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Date: Wed, 28 Nov 2018 20:16:21 +0200
From: Andy Shevchenko <andriy.shevchenko@...ux.intel.com>
To: Alexandre Belloni <alexandre.belloni@...tlin.com>
Cc: Rasmus Villemoes <rasmus.villemoes@...vas.dk>,
Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
linux-kernel@...r.kernel.org,
Alessandro Zummo <a.zummo@...ertech.it>,
linux-rtc@...r.kernel.org, Arnd Bergmann <arnd@...db.de>,
Joe Perches <joe@...ches.com>,
Mark Salyzyn <salyzyn@...roid.com>,
Geert Uytterhoeven <geert@...ux-m68k.org>,
Bartlomiej Zolnierkiewicz <b.zolnierkie@...sung.com>,
Dmitry Torokhov <dmitry.torokhov@...il.com>,
Guan Xuetao <gxt@...c.pku.edu.cn>,
Ingo Molnar <mingo@...nel.org>,
Jason Wessel <jason.wessel@...driver.com>,
Jonathan Corbet <corbet@....net>,
Jonathan Hunter <jonathanh@...dia.com>,
Krzysztof Kozlowski <krzk@...nel.org>,
"Rafael J. Wysocki" <rjw@...ysocki.net>,
Thierry Reding <thierry.reding@...il.com>
Subject: Re: [PATCH v3 01/20] lib/vsprintf: Print time and date in human
readable format via %pt
On Tue, Nov 20, 2018 at 11:27:57PM +0100, Alexandre Belloni wrote:
> Hello,
>
> (Please update my email address).
I will follow all recommendations.
New version coming soon...
Thanks for review!
>
> On 13/11/2018 19:17:10+0200, 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][rv] specifier.
> >
> > Note, users have to select PRINTK_PEXT_TIMEDATE option in a Kconfig.
> >
> > Cc: Arnd Bergmann <arnd@...db.de>
> > Cc: Bartlomiej Zolnierkiewicz <b.zolnierkie@...sung.com>
> > Cc: Dmitry Torokhov <dmitry.torokhov@...il.com>
> > Cc: Geert Uytterhoeven <geert@...ux-m68k.org>
> > Cc: Guan Xuetao <gxt@...c.pku.edu.cn>
> > Cc: Ingo Molnar <mingo@...nel.org>
> > Cc: Jason Wessel <jason.wessel@...driver.com>
> > Cc: Jonathan Corbet <corbet@....net>
> > Cc: Jonathan Hunter <jonathanh@...dia.com>
> > Cc: Krzysztof Kozlowski <krzk@...nel.org>
> > Cc: "Rafael J. Wysocki" <rjw@...ysocki.net>
> > Cc: Thierry Reding <thierry.reding@...il.com>
> > Signed-off-by: Andy Shevchenko <andriy.shevchenko@...ux.intel.com>
> > ---
> > Documentation/core-api/printk-formats.rst | 20 ++++
> > lib/test_printf.c | 6 +
> > lib/vsprintf.c | 140 ++++++++++++++++++++++
> > 3 files changed, 166 insertions(+)
> >
> > diff --git a/Documentation/core-api/printk-formats.rst b/Documentation/core-api/printk-formats.rst
> > index ff48b55040ef..8342a65eab0b 100644
> > --- a/Documentation/core-api/printk-formats.rst
> > +++ b/Documentation/core-api/printk-formats.rst
> > @@ -412,6 +412,26 @@ Examples::
> >
> > Passed by reference.
> >
> > +Time and date (struct rtc_time)
> > +-------------------------------
> > +
> > +::
> > +
> > + %ptR YYYY-mm-dd HH:MM:SS
> > + %ptRd YYYY-mm-dd
> > + %ptRt HH:MM:SS
> > + %ptR[dt][rv]
> > +
> > +For printing date and time as represented by struct rtc_time structure in
> > +human readable format.
> > +
> > +By default year will be incremented by 1900 and month by 1. Use %ptRr (raw)
> > +to suppress this behaviour. On the other hand when %ptRv is applied
> > +validation mechanism will be in use, i.e. numbers out of range will be
> > +replaced by ** or ****.
