Commit de91b25c authored Mar 24, 2015 by Herbert Xu Committed by David S. Miller Mar 23, 2015

rhashtable: Eliminate unnecessary branch in rht_key_hashfn



When rht_key_hashfn is called from rhashtable itself and params
is equal to ht->p, there is no point in checking params.key_len
and falling back to ht->p.key_len.

For some reason gcc couldn't figure out that params is the same
as ht->p.  So let's help it by only checking params.key_len when
it's a constant.

Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
Acked-by: Thomas Graf <tgraf@suug.ch>
Signed-off-by: David S. Miller <davem@davemloft.net>

parent d88252f9

include/linux/rhashtable.h

+6 −2

Original line number	Diff line number	Diff line
		@@ -199,8 +199,12 @@ static inline unsigned int rht_key_hashfn(
		struct rhashtable ht, const struct bucket_table tbl,
		const void *key, const struct rhashtable_params params)
		{
		return rht_bucket_index(tbl, params.hashfn(key, params.key_len ?:
		ht->p.key_len,
		/* params must be equal to ht->p if it isn't constant. */
		unsigned key_len = __builtin_constant_p(params.key_len) ?
		(params.key_len ?: ht->p.key_len) :
		params.key_len;

		return rht_bucket_index(tbl, params.hashfn(key, key_len,
		tbl->hash_rnd));
		}