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