linux/lib/cpumask.c
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   1#include <linux/slab.h>
   2#include <linux/kernel.h>
   3#include <linux/bitops.h>
   4#include <linux/cpumask.h>
   5#include <linux/export.h>
   6#include <linux/bootmem.h>
   7
   8/**
   9 * cpumask_next_and - get the next cpu in *src1p & *src2p
  10 * @n: the cpu prior to the place to search (ie. return will be > @n)
  11 * @src1p: the first cpumask pointer
  12 * @src2p: the second cpumask pointer
  13 *
  14 * Returns >= nr_cpu_ids if no further cpus set in both.
  15 */
  16int cpumask_next_and(int n, const struct cpumask *src1p,
  17                     const struct cpumask *src2p)
  18{
  19        while ((n = cpumask_next(n, src1p)) < nr_cpu_ids)
  20                if (cpumask_test_cpu(n, src2p))
  21                        break;
  22        return n;
  23}
  24EXPORT_SYMBOL(cpumask_next_and);
  25
  26/**
  27 * cpumask_any_but - return a "random" in a cpumask, but not this one.
  28 * @mask: the cpumask to search
  29 * @cpu: the cpu to ignore.
  30 *
  31 * Often used to find any cpu but smp_processor_id() in a mask.
  32 * Returns >= nr_cpu_ids if no cpus set.
  33 */
  34int cpumask_any_but(const struct cpumask *mask, unsigned int cpu)
  35{
  36        unsigned int i;
  37
  38        cpumask_check(cpu);
  39        for_each_cpu(i, mask)
  40                if (i != cpu)
  41                        break;
  42        return i;
  43}
  44EXPORT_SYMBOL(cpumask_any_but);
  45
  46/* These are not inline because of header tangles. */
  47#ifdef CONFIG_CPUMASK_OFFSTACK
  48/**
  49 * alloc_cpumask_var_node - allocate a struct cpumask on a given node
  50 * @mask: pointer to cpumask_var_t where the cpumask is returned
  51 * @flags: GFP_ flags
  52 *
  53 * Only defined when CONFIG_CPUMASK_OFFSTACK=y, otherwise is
  54 * a nop returning a constant 1 (in <linux/cpumask.h>)
  55 * Returns TRUE if memory allocation succeeded, FALSE otherwise.
  56 *
  57 * In addition, mask will be NULL if this fails.  Note that gcc is
  58 * usually smart enough to know that mask can never be NULL if
  59 * CONFIG_CPUMASK_OFFSTACK=n, so does code elimination in that case
  60 * too.
  61 */
  62bool alloc_cpumask_var_node(cpumask_var_t *mask, gfp_t flags, int node)
  63{
  64        *mask = kmalloc_node(cpumask_size(), flags, node);
  65
  66#ifdef CONFIG_DEBUG_PER_CPU_MAPS
  67        if (!*mask) {
  68                printk(KERN_ERR "=> alloc_cpumask_var: failed!\n");
  69                dump_stack();
  70        }
  71#endif
  72
  73        return *mask != NULL;
  74}
  75EXPORT_SYMBOL(alloc_cpumask_var_node);
  76
  77bool zalloc_cpumask_var_node(cpumask_var_t *mask, gfp_t flags, int node)
  78{
  79        return alloc_cpumask_var_node(mask, flags | __GFP_ZERO, node);
  80}
  81EXPORT_SYMBOL(zalloc_cpumask_var_node);
  82
  83/**
  84 * alloc_cpumask_var - allocate a struct cpumask
  85 * @mask: pointer to cpumask_var_t where the cpumask is returned
  86 * @flags: GFP_ flags
  87 *
  88 * Only defined when CONFIG_CPUMASK_OFFSTACK=y, otherwise is
  89 * a nop returning a constant 1 (in <linux/cpumask.h>).
  90 *
  91 * See alloc_cpumask_var_node.
  92 */
  93bool alloc_cpumask_var(cpumask_var_t *mask, gfp_t flags)
  94{
  95        return alloc_cpumask_var_node(mask, flags, NUMA_NO_NODE);
  96}
  97EXPORT_SYMBOL(alloc_cpumask_var);
  98
  99bool zalloc_cpumask_var(cpumask_var_t *mask, gfp_t flags)
 100{
 101        return alloc_cpumask_var(mask, flags | __GFP_ZERO);
 102}
 103EXPORT_SYMBOL(zalloc_cpumask_var);
 104
 105/**
 106 * alloc_bootmem_cpumask_var - allocate a struct cpumask from the bootmem arena.
 107 * @mask: pointer to cpumask_var_t where the cpumask is returned
 108 *
 109 * Only defined when CONFIG_CPUMASK_OFFSTACK=y, otherwise is
 110 * a nop (in <linux/cpumask.h>).
 111 * Either returns an allocated (zero-filled) cpumask, or causes the
 112 * system to panic.
 113 */
 114void __init alloc_bootmem_cpumask_var(cpumask_var_t *mask)
 115{
 116        *mask = memblock_virt_alloc(cpumask_size(), 0);
 117}
 118
 119/**
 120 * free_cpumask_var - frees memory allocated for a struct cpumask.
 121 * @mask: cpumask to free
 122 *
 123 * This is safe on a NULL mask.
 124 */
 125void free_cpumask_var(cpumask_var_t mask)
 126{
 127        kfree(mask);
 128}
 129EXPORT_SYMBOL(free_cpumask_var);
 130
 131/**
 132 * free_bootmem_cpumask_var - frees result of alloc_bootmem_cpumask_var
 133 * @mask: cpumask to free
 134 */
 135void __init free_bootmem_cpumask_var(cpumask_var_t mask)
 136{
 137        memblock_free_early(__pa(mask), cpumask_size());
 138}
 139#endif
 140
 141/**
 142 * cpumask_local_spread - select the i'th cpu with local numa cpu's first
 143 * @i: index number
 144 * @node: local numa_node
 145 *
 146 * This function selects an online CPU according to a numa aware policy;
 147 * local cpus are returned first, followed by non-local ones, then it
 148 * wraps around.
 149 *
 150 * It's not very efficient, but useful for setup.
 151 */
 152unsigned int cpumask_local_spread(unsigned int i, int node)
 153{
 154        int cpu;
 155
 156        /* Wrap: we always want a cpu. */
 157        i %= num_online_cpus();
 158
 159        if (node == -1) {
 160                for_each_cpu(cpu, cpu_online_mask)
 161                        if (i-- == 0)
 162                                return cpu;
 163        } else {
 164                /* NUMA first. */
 165                for_each_cpu_and(cpu, cpumask_of_node(node), cpu_online_mask)
 166                        if (i-- == 0)
 167                                return cpu;
 168
 169                for_each_cpu(cpu, cpu_online_mask) {
 170                        /* Skip NUMA nodes, done above. */
 171                        if (cpumask_test_cpu(cpu, cpumask_of_node(node)))
 172                                continue;
 173
 174                        if (i-- == 0)
 175                                return cpu;
 176                }
 177        }
 178        BUG();
 179}
 180EXPORT_SYMBOL(cpumask_local_spread);
 181