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

[Greg Kroah-Hartman]

On Fri, Apr 28, 2023 at 08:56:59AM +0200, 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.

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