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Commit 00c1d17a authored by Richard Cochran's avatar Richard Cochran Committed by Ingo Molnar
Browse files

clocksource/dummy_timer: Convert to hotplug state machine 



Install the callbacks via the state machine and let the core invoke
the callbacks on the already online CPUs.

Signed-off-by: default avatarRichard Cochran <rcochran@linutronix.de>
Signed-off-by: default avatarAnna-Maria Gleixner <anna-maria@linutronix.de>
Reviewed-by: default avatarSebastian Andrzej Siewior <bigeasy@linutronix.de>
Cc: Daniel Lezcano <daniel.lezcano@linaro.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: rt@linutronix.de
Link: http://lkml.kernel.org/r/20160713153336.130385842@linutronix.de


Signed-off-by: default avatarIngo Molnar <mingo@kernel.org>
parent 7e86e8bd

drivers/clocksource/dummy_timer.c

+6 −30
Original line number Diff line number Diff line
@@ -16,10 +16,9 @@ 


static DEFINE_PER_CPU(struct clock_event_device, dummy_timer_evt);



static void dummy_timer_setup(void)

static int dummy_timer_starting_cpu(unsigned int cpu)

{

	int cpu = smp_processor_id();

	struct clock_event_device *evt = raw_cpu_ptr(&dummy_timer_evt);

	struct clock_event_device *evt = per_cpu_ptr(&dummy_timer_evt, cpu);



	evt->name	= "dummy_timer";

	evt->features	= CLOCK_EVT_FEAT_PERIODIC |
@@ -29,36 +28,13 @@ static void dummy_timer_setup(void) 
	evt->cpumask	= cpumask_of(cpu);



	clockevents_register_device(evt);

	return 0;

}



static int dummy_timer_cpu_notify(struct notifier_block *self,

				      unsigned long action, void *hcpu)

{

	if ((action & ~CPU_TASKS_FROZEN) == CPU_STARTING)

		dummy_timer_setup();



	return NOTIFY_OK;

}



static struct notifier_block dummy_timer_cpu_nb = {

	.notifier_call = dummy_timer_cpu_notify,

};



static int __init dummy_timer_register(void)

{

	int err = 0;



	cpu_notifier_register_begin();

	err = __register_cpu_notifier(&dummy_timer_cpu_nb);

	if (err)

		goto out;



	/* We won't get a call on the boot CPU, so register immediately */

	if (num_possible_cpus() > 1)

		dummy_timer_setup();



out:

	cpu_notifier_register_done();

	return err;

	return cpuhp_setup_state(CPUHP_AP_DUMMY_TIMER_STARTING,

				 "AP_DUMMY_TIMER_STARTING",

				 dummy_timer_starting_cpu, NULL);

}

early_initcall(dummy_timer_register);

include/linux/cpuhotplug.h

+1 −0
Original line number Diff line number Diff line
@@ -37,6 +37,7 @@ enum cpuhp_state { 
	CPUHP_AP_ARM_VFP_STARTING,

	CPUHP_AP_PERF_ARM_STARTING,

	CPUHP_AP_ARM_ARCH_TIMER_STARTING,

	CPUHP_AP_DUMMY_TIMER_STARTING,

	CPUHP_AP_KVM_STARTING,

	CPUHP_AP_NOTIFY_STARTING,

	CPUHP_AP_ONLINE,