diff options
| -rw-r--r-- | net/netfilter/xt_hashlimit.c | 11 |
1 files changed, 10 insertions, 1 deletions
diff --git a/net/netfilter/xt_hashlimit.c b/net/netfilter/xt_hashlimit.c index 951d4c829674..651c1d26564a 100644 --- a/net/netfilter/xt_hashlimit.c +++ b/net/netfilter/xt_hashlimit.c @@ -105,7 +105,16 @@ static inline bool dst_cmp(const struct dsthash_ent *ent, static u_int32_t hash_dst(const struct xt_hashlimit_htable *ht, const struct dsthash_dst *dst) { - return jhash(dst, sizeof(*dst), ht->rnd) % ht->cfg.size; + u_int32_t hash = jhash2((const u32 *)dst, + sizeof(*dst)/sizeof(u32), + ht->rnd); + /* + * Instead of returning hash % ht->cfg.size (implying a divide) + * we return the high 32 bits of the (hash * ht->cfg.size) that will + * give results between [0 and cfg.size-1] and same hash distribution, + * but using a multiply, less expensive than a divide + */ + return ((u64)hash * ht->cfg.size) >> 32; } static struct dsthash_ent * |