> > +
> > +Passed by reference.
> > +
> > struct clk
> > ----------
> >
> > diff --git a/lib/test_printf.c b/lib/test_printf.c
> > index 53527ea822b5..97b7d14961d6 100644
> > --- a/lib/test_printf.c
> > +++ b/lib/test_printf.c
> > @@ -418,6 +418,11 @@ struct_va_format(void)
> > {
> > }
> >
> > +static void __init
> > +struct_rtc_time(void)
> > +{
> > +}
> > +
> > static void __init
> > struct_clk(void)
> > {
> > @@ -529,6 +534,7 @@ test_pointer(void)
> > uuid();
> > dentry();
> > struct_va_format();
> > + struct_rtc_time();
> > struct_clk();
> > bitmap();
> > netdev_features();
> > diff --git a/lib/vsprintf.c b/lib/vsprintf.c
> > index 37a54a6dd594..8455cbda8d6c 100644
> > --- a/lib/vsprintf.c
> > +++ b/lib/vsprintf.c
> > @@ -30,6 +30,7 @@
> > #include <linux/ioport.h>
> > #include <linux/dcache.h>
> > #include <linux/cred.h>
> > +#include <linux/rtc.h>
> > #include <linux/uuid.h>
> > #include <linux/of.h>
> > #include <net/addrconf.h>
> > @@ -822,6 +823,20 @@ static const struct printf_spec default_dec_spec = {
> > .precision = -1,
> > };
> >
> > +static const struct printf_spec default_dec02_spec = {
> > + .base = 10,
> > + .field_width = 2,
> > + .precision = -1,
> > + .flags = ZEROPAD,
> > +};
> > +
> > +static const struct printf_spec default_dec04_spec = {
> > + .base = 10,
> > + .field_width = 4,
> > + .precision = -1,
> > + .flags = ZEROPAD,
> > +};
> > +
> > static noinline_for_stack
> > char *resource_string(char *buf, char *end, struct resource *res,
> > struct printf_spec spec, const char *fmt)
> > @@ -1549,6 +1564,127 @@ char *address_val(char *buf, char *end, const void *addr, const char *fmt)
> > return special_hex_number(buf, end, num, size);
> > }
> >
> > +static noinline_for_stack
> > +char *date_str(char *buf, char *end, const struct rtc_time *tm, bool v, bool r)
> > +{
> > + int year = tm->tm_year + (r ? 0 : 1900);
> > + int mon = tm->tm_mon + (r ? 0 : 1);
> > +
> > + if (unlikely(v && (unsigned int)tm->tm_year > 200))
> > + buf = string(buf, end, "****", default_str_spec);
>
> I think you should drop the validation option. This is only used in a
> deprecated ABI and is mostly wrong as many RTCs will still be valid
> after 2100.
>
> > + else
> > + buf = number(buf, end, year, default_dec04_spec);
> > +
> > + if (buf < end)
> > + *buf = '-';
> > + buf++;
> > +
> > + if (unlikely(v && (unsigned int)tm->tm_mon > 11))
> > + buf = string(buf, end, "**", default_str_spec);
> > + else
> > + buf = number(buf, end, mon, default_dec02_spec);
> > +
> > + if (buf < end)
> > + *buf = '-';
> > + buf++;
> > +
> > + if (unlikely(v && (unsigned int)tm->tm_mday > 31))
> > + buf = string(buf, end, "**", default_str_spec);
>
> Same here, this doesn't protect February, April, June, September and
> November. There is one RTC that think that 31st of November is valid.
