From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753311Ab1LAHUg (ORCPT ); Thu, 1 Dec 2011 02:20:36 -0500 Received: from mail-yx0-f174.google.com ([209.85.213.174]:63025 "EHLO mail-yx0-f174.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753215Ab1LAHUe (ORCPT ); Thu, 1 Dec 2011 02:20:34 -0500 From: Yong Zhang To: linux-kernel@vger.kernel.org Cc: John Stultz , Thomas Gleixner Subject: [PATCH 1/3] clocksource: Also tweak ->maxadj in clocksource_calc_mult_shift() Date: Thu, 1 Dec 2011 15:20:14 +0800 Message-Id: <1322724016-9770-2-git-send-email-yong.zhang0@gmail.com> X-Mailer: git-send-email 1.7.5.4 In-Reply-To: <1322724016-9770-1-git-send-email-yong.zhang0@gmail.com> References: <1322724016-9770-1-git-send-email-yong.zhang0@gmail.com> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org There is still user of clocksource_calc_mult_shift(), and it's complement to commit d65670a7 [clocksource: Avoid selecting mult values that might overflow when adjusted] Signed-off-by: Yong Zhang Cc: John Stultz Cc: Thomas Gleixner --- include/linux/clocksource.h | 8 ++------ kernel/time/clocksource.c | 18 ++++++++++++++++++ 2 files changed, 20 insertions(+), 6 deletions(-) diff --git a/include/linux/clocksource.h b/include/linux/clocksource.h index c86c940..a02a8d7 100644 --- a/include/linux/clocksource.h +++ b/include/linux/clocksource.h @@ -314,12 +314,8 @@ static inline void __clocksource_updatefreq_khz(struct clocksource *cs, u32 khz) __clocksource_updatefreq_scale(cs, 1000, khz); } -static inline void -clocksource_calc_mult_shift(struct clocksource *cs, u32 freq, u32 minsec) -{ - return clocks_calc_mult_shift(&cs->mult, &cs->shift, freq, - NSEC_PER_SEC, minsec); -} +extern void +clocksource_calc_mult_shift(struct clocksource *cs, u32 freq, u32 minsec); #ifdef CONFIG_GENERIC_TIME_VSYSCALL extern void diff --git a/kernel/time/clocksource.c b/kernel/time/clocksource.c index cfc65e1..5119042 100644 --- a/kernel/time/clocksource.c +++ b/kernel/time/clocksource.c @@ -724,6 +724,24 @@ int __clocksource_register_scale(struct clocksource *cs, u32 scale, u32 freq) } EXPORT_SYMBOL_GPL(__clocksource_register_scale); +void clocksource_calc_mult_shift(struct clocksource *cs, u32 freq, u32 minsec) +{ + clocks_calc_mult_shift(&cs->mult, &cs->shift, freq, + NSEC_PER_SEC, minsec); + + /* + * for clocksources that have large mults, to avoid overflow. + * Since mult may be adjusted by ntp, add an safety extra margin + * + */ + cs->maxadj = clocksource_max_adjustment(cs); + while ((cs->mult + cs->maxadj < cs->mult) + || (cs->mult - cs->maxadj > cs->mult)) { + cs->mult >>= 1; + cs->shift--; + cs->maxadj = clocksource_max_adjustment(cs); + } +} /** * clocksource_register - Used to install new clocksources -- 1.7.5.4