[PATCH] net: Small bug on rxhash calculation
From: Chema Gonzalez <hidden>
Date: 2012-09-06 06:35:41
Subsystem:
networking [general], the rest · Maintainers:
"David S. Miller", Eric Dumazet, Jakub Kicinski, Paolo Abeni, Linus Torvalds
From 5c02179069826bfba9360383b88601b31ff05517 Mon Sep 17 00:00:00 2001
From: Chema Gonzalez <redacted>
Date: Wed, 5 Sep 2012 17:05:48 -0700
Subject: [PATCH] net: Small bug on rxhash calculation
While the (current) sorting of the ports/addresses is coherent
(you get the same rxhash for packets sharing the same (unsorted)
4-tuple), ports and addresses should not be sorted independently,
which currently are: For traffic between A=S:l and B=L:s, packets
in both directions would get their rxhash from hashing
{L, S, {s, l}}. The same rxhash is obtained from packets between
C=S:s and D=L:l.
This patch ensures traffic between A and B gets their rxhash
from {S, L, {s, l}}, and traffic between C and D from {S, L,
{l, s}}
The patch is co-written with Eric Dumazet [off-list ref]
Signed-off-by: Chema Gonzalez <redacted>
---
net/core/dev.c | 11 ++++++-----
1 files changed, 6 insertions(+), 5 deletions(-)
diff --git a/net/core/dev.c b/net/core/dev.c
index b1e6d63..dcc673d 100644
--- a/net/core/dev.c
+++ b/net/core/dev.c@@ -2655,15 +2655,16 @@ void __skb_get_rxhash(struct sk_buff *skb) if (!skb_flow_dissect(skb, &keys)) return; - if (keys.ports) { - if ((__force u16)keys.port16[1] < (__force u16)keys.port16[0]) - swap(keys.port16[0], keys.port16[1]); + if (keys.ports) skb->l4_rxhash = 1; - } /* get a consistent hash (same value on both flow directions) */ - if ((__force u32)keys.dst < (__force u32)keys.src) + if (((__force u32)keys.dst < (__force u32)keys.src) || + (((__force u32)keys.dst == (__force u32)keys.src) && + ((__force u16)keys.port16[1] < (__force u16)keys.port16[0]))) { swap(keys.dst, keys.src); + swap(keys.port16[0], keys.port16[1]); + } hash = jhash_3words((__force u32)keys.dst, (__force u32)keys.src, --
1.7.7.3