mm/allocpercpu.c

   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  */
  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_nr(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;
  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 EXPORT_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  */
 109 void *__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 }
 125 EXPORT_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  */
 134 void 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 }
 141 EXPORT_SYMBOL_GPL(percpu_free);