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From:   Sergey Senozhatsky <sergey.senozhatsky@gmail.com>
Date:   Thu, 16 Apr 2020 11:32:19 +0900
To:     Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Cc:     Petr Mladek <pmladek@suse.com>,
        Steven Rostedt <rostedt@goodmis.org>,
        Sergey Senozhatsky <sergey.senozhatsky@gmail.com>,
        linux-kernel@vger.kernel.org,
        Rasmus Villemoes <linux@rasmusvillemoes.dk>,
        Andrew Morton <akpm@linux-foundation.org>,
        Hans Verkuil <hverkuil@xs4all.nl>,
        Jonathan Corbet <corbet@lwn.net>,
        Alexandre Belloni <alexandre.belloni@bootlin.com>
Subject: Re: [PATCH v3 1/3] lib/vsprintf: Print time64_t in human readable
 format
Message-ID: <20200416023219.GA30641@jagdpanzerIV.localdomain>
References: <20200415170046.33374-1-andriy.shevchenko@linux.intel.com>
 <20200415170046.33374-2-andriy.shevchenko@linux.intel.com>
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On (20/04/15 20:00), Andy Shevchenko wrote:
[..]
>  #include <linux/of.h>
>  #include <net/addrconf.h>
> @@ -1819,6 +1820,29 @@ char *rtc_str(char *buf, char *end, const struct rtc_time *tm,
>  	return buf;
>  }
>  
> +static noinline_for_stack
> +char *time64_str(char *buf, char *end, const time64_t time,
> +		 struct printf_spec spec, const char *fmt)
> +{
> +	struct rtc_time rtc_time;
> +	struct tm tm;
> +
> +	time64_to_tm(time, 0, &tm);
> +
> +	rtc_time.tm_sec = tm.tm_sec;
> +	rtc_time.tm_min = tm.tm_min;
> +	rtc_time.tm_hour = tm.tm_hour;
> +	rtc_time.tm_mday = tm.tm_mday;
> +	rtc_time.tm_mon = tm.tm_mon;
> +	rtc_time.tm_year = tm.tm_year;
> +	rtc_time.tm_wday = tm.tm_wday;
> +	rtc_time.tm_yday = tm.tm_yday;
> +
> +	rtc_time.tm_isdst = 0;

Here you convert time64_t (signed, we also have unsigned version - timeu64_t)
to tm first and then convert tm to rtc_time. Will rtc_time64_to_tm() do the
trick?

	-ss