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 static 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  */
  34 static 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  */
  55 static 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  */
  82 static 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  */
 111 void *__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 }
 127 EXPORT_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  */
 136 void 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 }
 143 EXPORT_SYMBOL_GPL(percpu_free);