From 74665a9b4fca3420c07f1e583242a477b2eb34b0 Mon Sep 17 00:00:00 2001 From: Chema Gonzalez Date: Fri, 7 Sep 2012 13:40:50 +0000 Subject: [PATCH] net: small bug on rxhash calculation [ Upstream commit 6862234238e84648c305526af2edd98badcad1e0 ] In the current rxhash calculation function, while the sorting of the ports/addrs is coherent (you get the same rxhash for packets sharing the same 4-tuple, in both directions), ports and addrs are sorted independently. This implies packets from a connection between the same addresses but crossed ports hash to the same rxhash. For example, traffic between A=S:l and B=L:s is hashed (in both directions) from {L, S, {s, l}}. The same rxhash is obtained for packets between C=S:s and D=L:l. This patch ensures that you either swap both addrs and ports, or you swap none. Traffic between A and B, and traffic between C and D, get their rxhash from different sources ({L, S, {l, s}} for A<->B, and {L, S, {s, l}} for C<->D) The patch is co-written with Eric Dumazet Signed-off-by: Chema Gonzalez Signed-off-by: Eric Dumazet Signed-off-by: David S. Miller Signed-off-by: Greg Kroah-Hartman --- net/core/dev.c | 11 ++++++----- 1 file changed, 6 insertions(+), 5 deletions(-) diff --git a/net/core/dev.c b/net/core/dev.c index d8bc889b50c8..df6ee2884e7a 100644 --- a/net/core/dev.c +++ b/net/core/dev.c @@ -2559,16 +2559,17 @@ __u32 __skb_get_rxhash(struct sk_buff *skb) poff = proto_ports_offset(ip_proto); if (poff >= 0) { nhoff += ihl * 4 + poff; - if (pskb_may_pull(skb, nhoff + 4)) { + if (pskb_may_pull(skb, nhoff + 4)) ports.v32 = * (__force u32 *) (skb->data + nhoff); - if (ports.v16[1] < ports.v16[0]) - swap(ports.v16[0], ports.v16[1]); - } } /* get a consistent hash (same value on both flow directions) */ - if (addr2 < addr1) + if (addr2 < addr1 || + (addr2 == addr1 && + ports.v16[1] < ports.v16[0])) { swap(addr1, addr2); + swap(ports.v16[0], ports.v16[1]); + } hash = jhash_3words(addr1, addr2, ports.v32, hashrnd); if (!hash) -- 2.39.5