1b2441318SGreg Kroah-Hartman // SPDX-License-Identifier: GPL-2.0 21da177e4SLinus Torvalds /* 31da177e4SLinus Torvalds * Implementation of the hash table type. 41da177e4SLinus Torvalds * 57efbb60bSStephen Smalley * Author : Stephen Smalley, <sds@tycho.nsa.gov> 61da177e4SLinus Torvalds */ 71da177e4SLinus Torvalds #include <linux/kernel.h> 81da177e4SLinus Torvalds #include <linux/slab.h> 91da177e4SLinus Torvalds #include <linux/errno.h> 10ed1c9642SDave Jones #include <linux/sched.h> 111da177e4SLinus Torvalds #include "hashtab.h" 121da177e4SLinus Torvalds 137c620eceSKyeongdon Kim static struct kmem_cache *hashtab_node_cachep; 147c620eceSKyeongdon Kim 15e0ac568dSOndrej Mosnacek /* 16e0ac568dSOndrej Mosnacek * Here we simply round the number of elements up to the nearest power of two. 17e0ac568dSOndrej Mosnacek * I tried also other options like rouding down or rounding to the closest 18e0ac568dSOndrej Mosnacek * power of two (up or down based on which is closer), but I was unable to 19e0ac568dSOndrej Mosnacek * find any significant difference in lookup/insert performance that would 20e0ac568dSOndrej Mosnacek * justify switching to a different (less intuitive) formula. It could be that 21e0ac568dSOndrej Mosnacek * a different formula is actually more optimal, but any future changes here 22e0ac568dSOndrej Mosnacek * should be supported with performance/memory usage data. 23e0ac568dSOndrej Mosnacek * 24e0ac568dSOndrej Mosnacek * The total memory used by the htable arrays (only) with Fedora policy loaded 25e0ac568dSOndrej Mosnacek * is approximately 163 KB at the time of writing. 26e0ac568dSOndrej Mosnacek */ 27e0ac568dSOndrej Mosnacek static u32 hashtab_compute_size(u32 nel) 28e0ac568dSOndrej Mosnacek { 29e0ac568dSOndrej Mosnacek return nel == 0 ? 0 : roundup_pow_of_two(nel); 30e0ac568dSOndrej Mosnacek } 31e0ac568dSOndrej Mosnacek 3203414a49SOndrej Mosnacek int hashtab_init(struct hashtab *h, 3303414a49SOndrej Mosnacek u32 (*hash_value)(struct hashtab *h, const void *key), 3403414a49SOndrej Mosnacek int (*keycmp)(struct hashtab *h, const void *key1, 3503414a49SOndrej Mosnacek const void *key2), 36e0ac568dSOndrej Mosnacek u32 nel_hint) 371da177e4SLinus Torvalds { 3803414a49SOndrej Mosnacek h->size = hashtab_compute_size(nel_hint); 3903414a49SOndrej Mosnacek h->nel = 0; 4003414a49SOndrej Mosnacek h->hash_value = hash_value; 4103414a49SOndrej Mosnacek h->keycmp = keycmp; 4203414a49SOndrej Mosnacek if (!h->size) 4303414a49SOndrej Mosnacek return 0; 441da177e4SLinus Torvalds 4503414a49SOndrej Mosnacek h->htable = kcalloc(h->size, sizeof(*h->htable), GFP_KERNEL); 4603414a49SOndrej Mosnacek return h->htable ? 0 : -ENOMEM; 471da177e4SLinus Torvalds } 481da177e4SLinus Torvalds 491da177e4SLinus Torvalds int hashtab_insert(struct hashtab *h, void *key, void *datum) 501da177e4SLinus Torvalds { 511da177e4SLinus Torvalds u32 hvalue; 521da177e4SLinus Torvalds struct hashtab_node *prev, *cur, *newnode; 531da177e4SLinus Torvalds 54ed1c9642SDave Jones cond_resched(); 55ed1c9642SDave Jones 5603414a49SOndrej Mosnacek if (!h->size || h->nel == HASHTAB_MAX_NODES) 571da177e4SLinus Torvalds return -EINVAL; 581da177e4SLinus Torvalds 591da177e4SLinus Torvalds hvalue = h->hash_value(h, key); 601da177e4SLinus Torvalds prev = NULL; 611da177e4SLinus Torvalds cur = h->htable[hvalue]; 621da177e4SLinus Torvalds while (cur && h->keycmp(h, key, cur->key) > 0) { 631da177e4SLinus Torvalds prev = cur; 641da177e4SLinus Torvalds cur = cur->next; 651da177e4SLinus Torvalds } 661da177e4SLinus Torvalds 671da177e4SLinus Torvalds if (cur && (h->keycmp(h, key, cur->key) == 0)) 681da177e4SLinus Torvalds return -EEXIST; 691da177e4SLinus Torvalds 707c620eceSKyeongdon Kim newnode = kmem_cache_zalloc(hashtab_node_cachep, GFP_KERNEL); 71cb8d21e3SMarkus Elfring if (!newnode) 721da177e4SLinus Torvalds return -ENOMEM; 731da177e4SLinus Torvalds newnode->key = key; 741da177e4SLinus Torvalds newnode->datum = datum; 751da177e4SLinus Torvalds if (prev) { 761da177e4SLinus Torvalds newnode->next = prev->next; 771da177e4SLinus Torvalds prev->next = newnode; 781da177e4SLinus Torvalds } else { 791da177e4SLinus Torvalds newnode->next = h->htable[hvalue]; 801da177e4SLinus