| From 5e1ad74e5323596a8970a62bcee874422ba1d15e Mon Sep 17 00:00:00 2001 |
| From: Chema Gonzalez <chema@google.com> |
| Date: Fri, 7 Sep 2012 13:40:50 +0000 |
| Subject: net: small bug on rxhash calculation |
| |
| |
| From: Chema Gonzalez <chema@google.com> |
| |
| [ 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 <edumazet@google.com> |
| |
| Signed-off-by: Chema Gonzalez <chema@google.com> |
| Signed-off-by: Eric Dumazet <edumazet@google.com> |
| Signed-off-by: David S. Miller <davem@davemloft.net> |
| Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> |
| --- |
| net/core/dev.c | 11 ++++++----- |
| 1 file changed, 6 insertions(+), 5 deletions(-) |
| |
| --- a/net/core/dev.c |
| +++ b/net/core/dev.c |
| @@ -2617,15 +2617,16 @@ void __skb_get_rxhash(struct sk_buff *sk |
| 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, |
