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 /**
  67  * cpumask_next_wrap - helper to implement for_each_cpu_wrap
  68  * @n: the cpu prior to the place to search
  69  * @mask: the cpumask pointer
  70  * @start: the start point of the iteration
  71  * @wrap: assume @n crossing @start terminates the iteration
  72  *
  73  * Returns >= nr_cpu_ids on completion
  74  *
  75  * Note: the @wrap argument is required for the start condition when
  76  * we cannot assume @start is set in @mask.
  77  */
  78 int cpumask_next_wrap(int n, const struct cpumask *mask, int start, bool wrap)
  79 {
  80         int next;
  81
  82 again:
  83         next = cpumask_next(n, mask);
  84
  85         if (wrap && n < start && next >= start) {
  86                 return nr_cpumask_bits;
  87
  88         } else if (next >= nr_cpumask_bits) {
  89                 wrap = true;
  90                 n = -1;
  91                 goto again;
  92         }
  93
  94         return next;
  95 }
  96 EXPORT_SYMBOL(cpumask_next_wrap);
  97
  98 /* These are not inline because of header tangles. */
  99 #ifdef CONFIG_CPUMASK_OFFSTACK
 100 /**
 101  * alloc_cpumask_var_node - allocate a struct cpumask on a given node
 102  * @mask: pointer to cpumask_var_t where the cpumask is returned
 103  * @flags: GFP_ flags
 104  *
 105  * Only defined when CONFIG_CPUMASK_OFFSTACK=y, otherwise is
 106  * a nop returning a constant 1 (in <linux/cpumask.h>)
 107  * Returns TRUE if memory allocation succeeded, FALSE otherwise.
 108  *
 109  * In addition, mask will be NULL if this fails.  Note that gcc is
 110  * usually smart enough to know that mask can never be NULL if
 111  * CONFIG_CPUMASK_OFFSTACK=n, so does code elimination in that case
 112  * too.
 113  */
 114 bool alloc_cpumask_var_node(cpumask_var_t *mask, gfp_t flags, int node)
 115 {
 116         *mask = kmalloc_node(cpumask_size(), flags, node);
 117
 118 #ifdef CONFIG_DEBUG_PER_CPU_MAPS
 119         if (!*mask) {
 120                 printk(KERN_ERR "=> alloc_cpumask_var: failed!\n");
 121                 dump_stack();
 122         }
 123 #endif
 124         /* FIXME: Bandaid to save us from old primitives which go to NR_CPUS. */
 125         if (*mask) {
 126                 unsigned char *ptr = (unsigned char *)cpumask_bits(*mask);
 127                 unsigned int tail;
 128                 tail = BITS_TO_LONGS(NR_CPUS - nr_cpumask_bits) * sizeof(long);
 129                 memset(ptr + cpumask_size() - tail, 0, tail);
 130         }
 131
 132         return *mask != NULL;
 133 }
 134 EXPORT_SYMBOL(alloc_cpumask_var_node);
 135
 136 bool zalloc_cpumask_var_node(cpumask_var_t *mask, gfp_t flags, int node)
 137 {
 138         return alloc_cpumask_var_node(mask, flags | __GFP_ZERO, node);
 139 }
 140 EXPORT_SYMBOL(zalloc_cpumask_var_node);
 141
 142 /**
 143  * alloc_cpumask_var - allocate a struct cpumask
 144  * @mask: pointer to cpumask_var_t where the cpumask is returned
 145  * @flags: GFP_ flags
 146  *
 147  * Only defined when CONFIG_CPUMASK_OFFSTACK=y, otherwise is
 148  * a nop returning a constant 1 (in <linux/cpumask.h>).
 149  *
 150  * See alloc_cpumask_var_node.
 151  */
 152 bool alloc_cpumask_var(cpumask_var_t *mask, gfp_t flags)
 153 {
 154         return alloc_cpumask_var_node(mask, flags, NUMA_NO_NODE);
 155 }
 156 EXPORT_SYMBOL(alloc_cpumask_var);
 157
 158 bool zalloc_cpumask_var(cpumask_var_t *mask, gfp_t flags)
 159 {
 160         return alloc_cpumask_var(mask, flags | __GFP_ZERO);
 161 }
 162 EXPORT_SYMBOL(zalloc_cpumask_var);
 163
 164 /**
 165  * alloc_bootmem_cpumask_var - allocate a struct cpumask from the bootmem arena.
 166  * @mask: pointer to cpumask_var_t where the cpumask is returned
 167  *
 168  * Only defined when CONFIG_CPUMASK_OFFSTACK=y, otherwise is
 169  * a nop (in <linux/cpumask.h>).
 170  * Either returns an allocated (zero-filled) cpumask, or causes the
 171  * system to panic.
 172  */
 173 void __init alloc_bootmem_cpumask_var(cpumask_var_t *mask)
 174 {
 175         *mask = memblock_virt_alloc(cpumask_size(), 0);
 176 }
 177
 178 /**
 179  * free_cpumask_var - frees memory allocated for a struct cpumask.
 180  * @mask: cpumask to free
 181  *
 182  * This is safe on a NULL mask.
 183  */
 184 void free_cpumask_var(cpumask_var_t mask)
 185 {
 186         kfree(mask);
 187 }
 188 EXPORT_SYMBOL(free_cpumask_var);
 189
 190 /**
 191  * free_bootmem_cpumask_var - frees result of alloc_bootmem_cpumask_var
 192  * @mask: cpumask to free
 193  */
 194 void __init free_bootmem_cpumask_var(cpumask_var_t mask)
 195 {
 196         memblock_free_early(__pa(mask), cpumask_size());
 197 }
 198 #endif
 199
 200 /**
 201  * cpumask_local_spread - select the i'th cpu with local numa cpu's first
 202  * @i: index number
 203  * @node: local numa_node
 204  *
 205  * This function selects an online CPU according to a numa aware policy;
 206  * local cpus are returned first, followed by non-local ones, then it
 207  * wraps around.
 208  *
 209  * It's not very efficient, but useful for setup.
 210  */
 211 unsigned int cpumask_local_spread(unsigned int i, int node)
 212 {
 213         int cpu;
 214
 215         /* Wrap: we always want a cpu. */
 216         i %= num_online_cpus();
 217
 218         if (node == -1) {
 219                 for_each_cpu(cpu, cpu_online_mask)
 220                         if (i-- == 0)
 221                                 return cpu;
 222         } else {
 223                 /* NUMA first. */
 224                 for_each_cpu_and(cpu, cpumask_of_node(node), cpu_online_mask)
 225                         if (i-- == 0)
 226                                 return cpu;
 227
 228                 for_each_cpu(cpu, cpu_online_mask) {
 229                         /* Skip NUMA nodes, done above. */
 230                         if (cpumask_test_cpu(cpu, cpumask_of_node(node)))
 231                                 continue;
 232
 233                         if (i-- == 0)
 234                                 return cpu;
 235                 }
 236         }
 237         BUG();
 238 }
 239 EXPORT_SYMBOL(cpumask_local_spread);