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         struct cpumask tmp;
  20
  21         if (cpumask_and(&tmp, src1p, src2p))
  22                 return cpumask_next(n, &tmp);
  23         return nr_cpu_ids;
  24 }
  25 EXPORT_SYMBOL(cpumask_next_and);
  26
  27 /**
  28  * cpumask_any_but - return a "random" in a cpumask, but not this one.
  29  * @mask: the cpumask to search
  30  * @cpu: the cpu to ignore.
  31  *
  32  * Often used to find any cpu but smp_processor_id() in a mask.
  33  * Returns >= nr_cpu_ids if no cpus set.
  34  */
  35 int cpumask_any_but(const struct cpumask *mask, unsigned int cpu)
  36 {
  37         unsigned int i;
  38
  39         cpumask_check(cpu);
  40         for_each_cpu(i, mask)
  41                 if (i != cpu)
  42                         break;
  43         return i;
  44 }
  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  */
  62 bool 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 }
  75 EXPORT_SYMBOL(alloc_cpumask_var_node);
  76
  77 bool 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 }
  81 EXPORT_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  */
  93 bool alloc_cpumask_var(cpumask_var_t *mask, gfp_t flags)
  94 {
  95         return alloc_cpumask_var_node(mask, flags, NUMA_NO_NODE);
  96 }
  97 EXPORT_SYMBOL(alloc_cpumask_var);
  98
  99 bool zalloc_cpumask_var(cpumask_var_t *mask, gfp_t flags)
 100 {
 101         return alloc_cpumask_var(mask, flags | __GFP_ZERO);
 102 }
 103 EXPORT_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  */
 114 void __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  */
 125 void free_cpumask_var(cpumask_var_t mask)
 126 {
 127         kfree(mask);
 128 }
 129 EXPORT_SYMBOL(free_cpumask_var);
 130
 131 /**
 132  * free_bootmem_cpumask_var - frees result of alloc_bootmem_cpumask_var
 133  * @mask: cpumask to free
 134  */
 135 void __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_set_cpu_local_first - set i'th cpu with local numa cpu's first
 143  *
 144  * @i: index number
 145  * @numa_node: local numa_node
 146  * @dstp: cpumask with the relevant cpu bit set according to the policy
 147  *
 148  * This function sets the cpumask according to a numa aware policy.
 149  * cpumask could be used as an affinity hint for the IRQ related to a
 150  * queue. When the policy is to spread queues across cores - local cores
 151  * first.
 152  *
 153  * Returns 0 on success, -ENOMEM for no memory, and -EAGAIN when failed to set
 154  * the cpu bit and need to re-call the function.
 155  */
 156 int cpumask_set_cpu_local_first(int i, int numa_node, cpumask_t *dstp)
 157 {
 158         cpumask_var_t mask;
 159         int cpu;
 160         int ret = 0;
 161
 162         if (!zalloc_cpumask_var(&mask, GFP_KERNEL))
 163                 return -ENOMEM;
 164
 165         i %= num_online_cpus();
 166
 167         if (numa_node == -1 || !cpumask_of_node(numa_node)) {
 168                 /* Use all online cpu's for non numa aware system */
 169                 cpumask_copy(mask, cpu_online_mask);
 170         } else {
 171                 int n;
 172
 173                 cpumask_and(mask,
 174                             cpumask_of_node(numa_node), cpu_online_mask);
 175
 176                 n = cpumask_weight(mask);
 177                 if (i >= n) {
 178                         i -= n;
 179
 180                         /* If index > number of local cpu's, mask out local
 181                          * cpu's
 182                          */
 183                         cpumask_andnot(mask, cpu_online_mask, mask);
 184                 }
 185         }
 186
 187         for_each_cpu(cpu, mask) {
 188                 if (--i < 0)
 189                         goto out;
 190         }
 191
 192         ret = -EAGAIN;
 193
 194 out:
 195         free_cpumask_var(mask);
 196
 197         if (!ret)
 198                 cpumask_set_cpu(cpu, dstp);
 199
 200         return ret;
 201 }
 202 EXPORT_SYMBOL(cpumask_set_cpu_local_first);