Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 2620:137:e000::1:20 as permitted sender) client-ip=2620:137:e000::1:20;
Date:   Tue, 2 May 2023 14:23:07 +0200
From:   Petr Mladek <pmladek@suse.com>
To:     Rasmus Villemoes <linux@rasmusvillemoes.dk>
Cc:     Konrad =?iso-8859-1?Q?Gr=E4fe?= <k.graefe@gateware.de>,
        Quentin Schulz <quentin.schulz@theobroma-systems.com>,
        Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        Steven Rostedt <rostedt@goodmis.org>,
        Sergey Senozhatsky <senozhatsky@chromium.org>,
        Andy Shevchenko <andriy.shevchenko@linux.intel.com>,
        linux-usb@vger.kernel.org, linux-kernel@vger.kernel.org,
        Kyungmin Park <kyungmin.park@samsung.com>,
        Andrzej Pietrasiewicz <andrzej.p@collabora.com>,
        Felipe Balbi <balbi@ti.com>, stable@vger.kernel.org
Subject: Re: [PATCH v3 1/2] vsprintf: Add %p[mM]U for uppercase MAC address
Message-ID: <ZFEAq7r-awo0OYzp@alley>
References: <2023042625-rendition-distort-fe06@gregkh>
 <20230427115120.241954-1-k.graefe@gateware.de>
 <c075b668-8194-6aea-484c-0223f164cb4d@rasmusvillemoes.dk>
MIME-Version: 1.0
Content-Type: text/plain; charset=iso-8859-1
Content-Disposition: inline
Content-Transfer-Encoding: 8bit
In-Reply-To: <c075b668-8194-6aea-484c-0223f164cb4d@rasmusvillemoes.dk>
Precedence: bulk

On Fri 2023-04-28 08:56:59, Rasmus Villemoes wrote:
> On 27/04/2023 13.51, Konrad Gr?fe 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