Messages in this thread Patch in this message | | | From | Yong Zhang <> | Subject | [PATCH 1/3] clocksource: Also tweak ->maxadj in clocksource_calc_mult_shift() | Date | Thu, 1 Dec 2011 15:20:14 +0800 |
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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 <yong.zhang0@gmail.com> Cc: John Stultz <johnstul@us.ibm.com> Cc: Thomas Gleixner <tglx@linutronix.de> --- 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
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