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Commit 5588f5af authored by Sebastian Andrzej Siewior's avatar Sebastian Andrzej Siewior Committed by Thomas Gleixner
Browse files

lib/percpu_counter: 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 avatarSebastian Andrzej Siewior <bigeasy@linutronix.de>
Signed-off-by: default avatarThomas Gleixner <tglx@linutronix.de>
Cc: rt@linutronix.de
Link: http://lkml.kernel.org/r/20161103145021.28528-5-bigeasy@linutronix.de


Signed-off-by: default avatarThomas Gleixner <tglx@linutronix.de>
parent 308167fc

include/linux/cpuhotplug.h

+1 −0
Original line number Diff line number Diff line
@@ -33,6 +33,7 @@ enum cpuhp_state { 
	CPUHP_FS_BUFF_DEAD,

	CPUHP_PRINTK_DEAD,

	CPUHP_MM_MEMCQ_DEAD,

	CPUHP_PERCPU_CNT_DEAD,

	CPUHP_WORKQUEUE_PREP,

	CPUHP_POWER_NUMA_PREPARE,

	CPUHP_HRTIMERS_PREPARE,

lib/percpu_counter.c

+14 −11
Original line number Diff line number Diff line
@@ -158,25 +158,21 @@ EXPORT_SYMBOL(percpu_counter_destroy); 
int percpu_counter_batch __read_mostly = 32;

EXPORT_SYMBOL(percpu_counter_batch);



static void compute_batch_value(void)

static int compute_batch_value(unsigned int cpu)

{

	int nr = num_online_cpus();



	percpu_counter_batch = max(32, nr*2);

	return 0;

}



static int percpu_counter_hotcpu_callback(struct notifier_block *nb,

					unsigned long action, void *hcpu)

static int percpu_counter_cpu_dead(unsigned int cpu)

{

#ifdef CONFIG_HOTPLUG_CPU

	unsigned int cpu;

	struct percpu_counter *fbc;



	compute_batch_value();

	if (action != CPU_DEAD && action != CPU_DEAD_FROZEN)

		return NOTIFY_OK;

	compute_batch_value(cpu);



	cpu = (unsigned long)hcpu;

	spin_lock_irq(&percpu_counters_lock);

	list_for_each_entry(fbc, &percpu_counters, list) {

		s32 *pcount;
@@ -190,7 +186,7 @@ static int percpu_counter_hotcpu_callback(struct notifier_block *nb, 
	}

	spin_unlock_irq(&percpu_counters_lock);

#endif

	return NOTIFY_OK;

	return 0;

}



/*
@@ -222,8 +218,15 @@ EXPORT_SYMBOL(__percpu_counter_compare); 


static int __init percpu_counter_startup(void)

{

	compute_batch_value();

	hotcpu_notifier(percpu_counter_hotcpu_callback, 0);

	int ret;



	ret = cpuhp_setup_state(CPUHP_AP_ONLINE_DYN, "lib/percpu_cnt:online",

				compute_batch_value, NULL);

	WARN_ON(ret < 0);

	ret = cpuhp_setup_state_nocalls(CPUHP_PERCPU_CNT_DEAD,

					"lib/percpu_cnt:dead", NULL,

					percpu_counter_cpu_dead);

	WARN_ON(ret < 0);

	return 0;

}

module_init(percpu_counter_startup);