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 EXPORT_SYMBOL(cpumask_any_but);
  45
  46 /**
  47  * cpumask_next_wrap - helper to implement for_each_cpu_wrap
  48  * @n: the cpu prior to the place to search
  49  * @mask: the cpumask pointer
  50  * @start: the start point of the iteration
  51  * @wrap: assume @n crossing @start terminates the iteration
  52  *
  53  * Returns >= nr_cpu_ids on completion
  54  *
  55  * Note: the @wrap argument is required for the start condition when
  56  * we cannot assume @start is set in @mask.
  57  */
  58 int cpumask_next_wrap(int n, const struct cpumask *mask, int start, bool wrap)
  59 {
  60         int next;
  61
  62 again:
  63         next = cpumask_next(n, mask);
  64
  65         if (wrap && n < start && next >= start) {
  66                 return nr_cpumask_bits;
  67
  68         } else if (next >= nr_cpumask_bits) {
  69                 wrap = true;
  70                 n = -1;
  71                 goto again;
  72         }
  73
  74         return next;
  75 }
  76 EXPORT_SYMBOL(cpumask_next_wrap);
  77
  78 /* These are not inline because of header tangles. */
  79 #ifdef CONFIG_CPUMASK_OFFSTACK
  80 /**
  81  * alloc_cpumask_var_node - allocate a struct cpumask on a given node
  82  * @mask: pointer to cpumask_var_t where the cpumask is returned
  83  * @flags: GFP_ flags
  84  *
  85  * Only defined when CONFIG_CPUMASK_OFFSTACK=y, otherwise is
  86  * a nop returning a constant 1 (in <linux/cpumask.h>)
  87  * Returns TRUE if memory allocation succeeded, FALSE otherwise.
  88  *
  89  * In addition, mask will be NULL if this fails.  Note that gcc is
  90  * usually smart enough to know that mask can never be NULL if
  91  * CONFIG_CPUMASK_OFFSTACK=n, so does code elimination in that case
  92  * too.
  93  */
  94 bool alloc_cpumask_var_node(cpumask_var_t *mask, gfp_t flags, int node)
  95 {
  96         *mask = kmalloc_node(cpumask_size(), flags, node);
  97
  98 #ifdef CONFIG_DEBUG_PER_CPU_MAPS
  99         if (!*mask) {
 100                 printk(KERN_ERR "=> alloc_cpumask_var: failed!\n");
 101                 dump_stack();
 102         }
 103 #endif
 104
 105         return *mask != NULL;
 106 }
 107 EXPORT_SYMBOL(alloc_cpumask_var_node);
 108
 109 bool zalloc_cpumask_var_node(cpumask_var_t *mask, gfp_t flags, int node)
 110 {
 111         return alloc_cpumask_var_node(mask, flags | __GFP_ZERO, node);
 112 }
 113 EXPORT_SYMBOL(zalloc_cpumask_var_node);
 114
 115 /**
 116  * alloc_cpumask_var - allocate a struct cpumask
 117  * @mask: pointer to cpumask_var_t where the cpumask is returned
 118  * @flags: GFP_ flags
 119  *
 120  * Only defined when CONFIG_CPUMASK_OFFSTACK=y, otherwise is
 121  * a nop returning a constant 1 (in <linux/cpumask.h>).
 122  *
 123  * See alloc_cpumask_var_node.
 124  */
 125 bool alloc_cpumask_var(cpumask_var_t *mask, gfp_t flags)
 126 {
 127         return alloc_cpumask_var_node(mask, flags, NUMA_NO_NODE);
 128 }
 129 EXPORT_SYMBOL(alloc_cpumask_var);
 130
 131 bool zalloc_cpumask_var(cpumask_var_t *mask, gfp_t flags)
 132 {
 133         return alloc_cpumask_var(mask, flags | __GFP_ZERO);
 134 }
 135 EXPORT_SYMBOL(zalloc_cpumask_var);
 136
 137 /**
 138  * alloc_bootmem_cpumask_var - allocate a struct cpumask from the bootmem arena.
 139  * @mask: pointer to cpumask_var_t where the cpumask is returned
 140  *
 141  * Only defined when CONFIG_CPUMASK_OFFSTACK=y, otherwise is
 142  * a nop (in <linux/cpumask.h>).
 143  * Either returns an allocated (zero-filled) cpumask, or causes the
 144  * system to panic.
 145  */
 146 void __init alloc_bootmem_cpumask_var(cpumask_var_t *mask)
 147 {
 148         *mask = memblock_virt_alloc(cpumask_size(), 0);
 149 }
 150
 151 /**
 152  * free_cpumask_var - frees memory allocated for a struct cpumask.
 153  * @mask: cpumask to free
 154  *
 155  * This is safe on a NULL mask.
 156  */
 157 void free_cpumask_var(cpumask_var_t mask)
 158 {
 159         kfree(mask);
 160 }
 161 EXPORT_SYMBOL(free_cpumask_var);
 162
 163 /**
 164  * free_bootmem_cpumask_var - frees result of alloc_bootmem_cpumask_var
 165  * @mask: cpumask to free
 166  */
 167 void __init free_bootmem_cpumask_var(cpumask_var_t mask)
 168 {
 169         memblock_free_early(__pa(mask), cpumask_size());
 170 }
 171 #endif
 172
 173 /**
 174  * cpumask_local_spread - select the i'th cpu with local numa cpu's first
 175  * @i: index number
 176  * @node: local numa_node
 177  *
 178  * This function selects an online CPU according to a numa aware policy;
 179  * local cpus are returned first, followed by non-local ones, then it
 180  * wraps around.
 181  *
 182  * It's not very efficient, but useful for setup.
 183  */
 184 unsigned int cpumask_local_spread(unsigned int i, int node)
 185 {
 186         int cpu;
 187
 188         /* Wrap: we always want a cpu. */
 189         i %= num_online_cpus();
 190
 191         if (node == -1) {
 192                 for_each_cpu(cpu, cpu_online_mask)
 193                         if (i-- == 0)
 194                                 return cpu;
 195         } else {
 196                 /* NUMA first. */
 197                 for_each_cpu_and(cpu, cpumask_of_node(node), cpu_online_mask)
 198                         if (i-- == 0)
 199                                 return cpu;
 200
 201                 for_each_cpu(cpu, cpu_online_mask) {
 202                         /* Skip NUMA nodes, done above. */
 203                         if (cpumask_test_cpu(cpu, cpumask_of_node(node)))
 204                                 continue;
 205
 206                         if (i-- == 0)
 207                                 return cpu;
 208                 }
 209         }
 210         BUG();
 211 }
 212 EXPORT_SYMBOL(cpumask_local_spread);