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clockevents: Make tick handover explicit

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clockevents_notify() is a leftover from the early design of the
clockevents facility. It's really not a notification mechanism,
it's a multiplex call. We are way better off to have explicit
calls instead of this monstrosity.

Split out the tick_handover call and invoke it explicitely from
the hotplug code. Temporary solution will be cleaned up in later
patches.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
[ Rebase ]
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: John Stultz <john.stultz@linaro.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
Link: http://lkml.kernel.org/r/1658173.RkEEILFiQZ@vostro.rjw.lan
Signed-off-by: Ingo Molnar <mingo@kernel.org>
This commit is contained in:
Thomas Gleixner 2015-04-03 02:37:24 +02:00 committed by Ingo Molnar
parent ffa48c0d76
commit 52c063d1ad
7 changed files with 10 additions and 13 deletions
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1
include/linux/clockchips.h
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@ -11,7 +11,6 @@
/* Clock event notification values */
enum clock_event_nofitiers {
CLOCK_EVT_NOTIFY_ADD,
CLOCK_EVT_NOTIFY_CPU_DYING,
CLOCK_EVT_NOTIFY_CPU_DEAD,
};

2
include/linux/tick.h
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@ -19,12 +19,14 @@ extern void tick_unfreeze(void);
extern void tick_suspend_local(void);
/* Should be core only, but XEN resume magic and ARM BL switcher require it */
extern void tick_resume_local(void);
extern void tick_handover_do_timer(void);
#else /* CONFIG_GENERIC_CLOCKEVENTS */
static inline void tick_init(void) { }
static inline void tick_freeze(void) { }
static inline void tick_unfreeze(void) { }
static inline void tick_suspend_local(void) { }
static inline void tick_resume_local(void) { }
static inline void tick_handover_do_timer(void) { }
#endif /* !CONFIG_GENERIC_CLOCKEVENTS */
#ifdef CONFIG_TICK_ONESHOT

2
kernel/cpu.c
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@ -339,6 +339,8 @@ static int __ref take_cpu_down(void *_param)
return err;
cpu_notify(CPU_DYING | param->mod, param->hcpu);
/* Give up timekeeping duties */
tick_handover_do_timer();
/* Park the stopper thread */
kthread_park(current);
return 0;

4
kernel/time/clockevents.c
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@ -655,10 +655,6 @@ int clockevents_notify(unsigned long reason, void *arg)
raw_spin_lock_irqsave(&clockevents_lock, flags);
switch (reason) {
case CLOCK_EVT_NOTIFY_CPU_DYING:
tick_handover_do_timer(arg);
break;
case CLOCK_EVT_NOTIFY_CPU_DEAD:
tick_shutdown_broadcast_oneshot(arg);
tick_shutdown_broadcast(arg);

4
kernel/time/hrtimer.c
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@ -1707,10 +1707,6 @@ static int hrtimer_cpu_notify(struct notifier_block *self,
break;
#ifdef CONFIG_HOTPLUG_CPU
case CPU_DYING:
case CPU_DYING_FROZEN:
clockevents_notify(CLOCK_EVT_NOTIFY_CPU_DYING, &scpu);
break;
case CPU_DEAD:
case CPU_DEAD_FROZEN:
{

9
kernel/time/tick-common.c
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@ -332,20 +332,23 @@ out_bc:
tick_install_broadcast_device(newdev);
}
#ifdef CONFIG_HOTPLUG_CPU
/*
* Transfer the do_timer job away from a dying cpu.
*
* Called with interrupts disabled.
* Called with interrupts disabled. Not locking required. If
* tick_do_timer_cpu is owned by this cpu, nothing can change it.
*/
void tick_handover_do_timer(int *cpup)
void tick_handover_do_timer(void)
{
if (*cpup == tick_do_timer_cpu) {
if (tick_do_timer_cpu == smp_processor_id()) {
int cpu = cpumask_first(cpu_online_mask);
tick_do_timer_cpu = (cpu < nr_cpu_ids) ? cpu :
TICK_DO_TIMER_NONE;
}
}
#endif
/*
* Shutdown an event device on a given cpu:

1
kernel/time/tick-internal.h
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@ -20,7 +20,6 @@ extern int tick_do_timer_cpu __read_mostly;
extern void tick_setup_periodic(struct clock_event_device *dev, int broadcast);
extern void tick_handle_periodic(struct clock_event_device *dev);
extern void tick_check_new_device(struct clock_event_device *dev);
extern void tick_handover_do_timer(int *cpup);
extern void tick_shutdown(unsigned int *cpup);
extern void tick_suspend(void);
extern void tick_resume(void);