1/* $NetBSD: drm_random.c,v 1.2 2021/12/18 23:45:31 riastradh Exp $ */ 2 3// SPDX-License-Identifier: GPL-2.0 4#include <sys/cdefs.h> 5__KERNEL_RCSID(0, "$NetBSD: drm_random.c,v 1.2 2021/12/18 23:45:31 riastradh Exp $"); 6 7#include <linux/bitops.h> 8#include <linux/kernel.h> 9#include <linux/random.h> 10#include <linux/slab.h> 11#include <linux/types.h> 12 13#include "drm_random.h" 14 15static inline u32 drm_prandom_u32_max_state(u32 ep_ro, struct rnd_state *state) 16{ 17 return upper_32_bits((u64)prandom_u32_state(state) * ep_ro); 18} 19 20void drm_random_reorder(unsigned int *order, unsigned int count, 21 struct rnd_state *state) 22{ 23 unsigned int i, j; 24 25 for (i = 0; i < count; ++i) { 26 BUILD_BUG_ON(sizeof(unsigned int) > sizeof(u32)); 27 j = drm_prandom_u32_max_state(count, state); 28 swap(order[i], order[j]); 29 } 30} 31EXPORT_SYMBOL(drm_random_reorder); 32 33unsigned int *drm_random_order(unsigned int count, struct rnd_state *state) 34{ 35 unsigned int *order, i; 36 37 order = kmalloc_array(count, sizeof(*order), GFP_KERNEL); 38 if (!order) 39 return order; 40 41 for (i = 0; i < count; i++) 42 order[i] = i; 43 44 drm_random_reorder(order, count, state); 45 return order; 46} 47EXPORT_SYMBOL(drm_random_order); 48