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| author | David S. Miller <davem@davemloft.net> | 2016-07-01 16:07:50 -0400 |
|---|---|---|
| committer | David S. Miller <davem@davemloft.net> | 2016-07-01 16:07:50 -0400 |
| commit | eb70db8756717b90c01ccc765fdefc4dd969fc74 (patch) | |
| tree | 80c89c33271947ab3785bcaeb66bd21a8b416c7d /net/packet/af_packet.c | |
| parent | 08df7bc5001e7fc8bdb0a74e04ad2db5f797ed3d (diff) | |
| download | lwn-eb70db8756717b90c01ccc765fdefc4dd969fc74.tar.gz lwn-eb70db8756717b90c01ccc765fdefc4dd969fc74.zip | |
packet: Use symmetric hash for PACKET_FANOUT_HASH.
People who use PACKET_FANOUT_HASH want a symmetric hash, meaning that
they want packets going in both directions on a flow to hash to the
same bucket.
The core kernel SKB hash became non-symmetric when the ipv6 flow label
and other entities were incorporated into the standard flow hash order
to increase entropy.
But there are no users of PACKET_FANOUT_HASH who want an assymetric
hash, they all want a symmetric one.
Therefore, use the flow dissector to compute a flat symmetric hash
over only the protocol, addresses and ports. This hash does not get
installed into and override the normal skb hash, so this change has
no effect whatsoever on the rest of the stack.
Reported-by: Eric Leblond <eric@regit.org>
Tested-by: Eric Leblond <eric@regit.org>
Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'net/packet/af_packet.c')
| -rw-r--r-- | net/packet/af_packet.c | 2 |
1 files changed, 1 insertions, 1 deletions
diff --git a/net/packet/af_packet.c b/net/packet/af_packet.c index 9bff6ef16fa7..9f0983fa4d52 100644 --- a/net/packet/af_packet.c +++ b/net/packet/af_packet.c @@ -1341,7 +1341,7 @@ static unsigned int fanout_demux_hash(struct packet_fanout *f, struct sk_buff *skb, unsigned int num) { - return reciprocal_scale(skb_get_hash(skb), num); + return reciprocal_scale(__skb_get_hash_symmetric(skb), num); } static unsigned int fanout_demux_lb(struct packet_fanout *f, |