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clocksource: add unregister function to disable unusable clocksources 

On x86 the PIT might become an unusable clocksource. Add an unregister
function to provide a possibilty to remove the PIT from the list of
available clock sources.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
This commit is contained in:
Thomas Gleixner 2008-01-30 13:30:02 +01:00 committed by Ingo Molnar
parent 316da3b3fc
commit 4713e22ce8
3 changed files with 17 additions and 0 deletions
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1
arch/x86/kernel/i8253.c
View File

@ -13,6 +13,7 @@
#include <asm/delay.h>
#include <asm/i8253.h>
#include <asm/io.h>
#include <asm/hpet.h>
DEFINE_SPINLOCK(i8253_lock);
EXPORT_SYMBOL(i8253_lock);

1
include/linux/clocksource.h
View File

@ -215,6 +215,7 @@ static inline void clocksource_calculate_interval(struct clocksource *c,
/* used to install a new clocksource */
extern int clocksource_register(struct clocksource*);
extern void clocksource_unregister(struct clocksource*);
extern struct clocksource* clocksource_get_next(void);
extern void clocksource_change_rating(struct clocksource *cs, int rating);
extern void clocksource_resume(void);

15
kernel/time/clocksource.c
View File

@ -337,6 +337,21 @@ void clocksource_change_rating(struct clocksource *cs, int rating)
spin_unlock_irqrestore(&clocksource_lock, flags);
}
/**
* clocksource_unregister - remove a registered clocksource
*/
void clocksource_unregister(struct clocksource *cs)
{
unsigned long flags;
spin_lock_irqsave(&clocksource_lock, flags);
list_del(&cs->list);
if (clocksource_override == cs)
clocksource_override = NULL;
next_clocksource = select_clocksource();
spin_unlock_irqrestore(&clocksource_lock, flags);
}
#ifdef CONFIG_SYSFS
/**
* sysfs_show_current_clocksources - sysfs interface for current clocksource