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 {
  17         spinlock_t *tlocks = NULL;
  18         unsigned int i, size;
  19 #if defined(CONFIG_PROVE_LOCKING)
  20         unsigned int nr_pcpus = 2;
  21 #else
  22         unsigned int nr_pcpus = num_possible_cpus();
  23 #endif
  24
  25         if (cpu_mult) {
  26                 nr_pcpus = min_t(unsigned int, nr_pcpus, 64UL);
  27                 size = min_t(unsigned int, nr_pcpus * cpu_mult, max_size);
  28         } else {
  29                 size = max_size;
  30         }
  31
  32         if (sizeof(spinlock_t) != 0) {
  33                 if (gfpflags_allow_blocking(gfp))
  34                         tlocks = kvmalloc(size * sizeof(spinlock_t), gfp);
  35                 else
  36                         tlocks = kmalloc_array(size, sizeof(spinlock_t), gfp);
  37                 if (!tlocks)
  38                         return -ENOMEM;
  39                 for (i = 0; i < size; i++)
  40                         spin_lock_init(&tlocks[i]);
  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);