Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752343AbaJ0Frm (ORCPT ); Mon, 27 Oct 2014 01:47:42 -0400 Received: from mail-pd0-f181.google.com ([209.85.192.181]:54226 "EHLO mail-pd0-f181.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752261AbaJ0Frh (ORCPT ); Mon, 27 Oct 2014 01:47:37 -0400 From: "pang.xunlei" To: linux-kernel@vger.kernel.org, rtc-linux@googlegroups.com Cc: John Stultz , Thomas Gleixner , Alessandro Zummo , "pang.xunlei" Subject: [PATCH RFC 08/12] time: Add rtc_time_to_tm() safe version(using time64_t) Date: Mon, 27 Oct 2014 13:46:38 +0800 Message-Id: <1414388802-5866-7-git-send-email-pang.xunlei@linaro.org> X-Mailer: git-send-email 1.7.9.5 In-Reply-To: <1414388802-5866-1-git-send-email-pang.xunlei@linaro.org> References: <1414388802-5866-1-git-send-email-pang.xunlei@linaro.org> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org The kernel uses 32-bit signed value(time_t) for seconds since 1970-01-01:00:00:00, thus it will overflow at 2038-01-19 03:14:08 on 32-bit systems. We call this "2038 safety" issue. As part of addressing 2038 saftey for in-kernel uses, this patch adds the safe rtc_time_to_tm() using time64_t. After this patch, rtc_time_to_tm_unsafe() should be replaced by rtc_time_to_tm() one by one. Eventually, rtc_time_to_tm_unsafe() will be removed from the kernel when it has no users. Signed-off-by: pang.xunlei --- drivers/rtc/rtc-lib.c | 18 ++++++++++++++---- include/linux/rtc.h | 1 + 2 files changed, 15 insertions(+), 4 deletions(-) diff --git a/drivers/rtc/rtc-lib.c b/drivers/rtc/rtc-lib.c index 34bcca9..cbbc9a6 100644 --- a/drivers/rtc/rtc-lib.c +++ b/drivers/rtc/rtc-lib.c @@ -48,12 +48,12 @@ EXPORT_SYMBOL(rtc_year_days); /* * Convert seconds since 01-01-1970 00:00:00 to Gregorian date. */ -void rtc_time_to_tm_unsafe(unsigned long time, struct rtc_time *tm) +void rtc_time_to_tm(time64_t time, struct rtc_time *tm) { unsigned int month, year; int days; - days = time / 86400; + days = div_s64(time, 86400); time -= (unsigned int) days * 86400; /* day of the week, 1970-01-01 was a Thursday */ @@ -81,13 +81,23 @@ void rtc_time_to_tm_unsafe(unsigned long time, struct rtc_time *tm) tm->tm_mon = month; tm->tm_mday = days + 1; - tm->tm_hour = time / 3600; + tm->tm_hour = div_s64(time, 3600); time -= tm->tm_hour * 3600; - tm->tm_min = time / 60; + tm->tm_min = div_s64(time, 60); tm->tm_sec = time - tm->tm_min * 60; tm->tm_isdst = 0; } +EXPORT_SYMBOL(rtc_time_to_tm); + +/* TODO: [2038 safety] unsafe for legacy, and should be replaced by rtc_time_to_tm() */ +void rtc_time_to_tm_unsafe(unsigned long time, struct rtc_time *tm) +{ + time64_t time64; + + time64 = (time64_t)time; + rtc_time_to_tm(time64, tm); +} EXPORT_SYMBOL(rtc_time_to_tm_unsafe); /* diff --git a/include/linux/rtc.h b/include/linux/rtc.h index d1f878c..1994399 100644 --- a/include/linux/rtc.h +++ b/include/linux/rtc.h @@ -21,6 +21,7 @@ extern int rtc_year_days(unsigned int day, unsigned int month, unsigned int year extern int rtc_valid_tm(struct rtc_time *tm); extern int rtc_tm_to_time(struct rtc_time *tm, time64_t *time); extern int rtc_tm_to_time_unsafe(struct rtc_time *tm, unsigned long *time); +extern void rtc_time_to_tm(time64_t time, struct rtc_time *tm); extern void rtc_time_to_tm_unsafe(unsigned long time, struct rtc_time *tm); ktime_t rtc_tm_to_ktime(struct rtc_time tm); struct rtc_time rtc_ktime_to_tm(ktime_t kt); -- 1.7.9.5 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/