lib/cpumask.c

   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  */
  16 int 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 }
  24 EXPORT_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  */
  34 int 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 }
  44
  45 /* These are not inline because of header tangles. */
  46 #ifdef CONFIG_CPUMASK_OFFSTACK
  47 /**
  48  * alloc_cpumask_var_node - allocate a struct cpumask on a given node
  49  * @mask: pointer to cpumask_var_t where the cpumask is returned
  50  * @flags: GFP_ flags
  51  *
  52  * Only defined when CONFIG_CPUMASK_OFFSTACK=y, otherwise is
  53  * a nop returning a constant 1 (in <linux/cpumask.h>)
  54  * Returns TRUE if memory allocation succeeded, FALSE otherwise.
  55  *
  56  * In addition, mask will be NULL if this fails.  Note that gcc is
  57  * usually smart enough to know that mask can never be NULL if
  58  * CONFIG_CPUMASK_OFFSTACK=n, so does code elimination in that case
  59  * too.
  60  */
  61 bool alloc_cpumask_var_node(cpumask_var_t *mask, gfp_t flags, int node)
  62 {
  63         *mask = kmalloc_node(cpumask_size(), flags, node);
  64
  65 #ifdef CONFIG_DEBUG_PER_CPU_MAPS
  66         if (!*mask) {
  67                 printk(KERN_ERR "=> alloc_cpumask_var: failed!\n");
  68                 dump_stack();
  69         }
  70 #endif
  71
  72         return *mask != NULL;
  73 }
  74 EXPORT_SYMBOL(alloc_cpumask_var_node);
  75
  76 bool zalloc_cpumask_var_node(cpumask_var_t *mask, gfp_t flags, int node)
  77 {
  78         return alloc_cpumask_var_node(mask, flags | __GFP_ZERO, node);
  79 }
  80 EXPORT_SYMBOL(zalloc_cpumask_var_node);
  81
  82 /**
  83  * alloc_cpumask_var - allocate a struct cpumask
  84  * @mask: pointer to cpumask_var_t where the cpumask is returned
  85  * @flags: GFP_ flags
  86  *
  87  * Only defined when CONFIG_CPUMASK_OFFSTACK=y, otherwise is
  88  * a nop returning a constant 1 (in <linux/cpumask.h>).
  89  *
  90  * See alloc_cpumask_var_node.
  91  */
  92 bool alloc_cpumask_var(cpumask_var_t *mask, gfp_t flags)
  93 {
  94         return alloc_cpumask_var_node(mask, flags, NUMA_NO_NODE);
  95 }
  96 EXPORT_SYMBOL(alloc_cpumask_var);
  97
  98 bool zalloc_cpumask_var(cpumask_var_t *mask, gfp_t flags)
  99 {
 100         return alloc_cpumask_var(mask, flags | __GFP_ZERO);
 101 }
 102 EXPORT_SYMBOL(zalloc_cpumask_var);
 103
 104 /**
 105  * alloc_bootmem_cpumask_var - allocate a struct cpumask from the bootmem arena.
 106  * @mask: pointer to cpumask_var_t where the cpumask is returned
 107  *
 108  * Only defined when CONFIG_CPUMASK_OFFSTACK=y, otherwise is
 109  * a nop (in <linux/cpumask.h>).
 110  * Either returns an allocated (zero-filled) cpumask, or causes the
 111  * system to panic.
 112  */
 113 void __init alloc_bootmem_cpumask_var(cpumask_var_t *mask)
 114 {
 115         *mask = memblock_virt_alloc(cpumask_size(), 0);
 116 }
 117
 118 /**
 119  * free_cpumask_var - frees memory allocated for a struct cpumask.
 120  * @mask: cpumask to free
 121  *
 122  * This is safe on a NULL mask.
 123  */
 124 void free_cpumask_var(cpumask_var_t mask)
 125 {
 126         kfree(mask);
 127 }
 128 EXPORT_SYMBOL(free_cpumask_var);
 129
 130 /**
 131  * free_bootmem_cpumask_var - frees result of alloc_bootmem_cpumask_var
 132  * @mask: cpumask to free
 133  */
 134 void __init free_bootmem_cpumask_var(cpumask_var_t mask)
 135 {
 136         memblock_free_early(__pa(mask), cpumask_size());
 137 }
 138 #endif
 139
 140 /**
 141  * cpumask_local_spread - select the i'th cpu with local numa cpu's first
 142  * @i: index number
 143  * @node: local numa_node
 144  *
 145  * This function selects an online CPU according to a numa aware policy;
 146  * local cpus are returned first, followed by non-local ones, then it
 147  * wraps around.
 148  *
 149  * It's not very efficient, but useful for setup.
 150  */
 151 unsigned int cpumask_local_spread(unsigned int i, int node)
 152 {
 153         int cpu;
 154
 155         /* Wrap: we always want a cpu. */
 156         i %= num_online_cpus();
 157
 158         if (node == -1) {
 159                 for_each_cpu(cpu, cpu_online_mask)
 160                         if (i-- == 0)
 161                                 return cpu;
 162         } else {
 163                 /* NUMA first. */
 164                 for_each_cpu_and(cpu, cpumask_of_node(node), cpu_online_mask)
 165                         if (i-- == 0)
 166                                 return cpu;
 167
 168                 for_each_cpu(cpu, cpu_online_mask) {
 169                         /* Skip NUMA nodes, done above. */
 170                         if (cpumask_test_cpu(cpu, cpumask_of_node(node)))
 171                                 continue;
 172
 173                         if (i-- == 0)
 174                                 return cpu;
 175                 }
 176         }
 177         BUG();
 178 }
 179 EXPORT_SYMBOL(cpumask_local_spread);