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clocksource: Allow clocksource select to skip current clocksource

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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: Thomas 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: Thomas Gleixner <tglx@linutronix.de>
This commit is contained in:
Thomas Gleixner 2013-04-25 20:31:45 +00:00
parent 09ac369c82
commit f5a2e34375
1 changed files with 20 additions and 11 deletions
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31
kernel/time/clocksource.c
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@ -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) { }