mm/allocpercpu.c

   1 /*
   2  * linux/mm/allocpercpu.c
   3  *
   4  * Separated from slab.c August 11, 2006 Christoph Lameter <clameter@sgi.com>
   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  */
  21 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 EXPORT_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  */
  35 void __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 }
  41 EXPORT_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  */
  54 void *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 }
  71 EXPORT_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  */
  82 int __percpu_populate_mask(void *__pdata, size_t size, gfp_t gfp,
  83                            cpumask_t *mask)
  84 {
  85         cpumask_t populated = CPU_MASK_NONE;
  86         int cpu;
  87
  88         for_each_cpu_mask(cpu, *mask)
  89                 if (unlikely(!percpu_populate(__pdata, size, gfp, cpu))) {
  90                         __percpu_depopulate_mask(__pdata, &populated);
  91                         return -ENOMEM;
  92                 } else
  93                         cpu_set(cpu, populated);
  94         return 0;
  95 }
  96 EXPORT_SYMBOL_GPL(__percpu_populate_mask);
  97
  98 /**
  99  * percpu_alloc_mask - initial setup of per-cpu data
 100  * @size: size of per-cpu object
 101  * @gfp: may sleep or not etc.
 102  * @mask: populate per-data for cpu's selected through mask bits
 103  *
 104  * Populating per-cpu data for all online cpu's would be a typical use case,
 105  * which is simplified by the percpu_alloc() wrapper.
 106  * Per-cpu objects are populated with zeroed buffers.
 107  */
 108 void *__percpu_alloc_mask(size_t size, gfp_t gfp, cpumask_t *mask)
 109 {
 110         /*
 111          * We allocate whole cache lines to avoid false sharing
 112          */
 113         size_t sz = roundup(nr_cpu_ids * sizeof(void *), cache_line_size());
 114         void *pdata = kzalloc(sz, gfp);
 115         void *__pdata = __percpu_disguise(pdata);
 116
 117         if (unlikely(!pdata))
 118                 return NULL;
 119         if (likely(!__percpu_populate_mask(__pdata, size, gfp, mask)))
 120                 return __pdata;
 121         kfree(pdata);
 122         return NULL;
 123 }
 124 EXPORT_SYMBOL_GPL(__percpu_alloc_mask);
 125
 126 /**
 127  * percpu_free - final cleanup of per-cpu data
 128  * @__pdata: object to clean up
 129  *
 130  * We simply clean up any per-cpu object left. No need for the client to
 131  * track and specify through a bis mask which per-cpu objects are to free.
 132  */
 133 void percpu_free(void *__pdata)
 134 {
 135         if (unlikely(!__pdata))
 136                 return;
 137         __percpu_depopulate_mask(__pdata, &cpu_possible_map);
 138         kfree(__percpu_disguise(__pdata));
 139 }
 140 EXPORT_SYMBOL_GPL(percpu_free);