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 */
  21void 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}
  28EXPORT_SYMBOL_GPL(percpu_depopulate);
  29
  30/**
  31 * percpu_depopulate_mask - depopulate per-cpu data for some cpu's
  32 * @__pdata: per-cpu data to depopulate
  33 * @mask: depopulate per-cpu data for cpu's selected through mask bits
  34 */
  35void __percpu_depopulate_mask(void *__pdata, cpumask_t *mask)
  36{
  37        int cpu;
  38        for_each_cpu_mask(cpu, *mask)
  39                percpu_depopulate(__pdata, cpu);
  40}
  41EXPORT_SYMBOL_GPL(__percpu_depopulate_mask);
  42
  43/**
  44 * percpu_populate - populate per-cpu data for given cpu
  45 * @__pdata: per-cpu data to populate further
  46 * @size: size of per-cpu object
  47 * @gfp: may sleep or not etc.
  48 * @cpu: populate per-data for this cpu
  49 *
  50 * Populating per-cpu data for a cpu coming online would be a typical
  51 * use case. You need to register a cpu hotplug handler for that purpose.
  52 * Per-cpu object is populated with zeroed buffer.
  53 */
  54void *percpu_populate(void *__pdata, size_t size, gfp_t gfp, int cpu)
  55{
  56        struct percpu_data *pdata = __percpu_disguise(__pdata);
  57        int node = cpu_to_node(cpu);
  58
  59        /*
  60         * We should make sure each CPU gets private memory.
  61         */
  62        size = roundup(size, cache_line_size());
  63
  64        BUG_ON(pdata->ptrs[cpu]);
  65        if (node_online(node))
  66                pdata->ptrs[cpu] = kmalloc_node(size, gfp|__GFP_ZERO, node);
  67        else
  68                pdata->ptrs[cpu] = kzalloc(size, gfp);
  69        return pdata->ptrs[cpu];
  70}
  71EXPORT_SYMBOL_GPL(percpu_populate);
  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 */
  82int __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(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}
  97EXPORT_SYMBOL_GPL(__percpu_populate_mask);
  98
  99/**
 100 * percpu_alloc_mask - initial setup of per-cpu data
 101 * @size: size of per-cpu object
 102 * @gfp: may sleep or not etc.
 103 * @mask: populate per-data for cpu's selected through mask bits
 104 *
 105 * Populating per-cpu data for all online cpu's would be a typical use case,
 106 * which is simplified by the percpu_alloc() wrapper.
 107 * Per-cpu objects are populated with zeroed buffers.
 108 */
 109void *__percpu_alloc_mask(size_t size, gfp_t gfp, cpumask_t *mask)
 110{
 111        /*
 112         * We allocate whole cache lines to avoid false sharing
 113         */
 114        size_t sz = roundup(nr_cpu_ids * sizeof(void *), cache_line_size());
 115        void *pdata = kzalloc(sz, gfp);
 116        void *__pdata = __percpu_disguise(pdata);
 117
 118        if (unlikely(!pdata))
 119                return NULL;
 120        if (likely(!__percpu_populate_mask(__pdata, size, gfp, mask)))
 121                return __pdata;
 122        kfree(pdata);
 123        return NULL;
 124}
 125EXPORT_SYMBOL_GPL(__percpu_alloc_mask);
 126
 127/**
 128 * percpu_free - final cleanup of per-cpu data
 129 * @__pdata: object to clean up
 130 *
 131 * We simply clean up any per-cpu object left. No need for the client to
 132 * track and specify through a bis mask which per-cpu objects are to free.
 133 */
 134void percpu_free(void *__pdata)
 135{
 136        if (unlikely(!__pdata))
 137                return;
 138        __percpu_depopulate_mask(__pdata, &cpu_possible_map);
 139        kfree(__percpu_disguise(__pdata));
 140}
 141EXPORT_SYMBOL_GPL(percpu_free);
 142