Torvalds h->htable[hvalue] = newnode; 811da177e4SLinus Torvalds } 821da177e4SLinus Torvalds 831da177e4SLinus Torvalds h->nel++; 841da177e4SLinus Torvalds return 0; 851da177e4SLinus Torvalds } 861da177e4SLinus Torvalds 87bb242497SChad Sellers void *hashtab_search(struct hashtab *h, const void *key) 881da177e4SLinus Torvalds { 891da177e4SLinus Torvalds u32 hvalue; 901da177e4SLinus Torvalds struct hashtab_node *cur; 911da177e4SLinus Torvalds 9203414a49SOndrej Mosnacek if (!h->size) 931da177e4SLinus Torvalds return NULL; 941da177e4SLinus Torvalds 951da177e4SLinus Torvalds hvalue = h->hash_value(h, key); 961da177e4SLinus Torvalds cur = h->htable[hvalue]; 97dbc74c65SVesa-Matti Kari while (cur && h->keycmp(h, key, cur->key) > 0) 981da177e4SLinus Torvalds cur = cur->next; 991da177e4SLinus Torvalds 100cb8d21e3SMarkus Elfring if (!cur || (h->keycmp(h, key, cur->key) != 0)) 1011da177e4SLinus Torvalds return NULL; 1021da177e4SLinus Torvalds 1031da177e4SLinus Torvalds return cur->datum; 1041da177e4SLinus Torvalds } 1051da177e4SLinus Torvalds 1061da177e4SLinus Torvalds void hashtab_destroy(struct hashtab *h) 1071da177e4SLinus Torvalds { 1081da177e4SLinus Torvalds u32 i; 1091da177e4SLinus Torvalds struct hashtab_node *cur, *temp; 1101da177e4SLinus Torvalds 1111da177e4SLinus Torvalds for (i = 0; i < h->size; i++) { 1121da177e4SLinus Torvalds cur = h->htable[i]; 113dbc74c65SVesa-Matti Kari while (cur) { 1141da177e4SLinus Torvalds temp = cur; 1151da177e4SLinus Torvalds cur = cur->next; 1167c620eceSKyeongdon Kim kmem_cache_free(hashtab_node_cachep, temp); 1171da177e4SLinus Torvalds } 1181da177e4SLinus Torvalds h->htable[i] = NULL; 1191da177e4SLinus Torvalds } 1201da177e4SLinus Torvalds 1211da177e4SLinus Torvalds kfree(h->htable); 1221da177e4SLinus Torvalds h->htable = NULL; 1231da177e4SLinus Torvalds } 1241da177e4SLinus Torvalds 1251da177e4SLinus Torvalds int hashtab_map(struct hashtab *h, 1261da177e4SLinus Torvalds int (*apply)(void *k, void *d, void *args), 1271da177e4SLinus Torvalds void *args) 1281da177e4SLinus Torvalds { 1291da177e4SLinus Torvalds u32 i; 1301da177e4SLinus Torvalds int ret; 1311da177e4SLinus Torvalds struct hashtab_node *cur; 1321da177e4SLinus Torvalds 1331da177e4SLinus Torvalds for (i = 0; i < h->size; i++) { 1341da177e4SLinus Torvalds cur = h->htable[i]; 135dbc74c65SVesa-Matti Kari while (cur) { 1361da177e4SLinus Torvalds ret = apply(cur->key, cur->datum, args); 1371da177e4SLinus Torvalds if (ret) 1381da177e4SLinus Torvalds return ret; 1391da177e4SLinus Torvalds cur = cur->next; 1401da177e4SLinus Torvalds } 1411da177e4SLinus Torvalds } 1421da177e4SLinus Torvalds return 0; 1431da177e4SLinus Torvalds } 1441da177e4SLinus Torvalds 1451da177e4SLinus Torvalds 1461da177e4SLinus Torvalds void hashtab_stat(struct hashtab *h, struct hashtab_info *info) 1471da177e4SLinus Torvalds { 1481da177e4SLinus Torvalds u32 i, chain_len, slots_used, max_chain_len; 1491da177e4SLinus Torvalds struct hashtab_node *cur; 1501da177e4SLinus Torvalds 1511da177e4SLinus Torvalds slots_used = 0; 1521da177e4SLinus Torvalds max_chain_len = 0; 1535794ed76SColin Ian King for (i = 0; i < h->size; i++) { 1541da177e4SLinus Torvalds cur = h->htable[i]; 1551da177e4SLinus Torvalds if (cur) { 1561da177e4SLinus Torvalds slots_used++; 1571da177e4SLinus Torvalds chain_len = 0; 1581da177e4SLinus Torvalds while (cur) { 1591da177e4SLinus Torvalds chain_len++; 1601da177e4SLinus Torvalds cur = cur->next; 1611da177e4SLinus Torvalds } 1621da177e4SLinus Torvalds 1631da177e4SLinus Torvalds if (chain_len > max_chain_len) 1641da177e4SLinus Torvalds max_chain_len = chain_len; 1651da177e4SLinus Torvalds } 1661da177e4SLinus Torvalds } 1671da177e4SLinus Torvalds 1681da177e4SLinus Torvalds info->slots_used = slots_used; 1691da177e4SLinus Torvalds info->max_chain_len = max_chain_len; 1701da177e4SLinus Torvalds } 171aa8e712cSStephen Smalley 172aa8e712cSStephen Smalley void __init hashtab_cache_init(void) 1737c620eceSKyeongdon Kim { 1747c620eceSKyeongdon Kim hashtab_node_cachep = kmem_cache_create("hashtab_node", 1757c620eceSKyeongdon Kim sizeof(struct hashtab_node), 1767c620eceSKyeongdon Kim 0, SLAB_PANIC, NULL); 1777c620eceSKyeongdon Kim } 178