>
> > + else
> > + buf = number(buf, end, tm->tm_mday, default_dec02_spec);
> > +
> > + return buf;
> > +}
> > +
> > +static noinline_for_stack
> > +char *time_str(char *buf, char *end, const struct rtc_time *tm, bool v, bool r)
> > +{
> > + if (unlikely(v && (unsigned int)tm->tm_hour > 24))
> > + buf = string(buf, end, "**", default_str_spec);
> > + else
> > + buf = number(buf, end, tm->tm_hour, default_dec02_spec);
> > +
> > + if (buf < end)
> > + *buf = ':';
> > + buf++;
> > +
> > + if (unlikely(v && (unsigned int)tm->tm_min > 59))
> > + buf = string(buf, end, "**", default_str_spec);
> > + else
> > + buf = number(buf, end, tm->tm_min, default_dec02_spec);
> > +
> > + if (buf < end)
> > + *buf = ':';
> > + buf++;
> > +
> > + if (unlikely(v && (unsigned int)tm->tm_sec > 59))
> > + buf = string(buf, end, "**", default_str_spec);
>
> Some RTCs will consider 60 valid. So, really, instead of fixing all of
> those, I'd just get rid of the validation option.
>
> > + else
> > + buf = number(buf, end, tm->tm_sec, default_dec02_spec);
> > +
> > + return buf;
> > +}
> > +
> > +static noinline_for_stack
> > +char *rtc_str(char *buf, char *end, const struct rtc_time *tm, const char *fmt)
> > +{
> > + bool have_t = true, have_d = true;
> > + bool validate = false;
> > + bool raw = false;
> > + int count = 2;
> > + bool found;
> > +
> > + switch (fmt[count]) {
> > + case 'd':
> > + have_t = false;
> > + count++;
> > + break;
> > + case 't':
> > + have_d = false;
> > + count++;
> > + break;
> > + }
> > +
> > + found = true;
> > + do {
> > + switch (fmt[count++]) {
> > + case 'r':
> > + raw = true;
> > + break;
> > + case 'v':
> > + validate = true;
> > + break;
> > + default:
> > + found = false;
> > + break;
> > + }
> > + } while (found);
> > +
> > + if (have_d)
> > + buf = date_str(buf, end, tm, validate, raw);
> > + if (have_d && have_t) {
> > + if (buf < end)
> > + *buf = ' ';
>
> I'd go for ISO 8601 and use a 'T' here.
>
> > + buf++;
> > + }
> > + if (have_t)
> > + buf = time_str(buf, end, tm, validate, raw);
> > +
> > + return buf;
> > +}
> > +
> > +static noinline_for_stack
> > +char *timeanddate(char *buf, char *end, void *ptr, struct printf_spec spec,
> > + const char *fmt)
> > +{
> > + switch (fmt[1]) {
> > + case 'R':
> > + return rtc_str(buf, end, (const struct rtc_time *)ptr, fmt);
> > + default:
> > + return ptr_to_id(buf, end, ptr, spec);
> > + }
> > +}
> > +
> > static noinline_for_stack
> > char *clock(char *buf, char *end, struct clk *clk, struct printf_spec spec,
> > const char *fmt)
> > @@ -1828,6 +1964,8 @@ char *device_node_string(char *buf, char *end, struct device_node *dn,
> > * - 'd[234]' For a dentry name (optionally 2-4 last components)
> > * - 'D[234]' Same as 'd' but for a struct file
> > * - 'g' For block_device name (gendisk + partition number)
> > + * - 't[R][dt][rv]' For time and date as represented:
> > + * R struct rtc_time
> > * - 'C' For a clock, it prints the name (Common Clock Framework) or address
> > * (legacy clock framework) of the clock
> > * - 'Cn' For a clock, it prints the name (Common Clock Framework) or address
> > @@ -1952,6 +2090,8 @@ char *pointer(const char *fmt, char *buf, char *end, void *ptr,
> > return address_val(buf, end, ptr, fmt);
> > case 'd':
> > return dentry_name(buf, end, ptr, spec, fmt);
> > + case 't':
> > + return timeanddate(buf, end, ptr, spec, fmt);
> > case 'C':
> > return clock(buf, end, ptr, spec, fmt);
> > case 'D':
> > --
> > 2.19.1
> >
>
> --
> Alexandre Belloni, Bootlin
> Embedded Linux and Kernel engineering
> https://bootlin.com
--
With Best Regards,
Andy Shevchenko
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