clocksource: Save mult_orig in clocksource_disable() (c7121843) · Commits · 戴 / test

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 <damm@igel.co.jp> 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 <tglx@linutronix.de>

include/linux/clocksource.h

+13 −1

Original line number	Diff line number	Diff line
		@@ -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);
		}

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