From: Chema Gonzalez Date: Fri, 7 Sep 2012 13:40:50 +0000 (+0000) Subject: net: small bug on rxhash calculation X-Git-Url: https://openfabrics.org/gitweb/?a=commitdiff_plain;h=6862234238e84648c305526af2edd98badcad1e0;p=~shefty%2Frdma-dev.git 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 Signed-off-by: Chema Gonzalez Signed-off-by: Eric Dumazet Signed-off-by: David S. Miller --- diff --git a/net/core/dev.c b/net/core/dev.c index 83988362805..d7fe32c946c 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)) 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,