diff options
authorChema Gonzalez <chema@google.com>2012-09-07 13:40:50 +0000
committerDavid S. Miller <davem@davemloft.net>2012-09-08 18:41:48 -0400
commit6862234238e84648c305526af2edd98badcad1e0 (patch)
parent777bf135b77071672662c67f0abffcf433450d68 (diff)
net: small bug on rxhash calculation
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>
1 files changed, 6 insertions, 5 deletions
diff --git a/net/core/dev.c b/net/core/dev.c
index 83988362805e..d7fe32c946c1 100644
--- a/net/core/dev.c
+++ b/net/core/dev.c
@@ -2647,15 +2647,16 @@ void __skb_get_rxhash(struct sk_buff *skb)
if (!skb_flow_dissect(skb, &keys))
- 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,

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