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 int __first_cpu(const cpumask_t *srcp)
   9 {
  10         return min_t(int, NR_CPUS, find_first_bit(srcp->bits, NR_CPUS));
  11 }
  12 EXPORT_SYMBOL(__first_cpu);
  13
  14 int __next_cpu(int n, const cpumask_t *srcp)
  15 {
  16         return min_t(int, NR_CPUS, find_next_bit(srcp->bits, NR_CPUS, n+1));
  17 }
  18 EXPORT_SYMBOL(__next_cpu);
  19
  20 #if NR_CPUS > 64
  21 int __next_cpu_nr(int n, const cpumask_t *srcp)
  22 {
  23         return min_t(int, nr_cpu_ids,
  24                                 find_next_bit(srcp->bits, nr_cpu_ids, n+1));
  25 }
  26 EXPORT_SYMBOL(__next_cpu_nr);
  27 #endif
  28
  29 /**
  30  * cpumask_next_and - get the next cpu in *src1p & *src2p
  31  * @n: the cpu prior to the place to search (ie. return will be > @n)
  32  * @src1p: the first cpumask pointer
  33  * @src2p: the second cpumask pointer
  34  *
  35  * Returns >= nr_cpu_ids if no further cpus set in both.
  36  */
  37 int cpumask_next_and(int n, const struct cpumask *src1p,
  38                      const struct cpumask *src2p)
  39 {
  40         struct cpumask tmp;
  41
  42         if (cpumask_and(&tmp, src1p, src2p))
  43                 return cpumask_next(n, &tmp);
  44         return nr_cpu_ids;
  45 }
  46 EXPORT_SYMBOL(cpumask_next_and);
  47
  48 /**
  49  * cpumask_any_but - return a "random" in a cpumask, but not this one.
  50  * @mask: the cpumask to search
  51  * @cpu: the cpu to ignore.
  52  *
  53  * Often used to find any cpu but smp_processor_id() in a mask.
  54  * Returns >= nr_cpu_ids if no cpus set.
  55  */
  56 int cpumask_any_but(const struct cpumask *mask, unsigned int cpu)
  57 {
  58         unsigned int i;
  59
  60         cpumask_check(cpu);
  61         for_each_cpu(i, mask)
  62                 if (i != cpu)
  63                         break;
  64         return i;
  65 }
  66
  67 /* These are not inline because of header tangles. */
  68 #ifdef CONFIG_CPUMASK_OFFSTACK
  69 /**
  70  * alloc_cpumask_var_node - allocate a struct cpumask on a given node
  71  * @mask: pointer to cpumask_var_t where the cpumask is returned
  72  * @flags: GFP_ flags
  73  *
  74  * Only defined when CONFIG_CPUMASK_OFFSTACK=y, otherwise is
  75  * a nop returning a constant 1 (in <linux/cpumask.h>)
  76  * Returns TRUE if memory allocation succeeded, FALSE otherwise.
  77  *
  78  * In addition, mask will be NULL if this fails.  Note that gcc is
  79  * usually smart enough to know that mask can never be NULL if
  80  * CONFIG_CPUMASK_OFFSTACK=n, so does code elimination in that case
  81  * too.
  82  */
  83 bool alloc_cpumask_var_node(cpumask_var_t *mask, gfp_t flags, int node)
  84 {
  85         *mask = kmalloc_node(cpumask_size(), flags, node);
  86
  87 #ifdef CONFIG_DEBUG_PER_CPU_MAPS
  88         if (!*mask) {
  89                 printk(KERN_ERR "=> alloc_cpumask_var: failed!\n");
  90                 dump_stack();
  91         }
  92 #endif
  93         /* FIXME: Bandaid to save us from old primitives which go to NR_CPUS. */
  94         if (*mask) {
  95                 unsigned char *ptr = (unsigned char *)cpumask_bits(*mask);
  96                 unsigned int tail;
  97                 tail = BITS_TO_LONGS(NR_CPUS - nr_cpumask_bits) * sizeof(long);
  98                 memset(ptr + cpumask_size() - tail, 0, tail);
  99         }
 100
 101         return *mask != NULL;
 102 }
 103 EXPORT_SYMBOL(alloc_cpumask_var_node);
 104
 105 bool zalloc_cpumask_var_node(cpumask_var_t *mask, gfp_t flags, int node)
 106 {
 107         return alloc_cpumask_var_node(mask, flags | __GFP_ZERO, node);
 108 }
 109 EXPORT_SYMBOL(zalloc_cpumask_var_node);
 110
 111 /**
 112  * alloc_cpumask_var - allocate a struct cpumask
 113  * @mask: pointer to cpumask_var_t where the cpumask is returned
 114  * @flags: GFP_ flags
 115  *
 116  * Only defined when CONFIG_CPUMASK_OFFSTACK=y, otherwise is
 117  * a nop returning a constant 1 (in <linux/cpumask.h>).
