drivers/gpu/drm/lib/drm_random.c

   1 #include <linux/bitops.h>
   2 #include <linux/kernel.h>
   3 #include <linux/random.h>
   4 #include <linux/slab.h>
   5 #include <linux/types.h>
   6
   7 #include "drm_random.h"
   8
   9 static inline u32 drm_prandom_u32_max_state(u32 ep_ro, struct rnd_state *state)
  10 {
  11         return upper_32_bits((u64)prandom_u32_state(state) * ep_ro);
  12 }
  13
  14 void drm_random_reorder(unsigned int *order, unsigned int count,
  15                         struct rnd_state *state)
  16 {
  17         unsigned int i, j;
  18
  19         for (i = 0; i < count; ++i) {
  20                 BUILD_BUG_ON(sizeof(unsigned int) > sizeof(u32));
  21                 j = drm_prandom_u32_max_state(count, state);
  22                 swap(order[i], order[j]);
  23         }
  24 }
  25 EXPORT_SYMBOL(drm_random_reorder);
  26
  27 unsigned int *drm_random_order(unsigned int count, struct rnd_state *state)
  28 {
  29         unsigned int *order, i;
  30
  31         order = kmalloc_array(count, sizeof(*order), GFP_TEMPORARY);
  32         if (!order)
  33                 return order;
  34
  35         for (i = 0; i < count; i++)
  36                 order[i] = i;
  37
  38         drm_random_reorder(order, count, state);
  39         return order;
  40 }
  41 EXPORT_SYMBOL(drm_random_order);