root/mm/allocpercpu.c

DEFINITIONS

1. percpu_depopulate
2. __percpu_depopulate_mask
3. percpu_populate
4. __percpu_populate_mask
5. __percpu_alloc_mask
6. percpu_free

/*
 * linux/mm/allocpercpu.c
 *
 * Separated from slab.c August 11, 2006 Christoph Lameter
 */
#include <linux/mm.h>
#include <linux/module.h>

#ifndef cache_line_size
#define cache_line_size()       L1_CACHE_BYTES
#endif

/**
 * percpu_depopulate - depopulate per-cpu data for given cpu
 * @__pdata: per-cpu data to depopulate
 * @cpu: depopulate per-cpu data for this cpu
 *
 * Depopulating per-cpu data for a cpu going offline would be a typical
 * use case. You need to register a cpu hotplug handler for that purpose.
 */
static void percpu_depopulate(void *__pdata, int cpu)
{
        struct percpu_data *pdata = __percpu_disguise(__pdata);

        kfree(pdata->ptrs[cpu]);
        pdata->ptrs[cpu] = NULL;
}

/**
 * percpu_depopulate_mask - depopulate per-cpu data for some cpu's
 * @__pdata: per-cpu data to depopulate
 * @mask: depopulate per-cpu data for cpu's selected through mask bits
 */
static void __percpu_depopulate_mask(void *__pdata, cpumask_t *mask)
{
        int cpu;
        for_each_cpu_mask_nr(cpu, *mask)
                percpu_depopulate(__pdata, cpu);
}

#define percpu_depopulate_mask(__pdata, mask) \
        __percpu_depopulate_mask((__pdata), &(mask))

/**
 * percpu_populate - populate per-cpu data for given cpu
 * @__pdata: per-cpu data to populate further
 * @size: size of per-cpu object
 * @gfp: may sleep or not etc.
 * @cpu: populate per-data for this cpu
 *
 * Populating per-cpu data for a cpu coming online would be a typical
 * use case. You need to register a cpu hotplug handler for that purpose.
 * Per-cpu object is populated with zeroed buffer.
 */
static void *percpu_populate(void *__pdata, size_t size, gfp_t gfp, int cpu)
{
        struct percpu_data *pdata = __percpu_disguise(__pdata);
        int node = cpu_to_node(cpu);

        /*
         * We should make sure each CPU gets private memory.
         */
        size = roundup(size, cache_line_size());

        BUG_ON(pdata->ptrs[cpu]);
        if (node_online(node))
                pdata->ptrs[cpu] = kmalloc_node(size, gfp|__GFP_ZERO, node);
        else
                pdata->ptrs[cpu] = kzalloc(size, gfp);
        return pdata->ptrs[cpu];
}

/**
 * percpu_populate_mask - populate per-cpu data for more cpu's
 * @__pdata: per-cpu data to populate further
 * @size: size of per-cpu object
 * @gfp: may sleep or not etc.
 * @mask: populate per-cpu data for cpu's selected through mask bits
 *
 * Per-cpu objects are populated with zeroed buffers.
 */
static int __percpu_populate_mask(void *__pdata, size_t size, gfp_t gfp,
                                  cpumask_t *mask)
{
        cpumask_t populated;
        int cpu;

        cpus_clear(populated);
        for_each_cpu_mask_nr(cpu, *mask)
                if (unlikely(!percpu_populate(__pdata, size, gfp, cpu))) {
                        __percpu_depopulate_mask(__pdata, &populated);
                        return -ENOMEM;
                } else
                        cpu_set(cpu, populated);
        return 0;
}

#define percpu_populate_mask(__pdata, size, gfp, mask) \
        __percpu_populate_mask((__pdata), (size), (gfp), &(mask))

/**
 * percpu_alloc_mask - initial setup of per-cpu data
 * @size: size of per-cpu object
 * @gfp: may sleep or not etc.
 * @mask: populate per-data for cpu's selected through mask bits
 *
 * Populating per-cpu data for all online cpu's would be a typical use case,
 * which is simplified by the percpu_alloc() wrapper.
 * Per-cpu objects are populated with zeroed buffers.
 */
void *__percpu_alloc_mask(size_t size, gfp_t gfp, cpumask_t *mask)
{
        /*
         * We allocate whole cache lines to avoid false sharing
         */
        size_t sz = roundup(nr_cpu_ids * sizeof(void *), cache_line_size());
        void *pdata = kzalloc(sz, gfp);
        void *__pdata = __percpu_disguise(pdata);

        if (unlikely(!pdata))
                return NULL;
        if (likely(!__percpu_populate_mask(__pdata, size, gfp, mask)))
                return __pdata;
        kfree(pdata);
        return NULL;
}
EXPORT_SYMBOL_GPL(__percpu_alloc_mask);

/**
 * percpu_free - final cleanup of per-cpu data
 * @__pdata: object to clean up
 *
 * We simply clean up any per-cpu object left. No need for the client to
 * track and specify through a bis mask which per-cpu objects are to free.
 */
void percpu_free(void *__pdata)
{
        if (unlikely(!__pdata))
                return;
        __percpu_depopulate_mask(__pdata, &cpu_possible_map);
        kfree(__percpu_disguise(__pdata));
}
EXPORT_SYMBOL_GPL(percpu_free);