lib/bucket_locks.c

   1 #include <linux/export.h>
   2 #include <linux/kernel.h>
   3 #include <linux/mm.h>
   4 #include <linux/slab.h>
   5 #include <linux/vmalloc.h>
   6
   7 /* Allocate an array of spinlocks to be accessed by a hash. Two arguments
   8  * indicate the number of elements to allocate in the array. max_size
   9  * gives the maximum number of elements to allocate. cpu_mult gives
  10  * the number of locks per CPU to allocate. The size is rounded up
  11  * to a power of 2 to be suitable as a hash table.
  12  */
  13
  14 int __alloc_bucket_spinlocks(spinlock_t **locks, unsigned int *locks_mask,
  15                              size_t max_size, unsigned int cpu_mult, gfp_t gfp,
  16                              const char *name, struct lock_class_key *key)
  17 {
  18         spinlock_t *tlocks = NULL;
  19         unsigned int i, size;
  20 #if defined(CONFIG_PROVE_LOCKING)
  21         unsigned int nr_pcpus = 2;
  22 #else
  23         unsigned int nr_pcpus = num_possible_cpus();
  24 #endif
  25
  26         if (cpu_mult) {
  27                 nr_pcpus = min_t(unsigned int, nr_pcpus, 64UL);
  28                 size = min_t(unsigned int, nr_pcpus * cpu_mult, max_size);
  29         } else {
  30                 size = max_size;
  31         }
  32
  33         if (sizeof(spinlock_t) != 0) {
  34                 tlocks = kvmalloc_array(size, sizeof(spinlock_t), gfp);
  35                 if (!tlocks)
  36                         return -ENOMEM;
  37                 for (i = 0; i < size; i++) {
  38                         spin_lock_init(&tlocks[i]);
  39                         lockdep_init_map(&tlocks[i].dep_map, name, key, 0);
  40                 }
  41         }
  42
  43         *locks = tlocks;
  44         *locks_mask = size - 1;
  45
  46         return 0;
  47 }
  48 EXPORT_SYMBOL(__alloc_bucket_spinlocks);
  49
  50 void free_bucket_spinlocks(spinlock_t *locks)
  51 {
  52         kvfree(locks);
  53 }
  54 EXPORT_SYMBOL(free_bucket_spinlocks);