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183 lines
4.0 KiB
183 lines
4.0 KiB
// SPDX-License-Identifier: GPL-2.0 |
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/* |
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* Implementation of the hash table type. |
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* |
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* Author : Stephen Smalley, <[email protected]> |
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*/ |
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#include <linux/kernel.h> |
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#include <linux/slab.h> |
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#include <linux/errno.h> |
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#include "hashtab.h" |
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static struct kmem_cache *hashtab_node_cachep __ro_after_init; |
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/* |
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* Here we simply round the number of elements up to the nearest power of two. |
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* I tried also other options like rouding down or rounding to the closest |
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* power of two (up or down based on which is closer), but I was unable to |
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* find any significant difference in lookup/insert performance that would |
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* justify switching to a different (less intuitive) formula. It could be that |
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* a different formula is actually more optimal, but any future changes here |
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* should be supported with performance/memory usage data. |
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* |
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* The total memory used by the htable arrays (only) with Fedora policy loaded |
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* is approximately 163 KB at the time of writing. |
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*/ |
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static u32 hashtab_compute_size(u32 nel) |
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{ |
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return nel == 0 ? 0 : roundup_pow_of_two(nel); |
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} |
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int hashtab_init(struct hashtab *h, u32 nel_hint) |
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{ |
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h->size = hashtab_compute_size(nel_hint); |
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h->nel = 0; |
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if (!h->size) |
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return 0; |
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h->htable = kcalloc(h->size, sizeof(*h->htable), GFP_KERNEL); |
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return h->htable ? 0 : -ENOMEM; |
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} |
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int __hashtab_insert(struct hashtab *h, struct hashtab_node **dst, |
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void *key, void *datum) |
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{ |
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struct hashtab_node *newnode; |
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newnode = kmem_cache_zalloc(hashtab_node_cachep, GFP_KERNEL); |
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if (!newnode) |
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return -ENOMEM; |
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newnode->key = key; |
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newnode->datum = datum; |
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newnode->next = *dst; |
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*dst = newnode; |
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h->nel++; |
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return 0; |
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} |
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void hashtab_destroy(struct hashtab *h) |
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{ |
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u32 i; |
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struct hashtab_node *cur, *temp; |
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for (i = 0; i < h->size; i++) { |
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cur = h->htable[i]; |
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while (cur) { |
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temp = cur; |
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cur = cur->next; |
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kmem_cache_free(hashtab_node_cachep, temp); |
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} |
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h->htable[i] = NULL; |
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} |
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kfree(h->htable); |
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h->htable = NULL; |
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} |
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int hashtab_map(struct hashtab *h, |
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int (*apply)(void *k, void *d, void *args), |
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void *args) |
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{ |
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u32 i; |
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int ret; |
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struct hashtab_node *cur; |
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for (i = 0; i < h->size; i++) { |
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cur = h->htable[i]; |
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while (cur) { |
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ret = apply(cur->key, cur->datum, args); |
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if (ret) |
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return ret; |
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cur = cur->next; |
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} |
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} |
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return 0; |
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} |
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void hashtab_stat(struct hashtab *h, struct hashtab_info *info) |
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{ |
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u32 i, chain_len, slots_used, max_chain_len; |
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struct hashtab_node *cur; |
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slots_used = 0; |
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max_chain_len = 0; |
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for (i = 0; i < h->size; i++) { |
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cur = h->htable[i]; |
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if (cur) { |
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slots_used++; |
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chain_len = 0; |
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while (cur) { |
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chain_len++; |
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cur = cur->next; |
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} |
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if (chain_len > max_chain_len) |
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max_chain_len = chain_len; |
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} |
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} |
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info->slots_used = slots_used; |
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info->max_chain_len = max_chain_len; |
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} |
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int hashtab_duplicate(struct hashtab *new, struct hashtab *orig, |
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int (*copy)(struct hashtab_node *new, |
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struct hashtab_node *orig, void *args), |
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int (*destroy)(void *k, void *d, void *args), |
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void *args) |
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{ |
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struct hashtab_node *cur, *tmp, *tail; |
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int i, rc; |
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memset(new, 0, sizeof(*new)); |
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new->htable = kcalloc(orig->size, sizeof(*new->htable), GFP_KERNEL); |
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if (!new->htable) |
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return -ENOMEM; |
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new->size = orig->size; |
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for (i = 0; i < orig->size; i++) { |
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tail = NULL; |
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for (cur = orig->htable[i]; cur; cur = cur->next) { |
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tmp = kmem_cache_zalloc(hashtab_node_cachep, |
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GFP_KERNEL); |
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if (!tmp) |
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goto error; |
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rc = copy(tmp, cur, args); |
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if (rc) { |
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kmem_cache_free(hashtab_node_cachep, tmp); |
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goto error; |
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} |
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tmp->next = NULL; |
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if (!tail) |
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new->htable[i] = tmp; |
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else |
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tail->next = tmp; |
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tail = tmp; |
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new->nel++; |
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} |
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} |
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return 0; |
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error: |
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for (i = 0; i < new->size; i++) { |
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for (cur = new->htable[i]; cur; cur = tmp) { |
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tmp = cur->next; |
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destroy(cur->key, cur->datum, args); |
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kmem_cache_free(hashtab_node_cachep, cur); |
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} |
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} |
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kmem_cache_free(hashtab_node_cachep, new); |
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return -ENOMEM; |
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} |
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void __init hashtab_cache_init(void) |
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{ |
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hashtab_node_cachep = kmem_cache_create("hashtab_node", |
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sizeof(struct hashtab_node), |
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0, SLAB_PANIC, NULL); |
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}
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