From: Herbert Xu Date: Mon, 23 Mar 2015 13:50:20 +0000 (+1100) Subject: rhashtable: Eliminate unnecessary branch in rht_key_hashfn X-Git-Tag: firefly_0821_release~176^2~1974^2~163^2~7 X-Git-Url: http://demsky.eecs.uci.edu/git/?a=commitdiff_plain;h=de91b25c8011089f5dd99b9d24743db1f550ca4b;p=firefly-linux-kernel-4.4.55.git 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 Acked-by: Thomas Graf Signed-off-by: David S. Miller --- diff --git a/include/linux/rhashtable.h b/include/linux/rhashtable.h index 89d102270570..3851952781d7 100644 --- a/include/linux/rhashtable.h +++ b/include/linux/rhashtable.h @@ -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)); }