netfilter: nft_set_pipapo: Don't abuse unlikely() in pipapo_refill()

I originally used unlikely() in the if (match_only) clause, which
we hit on the mapping table for the last field in a set, to ensure
we avoid branching to the rest of for loop body, which is executed
more frequently.

However, Pablo reports, this is confusing as it gives the impression
that this is not a common case, and it's actually not the intended
usage of unlikely().

I couldn't observe any statistical difference in matching rates on
x864_64 and aarch64 without it, so just drop it.

Reported-by: Pablo Neira Ayuso <pablo@netfilter.org>
Fixes: 3c4287f62044 ("nf_tables: Add set type for arbitrary concatenation of ranges")
Signed-off-by: Stefano Brivio <sbrivio@redhat.com>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>

diff --git a/net/netfilter/nft_set_pipapo.c b/net/netfilter/nft_set_pipapo.c
index 579600b39f396ca94d7ab1e2daa65bbf81cbdd2a..feac8553f6d9210a3d7b847b297dea9ad5527858 100644 (file)
--- a/net/netfilter/nft_set_pipapo.c
+++ b/net/netfilter/nft_set_pipapo.c
@@ -503,7 +503,7 @@ static int pipapo_refill(unsigned long *map, int len, int rules,
                                return -1;
                        }
 
-                       if (unlikely(match_only)) {
+                       if (match_only) {
                                bitmap_clear(map, i, 1);
                                return i;
                        }