[PATCH nf-next] netfilter: nft_set_pipapo: increment data in one step

[PATCH nf-next] netfilter: nft_set_pipapo: increment data in one step

[Florian Westphal]

For unkown reason the C version increments the data pointer in two steps.
Switch to a single invocation of NFT_PIPAPO_GROUPS_PADDED_SIZE() helper,
like the avx2 implementation.

Signed-off-by: Florian Westphal <fw@strlen.de>
---
 net/netfilter/nft_set_pipapo.c | 4 +---
 1 file changed, 1 insertion(+), 3 deletions(-)

diff --git a/net/netfilter/nft_set_pipapo.c b/net/netfilter/nft_set_pipapo.c
index 7fd24e0cc428..50d4a4f04309 100644
--- a/net/netfilter/nft_set_pipapo.c
+++ b/net/netfilter/nft_set_pipapo.c
@@ -452,8 +452,6 @@ static struct nft_pipapo_elem *pipapo_get_slow(const struct nft_pipapo_match *m,
 			pipapo_and_field_buckets_4bit(f, res_map, data);
 		NFT_PIPAPO_GROUP_BITS_ARE_8_OR_4;
 
-		data += f->groups / NFT_PIPAPO_GROUPS_PER_BYTE(f);
-
 		/* Now populate the bitmap for the next field, unless this is
 		 * the last field, in which case return the matched 'ext'
 		 * pointer if any.
@@ -498,7 +496,7 @@ static struct nft_pipapo_elem *pipapo_get_slow(const struct nft_pipapo_match *m,
 		map_index = !map_index;
 		swap(res_map, fill_map);
 
-		data += NFT_PIPAPO_GROUPS_PADDING(f);
+		data += NFT_PIPAPO_GROUPS_PADDED_SIZE(f);
 	}
 
 	__local_unlock_nested_bh(&scratch->bh_lock);
-- 
2.52.0

Re: [PATCH nf-next] netfilter: nft_set_pipapo: increment data in one step

[Stefano Brivio]

On Wed, 18 Mar 2026 14:38:34 +0100
Florian Westphal <fw@strlen.de> wrote:

> For unkown reason the C version increments the data pointer in two steps.

That's because before commit e807b13cb3e3 ("nft_set_pipapo: Generalise
group size for buckets") pipapo_get() contained the whole lookup
implementation with __bitmap_and(), and 'data' was used as pointer to
move between bit groups, and incremented as we went through them.

With that commit, we don't need to keep 'data' updated during the
lookup anymore, so I just replaced the initial increment, but I didn't
notice that 'data' isn't used at all before the second increment now,
and that the two increments could be merged.

> Switch to a single invocation of NFT_PIPAPO_GROUPS_PADDED_SIZE() helper,
> like the avx2 implementation.
> 
> Signed-off-by: Florian Westphal <fw@strlen.de>

Reviewed-by: Stefano Brivio <sbrivio@redhat.com>

-- 
Stefano