1 // SPDX-License-Identifier: GPL-2.0 2 #include <linux/bitops.h> 3 #include <linux/kernel.h> 4 #include <linux/random.h> 5 #include <linux/slab.h> 6 #include <linux/types.h> 7 8 #include "drm_random.h" 9 10 static inline u32 drm_prandom_u32_max_state(u32 ep_ro, struct rnd_state *state) 11 { 12 return upper_32_bits((u64)prandom_u32_state(state) * ep_ro); 13 } 14 15 void drm_random_reorder(unsigned int *order, unsigned int count, 16 struct rnd_state *state) 17 { 18 unsigned int i, j; 19 20 for (i = 0; i < count; ++i) { 21 BUILD_BUG_ON(sizeof(unsigned int) > sizeof(u32)); 22 j = drm_prandom_u32_max_state(count, state); 23 swap(order[i], order[j]); 24 } 25 } 26 EXPORT_SYMBOL(drm_random_reorder); 27 28 unsigned int *drm_random_order(unsigned int count, struct rnd_state *state) 29 { 30 unsigned int *order, i; 31 32 order = kmalloc_array(count, sizeof(*order), GFP_KERNEL); 33 if (!order) 34 return order; 35 36 for (i = 0; i < count; i++) 37 order[i] = i; 38 39 drm_random_reorder(order, count, state); 40 return order; 41 } 42 EXPORT_SYMBOL(drm_random_order); 43