Subversion Repositories or1k_soc_on_altera_embedded_dev_kit

/*

 * Fast batching percpu counters.

 */

#include <linux/percpu_counter.h>

#include <linux/notifier.h>

#include <linux/mutex.h>

#include <linux/init.h>

#include <linux/cpu.h>

#include <linux/module.h>

#ifdef CONFIG_HOTPLUG_CPU

static LIST_HEAD(percpu_counters);

static DEFINE_MUTEX(percpu_counters_lock);

#endif

void percpu_counter_set(struct percpu_counter *fbc, s64 amount)

{

        int cpu;

        spin_lock(&fbc->lock);

        for_each_possible_cpu(cpu) {

                s32 *pcount = per_cpu_ptr(fbc->counters, cpu);

                *pcount = 0;

        }

        fbc->count = amount;

        spin_unlock(&fbc->lock);

}

EXPORT_SYMBOL(percpu_counter_set);

void __percpu_counter_add(struct percpu_counter *fbc, s64 amount, s32 batch)

{

        s64 count;

        s32 *pcount;

        int cpu = get_cpu();

        pcount = per_cpu_ptr(fbc->counters, cpu);

        count = *pcount + amount;

        if (count >= batch || count <= -batch) {

                spin_lock(&fbc->lock);

                fbc->count += count;

                *pcount = 0;

                spin_unlock(&fbc->lock);

        } else {

                *pcount = count;

        }

        put_cpu();

}

EXPORT_SYMBOL(__percpu_counter_add);

/*

 * Add up all the per-cpu counts, return the result.  This is a more accurate

 * but much slower version of percpu_counter_read_positive()

 */

s64 __percpu_counter_sum(struct percpu_counter *fbc)

{

        s64 ret;

        int cpu;

        spin_lock(&fbc->lock);

        ret = fbc->count;

        for_each_online_cpu(cpu) {

                s32 *pcount = per_cpu_ptr(fbc->counters, cpu);

                ret += *pcount;

        }

        spin_unlock(&fbc->lock);

        return ret;

}

EXPORT_SYMBOL(__percpu_counter_sum);

static struct lock_class_key percpu_counter_irqsafe;

int percpu_counter_init(struct percpu_counter *fbc, s64 amount)

{

        spin_lock_init(&fbc->lock);

        fbc->count = amount;

        fbc->counters = alloc_percpu(s32);

        if (!fbc->counters)

                return -ENOMEM;

#ifdef CONFIG_HOTPLUG_CPU

        mutex_lock(&percpu_counters_lock);

        list_add(&fbc->list, &percpu_counters);

        mutex_unlock(&percpu_counters_lock);

#endif

        return 0;

}

EXPORT_SYMBOL(percpu_counter_init);

int percpu_counter_init_irq(struct percpu_counter *fbc, s64 amount)

{

        int err;

        err = percpu_counter_init(fbc, amount);

        if (!err)

                lockdep_set_class(&fbc->lock, &percpu_counter_irqsafe);

        return err;

}

void percpu_counter_destroy(struct percpu_counter *fbc)

{

        if (!fbc->counters)

                return;

        free_percpu(fbc->counters);

#ifdef CONFIG_HOTPLUG_CPU

        mutex_lock(&percpu_counters_lock);

        list_del(&fbc->list);

        mutex_unlock(&percpu_counters_lock);

#endif

}

EXPORT_SYMBOL(percpu_counter_destroy);

#ifdef CONFIG_HOTPLUG_CPU

static int __cpuinit percpu_counter_hotcpu_callback(struct notifier_block *nb,

                                        unsigned long action, void *hcpu)

{

        unsigned int cpu;

        struct percpu_counter *fbc;

        if (action != CPU_DEAD)

                return NOTIFY_OK;

        cpu = (unsigned long)hcpu;

        mutex_lock(&percpu_counters_lock);

        list_for_each_entry(fbc, &percpu_counters, list) {

                s32 *pcount;

                unsigned long flags;

                spin_lock_irqsave(&fbc->lock, flags);

                pcount = per_cpu_ptr(fbc->counters, cpu);

                fbc->count += *pcount;

                *pcount = 0;

                spin_unlock_irqrestore(&fbc->lock, flags);

        }

        mutex_unlock(&percpu_counters_lock);

        return NOTIFY_OK;

}

static int __init percpu_counter_startup(void)

{

        hotcpu_notifier(percpu_counter_hotcpu_callback, 0);

        return 0;

}

module_init(percpu_counter_startup);

#endif