From c7121843685de2bf7f3afd3ae1d6a146010bf1fc Mon Sep 17 00:00:00 2001 From: Magnus Damm Date: Tue, 28 Jul 2009 14:09:55 -0700 Subject: clocksource: Save mult_orig in clocksource_disable() To fix the common case where ->enable() does not set up mult, make sure mult_orig is saved in mult on disable. Also add comments to explain why we do this. Signed-off-by: Magnus Damm Cc: johnstul@us.ibm.com Cc: lethal@linux-sh.org Cc: akpm@linux-foundation.org LKML-Reference: <20090618152432.10136.9932.sendpatchset@rx1.opensource.se> Signed-off-by: Thomas Gleixner --- include/linux/clocksource.h | 14 +++++++++++++- 1 file changed, 13 insertions(+), 1 deletion(-) diff --git a/include/linux/clocksource.h b/include/linux/clocksource.h index c56457c8334..1219be4fb42 100644 --- a/include/linux/clocksource.h +++ b/include/linux/clocksource.h @@ -293,7 +293,12 @@ static inline int clocksource_enable(struct clocksource *cs) if (cs->enable) ret = cs->enable(cs); - /* save mult_orig on enable */ + /* + * The frequency may have changed while the clocksource + * was disabled. If so the code in ->enable() must update + * the mult value to reflect the new frequency. Make sure + * mult_orig follows this change. + */ cs->mult_orig = cs->mult; return ret; @@ -309,6 +314,13 @@ static inline int clocksource_enable(struct clocksource *cs) */ static inline void clocksource_disable(struct clocksource *cs) { + /* + * Save mult_orig in mult so clocksource_enable() can + * restore the value regardless if ->enable() updates + * the value of mult or not. + */ + cs->mult = cs->mult_orig; + if (cs->disable) cs->disable(cs); } -- cgit v1.2.3-70-g09d2