 118  *
 119  * See alloc_cpumask_var_node.
 120  */
 121 bool alloc_cpumask_var(cpumask_var_t *mask, gfp_t flags)
 122 {
 123         return alloc_cpumask_var_node(mask, flags, NUMA_NO_NODE);
 124 }
 125 EXPORT_SYMBOL(alloc_cpumask_var);
 126
 127 bool zalloc_cpumask_var(cpumask_var_t *mask, gfp_t flags)
 128 {
 129         return alloc_cpumask_var(mask, flags | __GFP_ZERO);
 130 }
 131 EXPORT_SYMBOL(zalloc_cpumask_var);
 132
 133 /**
 134  * alloc_bootmem_cpumask_var - allocate a struct cpumask from the bootmem arena.
 135  * @mask: pointer to cpumask_var_t where the cpumask is returned
 136  *
 137  * Only defined when CONFIG_CPUMASK_OFFSTACK=y, otherwise is
 138  * a nop (in <linux/cpumask.h>).
 139  * Either returns an allocated (zero-filled) cpumask, or causes the
 140  * system to panic.
 141  */
 142 void __init alloc_bootmem_cpumask_var(cpumask_var_t *mask)
 143 {
 144         *mask = memblock_virt_alloc(cpumask_size(), 0);
 145 }
 146
 147 /**
 148  * free_cpumask_var - frees memory allocated for a struct cpumask.
 149  * @mask: cpumask to free
 150  *
 151  * This is safe on a NULL mask.
 152  */
 153 void free_cpumask_var(cpumask_var_t mask)
 154 {
 155         kfree(mask);
 156 }
 157 EXPORT_SYMBOL(free_cpumask_var);
 158
 159 /**
 160  * free_bootmem_cpumask_var - frees result of alloc_bootmem_cpumask_var
 161  * @mask: cpumask to free
 162  */
 163 void __init free_bootmem_cpumask_var(cpumask_var_t mask)
 164 {
 165         memblock_free_early(__pa(mask), cpumask_size());
 166 }
 167 #endif
 168
 169 /**
 170  * cpumask_set_cpu_local_first - set i'th cpu with local numa cpu's first
 171  *
 172  * @i: index number
 173  * @numa_node: local numa_node
 174  * @dstp: cpumask with the relevant cpu bit set according to the policy
 175  *
 176  * This function sets the cpumask according to a numa aware policy.
 177  * cpumask could be used as an affinity hint for the IRQ related to a
 178  * queue. When the policy is to spread queues across cores - local cores
 179  * first.
 180  *
 181  * Returns 0 on success, -ENOMEM for no memory, and -EAGAIN when failed to set
 182  * the cpu bit and need to re-call the function.
 183  */
 184 int cpumask_set_cpu_local_first(int i, int numa_node, cpumask_t *dstp)
 185 {
 186         cpumask_var_t mask;
 187         int cpu;
 188         int ret = 0;
 189
 190         if (!zalloc_cpumask_var(&mask, GFP_KERNEL))
 191                 return -ENOMEM;
 192
 193         i %= num_online_cpus();
 194
 195         if (numa_node == -1 || !cpumask_of_node(numa_node)) {
 196                 /* Use all online cpu's for non numa aware system */
 197                 cpumask_copy(mask, cpu_online_mask);
 198         } else {
 199                 int n;
 200
 201                 cpumask_and(mask,
 202                             cpumask_of_node(numa_node), cpu_online_mask);
 203
 204                 n = cpumask_weight(mask);
 205                 if (i >= n) {
 206                         i -= n;
 207
 208                         /* If index > number of local cpu's, mask out local
 209                          * cpu's
 210                          */
 211                         cpumask_andnot(mask, cpu_online_mask, mask);
 212                 }
 213         }
 214
 215         for_each_cpu(cpu, mask) {
 216                 if (--i < 0)
 217                         goto out;
 218         }
 219
 220         ret = -EAGAIN;
 221
 222 out:
 223         free_cpumask_var(mask);
 224
 225         if (!ret)
 226                 cpumask_set_cpu(cpu, dstp);
 227
 228         return ret;
 229 }
 230 EXPORT_SYMBOL(cpumask_set_cpu_local_first);