linux/mm/allocpercpu.c
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   1/*
   2 * linux/mm/allocpercpu.c
   3 *
   4 * Separated from slab.c August 11, 2006 Christoph Lameter
   5 */
   6#include <linux/mm.h>
   7#include <linux/module.h>
   8
   9#ifndef cache_line_size
  10#define cache_line_size()       L1_CACHE_BYTES
  11#endif
  12
  13/**
  14 * percpu_depopulate - depopulate per-cpu data for given cpu
  15 * @__pdata: per-cpu data to depopulate
  16 * @cpu: depopulate per-cpu data for this cpu
  17 *
  18 * Depopulating per-cpu data for a cpu going offline would be a typical
  19 * use case. You need to register a cpu hotplug handler for that purpose.
  20 */
  21static void percpu_depopulate(void *__pdata, int cpu)
  22{
  23        struct percpu_data *pdata = __percpu_disguise(__pdata);
  24
  25        kfree(pdata->ptrs[cpu]);
  26        pdata->ptrs[cpu] = NULL;
  27}
  28
  29/**
  30 * percpu_depopulate_mask - depopulate per-cpu data for some cpu's
  31 * @__pdata: per-cpu data to depopulate
  32 * @mask: depopulate per-cpu data for cpu's selected through mask bits
  33 */
  34static void __percpu_depopulate_mask(void *__pdata, cpumask_t *mask)
  35{
  36        int cpu;
  37        for_each_cpu_mask_nr(cpu, *mask)
  38                percpu_depopulate(__pdata, cpu);
  39}
  40
  41#define percpu_depopulate_mask(__pdata, mask) \
  42        __percpu_depopulate_mask((__pdata), &(mask))
  43
  44/**
  45 * percpu_populate - populate per-cpu data for given cpu
  46 * @__pdata: per-cpu data to populate further
  47 * @size: size of per-cpu object
  48 * @gfp: may sleep or not etc.
  49 * @cpu: populate per-data for this cpu
  50 *
  51 * Populating per-cpu data for a cpu coming online would be a typical
  52 * use case. You need to register a cpu hotplug handler for that purpose.
  53 * Per-cpu object is populated with zeroed buffer.
  54 */
  55static void *percpu_populate(void *__pdata, size_t size, gfp_t gfp, int cpu)
  56{
  57        struct percpu_data *pdata = __percpu_disguise(__pdata);
  58        int node = cpu_to_node(cpu);
  59
  60        /*
  61         * We should make sure each CPU gets private memory.
  62         */
  63        size = roundup(size, cache_line_size());
  64
  65        BUG_ON(pdata->ptrs[cpu]);
  66        if (node_online(node))
  67                pdata->ptrs[cpu] = kmalloc_node(size, gfp|__GFP_ZERO, node);
  68        else
  69                pdata->ptrs[cpu] = kzalloc(size, gfp);
  70        return pdata->ptrs[cpu];
  71}
  72
  73/**
  74 * percpu_populate_mask - populate per-cpu data for more cpu's
  75 * @__pdata: per-cpu data to populate further
  76 * @size: size of per-cpu object
  77 * @gfp: may sleep or not etc.
  78 * @mask: populate per-cpu data for cpu's selected through mask bits
  79 *
  80 * Per-cpu objects are populated with zeroed buffers.
  81 */
  82static int __percpu_populate_mask(void *__pdata, size_t size, gfp_t gfp,
  83                                  cpumask_t *mask)
  84{
  85        cpumask_t populated;
  86        int cpu;
  87
  88        cpus_clear(populated);
  89        for_each_cpu_mask_nr(cpu, *mask)
  90                if (unlikely(!percpu_populate(__pdata, size, gfp, cpu))) {
  91                        __percpu_depopulate_mask(__pdata, &populated);
  92                        return -ENOMEM;
  93                } else
  94                        cpu_set(cpu, populated);
  95        return 0;
  96}
  97
  98#define percpu_populate_mask(__pdata, size, gfp, mask) \
  99        __percpu_populate_mask((__pdata), (size), (gfp), &(mask))
 100
 101/**
 102 * percpu_alloc_mask - initial setup of per-cpu data
 103 * @size: size of per-cpu object
 104 * @gfp: may sleep or not etc.
 105 * @mask: populate per-data for cpu's selected through mask bits
 106 *
 107 * Populating per-cpu data for all online cpu's would be a typical use case,
 108 * which is simplified by the percpu_alloc() wrapper.
 109 * Per-cpu objects are populated with zeroed buffers.
 110 */
 111void *__percpu_alloc_mask(size_t size, gfp_t gfp, cpumask_t *mask)
 112{
 113        /*
 114         * We allocate whole cache lines to avoid false sharing
 115         */
 116        size_t sz = roundup(nr_cpu_ids * sizeof(void *), cache_line_size());
 117        void *pdata = kzalloc(sz, gfp);
 118        void *__pdata = __percpu_disguise(pdata);
 119
 120        if (unlikely(!pdata))
 121                return NULL;
 122        if (likely(!__percpu_populate_mask(__pdata, size, gfp, mask)))
 123                return __pdata;
 124        kfree(pdata);
 125        return NULL;
 126}
 127EXPORT_SYMBOL_GPL(__percpu_alloc_mask);
 128
 129/**
 130 * percpu_free - final cleanup of per-cpu data
 131 * @__pdata: object to clean up
 132 *
 133 * We simply clean up any per-cpu object left. No need for the client to
 134 * track and specify through a bis mask which per-cpu objects are to free.
 135 */
 136void percpu_free(void *__pdata)
 137{
 138        if (unlikely(!__pdata))
 139                return;
 140        __percpu_depopulate_mask(__pdata, &cpu_possible_map);
 141        kfree(__percpu_disguise(__pdata));
 142}
 143EXPORT_SYMBOL_GPL(percpu_free);
 144