linux/security/selinux/ss/hashtab.c

// SPDX-License-Identifier: GPL-2.0
/*
 * Implementation of the hash table type.
 *
 * Author : Stephen Smalley, <[email protected]>
 */

#include <linux/kernel.h>
#include <linux/slab.h>
#include <linux/errno.h>
#include "hashtab.h"
#include "security.h"

static struct kmem_cache *hashtab_node_cachep __ro_after_init;

/*
 * Here we simply round the number of elements up to the nearest power of two.
 * I tried also other options like rounding down or rounding to the closest
 * power of two (up or down based on which is closer), but I was unable to
 * find any significant difference in lookup/insert performance that would
 * justify switching to a different (less intuitive) formula. It could be that
 * a different formula is actually more optimal, but any future changes here
 * should be supported with performance/memory usage data.
 *
 * The total memory used by the htable arrays (only) with Fedora policy loaded
 * is approximately 163 KB at the time of writing.
 */
static u32 hashtab_compute_size(u32 nel)
{ … }

int hashtab_init(struct hashtab *h, u32 nel_hint)
{ … }

int __hashtab_insert(struct hashtab *h, struct hashtab_node **dst, void *key,
		     void *datum)
{ … }

void hashtab_destroy(struct hashtab *h)
{ … }

int hashtab_map(struct hashtab *h, int (*apply)(void *k, void *d, void *args),
		void *args)
{ … }

#ifdef CONFIG_SECURITY_SELINUX_DEBUG
void hashtab_stat(struct hashtab *h, struct hashtab_info *info)
{ … }
#endif /* CONFIG_SECURITY_SELINUX_DEBUG */

int hashtab_duplicate(struct hashtab *new, const struct hashtab *orig,
		      int (*copy)(struct hashtab_node *new,
				  const struct hashtab_node *orig, void *args),
		      int (*destroy)(void *k, void *d, void *args), void *args)
{ … }

void __init hashtab_cache_init(void)
{ … }