diff options
Diffstat (limited to 'security/selinux/ss/hashtab.c')
| -rw-r--r-- | security/selinux/ss/hashtab.c | 28 |
1 files changed, 24 insertions, 4 deletions
diff --git a/security/selinux/ss/hashtab.c b/security/selinux/ss/hashtab.c index ebfdaa31ee32..883f19d32c28 100644 --- a/security/selinux/ss/hashtab.c +++ b/security/selinux/ss/hashtab.c @@ -12,12 +12,29 @@ static struct kmem_cache *hashtab_node_cachep; +/* + * Here we simply round the number of elements up to the nearest power of two. + * I tried also other options like rouding 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) +{ + return nel == 0 ? 0 : roundup_pow_of_two(nel); +} + struct hashtab *hashtab_create(u32 (*hash_value)(struct hashtab *h, const void *key), int (*keycmp)(struct hashtab *h, const void *key1, const void *key2), - u32 size) + u32 nel_hint) { struct hashtab *p; - u32 i; + u32 i, size = hashtab_compute_size(nel_hint); p = kzalloc(sizeof(*p), GFP_KERNEL); if (!p) @@ -27,6 +44,9 @@ struct hashtab *hashtab_create(u32 (*hash_value)(struct hashtab *h, const void * p->nel = 0; p->hash_value = hash_value; p->keycmp = keycmp; + if (!size) + return p; + p->htable = kmalloc_array(size, sizeof(*p->htable), GFP_KERNEL); if (!p->htable) { kfree(p); @@ -46,7 +66,7 @@ int hashtab_insert(struct hashtab *h, void *key, void *datum) cond_resched(); - if (!h || h->nel == HASHTAB_MAX_NODES) + if (!h || !h->size || h->nel == HASHTAB_MAX_NODES) return -EINVAL; hvalue = h->hash_value(h, key); @@ -82,7 +102,7 @@ void *hashtab_search(struct hashtab *h, const void *key) u32 hvalue; struct hashtab_node *cur; - if (!h) + if (!h || !h->size) return NULL; hvalue = h->hash_value(h, key); |