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Commit 3f27c0d2 authored by Linus Torvalds's avatar Linus Torvalds
Browse files

Merge branch 'timers-for-linus-clocksource' of... 

Merge branch 'timers-for-linus-clocksource' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip

* 'timers-for-linus-clocksource' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip:
  clocksource: prevent selection of low resolution clocksourse also for nohz=on
  clocksource: sanity check sysfs clocksource changes
parents 9aaa6305 cd6d95d8

include/linux/tick.h

+3 −0
Original line number Diff line number Diff line
@@ -97,10 +97,12 @@ extern void tick_clock_notify(void); 
extern int tick_check_oneshot_change(int allow_nohz);

extern struct tick_sched *tick_get_tick_sched(int cpu);

extern void tick_check_idle(int cpu);

extern int tick_oneshot_mode_active(void);

# else

static inline void tick_clock_notify(void) { }

static inline int tick_check_oneshot_change(int allow_nohz) { return 0; }

static inline void tick_check_idle(int cpu) { }

static inline int tick_oneshot_mode_active(void) { return 0; }

# endif



#else /* CONFIG_GENERIC_CLOCKEVENTS */
@@ -109,6 +111,7 @@ static inline void tick_cancel_sched_timer(int cpu) { } 
static inline void tick_clock_notify(void) { }

static inline int tick_check_oneshot_change(int allow_nohz) { return 0; }

static inline void tick_check_idle(int cpu) { }

static inline int tick_oneshot_mode_active(void) { return 0; }

#endif /* !CONFIG_GENERIC_CLOCKEVENTS */



# ifdef CONFIG_NO_HZ

kernel/time/clocksource.c

+19 −1
Original line number Diff line number Diff line
@@ -509,6 +509,18 @@ static ssize_t sysfs_override_clocksource(struct sys_device *dev, 
		}

	}



	/*

	 * Check to make sure we don't switch to a non-highres capable

	 * clocksource if the tick code is in oneshot mode (highres or nohz)

	 */

	if (tick_oneshot_mode_active() &&

	    !(ovr->flags & CLOCK_SOURCE_VALID_FOR_HRES)) {

		printk(KERN_WARNING "%s clocksource is not HRT compatible. "

			"Cannot switch while in HRT/NOHZ mode\n", ovr->name);

		ovr = NULL;

		override_name[0] = 0;

	}



	/* Reselect, when the override name has changed */

	if (ovr != clocksource_override) {

		clocksource_override = ovr;
@@ -537,6 +549,12 @@ sysfs_show_available_clocksources(struct sys_device *dev, 


	spin_lock_irq(&clocksource_lock);

	list_for_each_entry(src, &clocksource_list, list) {

		/*

		 * Don't show non-HRES clocksource if the tick code is

		 * in one shot mode (highres=on or nohz=on)

		 */

		if (!tick_oneshot_mode_active() ||

		    (src->flags & CLOCK_SOURCE_VALID_FOR_HRES))

			count += snprintf(buf + count,

				  max((ssize_t)PAGE_SIZE - count, (ssize_t)0),

				  "%s ", src->name);

kernel/time/tick-oneshot.c

+17 −0
Original line number Diff line number Diff line
@@ -128,6 +128,23 @@ int tick_switch_to_oneshot(void (*handler)(struct clock_event_device *)) 
	return 0;

}



/**

 * tick_check_oneshot_mode - check whether the system is in oneshot mode

 *

 * returns 1 when either nohz or highres are enabled. otherwise 0.

 */

int tick_oneshot_mode_active(void)

{

	unsigned long flags;

	int ret;



	local_irq_save(flags);

	ret = __get_cpu_var(tick_cpu_device).mode == TICKDEV_MODE_ONESHOT;

	local_irq_restore(flags);



	return ret;

}



#ifdef CONFIG_HIGH_RES_TIMERS

/**

 * tick_init_highres - switch to high resolution mode