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Commit f5a2e343 authored by Thomas Gleixner's avatar Thomas Gleixner
Browse files

clocksource: Allow clocksource select to skip current clocksource 



Preparatory patch for clocksource unbind support.

Split out code from clocksource_select and modify it, so it skips the
current clocksource on request and tries to find a fallback
clocksource. Convert all existing users. No functional change.

Signed-off-by: default avatarThomas Gleixner <tglx@linutronix.de>
Cc: John Stultz <john.stultz@linaro.org>
Cc: Magnus Damm <magnus.damm@gmail.com>
Link: http://lkml.kernel.org/r/20130425143435.834965397@linutronix.de


Signed-off-by: default avatarThomas Gleixner <tglx@linutronix.de>
parent 09ac369c

kernel/time/clocksource.c

+20 −11
Original line number Diff line number Diff line
@@ -553,7 +553,7 @@ static u64 clocksource_max_deferment(struct clocksource *cs) 


#ifndef CONFIG_ARCH_USES_GETTIMEOFFSET



static struct clocksource *clocksource_find_best(bool oneshot)

static struct clocksource *clocksource_find_best(bool oneshot, bool skipcur)

{

	struct clocksource *cs;
@@ -566,6 +566,8 @@ static struct clocksource *clocksource_find_best(bool oneshot) 
	 * the best rating.

	 */

	list_for_each_entry(cs, &clocksource_list, list) {

		if (skipcur && cs == curr_clocksource)

			continue;

		if (oneshot && !(cs->flags & CLOCK_SOURCE_VALID_FOR_HRES))

			continue;

		return cs;
@@ -573,26 +575,20 @@ static struct clocksource *clocksource_find_best(bool oneshot) 
	return NULL;

}



/**

 * clocksource_select - Select the best clocksource available

 *

 * Private function. Must hold clocksource_mutex when called.

 *

 * Select the clocksource with the best rating, or the clocksource,

 * which is selected by userspace override.

 */

static void clocksource_select(void)

static void __clocksource_select(bool skipcur)

{

	bool oneshot = tick_oneshot_mode_active();

	struct clocksource *best, *cs;



	/* Find the best suitable clocksource */

	best = clocksource_find_best(oneshot);

	best = clocksource_find_best(oneshot, skipcur);

	if (!best)

		return;



	/* Check for the override clocksource. */

	list_for_each_entry(cs, &clocksource_list, list) {

		if (skipcur && cs == curr_clocksource)

			continue;

		if (strcmp(cs->name, override_name) != 0)

			continue;

		/*
@@ -618,6 +614,19 @@ static void clocksource_select(void) 
	}

}



/**

 * clocksource_select - Select the best clocksource available

 *

 * Private function. Must hold clocksource_mutex when called.

 *

 * Select the clocksource with the best rating, or the clocksource,

 * which is selected by userspace override.

 */

static void clocksource_select(void)

{

	return __clocksource_select(false);

}



#else /* !CONFIG_ARCH_USES_GETTIMEOFFSET */



static inline void clocksource_select(void) { }