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Date:   Fri, 28 Apr 2023 09:19:19 +0200
From:   Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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>,
        Petr Mladek <pmladek@suse.com>,
        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: <2023042842-embattled-collected-8638@gregkh>
References: <2023042625-rendition-distort-fe06@gregkh>
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 <c075b668-8194-6aea-484c-0223f164cb4d@rasmusvillemoes.dk>
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On Fri, Apr 28, 2023 at 08:56:59AM +0200, 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.

But sprintf() already creates mac address strings today, adding
yet-another-modifier makes it so that we don't have to hand-roll this
type of logic in the individual drivers that require it.

thanks,

greg k-h