn into vsprintf().
> 
> Best Regards,
> Petr

I do agree as well. That would basically be v1 [1] without the 
hand-crafted string_upper(). (I didn't know the function.)

Regards,
Konrad

[1]: 
https://lore.kernel.org/linux-usb/94afd6e0-7300-e8f4-d52e-c21acec04f5b@gateware.de/

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