Re: [PATCH v2 6/6] lib/vsprintf: Add %pfw conversion specifier for printing fwnode names

From: Andy Shevchenko
Date: Tue Mar 26 2019 - 09:24:57 EST


On Tue, Mar 26, 2019 at 02:11:35PM +0100, Rasmus Villemoes wrote:
> On 26/03/2019 13.41, Sakari Ailus wrote:
> > Add support for %pfw conversion specifier (with "f" and "P" modifiers) to
> > support printing full path of the node, including its name ("f") and only
> > the node's name ("P") in the printk family of functions. The two flags
> > have equivalent functionality to existing %pOF with the same two modifiers
> > ("f" and "P") on OF based systems. The ability to do the same on ACPI
> > based systems is added by this patch.

> > + for (pass = false; strspn(fmt, modifiers); fmt++, pass = true) {
> > + if (pass) {
> > + if (buf < end)
> > + *buf = ':';
> > + buf++;
> > + }
> > +
> > + switch (*fmt) {
> > + case 'f': /* full_name */
> > + buf = fwnode_gen_full_name(fwnode, buf, end);
> > + break;
> > + case 'P': /* name */
> > + buf = string(buf, end, fwnode_get_name(fwnode),
> > + str_spec);
> > + break;
> > + default:
> > + break;
> > + }
> > + }
>
> This seems awfully complicated. Why would anyone ever pass more than one
> of 'f' and 'P'? Why not just
>
> switch(*fmt) {
> case 'P':
> ...
> case 'f':
> default:
> ...
> }
>
> which avoids the loop and the strcspn. Or, drop the default: case and
> don't have logic at all for falling back to 'f' if neither is present.
>
> > + return widen_string(buf, buf - buf_start, end, spec);
> > +}

My point as well (as per sent comments against previous version).
Sakari, can you add test cases at the same time?

> > return device_node_string(buf, end, ptr, spec, fmt + 1);

> > + return fwnode_string(buf, end, ptr, spec, fmt + 1);
>
> Why not pass fmt+2; we know that fmt+1 points at a 'w'. Just to avoid
> doing the fmt++ inside fwnode_string().

I guess in order to be consistent with existing %pOF case. But wouldn't be
better to fix %pOF for that sooner or later?

--
With Best Regards,
Andy Shevchenko