Re: [PATCH v5 02/21] lib/vsprintf: Print time and date in human readable format via %pt

From: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
To: Petr Mladek <pmladek@suse.com>
Cc: Alessandro Zummo <a.zummo@towertech.it>,
	Alexandre Belloni <alexandre.belloni@bootlin.com>,
	linux-rtc@vger.kernel.org, Arnd Bergmann <arnd@arndb.de>,
	Joe Perches <joe@perches.com>, Mark Salyzyn <salyzyn@android.com>,
	Geert Uytterhoeven <geert@linux-m68k.org>,
	linux-kernel@vger.kernel.org,
	Rasmus Villemoes <rasmus.villemoes@prevas.dk>,
	Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
	Bartlomiej Zolnierkiewicz <b.zolnierkie@samsung.com>,
	Dmitry Torokhov <dmitry.torokhov@gmail.com>,
	Guan Xuetao <gxt@mprc.pku.edu.cn>, Ingo Molnar <mingo@kernel.org>,
	Jason Wessel <jason.wessel@windriver.com>,
	Jonathan Corbet <corbet@lwn.net>,
	Jonathan Hunter <jonathanh@nvidia.com>,
	Krzysztof Kozlowski <krzk@kernel.org>,
	"Rafael J. Wysocki" <rjw@rjwysocki.net>,
	Thierry Reding <thierry.reding@gmail.com>
Subject: Re: [PATCH v5 02/21] lib/vsprintf: Print time and date in human readable format via %pt
Date: Tue, 4 Dec 2018 18:12:42 +0200	[thread overview]
Message-ID: <20181204161242.GD10650@smile.fi.intel.com> (raw)
In-Reply-To: <20181204133028.xkdnc5bqtqlnb3zu@pathway.suse.cz>

On Tue, Dec 04, 2018 at 02:30:28PM +0100, Petr Mladek wrote:
> On Thu 2018-11-29 12:59:40, Andy Shevchenko wrote:
> > There are users which print time and date represented by content of
> > struct rtc_time in human readable format.
> > 
> > Instead of open coding that each time introduce %ptR[dt][r] specifier.

> > +static void __init
> > +struct_rtc_time(void)
> > +{
> > +}
> 
> Just by chance, do you have any plans to add the test code? ;-)
> 
> I understand that you did now want to spend time on it before
> the real change was accepted.

You see, there were several iterations with no consensus on everything:
specifier format changed 3 times, for example.

But it might be good idea to eventually add couple simple tests at some point.

Is it a show stopper?

> > +	found = true;
> > +	do {
> > +		switch (fmt[count++]) {
> > +		case 'r':
> > +			raw = true;
> > +			break;
> > +		default:
> > +			found = false;
> > +			break;
> > +		}
> > +	} while (found);
> 
> I guess that the while cycle is remainder from an older version and
> should not be here. It handles only the final 'r' now.

See again above. Do you insist to make a change now?

> > +	if (have_d)
> > +		buf = date_str(buf, end, tm, raw);
> > +	if (have_d && have_t) {
> > +		/* Respect ISO 8601 */
> > +		if (buf < end)
> > +			*buf = 'T';
> 
> I checked several conversion patches and the original code did not use
> the ISO format. The change makes sense (even though I personally
> do not like the format much ;-)
> 
> Anyway, people might expect that the conversion is 1:1. The change
> should get mentioned in the affected patches so that people are
> not later surprised.

It's defined in cover letter, all ABI cases are _not_ changed.
The rest either information or, in most cases, debug messages.
Alexandre is OK with the change, he actually requested this.

> > +static noinline_for_stack
> > +char *timeanddate(char *buf, char *end, void *ptr, struct printf_spec spec,
> > +		  const char *fmt)
> 
> Please, rename the function to time_and_date(). It is the style used
> in this source file and it is much easier to read.

OK.

> Otherwise, the patch looks fine. It helps to remove the many variants
> of the code and unifies the output format.

Thanks for review!

-- 
With Best Regards,
Andy Shevchenko